Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy (v.85, #1)
Synthesis, spectral characterization and biological activity of zinc(II) complexes with 3-substituted phenyl-4-amino-5-hydrazino-1, 2, 4-triazole Schiff bases
by A.K. Singh; O.P. Pandey; S.K. Sengupta (pp. 1-6).
Zinc(II) complexes with 3-substituted phenyl-4-amino-5-hydrazino-1, 2, 4-triazole Schiff bases have been synthesized and characterized. Their microbial activities have been evaluated.Display Omitted► The zinc(II) complexes were synthesized by multi-step reactions and characterized. ► Zinc(II) complexes show significant antifungal and antibacterial activity. ► These zinc(II) complexes offer possibility for new type of economically affordable pesticides.New Zn(II) complexes have been synthesized by the reactions of zinc(II) acetate with Schiff bases derived from 3-substituted phenyl-4-amino-5-hydrazino-1, 2, 4-triazole and benzaldehyde, 2-hydroxyacetophenone or indoline-2,3-dione. All these complexes are soluble in DMF and DMSO; low molar conductance values indicate that they are non-electrolytes. Elemental analyses suggest that the complexes have 1:1 stoichiometry of the type [ZnL(H2O)2], [ZnL′(OAc)2(H2O)2] (L=dianionic Schiff bases derived from 3-(substituted phenyl)-4-amino-5-hydrazino-1, 2, 4-triazole and 2-hydroxyacetophenone or indoline-2,3-dione; L′=neutral Schiff bases derived from 3-(substituted phenyl)-4-amino-5-hydrazino-1, 2, 4-triazole and benzaldehyde) and they were characterized by FT-IR,1H NMR,13C NMR and FAB mass. All these Schiff bases and their complexes have also been screened for their antibacterial activities against Bacillus subtilis, Escherichia coli and antifungal activities against Colletotrichum falcatum, Aspergillus niger, Fusarium oxysporium and Carvularia pallescence by petriplates methods.
Keywords: Zn(II); Schiff bases; FT-IR; 1; H NMR; 13; C NMR; Antifungal and antibacterial
H/D isotopic recognition in hydrogen bonded systems: H/D isotopic self-organization effects in the IR spectra of the hydrogen bond in 2-methylimidazole crystals
by Henryk T. Flakus; Barbara Hachuła; Agnieszka Stolarczyk (pp. 7-16).
This paper presents the results of experimental and theoretical study of the polarized IR spectra of H12345 2-methylimidazole and its H1D2345, D1H2345 and D12345 deuterium derivative crystals.Display Omitted► The polarized IR spectra of 2-methylimidazole were quantitatively analyzed. ► The in- and inter-chain H/D isotopic self-organization effects were found. ► The self-organization mechanism involved all four hydrogen bonds from each unit cell.Polarized IR spectra of H12345 2-methylimidazole and of its H1D2345, D1H2345 and D12345 deuterium derivative crystals are reported and interpreted within the limits of the “ strong- coupling” theory. The spectra interpretation facilitated the recognition of the H/D isotopic “ self-organization” phenomenon, which depends on a non-random distribution of protons and deuterons in the lattices of isotopically diluted crystal samples. The H/D isotopic “ self- organization” mechanism engaged all four hydrogen bonds from each unit cell. These effects basically resulted from the dynamical co- operative interactions involving adjacent hydrogen bonds in each hydrogen bond chain. A weaker exciton coupling involved the closely spaced hydrogen bonds; each belonging to a different chain of associated 2-methylimidazole molecules. The high intensity of the narrow band at ca. 1880cm−1 was interpreted as the result of coupling between the γN–H⋯N proton bending “ out of plane” vibration overtone and the νN–H proton stretching vibration.
Keywords: Hydrogen bond; Molecular crystals; Polarized IR spectra; H/D isotopic effects; Linear dichroic effects; Isotopic dilution; Dynamical co-operative interactions
Solution and solid state characterization of oxo-centered trinuclear iron(III) acetate complexes [Fe3(μ3-O)(μ-OAc)6(L)3]+
by Vahid Amani; Nasser Safari; Hamid Reza Khavasi (pp. 17-24).
Display Omitted► Trinuclear oxo-centered iron carboxylato complexes were synthesized. ► There is a lack of thorough characterization of the oxo-centered iron complexes in solution. ► Paramagnetic1H NMR is introduced as a good probe for the characterization of a family of these complexes in solution. ► Ligand coordinated to iron varies as: CH3OH, CH3CN, DMSO, H2O, py and acetone in solution.[Fe3(μ3-O)(μ-OAc)6(py)3][FeBr4]2[py·H], complex (1), (OAc is acetate) was prepared from the reaction of FeBr3 with pyridine in 1.2 molar aqueous HBr and 2.4 molar aqueous CH3COOH. Recrystallization of1 in acetonitrile produced the [Fe3(μ3-O)(μ-OAc)6(py)3][FeBr4] complex (2). Both complexes were characterized by IR and1H NMR spectroscopies and their structures were studied using the single-crystal diffraction method. There is a lack of thorough characterization of the titled compounds in solution. Paramagnetic1H NMR is introduced as a good probe for the characterization of a family of titled compounds in solution when the L ligand coordinated to iron varies as: CH3OH, CH3CN, DMSO, H2O, py and acetone.
Keywords: Oxo-centered; Trinuclear; Iron(III); Acetate; Paramagnetic; 1; H NMR; Crystal structure
Spectroscopic studies on Solvatochromism of mixed-chelate copper(II) complexes using MLR technique
by Hamid Golchoubian; Golasa Moayyedi; Hakimeh Fazilati (pp. 25-30).
Mixed-chelate copper(II) complexes with a general formula [Cu(acac)(diamine)]X where acac=acetylacetonate ion, diamine=N,N-dimethyl,N′-benzyl-1,2-diaminoethane and X=BPh4−, PF6−, ClO4− and BF4− have been prepared. The complexes were characterized on the basis of elemental analysis, molar conductance, UV–vis and IR spectroscopies. The complexes are solvatochromic and their solvatochromism were investigated by visible spectroscopy. All complexes demonstrated the positive solvatochromism and among the complexes [Cu(acac)(diamine)]BPh4·H2O showed the highest Δ νmax value. To explore the mechanism of interaction between solvent molecules and the complexes, different solvent parameters such as DN, AN, α and β using multiple linear regression (MLR) method were employed. The statistical results suggested that the DN parameter of the solvent plays a dominate contribution to the shift of the d–d absorption band of the complexes.
Keywords: Mixed-chelate; Solvatochromism; MLR method; Copper(II) complexes; Counter ion
Physicochemical and solvatochromic analysis of an imidazole derivative as NLO material
by Jayaraman Jayabharathi; Venugopal Thanikachalam; Marimuthu Venkatesh Perumal (pp. 31-37).
Display Omitted► Catalan-Taft parameter: the coefficient shows acidity of the solvent, Cα or CSA has a negative value. ► Octupolar and dipolar components of dfppip: the steric interaction must be reduced in order to obtain larger β0 values. ► NBO analysis: elucidates the intramolecular, hybridization and delocalization within the molecule. ► Electronic properties: probable charge transfer (CD) taking place inside the chromophore. ► Bar Diagram: the charge distribution of dfppip was calculated by the NBO and Mulliken methods.Bioactive imidazole derivative, 2-(2,4-difluorophenyl)-1-phenyl-1H-imidazo[4,5-f][1,10]phenanthroline, has been synthesized and characterized by IR, UV–vis, NMR and elemental (CHN) analysis. The electric dipole moment ( μ) and the hyperpolarizability ( β) have been studied both experimentally and theoretically, which reveals that the synthesized imidazole derivative possesses non-linear optical (NLO) behavior. This chromophore possess more appropriate ratio of off-diagonal versus diagonal β tensorial component ( r= βxyy/ βxxx=−0.19) which reflects the in plane nonlinearity anisotropy. Since they have largest μβ0 value, the reported imidazole can be used as potential NLO material. Within this context, reasonable conclusions concerning the steric hindrance in the chromospheres, push–pull character, hyperpolarizability of the imidazole and their application as NLO materials will be drawn. The solvent effect on the absorption and fluorescence bands was analyzed by a multi-component linear regression in which several solvent parameters were analyzed simultaneously.
Keywords: DFT; NLO; NBO; Multi-component linear regression; Octupolar and dipolar components
Reversible “off–on” fluorescent chemosensor for Hg2+ based on rhodamine derivative
by Weimin Liu; Jianhong Chen; Liwei Xu; Jiasheng Wu; Haitao Xu; Hongyan Zhang; Pengfei Wang (pp. 38-42).
