Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy (v.68, #5)
Editorial Board (CO2).
The calculations of phonon dispersion relations for single-wall carbon armchair and zigzag nanotubes by Yufang Wang; Bin Zhang; Qinghua Jin; Baohui Li; Datong Ding; Xuewei Cao (1149-1152).
A 3D single-wall carbon nanotube can be viewed as a 2D graphite sheet rolled into a 3D cylinder. In the study of dispersion relations of carbon nanotubes, the consistent force parameters for 2D graphite sheets have to be modified to include the curvature effect. The present paper reports a series of calculations of phonon dispersion relations for single-wall carbon armchair, zigzag nanotube in which the curvature effect has been properly treated. The symmetry of crystal vibration mode at the centre of Brillouin zone is analyzed based on our numeric results and the structure symmetry of the nanotubes.
Keywords: Single-wall carbon nanotubes; Raman and IR active vibration; Phonon dispersion; Structure symmetry;
Synthesis and NMR spectral studies of N-chloroacetyl-2,6-diarylpiperidin-4-ones by G. Aridoss; S. Balasubramanian; P. Parthiban; S. Kabilan (1153-1163).
A series of 2,6-diarylpiperidin-4-ones having electron withdrawing chloroacetyl group at the heterocyclic nitrogen were synthesized. Unambiguous characterizations of the synthesized compounds were achieved by one-dimensional (1H NMR and 13C NMR) and two-dimensional (HOMOCOSY, NOESY and HSQC spectra for compounds 8 and 9 and HOMOCOSY spectrum only for 10) NMR spectroscopic data. The conformational preferences of N-chloroacetyl-2,6-diarylpiperidin-4-ones with and without alkyl substituent at C-3 and C-5 (8–14) have also been discussed using the spectral studies. The spectral data and extracted coupling constant values suggest that the compounds 8, 12 and 14 adopt flattened boat conformation whereas the remaining compounds exist in twist-boat conformations in solution with coplanar orientation of the chloroacetyl moiety present at the heterocyclic nitrogen. The substituent parameters for the chloroacetyl moiety on the heterocyclic ring carbons have also been derived and discussed elaborately on the basis of their steric, electronic and γ-eclipsing interaction. This substituent at the nitrogen causes a substantial change on the chemical shifts of ring carbons and the associated protons.
Keywords: 1H NMR; 13C NMR; 2D techniques; Conformation; Substituent effect; 2,6-Diarylpiperidin-4-ones; Chloroacetylation;
Interaction of water-soluble cationic porphyrin with anionic surfactant by Wen-Ge Qiu; Zong-Feng Li; Guang-Mei Bai; Sheng-Nan Meng; Hong-Xing Dai; Hong He (1164-1169).
The interaction of a cationic water-soluble porphyrin, 5,10,15,20-tetrakis [4-(3-pyridiniumpropoxy)phenyl]porphyrin tetrakisbromide (TPPOC3Py), with anionic surfactant, sodium dodecyl sulfate (SDS), in aqueous solution has been studied by means of UV–vis, 1H NMR, fluorescence, circular dichroism (CD) spectra and dynamic laser light scattering (DLLS), and it reveals that TPPOC3Py forms porphyrin-surfactant complexes (aggregates), including ordered structures J- and H-aggregates, induced by association with surfactant monomers below the SDS critical micelle concentration (cmc), and forms micellized monomer upon the cmc, respectively. The position of TPPOC3Py in the micelle is determined, which is not in the micelle core instead of intercalated among the SDS chains, most likely with the pyridinium group extending into the polar headgroup region of the micelle.
Keywords: Water-soluble porphyrin; Surfactant; Premicellar aggregate; Micellized monomer;
Theoretical calculations and vibrational spectra of 1,4-benzodioxan in its S1(π, π*) electronic excited state by Juan Yang; Jaebum Choo; Ohyun Kwon; Jaan Laane (1170-1173).
The structure and vibrational frequencies of 1,4-benzodioxan in its S1(π, π*) electronic state have been calculated using the GAUSSIAN 03 and TURBOMOLE programs. The results have been compared to experimental data and also to the ground state. Structural data for the T1(π, π*) state have also been calculated. The theoretical frequencies agree very well with the experimental values for the S0 electronic ground state but are less accurate for the S1 excited state. Nonetheless, they provide valuable guidance for excited state calculations.
Keywords: 1,4-Benzodioxan; Vibrational spectra; Theoretical calculations; Molecular structures; Electronic states;
A sequential injection method for the fluorimetric determination of aluminum in drinking water using 8-hydroxy-7-(4-sulfo-1-naphthylazo)-5-quinoline sulfonic acid by Salma M.Z. Al-Kindy; Salwa S. Al-Ghamari; Fakhr Eldin O. Suliman (1174-1179).
A robust and simple sequential injection (SI) method for the assay of aluminum ions in drinking water is described. The method is based on the complex formation between aluminum and 8-hydroxy-7-(4-sulfo-1-naphthylazo)-5-quinoline sulfonic acid (HSNQ). The fluorescence of the complex is monitored at an emission wavelength of 492 nm with excitation at 357 nm. The HSNQ concentration, aspirated reagent and sample volumes were optimized simultaneously using 33 full factorial design. The optimum operating conditions are aspirated sample and reagent volumes of 90 and 70 μL, respectively, and HSNQ concentration of 20 μM. With these conditions linear calibration curves were obtained from 100 to 800 ppb. The detection limit was 4 ppb. The maximum relative standard deviation of the method was 1.43% (n = 5). The method was successfully applied for the determination of aluminum in drinking water samples.
Keywords: Aluminum; SIA; Spectrofluorimetry 8-hydroxy-7-(4-sulfo-1-naphthylazo)-5-quinoline sulfonic acid (HSNQ); Water analysis;
Investigation of the effect of tanshinone IIA on nitric oxide production in human vascular endothelial cells by fluorescence imaging by Ke-Jing Huang; Hong Wang; Wan-Zhen Xie; Hua-Shan Zhang (1180-1186).
Nitric oxide (NO) has been proved to be a potent vasodilator that played an important role in regulating vascular tones. Tanshinone, one of the active components of Radix Salvia miltiorrhiza, was used widely in clinics in China for treating cardiovascular diseases. The objective of this study was to sensitively and specifically investigate the effects of tanshinone IIA, one important pharmacological constituent of tanshinone, on the release of NO from human vascular endothelial cells (HVECs) by fluorescence imaging with an excellent fluorescent probe 1,3,5,7-tetramethyl-2,6-dicarbethoxy-8-(3′,4′-diaminophenyl)-difluoroboradiaza-s-indacence (TMDCDABODIPY). After cells were incubated with tanshinone IIA, TMDCDABODIPY was employed to label NO. Following the tagging, real-time imaging of NO release from the cells was performed with inverted fluorescence microscope. The results of the experiments showed that tanshinone IIA could induce NO production significantly enhanced in HVECs. The activation of NO by tanshinone IIA may be employed therapeutically in modulating NO production in HVECs.
Keywords: Tanshinone IIA; Nitric oxide; 1,3,5,7-Tetramethyl-2,6-dicarbethoxy-8-(3′,4′-diaminophenyl)-difluoroboradiaza-s-indacence; Imaging; Human vascular endothelial cells;
Spectroscopic and structural elucidation of l-tyrosine-containing dipeptides valyl-tyrosine and tyrosyl-alanine: Solid-state IR-LD spectroscopy, quantum chemical calculations and vibrational analysis by Bojidarka B. Koleva; Tsonko M. Kolev; Michael Spiteller (1187-1196).
l-Tyrosine-containing dipeptides valyl-tyrosine (H-Val-Tyr-OH) and tyrosyl-alanine (H-Tyr-Ala-OH) are characterized structurally by means of quantum chemical ab initio calculations and solid-state linear-dichroic infrared (IR-LD) spectroscopy. The IR-characteristic bands are assigned by application of reducing-difference procedure for polarized IR-spectra interpretation. Infrared data obtained are supported as well by the made vibrational analysis. The structures of both peptides are predicted on the basis of conformational analysis and structural information, obtained by the shown IR-spectroscopic tool.
Keywords: H-Val-Tyr-OH; H-Tyr-Ala-OH; IR-LD analysis; 1H and 13C NMR; Ab initio calculations;
Structural determination of Zn and Cd–DTPA complexes: MS, infrared, 13C NMR and theoretical investigation by Vanézia L. Silva; Ruy Carvalho; Matheus P. Freitas; Cláudio F. Tormena; Walclée C. Melo (1197-1200).
The joint application of MS, infrared and 13C NMR techniques for the determination of metal–DTPA structures (metal = Zn and Cd; DTPA = diethylenetriaminepentacetic acid) is reported. Mass spectrometry allowed determining the 1:1 stoichiometry of the complexes, while infrared analysis suggested that both nitrogen and carboxyl groups are sites for complexation. The 13C NMR spectrum for the cadmium-containing complex evidenced the existence of free and complexed carboxyl groups, due to a straight singlet at 179.0 ppm (free carboxylic 13C) and to two broad singlets or a broad doublet at 178.3 ppm (complexed carboxylic 13C, 2 J Cd–C(=O) = 45.2 Hz). A similar interpretation might be given for the zinc derivative and, with the aid of DFT calculations, structures for both complexes were then proposed.
Keywords: Zn/Cd complexes; DTPA; MS; Infrared; 13C NMR; DFT calculations;
Calibration in non-linear NIR spectroscopy using principal component artificial neural networks by Ying Dou; Tingting Zou; Tong Liu; Nan Qu; Yulin Ren (1201-1206).
Near-infrared (NIR) spectroscopy was used in simultaneous, non-destructive analysis of antipyriine and caffeine citrate tablets. Principal component artificial neural networks (PC-ANNs) were used to construct models for the analytes, using the testing set for external validation. Four pretreated spectra, namely, first-derivative, second-derivative, standard normal variate (SNV) and multiplicative scatter correction (MSC) spectra led to simplified and more robust models than conventional spectra. In PC-ANNs models, the spectra data were analyzed by principal component analysis (PCA) firstly. Then the scores of the principal compounds (PCs) were chosen as input nodes for input layer instead of the spectra data. The artificial neural networks (ANNs) models using the spectra data as input nodes were also established, which were compared with the PC-ANNs models. The result shows the SNV model of PC-ANNs multivariate calibration has the lowest training error and predicting error. The concept of the degree of approximation was introduced and performed as the selective criterion of the optimum network parameters.
Keywords: PC-ANNs; Pretreated spectra; Antipyriine and caffeine citrate tablets; Degree of approximation;
Complexations of Hg(CN)2 with imidazolidine-2-thione and its derivatives: Solid state, solution NMR and antimicrobial activity studies by Mohamed I.M. Wazeer; Anvarhusein A. Isab (1207-1212).
The preparation and characterization of new mercuric complexes of formula L2Hg(CN)2 with L being imidazolidine-2-thione (Imt) and its substituted derivatives, 1,3-diazinane-2-thione (Diaz), 1,3-diazipane-2-thione (Diap), are described. The solution and solid-state 13C NMR show a significant shift of the C＝S carbon resonance of the ligands, while the other resonances are relatively unaffected, indicating that most likely the solid-state structure is maintained in solution as well. The principal components of the 199Hg shielding tensors were determined from solid-state NMR data. Antimicrobial activity studies of the free ligands and their complexes show that ligands exhibit substantial antibacterial activities compare to their Hg(II) complexes.
Keywords: Mercuric cyanide complexes; Imidazolidine-2-thione; CP MAS NMR; Antibacterial activity;
Crystal growth, thermal and optical studies on a semiorganic nonlinear optical material for blue-green laser generation by J. Ramajothi; S. Dhanuskodi (1213-1219).