Display Omitted► We report a novel and simple fluorescent chemosensor1 based on rhodamine. ► Chemosensor1 shows unique selectivity for Hg2+ over other cations. ► The reversibility of1 is demonstrated by the alternate addition of Hg2+ and TBAI.A novel and simple fluorescent chemosensor based on rhodamine was designed and synthesized to detect Hg2+ with high selectivity. The structure of chemosensor1 was characterized by IR,1H NMR, and HRMS spectroscopies. Chemosensor1 exhibited distinct fluorescent and colorimetric changes toward Hg2+ in an ethanol/water (80/20, v/v) solution, which resulted in the formation of1/Hg2+ complex with the Hg2+-induced ring opening of the spirolactam ring in rhodamine. The reversibility of chemosensor1 was verified through its spectral response toward Hg2+ ions and TBAI (tetrabutylammonium iodide) titration experiments.
Keywords: Fluorescent spectroscopy; Hg; 2+; chemosensor; Rhodamine B; Off–on; Reversibility
Molecular structure, polarizability, hyperpolarizability analysis and spectroscopic characterization of 1-(chloromethyl)-2-methylnaphthalene with experimental (FT-IR and FT-Raman) techniques and quantum chemical calculations
by P.B. Nagabalasubramanian; M. Karabacak; S. Periandy (pp. 43-52).
Display Omitted► Geometry and frequencies of 1-(chloromethyl)-2-methylnaphthalne were calculated. ► The calculated DFT/B3LYP results were compared with both FT-IR and FT-Raman data. ► The thermodynamic properties at different temperatures were calculated and interpreted. ► The electronic properties were performed by TD–DFT approach for different solvents.In this work, the FT-IR and FT-Raman spectrum of 1-(chloromethyl)-2-methyl naphthalene (abbreviated as 1-ClM-2MN, C12H11Cl) have been recorded in the region 3600–10cm−1. The optimum molecular geometry, normal mode wavenumbers, infrared and Raman intensities, Raman scattering activities, corresponding vibrational assignments, Mullikan atomic charges and thermo-dynamical parameters were investigated with the help of HF and B3LYP (DFT) method using 6-311G(d,p), 6-311++G(d,p) basis sets. Also, the dipole moment, linear polarizabilities, anisotropy, first and second hyperpolarizabilities values were also computed using the same basis set. Reliable vibrational assignments were made on the basis of total energy distribution (TED) calculated with scaled quantum mechanical (SQM) method. The correlation equations between heat capacities, entropies, enthalpy changes and temperatures were fitted by quadratic formulas. Lower value in the HOMO and LUMO energy gap explains the eventual charge transfer interactions taking place within the molecule. UV–vis spectral analysis of 1-ClM-2MN has been researched by theoretical calculations. In order to understand the electronic transitions of the compound, TD–DFT calculations on electronic absorption spectra in gas phase and solvent (DMSO and chloroform) were performed. The calculated frontier orbital energies, absorption wavelengths ( λ), oscillator strengths ( f) and excitation energies ( E) for gas phase and solvent are also illustrated.
Keywords: 1-(Chloromethyl)-2-methyl naphthalene; FT-IR and FT-Raman; HOMO–LUMO; HF and B3LYP; NLO
De novo design, synthesis and spectroscopic characterization of chiral benzimidazole-derived amino acid Zn(II) complexes: Development of tryptophan-derived specific hydrolytic DNA artificial nuclease agent
by Shazia Parveen; Farukh Arjmand (pp. 53-60).
Display Omitted► Chiral benzimidazole ligand, 1,2-bis(1H-benzimidazol-2-yl)ethane-1,2-diol as a building block for dizinc(II) complexes1–3. ► The binding studies of the organotin complexes1–3 with CT DNA. ► The in vitro DNA binding studies reveal that all these complexes bind to CT DNA non-covalently via electrostatic interaction. ► The complex1 exhibits remarkable DNA cleavage activity with supercoiled pBR322 in the presence of different activators. ► Complex1 cleaves DNA efficiently involving hydrolytic cleavage mechanism.Novel ternary dizinc(II) complexes1–3, derived from 1,2-bis(1H-benzimidazol-2-yl)ethane-1,2-diol andl-form of amino acids (viz., tryptophan, leucine and valine) were synthesized and characterized by spectroscopic (IR,1H NMR, UV–vis, ESI-MS) and other analytical methods. To evaluate the biological preference of chiral drugs for inherently chiral target DNA, interaction of1–3 with calf thymus DNA in Tris–HCl buffer was studied by various biophysical techniques which reveal that all these complexes bind to CT DNA non-covalently via electrostatic interaction. The higher Kb value ofl-tryptophan complex1 suggested greater DNA binding propensity. Further, to evaluate the mode of action at the molecular level, interaction studies of complexes1 and2 with nucleotides (5′-GMP and 5′-TMP) were carried out by UV–vis titrations,1H and31P NMR which implicates the preferential selectivity of these complexes to N3 of thymine rather than N7 of guanine. Furthermore, complex1 exhibits efficient DNA cleavage with supercoiled pBR322. The complex1 cleaves DNA efficiently involving hydrolytic cleavage pathway. Such chiral synthetic hydrolytic nucleases with asymmetric centers are gaining considerable attention owing to their importance in biotechnology and drug design, in particular to cleave DNA with sequence selectivity different from that of the natural enzymes.
Keywords: Chiral dizinc(II) complexes; Benzimidazole scaffold; In vitro; DNA binding; 5′-GMP and 5′-TMP; pBR322 hydrolytic cleavage
Infrared spectroscopic analysis of human interstitial fluid in vitro and in vivo using FT-IR spectroscopy and pulsed quantum cascade lasers (QCL): Establishing a new approach to non invasive glucose measurement
by Miguel Pleitez; Hermann von Lilienfeld-Toal; Werner Mäntele (pp. 61-65).
Display Omitted► The composition of interstitial fluid was studied by ATR-FT-IR spectroscopy. ► Interstitial fluid was simulated as a combination of glucose and albumin. ► Glucose was measured in interstitial fluid by photacoustic spectroscopy.Interstitial fluid, i.e. the liquid present in the outermost layer of living cells of the skin between the Stratum corneum and the Stratum spinosum, was analyzed by Fourier transform infrared spectroscopy and by infrared spectroscopy using pulsed quantum cascade infrared lasers with photoacoustic detection. IR spectra of simulated interstitial fluid samples and of real samples from volunteers in the 850–1800cm−1 range revealed that the major components of interstitial fluid are albumin and glucose within the physiological range, with only traces of sodium lactate if at all. The IR absorbance of glucose in interstitial fluid in vivo was probed in healthy volunteers using a setup with quantum cascade lasers and photoacoustic detection previously described . A variation of blood glucose between approx. 80mg/dl and 250mg/dl in the volunteers was obtained using the standard oral glucose tolerance test (OGT). At two IR wavelengths, 1054cm−1 and 1084cm−1, a reasonable correlation between the photoacoustic signal from the skin and the blood glucose value as determined by conventional glucose test sticks using blood from the finger tip was obtained. The infrared photoacoustic glucose signal (PAGS) may serve as the key for a non-invasive glucose measurement, since the glucose content in interstitial fluid closely follows blood glucose in the time course and in the level (a delay of some minutes and a level of approx. 80–90% of the glucose level in blood). Interstitial fluid is present in skin layers at a depth of only 15–50μm and is thus within the reach of mid-IR energy in an absorbance measurement. A non-invasive glucose measurement for diabetes patients based on mid-infrared quantum cascade lasers and photoacoustic detection could replace the conventional measurement using enzymatic test stripes and a drop of blood from the finger tip, thus reducing pain and being a cost-efficient alternative for millions of diabetes patients.
Keywords: Abbreviations; ISF; interstitial fluid; QCL; quantum cascade lasers; IR; infrared; FT-IR; Fourier transform infrared; ATR; attenuated total reflection; OGT; oral glucose tolerance test; PBS; physiological buffer solution; PA; photoacoustic; PAGS; photoacoustic glucose signalInfrared spectroscopy; FT-IR; Quantum cascade lasers (QCL); Attenuated total reflection (ATR); Blood glucose; Non-invasive glucose measurement; Interstitial fluid; Diabetes
Electronic absorption and vibrational spectra and nonlinear optical properties ofl-valinium succinate
by C. Jesintha John; T.S. Xavier; G. Lukose; I. Hubert Joe (pp. 66-73).
Display Omitted► In this study we have examined the Density functional theory computational methods and compared with the vibrational spectra for interpreting and predicting the various molecular properties ofl-valinium succinate. ► The hydrogen bonding and the possible interactions were also calculated by using NBO analysis. ► The HOMO–LUMO energy gap is calculated to show the charge transfer interaction involving donor and acceptor groups.FT-Raman and FTIR techniques have been applied to investigate the potential nonlinear optical materiall-valinium succinate. A detailed interpretation of the vibrational spectra was carried out with the aid of potential energy distribution analysis. Density functional theory is applied to explore the nonlinear optical properties of the molecule. Good consistency is found between the calculated results and the experimental data for IR and Raman spectra. The natural bond orbital analysis confirms the occurrence of strong intramolecular N–H⋯O hydrogen bonding.