The semiorganic nonlinear optical material l-histidine bromide (l-HB) has been synthesized in aqueous solution and characterized by FT-IR, FT-Raman and FT-NMR spectroscopic techniques. The single crystals with dimensions 9 mm × 4 mm × 3 mm were grown by slow evaporation techniques. The grown crystals were subjected to single crystal X-ray diffraction to determine the unit cell dimensions. The thermal stability of the grown crystal was analyzed by thermogravimetric (TG), differential thermal (DT) and differential scanning calorimetric (DSC) analyses. The UV–vis transmittance spectrum shows that it has a good optical transmittance in the entire visible region with the lower cutoff wavelength at 220 nm. The SHG conversion efficiency and laser damage threshold were measured using a Nd:YAG laser (1064 nm). The optical birefringence was measured in the visible region as a function of temperature in the range 30–150 °C by interference technique.
Keywords: Crystal growth from solution; Nonlinear optical material; Birefringence; Thermal analysis; Laser damage threshold;
Application of spectrophotometric, densitometric, and HPLC techniques as stability indicating methods for determination of Zaleplon in pharmaceutical preparations by Fadia H. Metwally; M. Abdelkawy; Nada S. Abdelwahab (1220-1230).
Spectrophotometric, spectrodensitometric and HPLC are stability indicating methods described for determination of Zaleplon in pure and dosage forms.As Zaleplon is easily degradable, the proposed techniques in this manuscript are adopted for its determination in presence of its alkaline degradation product, namely N-[4-(3-cyano-pyrazolo[1,5a]pyridin-7-yl)-phenyl]-N-ethyl-acetamide. These approaches are successfully applied to quantify Zaleplon using the information included in the absorption spectra of appropriate solutions.The second derivative (D2) spectrophotometric method, allows determination of Zaleplon without interference of its degradate at 235.2 nm using 0.01N HCl as a solvent with obedience to Beer's law over a concentration range of 1–10 μg ml−1 with mean percentage recovery 100.24 ± 0.86%.The first derivative of the ratio spectra (1DD) based on the simultaneous use of (1DD) and measurement at 241.8 nm using the same solvent and over the same concentration range as (D2) spectrophotometric method, with mean percentage recovery 99.9 ± 1.07%.The spectrodensitometric analysis allows the separation and quantitation of Zaleplon from its degradate on silica gel plates using chloroform:acetone:ammonia solution (9:1:0.2 by volume) as a mobile phase. This method depends on quantitave densitometric evaluation of thin layer chromatogram of Zaleplon at 338 nm over a concentration range of 0.2–1 μg band−1, with mean percentage recovery 99.73 ± 1.35.Also a reversed-phase liquid chromatographic method using 5-C8 (22 cm × 4.6 mm i.d. 5 μm particle size) column was described and validated for quantitation of Zaleplon using acetonitrile:deionised water (35:65, v/v) as a mobile phase using Paracetamol as internal standard and a flow rate of 1.5 ml min−1 with UV detection of the effluent at 232 nm at ambient temperature over a concentration range of 2–20 μg ml−1 with mean percentage recovery 100.19 ± 1.15%.The insignificance difference of the proposed methods results with those of the reference one proved their accuracy and precision.
Keywords: Zaleplon; Derivative spectrophotometry; Derivative ratio spectrodensitometry; HPLC;
Synthesis, characterization and photochromic studies of three novel calixarene–Schiff bases by Zhi Liang; Zhilian Liu; Yunhua Gao (1231-1235).
Synthesis and characterization of three novel Schiff bases based on calixarene are described. The synthesis of these compounds had been achieved by the condensation of salicylaldehyde derivatives with the amine group of upper rim of de-butylcalixarene in ethanol. The structures of new compounds were confirmed on the basis of IR, 1H NMR, 13C NMR, MS and elementary analysis. Photochromic properties of compounds were studied in CH3CN by UV/vis and fluorescence spectra. These Schiff base–calixarene can be used in certain ‘supermolecular electronic devices’ through combining the photochromic behaviors with others such as non-linear optical or charge transfer properties.
Keywords: Calixarene; Schiff base; Photochromism;
Hartree-Fock, Møller-Plesset calculations and dynamic NMR study of 3,3-dimethoxy-1-(imidazolidin-2-ylidene)propan-2-one by Ali Hassanzadeh; Hossein Loghmani-Khouzani; Majid Mirmohammad Sadeghi; Mohammad Hassan Ghorbani (1236-1243).
The experimental 1H, 13C NMR spectra of 3,3-dimethoxy-1-(imidazolidin-2-ylidene)propan-2-one were recorded in CDCl3 at temperature range 213–323 K. The variable temperature spectra revealed a dynamic NMR effect which is attributed to restricted rotation around the C＝C double bond. Fast exchange processes of deuterium atoms between CDCl3 and 3,3-dimethoxy-1-(imidazolidin-2-ylidene)propan-2-one or fast exchange of proton between nitrogen and oxygen atoms of carbonyl group is also revealed by broadening of N–H (singlet) proton NMR signals. Proton and carbon theoretical chemical shifts of the title molecule were calculated by using RHF and MP2-GIAO levels and different basis sets in gas phase at 298 K. The calculated proton chemical shifts show that the experimental values have no agreement with theoretical values, but for carbon chemical shifts a good agreement achieved by using RHF with 6-31G basis set and MP2/3-21G, 6-31G basis sets. Discrepancies are attributed to either the limitations of calculating program, because the change of the structure while rotation are not considered. The results showed that to select of basis set has more important rule, because RHF–GIAO level calculation with 6-31G basis set in gas phase can excellently reproduce the 13C NMR spectrum. Moreover, MP2/3-21G, 6-31G calculation has not significant influence on 13C NMR chemical shifts with respect to RHF–6-31G.