Keywords: FT-Raman; FTIR; Density functional theory; Potential energy distribution; Intramolecular charge transfer; Natural bond orbital analysis
Self-induced pressure shift and temperature dependence measurements of CO2 at 2.05μm with a tunable diode laser spectrometer
by Jingsong Li; Georges Durry; Julien Cousin; Lilian Joly; Bertrand Parvitte; Virginie Zeninari (pp. 74-78).
Display Omitted► We report on self-shift coefficients for 8 absorption lines of CO2 at 2.05μm. ► A high-resolution TDLAS coupled to a cryogenically cooled cell was used. ► Temperature-dependencies of the self-shift coefficients are also determined. ► These parameters are carefully compared with results in other vibrational bands.By using a high resolution tunable diode laser absorption spectrometer combined with a cryogenically cooled optical multi-pass cell, we have measured the self-induced pressure shift coefficients for 8 transitions in the R branch of the (2001)III←(0000)I band of carbon dioxide around 2.05μm. This spectral region is of particular interest for the monitoring of atmospheric CO2 with Differential Absorption Lidars (DiAL). The measurement of these shift coefficients was realized at five different temperatures ranging from 218 to 292K in order to determine their temperature dependence. The results are thoroughly compared to previous values reported in the literature for the (2001)III←(0000)I band of CO2. The temperature dependence of the self-induced pressure shifts are reported experimentally for the first time for this specific CO2 band.
Keywords: Carbon dioxide; Near-infrared; Self-induced shifts; Temperature dependence; TDLAS
Investigation of the behavior of HSA upon binding to amlodipine and propranolol: Spectroscopic and molecular modeling approaches
by Mohammad Reza Housaindokht; Zeinab Rouhbakhsh Zaeri; Mahmood Bahrololoom; Jamshid Chamani; Mohammad Reza Bozorgmehr (pp. 79-84).
The interaction between human serum albumin (HSA) and the two drugs – amlodipine and propranolol – was investigated by different methods. The results indicated that amlodipine give rise an increase, while propranolol leads to a decrease in α-helix content of HSA. Data obtained by molecular modeling study suggested that these drugs bind in different sites in subdomain IIA and IIIA with different affinity.Display Omitted► The interaction of HSA with two drugs – amlodipine and propranolol – was investigated. The binding constants of amlodipine and propranolol with HSA were estimated. Amlodipine induces an increase and propranolol a decrease of α-helices content of HSA. These drugs bind in different sites in subdomain IIA and IIIA with different affinity.The interaction between human serum albumin (HSA) and two drugs – amlodipine and propranolol – was investigated using fluorescence, UV absorption and circular dichroism (CD) spectroscopy. In addition, the binding site was established by applying molecular modeling technique. Fluorescence data suggest that amlodipine will quench the intrinsic fluorescence of HSA; whereas propranolol enhances the fluorescence of HSA. The binding constants for the interaction of amlodipine and propranolol with HSA were found to be 3.63×105M−1 and 2.29×104M−1, respectively. The percentage of secondary structure feature of each one of the HSA-bound drugs, i.e. the α-helix content, was estimated empirically by circular dichroism. The results indicated that amlodipine causes an increase, and that propranolol leads to a decrease in α-helix content of HSA. The spectroscopic analysis indicates that the binding mechanisms of the two drugs are different from each other. The data obtained by the molecular modeling study indicated that these drugs bind, with different affinity, to different sites located in subdomain IIA and IIIA.
Keywords: Human serum albumin; Amlodipine; Propranolol; Binding constants; Circular dichroism; Molecular modeling
Synthesis, spectroscopic characterizations and quantum chemical computational studies of ( Z)-4-[( E)-(4-fluorophenyl)diazenyl]-6-[(3-hydroxypropylamino)methylene]-2-methoxycyclohexa-2,4-dienone
by Çiğdem Albayrak; Mustafa Odabaşoğlu; Arzu Özek; Orhan Büyükgüngör (pp. 85-91).
Display Omitted► The study emphasizes the role of hydrogen bond in crystal packing. ► The effects of solvents on proton transfer process are investigated. ► The tautomerism depending on solute–solution interactions is underlined.In this study, the molecular structure and spectroscopic properties of the title compound were characterized by X-ray diffraction, FT-IR and UV–vis spectroscopies. These properties were also investigated using DFT method. The most convenient conformation of title compound was firstly determined. The geometry optimizations in gas phase and solvent media were performed by DFT methods with B3LYP adding 6-31G(d) basis set. The differences between crystal and computational structures are due to crystal packing in which hydrogen bonds play an important role. UV–vis spectra were recorded in different organic solvents. The results show that title compound exists in both keto and enol forms in DMSO, EtOH but it tends to shift towards enol form in benzene. The polar solvents facilitate the proton transfer by decreasing the activation energy needed for Transition State. The formation of both keto and enol forms in DMSO and EtOH is due to decrease in the activation energy. TD-DFT calculations starting from optimized geometry were carried out in both gas and solution phases to calculate excitation energies of the title compound. The non-linear optical properties were computed at the theory level and the title compound showed a good second order non-linear optical property. In addition, thermodynamic properties were obtained in the range of 100–500K.
Keywords: Schiff Base; Azo dye; Non-linear optical properties; DFT; TD-DFT; Spectral characterization
Combined experimental and theoretical studies on the vibrational spectra of 2-quinolinecarboxaldehyde
by V. Küçük; A. Altun; M. Kumru (pp. 92-98).
Display Omitted► Frequencies and geometries of the possible two conformers of 2-quinolinecarboxaldehyde were calculated.► The HF and B3LYP results were compared with experimental FT-IR, FT-FIR, and FT-Raman data. ► The conformational analysis of 2-quinolinecarboxaldehyde was performed.Combined experimental and theoretical studies have been performed on the structure and vibrational spectra (IR and Raman spectra including far region) of 2-quinolinecarboxaldehyde. Hartree–Fock (HF) and density functional B3LYP calculations have been employed with the 6-311++G(d,p) basis set for investigating the structural and spectroscopic properties of two possible aldehyde rotamers of 2-quinolinecarboxaldehyde. When the O atom of the aldehyde is farther away than the nitrogen atom of the quinoline, 2-quinolinecarboxaldehyde has the lowest possible energy, and thus is in its ground state. The computed vibrational frequencies of this lowest energy rotamer agree also slightly better than those of the higher energy rotamer with the experimental frequencies after the computed frequencies are scaled.
Keywords: 2-Quinolinecarboxaldehyde; IR spectrum; Raman spectrum; Normal modes; HF; DFT
Green synthesis of well-dispersed gold nanoparticles using Macrotyloma uniflorum
by S. Aswathy Aromal; V.K. Vidhu; Daizy Philip (pp. 99-104).
Display Omitted► Well-dispersed spherical gold nanoparticles are obtained at room temperature. ► The method is independent of seasonal variations. ► HRTEM images, SAED and XRD patterns show good crystallinity of the samples. ► FTIR spectrum shows the involvement of proteins in capping of gold nanoparticles. ► Polyphenols are expected to bring about the reduction of metal ions.The synthesis of metal nanoparticles of different sizes, shapes, chemical composition and controlled monodispersity is an important area of research in nanotechnology because of their interesting physical properties and technological applications. Present work describes an eco-friendly method for the synthesis of spherical gold nanoparticles using aqueous extract of Macrotyloma uniflorum. The effects of quantity of extract, temperature and pH on the formation of nanoparticles are studied. The nanoparticles are characterized by UV–visible spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD) and FTIR analysis. The high crystallinity of nanoparticles with fcc phase is evident from HRTEM images, SAED and XRD patterns. Synthesized nanoparticles have size in the range 14–17nm. FTIR spectrum indicates the presence of different functional groups present in the bio-molecule capping the nanoparticles. The possible mechanism leading to the formation of gold nanoparticles is suggested.
Keywords: Biosynthesis; Gold nanoparticles; Macrotyloma uniflorum; Surface plasmon resonance
Solvatochromism effects on the dipole moments and photo-physical behavior of some azo sulfonamide dyes
by M.S. Zakerhamidi; S. Ahmadi-Kandjani; M. Moghadam; E. Ortyl; S. Kucharski (pp. 105-110).
Display Omitted► The dipolarity/polarizability and hydrogen bonding controlled azo sulfonamide interactions. ► The azo sulfonamide shows large change in the dipole moment on excitation. ► The azo sulfonamide dyes structural configuration can be changed in excited state. ► TICT increases planarity and polarity of azo sulfonamide dye upon excitation.Absorption and emission spectra of three azo sulfonamide dyes with various molecular structures have been studied in different solvents. The solute photo-physical behavior depends strongly on the solvent–solute interactions and solvent microenvironment. In order to understand the effect of intermolecular interactions on spectral behaviors of these dyes in different solvents and to conceive nature and extent of solvent–solute interactions the spectral variations were analyzed by the linear solvation energy relationships concept. In addition, by means of solvatochromic method the dipole moments of these dyes, in ground and excited states, were investigated.
Keywords: Azo sulfonamide dye; Solvent–solute interaction; Linear solvation energy relationship; Solvent polarity scale; Dipole moment; Twisted intramolecular charge transfer (TICT)
Surface-enhanced Raman scattering study of riboflavin on borohydride-reduced silver colloids: Dependence of concentration, halide anions and pH values
by Fangfang Liu; Huaimin Gu; Yue Lin; Yajing Qi; Xiao Dong; Junxiang Gao; Tiantian Cai (pp. 111-119).
Display Omitted► New adsorption geometries of riboflavin molecules on silver surface were verified. ► The optimum concentration for the SERS of riboflavin was found at 10−6mol/L. ► The addition of 0.2mol/L halide leads to the changes of SERS intensity and profile. ► The protonated and deprotonated molecular species of riboflavin adsorbed were proved.The influences of concentration, halide anions and pH on the surface-enhanced Raman scattering (SERS) of riboflavin adsorbed on borohydride-reduced silver colloids were studied. The optimum concentration for the SERS of riboflavin is 10−6mol/L while the SERS enhancement varies for different modes. The addition of 0.2mol/L halide (NaCl, NaBr, and NaI) aqueous solutions, leads to a general decrease of the SERS intensity and a change of spectral profile of riboflavin excited at 514.5nm. Riboflavin interacts with the silver surface possibly through the CO and N–H modes of the uracil ring. The SERS spectra of riboflavin were recorded in the 3.4–11.6 pH range. By analyzing several SERS marker bands, the protonated, deprotonated or the coexistence of both molecular species adsorbed on the colloidal silver particles was proved.
Keywords: Riboflavin; Surface-enhanced Raman scattering spectroscopy; Silver colloids; Concentration; Halide anions; pH
Interaction between phillygenin and human serum albumin based on spectroscopic and molecular docking
by W. Song; M.Z. Ao; Y. Shi; L.F. Yuan; X.X. Yuan; L.J. Yu (pp. 120-126).
The interaction between HSA and phillygenin at physiological conditions by fluorescence, circular dichroism (CD), UV–vis spectroscopy and molecular docking to enrich our knowledge of the interaction dynamics of phillygenin to the important plasma protein HSA, and it is also expected to provide important information of designs of new inspired drugs.Display Omitted► We investigate the interaction between HSA and phillygenin. ► Fluorescence, CD and UV spectra study shows complex formation between phillygenin and HSA. ► The fluorescence quenching of HSA by phillygenin was static mechanism. ► Van der Waals forces and hydrogen bonds play a role in stabilizing the complex. ► Metal ions and ethanol can increase the concentration of free phillygenin.In this paper, the interaction of human serum albumin (HSA) with phillygenin was investigated by fluorescence, circular dichroism (CD), UV–vis spectroscopic and molecular docking methods under physiological conditions. The Stern–Volmer analysis indicated that the fluorescence quenching of HSA by phillygenin resulted from static mechanism, and the binding constants were 1.71×105, 1.61×105 and 1.47×104 at 300, 305 and 310K, respectively. The results of UV–vis spectra show that the secondary structure of the protein has been changed in the presence of phillygenin. The CD spectra showed that HSA conformation was altered by phillygenin with a major reduction of α-helix and an increase in β-sheet and random coil structures, indicating a partial protein unfolding. The distance between donor (HSA) and acceptor (phillygenin) was calculated to be 3.52nm and the results of synchronous fluorescence spectra showed that binding of phillygenin to HSA can induce conformational changes in HSA. Molecular docking experiments found that phillygenin binds with HSA at IIIA domain of hydrophobic pocket with hydrogen bond interactions. The ionic bonds were formed with the O (4), O (5) and O (6) of phillygenin with nitrogen of ASN109, ARG186 and LEU115, respectively. The hydrogen bonds are formed between O (2) of phillygenin and SER419. In the presence of copper (II), iron (III) and alcohol, the apparent association constant K A and the number of binding sites of phillygenin on HSA were both decreased in the range of 88.84–91.97% and 16.09–18.85%, respectively. In view of the evidence presented, it is expected to enrich our knowledge of the interaction dynamics of phillygenin to the important plasma protein HSA, and it is also expected to provide important information of designs of new inspired drugs.
Keywords: Phillygenin; Human serum albumin; Binding study; Fluorescence quenching; CD spectroscopy; UV–vis spectroscopy; Molecular docking
Studies on the complexation of neodymium(III) ion with 1,2,4-1H-triazole and 1,2,3-benzotriazole in absence and presence of calcium(II) ion in aqueous and some selected different aquated organic solvents by an absorption spectroscopy involving 4f–4f transitions
by Bimola Huidrom; N. Ranjana Devi; Th. David Singh; N. Rajmuhon Singh (pp. 127-133).
Display Omitted► Coordination behavior of Nd(III) with 1,2,4-1H-triazole and 1,2,3-benzotriazole. ► Existence of inner sphere complexes. ► Percent covalency of the complexes. ► Evidence of the solvent interaction with the metal ion.The absorption spectra of trivalent neodymium ion with 1,2,4-1H-triazole and 1,2,3-benzotriazole in absence and presence of calcium(II) ion in aqueous and some selected different aquated organic solvents have been recorded in the visible and near infrared regions. From the data available in the absorption spectra, various spectroscopic parameters such as Slator–Condon ( F k), Lande spin–orbit coupling constant ( ξ4f), nephelauxetic ratio ( β), bonding parameter ( b1/2), percent covalency ( δ), oscillator strength ( P) and Judd–Ofelt intensity ( T λ) parameters have been evaluated. The Judd–Ofelt intensity, T λ ( λ=2, 4, 6) parameters are utilized in evaluating the Pcal from various excited states of trivalent neodymium ions and ratifying as an inner sphere complexations.
Keywords: Absorption spectra; Energy parameter; Intensity parameter; 1,2,4-1H-triazole; 1,2,3-Benzotriazole
Metal-enhanced fluorescence exciplex emission
by Yongxia Zhang; Buddha L. Mali; Chris D. Geddes (pp. 134-138).
Metal-enhanced exciplex formation studied using Silver island films to enhance both monomer and complex (exciplex) formation in the near-field.Display Omitted► The first observation of metal-enhanced exciplex fluorescence. ► The first study of enhanced monomer and exciplex emission. ► Enhanced absorption attributed the enhanced emission. ► The emission is both surface plasmon coupled and radiated by the nanoparticles.In this letter, we report the first observation of metal-enhanced exciplex fluorescence, observed from anthracene in the presence of diethylaniline. Anthracene in the presence of diethylaniline in close proximity to Silver Island Films (SIFs) shows enhanced monomer and exciplex emission as compared to a non-silvered control sample containing no silver nanoparticles. Our findings suggest two complementary methods for the enhancement: (i) surface plasmons can radiate coupled monomer and exciplex fluorescence efficiently, and (ii) enhanced absorption (enhanced electric near-field) further facilitates enhanced emission. Our exciplex studies help us to further understand the complex photophysics of the metal-enhanced fluorescence technology.
Keywords: Abbreviations; MEF; Metal enhanced fluorescence; Exciplex; Excited state complexMonomer fluorescence; Exciplex fluorescence; Surface enhanced fluorescence; Plasmon enhanced fluorescence; Radiative decay engineering; Metal-enhanced fluorescence; Metal-enhanced exciplex fluorescence
Flow injection analysis of ketoprofen based on the order transform second chemiluminescence reaction
by Yafeng Zhuang; Guiping Cao; Chuanqin Ge (pp. 139-144).