Keywords: Hartree-Fock and Møller-Plesset NMR chemical shift calculation; Dynamic NMR; Heterocyclic α-oxoketene aminals;
Utility of 7,7,8,8-tetracyanoquinodimethane charge transfer reagent for the spectrophotometric determination of trazodone, amineptine and amitriptyline hydrochlorides by Gehad G. Mohamed; Faten A.F. Nour El-Dien; Nehad A. Mohamed (1244-1249).
A simple and rapid spectrophotometric method has been developed for the determination of tricyclic anti-depressant drugs such as trazodone (TZH), amineptine (APH) and amitriptyline (ATPH) hydrochlorides in pure form and in different pharmaceutical preparations. The charge transfer (CT) reaction between TZH, APH and ATPH as electron donors and TCNQ as electron acceptor was utilized for their spectrophotometric determination. The optimum experimental conditions, like time, temperature, stoichiometry, solvents, for the CT complex formation are established. The method permits the determination of TZH, APH and ATPH over a concentration range of 10–400, 10–440 and 10–300 μg ml−1, respectively. The sensitivity (S) is found to be 0.09, 0.087 and 0.069 g cm−2 for TZH, APH and ATPH, respectively. The SD values are found to be 0.146–0.293, 0.154–0.285 and 0.091–0.212 and RSD values are 0.142–1.92, 0.297–1.92 and 0.212–0.915 for TZH, APH and ATPH, respectively. The low values of the relative standard deviation indicate the high accuracy and precision of the method. The mean recovery values obtained together with a high correlation coefficient values, amount in the range 98–101.5, 98.7–102.9 and 93–101.9 for TZH, APH and ATPH, respectively. The method is applicable for the assay of the investigated drugs in different dosage forms and the results are in good agreement with those obtained by the official method.
Keywords: Spectrophotometric; THZ; APH and ATPH determination; TCNQ; Pharmaceutical preparations;
Spectroscopic and electrochemical investigation with coordination stabilities: Mononuclear manganese(II) complexes derived from different constituents macrocyclic ligands by Rajiv Kumar; S. Chnadra; Parashuram Mishra (1250-1255).
Since the manganese(II) complexes are known as having a high degree of stability, some of them may be able to play a very important role in biosystems. We prepared manganese(II) complexes with different chromospheres containing macrocyclic ligands bearing N, S and O like functional donor atoms in order to obtain different models of compounds. So these new manganese(II) complexes were derived from macrocyclic ligands by chelating them with metal ions.Thus, two macrocyclic ligands, L1: 2,4-diphenyl-1,5-diaza-8,12-dioxo-6,7:13,14-dibenzocyclo tetradeca-1,4-diene[N2O2]ane; L2: 2,4,9,11-tetraphenyl-6,13-dimethyl-1,5,8,12-traazacyclotertr-adeca-1,4,8,11-tetraene[N4]ane; and two more different form first one viz.—L3: 1,7-diaza-4-monothia-10,14-dioxo-8,9:15,16-cyclohexadecane[N2O2S]ane and L4: 4,13-diaoxa-1,7,10,16-hexazacyclooctadecane[N4O2]ane were prepared and their capacity to retain the manganese(II) ion in solid as well as aqueous solution was determined from various physiochemical techniques viz: characterized by elemental analyses, molar conductance measurements, magnetic susceptibility measurements, mass, IR, electronic, ESR spectral studies and cyclic voltammetric measurements.
Keywords: Macrocyclic ligands; 1H NMR; IR; EPR; Manganese(III) complexes;
Mononuclear and binuclear sandwich copper(II) complexes with poly(pyrazolyl)borate ligands: Syntheses, structures and properties by Y.H. Xing; X.J. Zhang; Z. Sun; J. Han; Y.H. Zhang; B.L. Zhang; M.F. Ge; S.Y. Niu (1256-1262).
A series of Cu(II) complexes Cu2[μ-pz]2[HB(pz)3]2 (1), Cu[H2B(pz)2]2 (2), Cu[HB(pz)3]2 (3), Cu[HB(pzMe2)3]2 (4), Cu[B(pz)4]2 (5) (pz = pyrazole), have been synthesized and characterized by elemental analysis, IR, UV–vis, X-ray diffraction, thermal analysis and theoretical analysis. The IR spectra give the Cu–N vibration modes at 322, 366, 344, 387, and 380 cm−1 in complexes 1–5, respectively. The UV spectra show all the complexes have same UV absorption at 232 nm; there is another band at 332 nm for complexes 1, 2 and 4, while for complexes 3 and 5, the bands are at 272 and 308 nm, respectively. Complex 1 has a binuclear structure in which two pyrazole ligands bridge two Cu-Tp units. In 2–5, the Cu(II) centers are coordinated with dihydrobis(pyrazolyl)borate (Bp), hydrotris(pyrazolyl)borate (Tp), hydrotris(3,5-Me2pyrazolyl)borate (Tp′), tetrakis(pyrazolyl)borate (Tkp) respectively to form a mononuclear structure. The results of thermal analysis for complexes 1–5 are discussed too.
Keywords: Poly(pyrazolyl)borate; Copper complexes; Spectra properties; Thermal analyses; Quantum chemical calculations;
Spectroscopic investigation of inner filter effect by magnolol solutions by Hongmei Li; YuzhuHu (1263-1268).
Spectroscopy is useful tool for aggregation studies on fluorephores. One of the major problems with this technique is that the inner filter effect becomes unavoidable since the samples are used at high concentration. In this work, our investigation on magnolol spectroscopic properties shows that the inner filter effect (IFE) of fluorescence plays a critical role in the spectra of magnolol. The strong dependence of the fluorescence parameters on the concentration accounts for the apparent experimental evidence of magnolol aggregation at high concentrations. There are some questions despite the aggregation model based on fluorescent aggregates seems to describe the behavior of the system. The mathematical correction on the emission intensities shows the linear fluorescence–concentration relationship. Furthermore, we propose a mathematic model of excitation spectrum based on the primary IFE (absorption of light of excitation wavelength), which provide a correct explanation of the unusual spectral shift and spectral narrowing in the excitation spectra of magnolol at high concentrations. The shapes of spectra are completely independent on magnolol aggregation and are due only to experimental artifacts, i.e. IFE.
Keywords: Magnolol; Aggregation; Inner filter effect; Excitation spectrum; Correction;
Investigation on infrared spectra of androsterone in single solvents by Qing Liu; Chao Cong; Hui Zhang (1269-1273).
The infrared absorption spectra of the androsterone in 19 pure organic solvents have been investigated. The carbonyl stretching vibration frequencies of androsterone observed in the solvents were correlated with the empirical parameters G, Swain parameters (A j and B j ) and the linear solvation energy relationships (LSER). The applicabilities of different parameters were discussed and the solute–solvent interactions in single solvents were studied in detail. The correlation results indicated that the LSER is optimal for a complete description of solute–solvent interactions while G-values and Swain parameters are unilateral.
Keywords: Infrared spectra; Solvent effects; Empirical solvent parameters; Androsterone;
A spectrophotometric study of the charge transfer complexes of fullerene with different tert-butylcalixcrowns by Shehadeh A. Mizyed; Elita Al-Jarrah; Deeb Marji; Muhammad Ashram (1274-1277).
Formation of the charge-transfer complexes between various calixcrowns (1–4) and fullerene were studied in toluene solution using UV–vis spectrophotometry. The stability constants and the thermodynamic data of the resulting 1:1 complexes were determined and were found to decrease with increasing the size of the crown moiety of the calixcrown. Except the complex of 3, all the complexes were found to be enthalpy stabilized but disfavored in terms of entropy.
Keywords: Charge-transfer complexes; Calixcrownethers; Fullerene; UV–vis spectrophotometry;
Perchlorate mixed–ligand copper(II) complexes of β-diketone and ethylene diamine derivatives: Thermal, spectroscopic and biochemical studies by Usama El-Ayaan; Nashwa M. El-Metwally; Magdy M. Youssef; Serry A.A. El Bialy (1278-1286).
The present work carried out a study on perchlorate mixed–ligand copper(II) complexes which have been synthesized from ethylenediamine derivatives (3a–c) and β-diketones. These complexes, namely [Cu(DA-Cl)(acac)H2O]ClO4 4, [Cu(DA-Cl)(bzac)H2O]H2O.ClO4 5, [Cu(DA-OMe)(acac)H2O]ClO4 6, [Cu(DA-OMe)(bzac)H2O]ClO4 7, [Cu(DA-H)(acac)H2O]2H2O.ClO4 8 and [Cu(DA-H)(bzac)H2O]ClO4 9 (where acac, acetylacetonate and bzac, benzoylacetonate) were characterized by elemental analysis, spectral (IR and UV–vis) and magnetic moment measurements. Thermal properties and decomposition kinetics of all complexes are investigated. The interpretation, mathematical analysis and evaluation of kinetic parameters (E, A, ΔH, ΔS and ΔG) of all thermal decomposition stages have been evaluated using Coats–Redfern equation. The biochemical studies showed that, the diamines 3a–c have powerful effects on degradation of DNA and protein. The antibacterial screening demonstrated that, the diamine (DA-Cl), 3b has the maximum and broad activities against Gram +ve and Gram −ve bacterial strains.
Keywords: Ethylene diamine derivatives; Thermal degradation kinetics; Biochemical; DNA; Antibacterial;
A theoretical investigation on the geometry and vibrational spectra of 10,10,2,6,5-pentamethyl-1-hydroxychroman: A model of α-tocopherol by Yong Guo; Yuanqiang Zhu; Ying Xue; Daiqian Xie (1287-1295).
In the present study, density functional theory calculations with the combined Becke's three-parameter exchange functional in combination with the Lee, Yang, and Parr correlation functional (B3LYP) exchange-correlation energy functions were performed by using the 6-311G** basis set to study the structure and vibrational spectra of 10,10,2,6,5-pentamethyl-1-hydroxychroman (a model of α-tocopherol). The fully optimized geometry of the molecule was found to be very consistent with the X-ray crystal structure. The predicted vibrational frequencies made it possible to give a reliable assignment of the IR spectrum of the molecule according to the potential energy distributions (PEDs).
Keywords: Vibrational spectra; 10,10,2,6,5-Pentamethyl-1-hydroxychroman; Density functional theory; PEDs;
Vibrational spectra of dipropylsulfoxide by Shiraz A. Markarian; Liana S. Gabrielian; Sergio Bonora (1296-1304).
FTIR and Raman spectra analysis of pure dipropylsulfoxide (DPSO), binary mixtures of DPSO/CCl4, and DPSO/water has been first performed.The complex pattern of spectra has been explained on the basis of molecular interactions between DPSO and other molecules and, in the aqueous solutions, the role of both hydrophilic and hydrophobic interactions have been discussed depending on the concentrations. The changes in the intensities and in the frequencies of DPSO bands on concentration have been considered.The curve fitting procedure has been performed for both S＝O and C–H stretching region, and, on the basis of deconvolution results different type of molecular interactions have been considered. Density function theory DFT/(B3LYP) method has been used to determine the optimized geometry for free DPSO and for 1 DPSO:1 water complex. On the basis of the 6-31 + G(d) quality sets parameters, the DFT calculated bond parameters and harmonic vibrations are in a very good agreement with experimental data.
Keywords: FTIR; Raman spectroscopy; Dipropylsulfoxide;
Optical absorption spectroscopic studies on holmium(III) complexes with β-diketone and heterocyclic amines by A.A. Ansari; H. Arshad Hussain; K. Iftikhar (1305-1312).