Display Omitted► A new method for the determination of ketoprofen has been reported. ► First explores an order-transform-second-chemiluminescence (OTSCL) method. ► A mechanism for the OTSCL has been proposed. ► The OTSCL method has been successfully applied to pharmaceutical formulations.This paper explores an order-transform-second-chemiluminescence (OTSCL) method combining the flow injection technique for the determination of ketoprofen. When ketoprofen solution was injected into the mixture after the end of the reaction of alkaline luminol and sodium periodate or sodium periodate solution was injected into the reaction mixture of ketoprofen and alkaline luminol, a new chemiluminescence (CL) reaction was initiated and strong CL signal was detected. A mechanism for the OTSCL has been proposed on the basis of the chemiluminescence kinetic characteristic, UV–visible absorption and chemiluminescent spectra. Under optimal experimental conditions, the CL response is proportional to the concentration of ketoprofen over the range of 2.0×10−7 to 1.0×10−5mol/L with a correlation coefficient of 0.9950 and a detection limit of 8.0×10−9mol/L (3 σ). The relative standard deviation for 11 repetitive determinations of 1.0×10−6mol/L ketoprofen is 2.9%. The utility of this method was demonstrated by determining ketoprofen in pharmaceutical formulations without interference from its potential impurities.
Keywords: Ketoprofen determination; Order-transform-second-chemiluminescence; Flow injection analysis; Luminol; Sodium periodate
NMR, UV, FT-IR, FT-Raman spectra and molecular structure (monomeric and dimeric structures) investigation of nicotinic acid N-oxide: A combined experimental and theoretical study
by Ahmet Atac; Mehmet Karabacak; Caglar Karaca; Etem Kose (pp. 145-154).
Display Omitted► Spectroscopic properties of nicotinic acid N-oxide were examined by NMR, UV, FT-IR, FT-Raman and DFT. ► All results were compared with experimental (FT-IR, FT-Raman, UV,1H,13C NMR) spectra. ► The electronic properties (HOMO and LUMO energies, absorption wavelength and excitation energies) were performed DFT.In this work, the experimental and theoretical UV, NMR, and vibrational features of nicotinic acid N-oxide (abbreviated as NANO, C6H5NO3) were studied. The ultraviolet (UV) absorption spectrum of studied compound that dissolved in water was examined in the range of 200–800nm. FT-IR and FT-Raman spectra in solid state were observed in the region 4000–400cm−1 and 3500–50cm−1, respectively. The1H and13C NMR spectra in DMSO were recorded. The geometrical parameters, energies and the spectroscopic properties of NANO were obtained for all four conformers from density functional theory (DFT) B3LYP/6-311++G(d,p) basis set calculations. There are four conformers, C n, n=1–4 for this molecule. The computational results identified the most stable conformer of title molecule as the C1 form. The complete assignments were performed on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method.13C and1H nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by using the gauge-invariant atomic orbital (GIAO) method. The electronic properties, such as excitation energies, absorption wavelengths, HOMO and LUMO energies, were performed by CIS approach. Finally the calculation results were applied to simulate infrared, Raman, and UV spectra of the title compound which show good agreement with observed spectra.
Keywords: Nicotinic acid; N; -oxide; DFT; NMR, UV, FT-IR and FT-Raman; HOMO–LUMO
Analysis of pottery samples from Bourewa, the earliest known Lapita site in Fiji
by Joanne S. Rutherford; Matthew J. Almond; Patrick D. Nunn (pp. 155-159).
Display Omitted► We have carried out a study of the mineralogy of Lapita pottery samples from Bourwera – the earliest known Lapita site in Fiji. ► We show that the samples clearly divide into two types – with or without calcite. ► We demonstrate the effectiveness of using a range of analytical methods.We have carried out a thorough mineralogical analysis of 16 pottery samples from the Lapita site of Bourwera in Fiji, using micromorphological techniques with optical and polarising microscopes. While the overall mineralogy of all of the samples is similar the samples clearly divide into two groups, namely those with or without the mineral calcite. Our findings are backed up by chemical analysis using SEM–EDX and FTIR. SEM–EDX shows the clear presence of inclusions of calcite in some of the samples; FTIR shows bands arising from calcite in these samples. The study suggests that it is likely that more than one clay source was used for production of this pottery, but that most of the pottery comes from a single source. This finding is in line with previous studies which suggest some trading of pottery between the Fijian islands but a single source of clay for most of the pottery found at Bouwera. We found no evidence for the destruction of CaCO3 by heating upon production of the pottery in line with the known technology of the Lapita people who produced earthenware pottery but not high temperature ceramics.
Keywords: Infrared spectroscopy; Mineralogy; Pottery analysis; Fijian pottery; Lapita pottery; X-ray diffraction
Synthesis and spectroscopic characterization of Cu(II) containing chlorocadmiumphosphate Cd(HPO4)Cl·[H3N(CH2)6NH3]0.5 crystals
by Ch. Rama Krishna; Ch. Venkata Reddy; U.S. Udayachandran Thampy; A.V. Chandrasekhar; Y.P. Reddy; P. Sambasiva Rao; R.V.S.S.N. Ravikumar (pp. 160-164).
This figure illustrates the FT-IR spectrum of copper ions doped chlorocadmiumphosphate crystals. The spectrum shows the characteristic vibrational bands of phosphate ions and as well as organic amine molecules.Display Omitted► This method is simple to synthesize frame-work materials at room temperature. ► The prepared samples are highly crystalline and stable up to 300°C temperature. ► Site symmetry for copper ions is tetragonal elongated octahedral site symmetry.Chlorocadmiumphosphate Cd(HPO4)Cl·[H3N(CH2)6NH3]0.5 crystals containing Cu(II) ions have been successfully synthesized at room temperature by using organic amine 1,6-diamino hexane as a template. The samples are characterized by X-ray powder diffraction, Thermal and spectroscopic studies. These are crystallizes in the monoclinic crystal system with cell dimensions: a=1.7697, b=0.6576, c=1.9026nm and β=106.5°. FT-IR spectrum showed the absorption bands related to PO4, NH3+ ions and other organic molecule vibrations originated from the templated molecule. The prepared crystals are stable at room temperature and as well as up to around 300°C which were confirmed by thermal analysis. Optical absorption and EPR studies suggest that Cu(II) ion enters in to the lattice as tetragonally distorted octahedral symmetry, for which crystal field and spin-Hamiltonian parameters are calculated. Bonding parameters are suggesting that there exists partial covalent nature between Cu(II) ions and ligands.
Keywords: Chlorocadmiumphosphate crystals; Copper ions; Powder XRD investigations; Thermal analysis; Spectroscopic studies
Resonance Raman and density functional study of the excited state structural dynamics of 3-amino-2-cyclohexen-1-one in water and acetonitrile solvents
by Xiao-Xian Sui; Lei Li; Yanying Zhao; Hui-Gang Wang; Ke-Mei Pei; Xuming Zheng (pp. 165-172).
Display Omitted► The vibrational assignments of 3-amino-2-cyclohexen-1-one were carried out. ► The Franck–Condon region structural dynamics were obtained. ► The absorption spectrum and absolute resonance Raman cross-sections were simulated. ► Modulation of S π/ S n vibronic coupling or curve crossing by solvents was studied.FT-Raman and/or FT-IR spectra of 3-amino-2-cyclohexen-1-one (ACyO) in solid state and/or in solvents of water and acetonitrile were obtained. Density functional theory calculations were done to help elucidate the vibrational band assignments. The A-band resonance Raman spectra of ACyO were acquired in water and acetonitrile solvents to examine the excited state structural dynamics and the state-mixing or curve-crossing tuned by solvents. A preliminary resonance Raman intensity analysis using the time-dependent wave-packet theory and simple model was done for ACyO in acetonitrile solvent. Resonance Raman spectroscopic probing of the excited state curve-crossing or state-mixing was proposed.
Keywords: 3-Amino-2-cyclohexen-1-one; Resonance Raman; Excited state structural dynamics; Time-dependent wave-packet theory
Vibrational spectroscopic study of the mineral pitticite Fe, AsO4, SO4, H2O
by Ray L. Frost; Yunfei Xi; Keqin Tan; Graeme J. Millar; Sara J. Palmer (pp. 173-178).
Display Omitted► We have synthesised the analogue of the mineral pitticite. ► Pitticite is X-ray non-diffracting. ► Vibrational spectroscopy is one of the few methods which can be used to determine the molecular structure of pitticite. ► Formation of pitticite has implications for arsenate accumulation.Some minerals are colloidal and show no X-ray diffraction patterns. Vibrational spectroscopy offers one of the few methods for the determination of the structure of these minerals. Among this group of minerals is pitticite, simply described as (Fe, AsO4, SO4, H2O). In this work, the analogue of the mineral pitticite has been synthesised. The objective of this research is to determine the molecular structure of the mineral pitticite using vibrational spectroscopy. Raman and infrared bands are attributed to the AsO43−, SO42− and water stretching and bending vibrations. The Raman spectrum of the pitticite analogue shows intense peaks at 845 and 837cm−1 assigned to the AsO43− stretching vibrations. Raman bands at 1096 and 1182cm−1 are attributed to the SO42− antisymmetric stretching bands. Raman spectroscopy offers a useful method for the analysis of such colloidal minerals.
Keywords: Raman spectroscopy; Pitticite; Arsenate; Sulphate; Scorodite; Känkite
FT-IR, FT-Raman, NMR and UV–vis spectra, vibrational assignments and DFT calculations of 4-butyl benzoic acid
by M. Karabacak; Z. Cinar; M. Kurt; S. Sudha; N. Sundaraganesan (pp. 179-189).
Display Omitted► The FTIR and FT-Raman spectra of 4-butyl benzoic acid were recorded. ► The vibrational frequencies were calculated for monomer and dimer by DFT method. ► NMR and UV–vis spectra were also recorded and compared with calculated ones. ► Benzoic acid derivatives have good anti-tumor properties.The solid phase FTIR and FT-Raman spectra of 4-butyl benzoic acid (4-BBA) have been recorded in the regions 400–4000 and 50–4000cm−1, respectively. The spectra were interpreted in terms of fundamentals modes, combination and overtone bands. The structure of the molecule was optimized and the structural characteristics were determined by density functional theory (DFT) using B3LYP method with 6-311++G(d,p) as basis set. The vibrational frequencies were calculated for monomer and dimer by DFT method and were compared with the experimental frequencies, which yield good agreement between observed and calculated frequencies. The infrared and Raman spectra were also predicted from the calculated intensities.13C and1H NMR spectra were recorded and13C and1H nuclear magnetic resonance chemical shifts of the molecule were calculated using the gauge independent atomic orbital (GIAO) method. UV–visible spectrum of the compound was recorded in the region 200–400nm and the electronic properties HOMO and LUMO energies were measured by time-dependent TD-DFT approach. The geometric parameters, energies, harmonic vibrational frequencies, IR intensities, Raman intensities, chemical shifts and absorption wavelengths were compared with the available experimental data of the molecule.
Keywords: DFT; Vibrational spectra; NMR; UV–vis spectra; 4-Butyl benzoic acid; Dimer
Influence of Cd2+, Hg2+ and Pb2+ on (+)-catechin binding to bovine serum albumin studied by fluorescence spectroscopic methods
by Mijun Peng; Shuyun Shi; Yuping Zhang (pp. 190-197).
The presence of toxic heavy metal ions significantly affected the binding modes and binding affinities of (+)-catechin to BSA, and the effects depended on the types of metal ions.Display Omitted► Effect of heavy metal ions on (+)-catechin binding with BSA has been studied. ► Binding affinities and binding modes of (+)-catechin to BSA have been changed. ► Conformational change was the main factor to change the binding affinity. ► The results were related to the toxic ions/drug interference.The effect of heavy metal ions, Cd2+, Hg2+ and Pb2+ on (+)-catechin binding to bovine serum albumin (BSA) has been investigated by spectroscopic methods. The results indicated that the presence of heavy metal ions significantly affected the binding modes and binding affinities of (+)-catechin to BSA, and the effects depend on the types of heavy metal ion. One binding mode was found for (+)-catechin with and without Cd2+, while two binding modes – a weaker one at low concentration and a stronger one at high concentration were found for (+)-catechin in the presence of Hg2+ and Pb2+. The presence of Cd2+ decreased the binding affinities of (+)-catechin for BSA by 20.5%. The presence of Hg2+ and Pb2+ decreased the binding affinity of (+)-catechin for BSA by 8.9% and 26.7% in lower concentration, respectively, and increased the binding affinity of (+)-catechin for BSA by 5.2% and 9.2% in higher concentration, respectively. The changed binding affinity and binding distance of (+)-catechin for BSA in the presence of Cd2+, Hg2+ and Pb2+ were mainly because of the conformational change of BSA induced by heavy metal ions. However, the quenching mechanism for (+)-catechin to BSA was based on static quenching combined with non-radiative energy transfer irrespective of the absence or presence of heavy metal ions.
Keywords: (+)-Catechin; Bovine serum albumin; Heavy metal ion; Fluorescence quenching; Interaction
Experimental, theoretical calculations of the vibrational spectra and conformational analysis of 2,4-di-tert-butylphenol
by S. Kalaichelvan; N. Sundaraganesan; O. Dereli; U. Sayin (pp. 198-209).
Display Omitted► FT-IR and FT-Raman spectra of 2,4-DTBP were recorded. ► Molecular geometry, harmonic frequencies and bonding features have been calculated. ► 2,4-DTBP is used as antioxidant in food.In the present work, we reported a combined experimental and theoretical study on conformational stability, molecular structure and vibrational spectra of 2,4-di-tert-butylphenol (2,4-DTBP). The FT-IR (400–4000cm−1) and FT-Raman spectra (50–3500cm−1) of 2,4-DTBP were recorded. The molecular geometry, harmonic vibrational frequencies and bonding features of 2,4-DTBP in the ground-state have been calculated by using the density functional BLYP/B3LYP methods. The energy calculated by time-dependent density functional theory (TD-DFT) result complements with the experimental findings. The calculated highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energies show that charge transfer occurs within the molecule. Finally the calculation results were compared with measured infrared and Raman spectra of the title compound which showed good agreement with observed spectra.
Keywords: FT-IR; FT-Raman; Conformational stability; Vibrational spectra; HOMO–LUMO; 2,4-di-tert-butylphenol
Synthesis of 1,4-dihydropyridines under solvent free conditions and investigation of their photo physical properties
by J. Ramchander; Gajula Raju; N. Rameshwar; T. Sheshashena Reddy; A. Ram Reddy (pp. 210-216).
The chemical shift of the proton attached to C-4 in1H NMR and the carbonyl stretching frequency of bis acetyl groups at 3 and 5-positions in 4-aryl-1,4-dihydropyridines exhibited a linear relationship with Hammet's substituent constants. However no such relationship exists between the Hammet's substituent constants and the electronic absorption maxima, fluorescence emission maxima, fluorescence quantum efficiency and Stokes shift.Display Omitted► The paper deals with the synthesis of 1,4-dihydropyridines using Y(OTf)3 as catalyst. ► The 1,4-dihydropyridines are not bright fluorescent but are dim fluorescent. ► The photo physical properties of these molecules are solvent and substituent dependent.Synthesis of five 4-aryl substituted 1,4-dihydropyridines was developed following condensation of multi component reaction strategy using yttrium triflate as a catalyst. The absorption and fluorescence properties of structurally related 4-aryl 1,4-dihydropyridines in different solvents of varied polarities was investigated. The absorption maxima of these compounds follow no order of solvent polarity and nature of substitution. The spectral characteristics are solvent and compound specific. Fluorophores with electron withdrawing group have larger fluorescence quantum yields and greater solvatochromism than the compounds with electron donating groups. Protic solvents yielded higher fluorescence quantum efficiency. The chemical shift of the proton attached to C-4 and the carbonyl stretching frequency of bis acetyl groups at 3 and 5-positions exhibited a linear relationship with Hammett's para substituent constants while no such relationship exists between the latter and electronic absorption maxima, fluorescence emission maxima, fluorescence quantum efficiency and Stokes shift.
Keywords: Dihydropyridine; Solvatochromism; Stokes shift; Fluorophore
CdTe nanocrystals-enhanced chemiluminescence from peroxynitrous acid–carbonate and its application to the direct determination of nitrite
by Hongxia Zhang; Lijuan Zhang; Chao Lu; Lixia Zhao; Zhixia Zheng (pp. 217-222).
Display Omitted► CdTe nanocrystals can greatly enhance a weak CL emission from ONOOH–Na2CO3 system. ► The enhancement mechanism of CdTe nanocrystals on ONOOH–Na2CO3 was discussed. ► CdTe nanocrystals–ONOOH–Na2CO3 CL system was used for the direct determination of nitrite.It was found that CdTe semiconductor nanocrystals (NCs) can induce a great sensitized effect on chemiluminescence (CL) emission from peroxynitrous acid (ONOOH)–Na2CO3 system. CL spectra, fluorescence (FL) spectra, and the quenching effect of reactive oxygen species were used to investigate the CL reaction mechanism. The CL intensity was proportional to the concentration of nitrite in the range from 0.05 to 50μM. The detection limit ( S/ N=3) was 0.024μM and the relative standard deviation (RSD) for five repeated measurements of 0.5μM nitrite was 4.2%. This method has been successfully applied to determine nitrite in well water samples with recoveries of 94.0–100.5%. This was the first work for direct (not inhibition effect) determination of analytes using semiconductor NCs-based CL sensor.
Keywords: Semiconductor nanocrystals; Chemiluminescence; Peroxynitrous acid; Carbonate; Nitrite
Exploring the DNA binding mode of transition metal based biologically active compounds
by N. Raman; S. Sobha (pp. 223-234).