The optical absorption spectra of [Ho(acac)3(H2O)2]·H2O, [Ho(acac)3phen] and [Ho(acac)3bpy] (where acac is the anion of acetylacetone; phen is 1,10-phenanthroline and bpy is 2,2′-bipyridyl) complexes in the visible region, in a series of non-aqueous solvents (methanol, ethanol, isopropanol, chloroform, acetonitrile and pyridine.) have been analyzed. The largest intensity variation was observed in the 5G6 ← 5I8 (centered at 450 nm), and 5G5, 3H5, 3H6 ← 5I8 (centered at 360 nm) transition regions. The band shape and oscillator strength of the hypersensitive transitions display pronounced changes as compared to Ho3+ aqua-ion. The band shapes of the hypersensitive transitions show remarkable changes on passing from aqueous solution to various non-aqueous solutions which is the result of change in the environment about the Ho(III) ion in the various solutions and suggests coordination of solvent molecule(s), in some cases. The results clearly show that among the solvents studied pyridine is the most effective in promoting the 4f–4f spectral intensity. It has been inferred from this study that 2,2′-bipyridyl is a stronger ligand for heavier lanthanides. A comparative account of hypersensitivity in the present complexes with those of other adducts of Ho(β-diketoenolate)3 with heterocyclic amines is discussed. The TGA analyses showed that the phen complex is thermally more stable over its bpy analogue.
Keywords: Lanthanide complexes; Holmium complexes; Pentanedione complexes; f–f absorption spectra; Hypersensitivity; Oscillator strength;
Comparison of the adsorption orientation for 2-mercaptobenzothiazole and 2-mercaptobenzoxazole by SERS spectroscopy by Chul Jae Lee; Seung Yong Lee; Mohammad Rezaul Karim; Mu Sang Lee (1313-1319).
In this study, the adsorption orientation for 2-mercaptobenzothiazole (MBT) and 2-mercaptobenzoxazole (MBO) on to silver mirror and silver sol substrates have been studied by surface enhanced Raman scattering (SERS). The MBT and MBO were chemisorbed on both silver mirror and silver sol after deprotonation with a tilted orientation to the silver surfaces. The surface enhanced properties of MBT and MBO showed that the substrate of silver mirror was superior to the sliver sol. The SERS spectra of MBT and MBO revealed that both of the MBT and MBO were adsorbed on silver surfaces strongly by a common sulfur molecule and a sulfur atom from MBT and an oxygen atom from MBO. Therefore, the adsorption orientation of MBT and MBO was little tilted perpendicularly to the silver surfaces. The adsorption geometry did not undergo any significant changes in acidic and basic solutions. It showed that the adsorption orientation for MBT and MBO were stable in the both solutions.
Keywords: Surface-enhanced Raman spectroscopy; MBT; MBO; Silver mirror; Silver sol;
Comparison effects of different doping on spin-Peierls transition in CuGeO3 by Orhan Yalçın (1320-1325).
The comparison between non-magnetic spin-Peierls (SP) and magnetic Néel ground states have been investigated in CuGeO3 doped with Zn2+, Ni2+ and Mn2+ ions by using the electron spin resonance (ESR) techniques in the temperature range of 3–300 K. It was concluded that the one-dimensional (1D) antiferromagnetic (AF) spin chain formed of spin-1/2 (Cu2+) ions is broken by spin-0 (Zn2+), spin-1 (Ni2+), and spin-5/2 (Mn2+) ions, giving uncoupled spins at the end of the chains that give extra contribution to the spectra at lower temperature. An almost linearly dependence of frequency of resonance field has been showed for X-, K- and Q-band spectra. By the analysis of resonance field–frequency relations, the effects of the internal field is refined and thus the spectroscopic g-factor and internal field were calculated to be g = 1.9386 and H i = 148 G, respectively.
Keywords: Electron spin resonance; Spin-Peierls transition; CuGeO3; Doping effect;
Ab initio studies of the λ max of naphthoquinones dyes by Eric A. Perpète; Christophe Lambert; Valérie Wathelet; Julien Preat; Denis Jacquemin (1326-1333).
Using a state-of-the-art time-dependent density functional (TD-DFT) approach that includes the explicit consideration of bulk medium effects on both the ground-state geometry and the electronic spectrum, we have determined the λ max of 86 naphthoquinones (NQ) dyes in various solvents for a total of 151 cases. In most cases, TD-DFT provides the correct ordering of transitions for substituted NQ dyes. Comparisons with experimental values lead to a mean signed error of −7.2 nm (0.039 eV) and a mean absolute error of 20.1 nm (0.113 eV). It turns out that the average errors are smaller for the hydroxy and methoxy derivatives, than for amino substituted dyes. It is also demonstrated that the statistical treatment of the data does not significantly improve the agreement between the experimental and the theoretical values. We also discuss average basis set effects and solvatochromism.
Keywords: Naphthoquinones; Visible spectra; TD-DFT; PCM;
Vibrational spectra and ab initio analysis of tert-butyl, trimethylsilyl, trimethylgermyl, trimethylstannyl, and trimethylplumbyl derivatives of 3,3-dimethylcyclopropene by Yu.N. Panchenko; G.R. De Maré; V.I. Pupyshev; A.V. Abramenkov (1334-1339).
The changes in the vibrational frequencies of 1-tert-butyl and 1,2-di-tert-butyl derivatives of 3,3-dimethylcyclopropene brought about by substitution of the central carbon atom (X) of the tert-butyl moieties by Si, Ge, Sn, or Pb atoms are examined. The most important decrease in the vibrational frequencies implicating the X(CH3)3 moieties is noted for substitution of X = C by Si. The substitutions of Si by Ge or Ge by Sn or Sn by Pb are not accompanied by the pronounced frequency shifts observed for the C → Si transition. An explanation is given for trends in these vibrational frequencies for the transitions X = C → Si → Ge → Sn → Pb. It is concluded that there are lower limiting values of the vibrational frequencies of a molecular moiety which are approached when the mass of its isovalent atom is increased. This leads to the formation of cluster regions in the vibrational spectra for the frequencies of the SnC3 and PbC3 moieties.
Keywords: 3,3-Dimethyl-1,2-bis(tert-butyl)cyclopropene; 3,3-Dimethyl-1,2-bis(trimethylsilyl)cyclopropene; 3,3-Dimethyl-1,2-bis(trimethylgermyl)cyclopropene; 3,3-Dimethyl-1,2-bis(trimethylstannyl)cyclopropene; 3,3-Dimethyl-1-(t-butyl)cyclopropene; 3,3-Dimethyl-1-(trimethylsilyl)cyclopropene; 3,3-Dimethyl-1-(trimethylgermyl)cyclopropene; 3,3-Dimethyl-1-(trimethylstannyl)cyclopropene; 3,3-Dimethyl-1-(trimethylplumbyl)cyclopropene; Isovalent heteroatoms; Vibrational spectra;
Identification of the monoanions and of their complexes with lithium salts possibly formed in solution during the alkylation of lithiated phenylacetonitrile dianions: Infrared spectroscopy and density functional theory calculations by Jacques Corset; Martine Castellà-Ventura; Françoise Froment; Tekla Strzalko; Lya Wartski (1340-1346).
The carbanionic species possibly formed during the first alkylation step of phenylacetonitrile lithiated anion by CH3I and PhCH2Cl in THF–hexane solution and their complexes with the lithium salt formed have been observed by infrared spectrometry and characterized by density functional theory calculations. The spectra of alkylated phenylacetonitrile lithiated anion monomers and dimers have been identified in good agreement with calculations. The wave numbers of the vibrational modes of the alkylated species differ significantly from those of PhCHCNLi species, but do not depend appreciably on the substituent nature. Nevertheless with the methyl substituent, the isomerization equilibrium of the monomer is noticeably shifted toward the bridged (C-lithiated) species. The formation of a heterodimer at the expense of the dimer after addition of LiCl has been confirmed by experiment.
Keywords: Lithiated phenylacetonitrile; Lithiated alkylated phenylacetonitrile; Monoanions; Heterodimers; IR spectra; DFT calculations;
The molecular structure and vibrational spectra of 2-chloro-N-(diethylcarbamothioyl)benzamide by Hartree–Fock and density functional methods by Hakan Arslan; Ulrich Flörke; Nevzat Külcü; Gün Binzet (1347-1355).
2-Chloro-N-(diethylcarbamothioyl)benzamide (C12H15ClN2OS) has been synthesized and characterized by elemental analysis and IR spectroscopy. The crystal and molecular structure of the title compound has been determined from single crystal X-ray diffraction data. It crystallizes in the orthorhombic space group Pbca, Z = 8 with a = 9.581(3) Å, b = 9.992(3) Å, c = 26.640(8) Å, V = 2550.5(13) Å3 and D calc = 1.410 Mg/m3. The molecular geometry and vibrational frequencies of 2-chloro-N-(diethylcarbamothioyl)benzamide in the ground state have been calculated using the Hartree–Fock and density functional using Becke's three-parameter hybrid method with the Lee, Yang and Parr correlation functional (B3LYP) methods with 3-21G and 6-31G(d) basis sets. The calculated geometric parameters were compared to the corresponding X-ray structure of the title compound. The raw B3LYP frequencies approximate the experimental data much better than the results of Hartree–Fock. The scaled B3LYP/6-31G(d) results were more reliable than those obtained using the B3LYP/3-21G method with the mean absolute deviation about 13.7 cm−1. On the basis of the comparison between calculated and experimental results, assignments of fundamental vibrational modes were examined.
Keywords: 2-Chloro-N-(diethylcarbamothioyl)benzamide; Thiourea; DFT; HF; Infrared spectrum; Molecular calculations;
Synthesis of functionalized CdTe/CdS QDs for spectrofluorimetric detection of BSA by Ying Yu; Yan Lai; Xiuli Zheng; Jianzhong Wu; Zhaoyang Long; Chunsui Liang (1356-1361).
Luminescent quantum dots (QDs)-semiconductor nanocrystals are a promising alternative to organic dyes for fluorescence-based applications. We have developed procedures to use CdS to encapsulate CdTe and synthesize a new kind of functionalized CdTe/CdS QDs for the quantitative and selective determination of bovine serum albumin (BSA). Maximum fluorescence intensity was produced at pH 6.83, with excitation and emission wavelengths at 336 and 524 nm, respectively. Under optimal conditions, the straight line equation: ΔF = 6.84 + 62.29 C (10−6 mol dm−3) was found between the relative fluorescence intensity and the concentration of BSA in the range of 0–1.2 × 10−6 mol dm−3, and the limit of detection was 5.4 × 10−8 mol dm−3. Based on this approach, a novel quantitative method for the determination of BSA is presented in this paper.
Keywords: Quantum dots/QDs; Spectrofluorimetric detection; Nanoparticles; Bovine serum albumin;
Preparation, properties and infrared spectral studies of N-(p-ethylphenyl)thiobenzohydroxamic acid by Rita Kakkar; Amita Dua; Sheza Zaidi (1362-1369).
The preparation of N-(p-ethylphenyl)thiobenzohydroxamic acid and its spectral properties are described in this paper. The preferred conformation of the acid is investigated by both infrared techniques and theoretical calculations at the DFT level. It is found that the acid exists in the cis thione (Z) form, rather than the trans form (E) in the gas phase. Both infrared spectroscopy and theoretical calculations show that this structure is stabilized by intramolecular hydrogen bonding.
Keywords: Thiobenzohydroxamic acid; IR; DFT; B3LYP; Conformation;
Fourier transform infrared spectrum, vibrational analysis and structural determinations of the trans-bis(glycine)nickel(II) complex by means of the RHF/6-311G and DFT:B3LYP/6-31G and 6-311G methods by Joanna Maria Ramos; Otavio Versiane; Judith Felcman; Claudio A. Téllez Soto (1370-1378).