. The synthesized complexes are effective minor groove binders. They contribute to the development of novel useful DNA probes and promise in inhibiting pathogen and are currently under development as potential anti-bacterial drugs.Display Omitted► Computer docking technique plays an important role in the drug design discovery. ► The newly synthesized complexes will act as potential therapeutic agents. ► The complexes display good DNA binding and chemical nuclease activity. ► The scope of this work is to develop the novel antitumor drugs targeted to DNA. ► 4-Aminoantipyrine based metal complexes are found to be good antibacterial agents.Few novel 4-aminoantipyrine derived Schiff bases and their metal complexes were synthesized and characterized. Their structural features and other properties were deduced from the elemental analysis, magnetic susceptibility and molar conductivity as well as from mass, IR, UV–vis,1H NMR and EPR spectral studies. The binding of the complexes with CT-DNA was analyzed by electronic absorption spectroscopy, viscosity measurement, and cyclic voltammetry. The interaction of the metal complexes with DNA was also studied by molecular modeling with special reference to docking. The experimental and docking results revealed that the complexes have the ability of interaction with DNA of minor groove binding mode. The intrinsic binding constants ( Kb) of the complexes with CT-DNA were found out which show that they are minor groove binders. Gel electrophoresis assay demonstrated the ability of the complexes to cleave the pUC19 DNA in the presence of AH2 (ascorbic acid). Moreover, the oxidative cleavage studies using distamycin revealed the minor groove binding for the newly synthesized 4-aminoantipyrine derived Schiff bases and their metal complexes. Evaluation of antibacterial activity of the complexes against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus epidermidis, and Klebsiella pneumoniae exhibited that the complexes have potent biocidal activity than the free ligands.
Keywords: Biologically active complexes; Schiff base; DNA binding; Molecular docking; Chemical nuclease activity; Biocidal activity
Synthesis, characterization and antioxidant capacity of naringenin-oxime
by Baki Türkkan; Mustafa Özyürek; Mustafa Bener; Kubilay Güçlü; Reşat Apak (pp. 235-240).
Antioxidant activity and synthesis of new naringenin-oxime (NG-Ox) are reported.Display Omitted► Naringenin oxime (NG-Ox) was characterized by various spectral techniques. ► NG-Ox screened for its antioxidant capacity and radical scavenging activity. ► NG-Ox showed higher antioxidant capacity as compared to pure naringenin (NG).The recognition of the benefits of polyphenolic antioxidants is eliciting increasing interest in the search for new polyphenolic derivatives with improved antioxidant activity. Since naringenin (4′,5,7-trihydroxyflavanone) (NG) is one of the most abundant citrus and grapefruit polyphenolics and flavanone oximes were used in the synthesis of anticancer and radioprotector compounds having antiradical activity, the corresponding oxime of NG, naringenin oxime (NG-Ox), was synthesized and investigated. The structure of NG-Ox was characterized by FT-IR,1H NMR, elemental analysis, and the synthesized compound was screened for its antioxidant capacity by using the cupric reducing antioxidant capacity (CUPRAC) method. Trolox equivalent antioxidant capacity (TEAC) of NG-Ox was measured to be higher than that of the parent compound, NG. Other parameters of antioxidant activity (scavenging effects onOH, O2−, and H2O2) of NG-Ox were also determined.
Keywords: Naringenin; Naringenin oxime; Flavanone oximes; Antioxidant activity; Cupric reducing antioxidant capacity (CUPRAC) assay
A structural and spectroscopic study on para-aminohippuric acid with experimental and theoretical approaches
by Mehmet Karabacak; Zeliha Cinar; Mehmet Cinar (pp. 241-250).
Display Omitted► The spectroscopic properties of para-amino hippuric acid were examined by FT-IR, FT-Raman and UV techniques and DFT/B3LYP method. ► The complete assignments are performed on the basis of the total energy distribution (TED). ► HOMO and LUMO energies, absorption wavelength and excitation energies were calculated. ► Polarizability and first hyperpolarizability of para-amino hippuric acid were calculated. ► Thermodynamic properties and their correlations with temperature were obtained from the theoretical vibrations.In this work, the molecular conformation, vibrational and electronic analysis of para-aminohippuric acid (pAHA, C9H10N2O3) were presented for the ground state using experimental techniques (FT-IR, FT-Raman and UV) and density functional theory (DFT) employing B3LYP exchange correlation with the 6-311++G(d,p) basis set. FT-IR and FT-Raman spectra were recorded in the regions of 400–4000cm−1 and 50–4000cm−1, respectively. The UV absorption spectra of the compound that dissolved in ethanol and water solution were recorded in the range of 190–400nm. Potential energy curve was computed by means of scanning NCCO torsion angle. The geometry optimization and the energies associated possible four conformers (C1–C4) were computed. The computational results diagnose the most stable conformer of pAHA as the C1 form. Optimized structure of compound was interpreted and compared with the earlier reported experimental values. The complete assignments of fundamental vibrations were performed on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. A study on the electronic properties, such as frontier molecular energies, absorption wavelengths and oscillator strengths, were predicted by time-dependent DFT (TD-DFT) approach, while taking solvent effects into account. To investigate non-linear optical properties: polarizability, anisotropy of polarizability and molecular first hyperpolarizability of molecule were computed. Thermodynamic properties (heat capacity, entropy and enthalpy) of the title compound at different temperatures were calculated.
Keywords: Para-aminohippuric acid; DFT; FT-IR; FT-Raman and UV spectra; Frontier molecular orbitals; NLO
FT-IR, FT-Raman and UV spectral investigation; computed frequency estimation analysis and electronic structure calculations on 1-nitronaphthalene
by M. Govindarajan; M. Karabacak (pp. 251-260).
Display Omitted► Spectroscopic properties of Nitronaphthalene were examined by DFT method. ► All results were compared with experimental FT-IR and FT-Raman spectra. ► HOMO and LUMO, absorption wavelength and excitation energies were performed. ► The important thermodynamical parameters are reported. ► Molecular electrostatic potential distribution of Nitronaphthalene was calculated.In this work, the vibrational spectral analysis was carried out by using FT-Raman and FT-IR spectroscopy in the range 100–4000cm−1 and 400–4000cm−1 respectively, for 1-nitronaphthalene (C10H7NO2) molecule. The molecular structure, fundamental vibrational frequencies and intensity of the vibrational bands are interpreted with the aid of structure optimizations and normal coordinate force field calculations based density functional theory (DFT) and ab initio HF methods and different basis sets combination. The complete vibrational assignments of wavenumbers were made on the basis of total energy distribution (TED). The results of the calculations were applied to simulated spectra of the title compound, which show excellent agreement with observed spectra. The scaled B3LYP/6-311++G(d,p) results show the best agreement with the experimental values over the other methods. The energy and oscillator strength calculated by time-dependent density functional theory (TD-DFT) complements with the experimental findings. Thermodynamic properties of the title compound at different temperatures have been calculated. Besides, frontier molecular orbitals (FMO), molecular electrostatic potential (MEP) were performed.
Keywords: FT-IR; FT-Raman; 1-Nitronapthalene; HOMO–LUMO; DFT and B3LYP
Determination of structural and vibrational spectroscopic properties of 2-, 3-, 4-nitrobenzenesulfonamide using FT-IR and FT-Raman experimental techniques and DFT quantum chemical calculations
by Mehmet Karabacak; Emel Postalcilar; Mehmet Cinar (pp. 261-270).
Display Omitted► Molecular structure of 2-, 3-, 4-nitrobenzenesulfonamide molecules was studied using DFT/B3LYP. ► Spectroscopic properties of organic molecule were examined by FT-IR, FT-Raman techniques and DFT. ► The complete assignments are performed on the basis of the total energy distribution (TED). ► All results were compared with experimental (FT-IR and FT-Raman) spectra.In this work, the molecular conformation and vibrational analysis of 2-, 3-, 4-nitrobenzenesulfonamide (abbreviated as 2-, 3-, 4-NBSA) were presented for the ground state using experimental techniques (FT-IR and FT-Raman) and density functional theory (DFT) employing B3LYP exchange correlation with the 6-311++G(d,p) basis set. The complete assignments of fundamental vibrations were performed on the basis of the experimental results and total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. The effects of the nitro group substituent on the characteristic benzene sulfonamides bands in the spectra were discussed. Raman activities calculated by DFT method have been converted to the corresponding Raman intensities using Raman scattering theory. Optimized structure of compounds were interpreted and compared with the earlier reported experimental values for studied molecules. The observed and the calculated geometric parameters and vibrational wavenumbers were compared and found to be in good agreement.
Keywords: 2-, 3-, 4-Nitrobenzenesulfonamide; DFT; FT-IR and FT-Raman spectra
Theoretical investigations of α,α,α-trifluoro-3, -p and o-nitrotoluene by means of density functional theory
by G. Yildirim; S.D. Senol; M. Dogruer; O. Ozturk; A. Senol; A.T. Tasci; C. Terzioglu (pp. 271-282).
The electrostatic potential ESP figure presents that the most negative ESP is spread over the oxygen and fluorine atoms, indicating the delocalization of π-electrons over the nitro and trifluoromethyl groups for the α,α,α-trifluoro-o-nitrotoluene. The figure also reveals the extended conjugation of the benzene ring with these groups. Furthermore, the 2D contour of total charge density of the compound studied is presented in the same figure. Based on the contour, blue color in the molecule studied is found to be the predominance because of the positive charge distribution of the title compound.Display Omitted► This study deals with novel theoretical aspects and novel applications of the molecules. ► FMO, MEP and ESP are also performed via quantum computational methods (DFT). ► NMR and UV–vis spectra are investigated found to be in good agreement with experimental results. ► Transition state and energy band gap were determined for studies of the compounds. ► The charge transfer within the molecules is investigated by HOMO and LUMO analyses.This study reports the optimized molecular structures, vibrational frequencies including Infrared intensities and Raman activities, corresponding vibrational assignments,1H and13C NMR chemical shifts, the magnitudes of the JCH and JCC coupling constants, Ultraviolet–visible (UV–vis) spectra, thermodynamic properties and atomic charges of the title compounds, α,α,α-trifluoro-3, -p and o-nitrotoluene, in the ground state by means of the density functional theory (DFT) with the standard B3LYP/6-311++G(d,p) method and basis set combination for the first time. Theoretical vibrational spectra were interpreted by normal coordinate analysis based on scaled density functional force field. The results show that the vibrational frequencies and chemical shifts calculated were obtained to be in good agreement with the experimental data. Based on the comparison between experimental results and theoretical data, the calculation level chosen is powerful approach for understanding the identification of all the molecules studied. In addition, not only were frontier molecular orbitals (HOMO and LUMO), molecular electrostatic potential (MEP) and electrostatic potential (ESP) simulated but also the dipole moment, softness, electronegativity, chemical hardness, electrophilicity index, transition state and energy band gap values were predicted. According to the investigations, all compounds were found to be useful to bond metallically and interact intermolecularly; however, the thermodynamic properties confirm that the α,α,α-trifluoro-p-nitrotoluene was more reactive and more polar than the others.
Keywords: α,α,α-Trifluoro-3, -p and o-nitrotoluene; B3LYP; MEP; ESP
Determination of phenol by flow-injection with chemiluminescence detection based on the hemin-catalysed luminol–hydrogen peroxide reaction
by Wenwen Liu; Wei Cao; Weihua Liu; Kang Du; Pixue Gong (pp. 283-287).
Display Omitted► Hemin-catalysed luminol chemiluminescence was used for determination of phenol. ► Maximum reaction velocity and Michaelis constant were calculated. ► The proposed method has lower detection limit.This study established a novel flow injection (FI) methodology for the determination of phenol in aqueous samples based on luminol chemiluminescence (CL) detection. The method was based on the inhibition that phenol caused on the hemin-catalysed chemiluminescence reaction between luminol and hydrogen peroxide in alkaline solution. Optimum conditions and possible mechanisms have been investigated. The linear range was 2.0×10−9 to 4.0×10−7gmL−1 for phenol. The proposed method is sensitive with a detection limit of 4.0×10−10gmL−1. The relative standard deviation for 11 measurements was 2.3% for 1.0×10−7gmL−1 phenol. The method was applied for the determination of phenol in waste water samples. The results obtained compared well with those by an official method.
Keywords: Key words; Flow injection; Chemiluminescence; Phenol; Luminol; Hydrogen peroxide; Hemin
The synthesis of highly water-dispersible and targeted CdS quantum dots and it is used for bioimaging by confocal microscopy
by Guangcheng Wei; Miaomiao Yan; Liying Ma; Huaibin Zhang (pp. 288-292).
Display Omitted► In our study, the CdS QDs (CdS–MAA–PEI–FA) prepared has highly photostable, very excellent water-dispersible and effective targeted delivery ability to cell. ► The rapid bioimaging of CdS was verified by confocal microscopy, and the imaging effect is very well. ► This provides us a new choice for the bioimaging and fluorescence labeling.Synthesis of a highly dispersed hydrophilic CdS nanocrystals and their use as fluorescence labeling for live cell imaging is reported here. By carefully manipulating the surface of CdS nanocrystals, the dispersions of CdS–MAA–PEI–FA nanocrystals with high photostability is prepared. The receptor-mediated delivery of folic acid conjugated quantum dots into folate-receptor-positive cell lines such as CBRH7919 liver cancer cells was demonstrated by confocal microscopy. In the future, the further modified CdS nanoparticles can be used for the tissue imaging in vivo studies.
Keywords: QDs; CdS; Folic acid; Nanoparticles; Cell imaging
A new Schiff base system bearing two naphthalene groups as fluorescent chemodosimeter for Zn2+ ion and its logic gate behavior
by Reza Azadbakht; Hassan Keypour (pp. 293-297).
Display Omitted► The chemodosimeter exhibited single recognition for Zn2+ with a dramatic color change. ► The compound could be used as an on–off switch chemodosimeter. ► The compound is capable to mimic AND logic gate with Zn2+ ions and triethylamine as inputs.1-((E)-(2-((2-nitrobenzyl)(2-((E)-(2-hydroxynaphthalen-1-yl)methyleneamino)ethyl)amino)ethylimino)methyl)naphthalen-2-ol (H2L), The new compound featuring two naphthalene units was synthesized and characterized. We find that H2L has high selectivity and sensitivity to detect Zn2+ ion over other metal ions such as Na+, Ag+, Cd2+, Co2+, Cr3+, Cu2+, Hg2+, Mn2+, Ni2+, Fe3+, and the sensitivity is about 10−7M. The fluorescent changes of H2L upon the addition of cations Zn2+ and triethylamine is utilized as an AND logic gate at the molecular level, using Zn2+ and triethylamine as chemical inputs and the fluorescence intensity signal as output.
Keywords: Chemodosimeter; Fluorescence; Schiff base; Logic gate; Zn; 2+; ions
Inclusion complexes of phosphorylated daidzein derivatives with β-cyclodextrin: Preparation and inclusion behavior study
by Yongmei Xiao; Liangru Yang; Pu Mao; Jinwei Yuan; Yuxia Deng; Lingbo Qu (pp. 298-302).
Display Omitted► Phosphorylated daidzein derivatives featuring different chain lengths were synthesized. ► Their inclusion complexes with CD were prepared by coprecipitation method. ► The inclusion behavior was studied by fluorescence, UV, FT-IR, MS and NMR. ► The results showed that only daidzein derivative3a entered the cavity of CD. ► 1:1 inclusion was formed and the formation constant was 175(mol/L)−1.In the present work the feasibility of β-cyclodextrin in complexation was explored, as a tool for improving the solubility and biological ability of daidzein derivatives. A series of phosphorylated daidzein derivatives featuring different chain lengths were synthesized through a modified Atherton–Todd reaction and their inclusion complexes with βCD were prepared by coprecipitation method. The inclusion complexation behavior was studied by fluorescence, UV, FT-IR, MS and1H NMR. The results showed that only phosphorylated daidzein derivative carrying small substituent group ((C2H5O)2PO) entered the cavity of βCD and formed 1:1 inclusion complex. The formation constant was 175(mol/L)−1.
Keywords: Phosphorylated daidzein; β-Cyclodextrin; Inclusion complex
Comparison of DFT methods for molecular structure and vibration spectra of ofloxacin calculations
by Yue Yang; Hongwei Gao (pp. 303-309).
Display Omitted► We investigated the molecular structure and vibrational spectra of ofloxacin by DFT. ► MPW1PW91/LANL2MB and SDD afford the best quality to predict the structure of ofloxacin. ► LSDA/SDD and LANL2DZ levels show better performance to predict the vibration spectra of ofloxacin.Comparison of the performance of different density functional theory (DFT) methods at various basis sets in predicting molecular and vibration spectra of ofloxacin was reported. The methods employed in this study comprise six functionals, namely, mPW1PW91, HCTH, LSDA, PBEPBE, B3PW91 and B3LYP. Different basis sets including LANL2DZ, SDD, LANL2MB, 6-31g, 6-311g and 3-21g were also examined. Comparison between the calculated and experimental data indicates that the mPW1PW91/6-311g level afford the best quality to predict the structure of ofloxacin. The results also indicate that B3LYP/LANL2DZ level show better performance in the vibration spectra prediction of ofloxacin than other DFT methods.
Keywords: DFT; Basis sets; Molecular structure; Vibration spectra; Ofloxacin