The trans-bis(glycine)nickel(II) complex was synthesized, and the Fourier transform infrared spectra in the regions 4000–370 cm−1 and 700–30 cm−1 were measured. Band deconvolution analysis and the second derivative of the infrared spectrum were also performed. The determination of the geometrical structure in the trans position of the glycine ligands around Ni(II) for the trans-bis(glycine)nickel(II) complex as well as the vibrational assignment were assisted by RHF/6-311G and by Density Functional Theory calculations, DFT:B3LYP/6-31G and 6-311G basis sets. A full discussion of the framework vibrational modes was done using as criteria the geometry study of distorted structures generated for the vibrational modes. Incidentally, Normal Coordinate Analysis was carried out for the Ni(N)2(O)2 structural fragment. The calculated DFT spectra in the high- and low-energy regions agree with the observed ones.
Keywords: trans-Bis(glycine)nickel(II) complex; Structure and vibrational spectra; DFT:B3LYP/6-311G and 6-31G basis sets;
Optical T–T absorption of salicylidene-p-toluidine in solution by İpek Ş. Karaaslan; Fuat Bayrakçeken (1379-1381).
The observation of triplet–triplet absorption of salicylidene-p-toluidine, is complicated by the possible colored isomer formation during the optical pumping. The short-lived (singlet–singlet) and long-lived (triplet–triplet) absorption spectra were recorded phographically by microsecond flash and nanosecond laser flash photolysis techniques. Salicylidene-aniline complexes were purified by repeated recrystallisation until further recrystallisation produced no further changes for X-ray diffraction pattern and optical absorption, emission properties.
Keywords: T–T absorption; Salicylidene-p-toluidine; T–T fluorescence; Entropy change; Activation energy;
Synthesis, characterization and thermal studies on metal complexes of new azo compounds derived from sulfa drugs by Gehad G. Mohamed; Mohamed A.M. Gad-Elkareem (1382-1387).
Four new azo ligands, L1 and HL2–4, of sulfa drugs have been prepared and characterized. [MX2(L1)(H2O) m ]·nH2O; [(MX2)2(HL2 or HL3)(H2O) m ]·nH2O and [M2X3(L4)(H2O)]·nH2O; M = Co(II), Ni(II) and Cu(II) (X = Cl) and Zn(II) (X = AcO); m = 0–4 and n = 0–3, complexes were prepared. Elemental and thermal analyses (TGA and DTA), IR, solid reflectance spectra, magnetic moment and molar conductance measurements have accomplished characterization of the complexes. The IR data reveal that HL1 and HL2–3 ligands behave as a bidentate neutral ligands while HL4 ligand behaves as a bidentate monoionic ligand. They coordinated to the metal ions via the carbonyl O, enolic sulfonamide ―S(O)OH, pyrazole or thiazole N and azo N groups. The molar conductance data reveal that the chelates are non-electrolytes. From the solid reflectance spectra and magnetic moment data, the complexes were found to have octahedral, tetrahedral and square planar geometrical structures. The thermal behaviour of these chelates shows that the water molecules (hydrated and coordinated) and the anions are removed in a successive two steps followed immediately by decomposition of the ligand in the subsequent steps. The activation thermodynamic parameters, such as, E *, ΔH *, ΔS * and ΔG * are calculated from the TG curves applying Coats–Redfern method.
Keywords: Sulfa drugs; Metal complexes; IR; Conductance; Solid reflectance; Magnetic moment; Thermal analysis;
Laser-induced temperature dependent triplet state lifetime of rubreneperoxide by Fuat Bayrakçeken; Papatya C. Sevinç (1388-1392).
A number of photophysical properties of three different types of rubreneperoxides have been measured experimentally by flash spectroscopy technique, including the two-photon absorption, fluorescence, delayed fluorescence and temperature dependent triplet–triplet absorption spectra. Excited singlet and triplet state lifetimes are temperature dependent. Lowest triplet state lifetimes were measured from 77 K to 50 °C. Experimental observations showed that as we decreased the temperature of rubreneperoxides, most of the molecules migrate to the lowest vibrational and rotational energy levels of the ground electronic state. Similar migration is also observed for the lowest triplet state. Therefore at 77 K, we can get the clean absorption an emission spectra and decay curves for the lowest triplet state. At 50 °C, due to the P- and/or E-type of delayed fluorescences, decay of T1 state, in other words disappearance of the T1 state is becoming faster than at low temperature (below room temperature).
Keywords: Rubrene; Rubreneperoxide; T–T absorption; T–T decay; Fused silica; Sensitized fluorescence;
Synthesis and characterization of norfloxacin-transition metal complexes (group 11, IB): Spectroscopic, thermal, kinetic measurements and biological activity by Moamen S. Refat (1393-1405).
The investigation of the new structures of Ag(I), Cu(II) and Au(III) complexes, [Ag2(Nor)2](NO3)2, [Cu(Nor)2(H2O)2]SO4·5H2O and [Au(Nor)2 (H2O)2]Cl3 (where, Nor = norfloxacin) was done during the reaction of silver(I), copper(II) and gold(III) ions with norfloxacin drug ligand. Elemental analysis of CHN, infrared, electronic, 1H NMR and mass spectra, as well as thermo gravimetric analysis (TG and DTG) and conductivity measurements have been used to characterize the isolated complexes. The powder XRD studies confirm the amorphous nature of the complexes. The norfloxacin ligand is coordinated to Ag(I) and Au(III) ions as a neutral monodentate chelating through the N atom of piperidyl ring, but the copper(II) complex is coordinated through the carbonyl oxygen atom (quinolone group) and the oxygen atom of the carboxylic group. The norfloxacin and their metal complexes have been biologically tested, which resulted in norfloxacin complexes showing moderate activity against the gram positive and gram negative bacteria as well as against fungi.
Keywords: Norfloxacin; Gold(III) complex; Biological activity; Kinetic data; Infrared spectra;
Temperature sensing behaviour of the stark sublevels by Vineet Kumar Rai; S.B. Rai (1406-1409).
The temperature dependence of the fluorescence intensity ratio of the two stark components of 4S3/2 → 4I15/2 transition using 800 nm radiation from a Ti–sapphire laser pumped by the second harmonic of Nd:YVO4 laser has been augmented in Er3+ doped tellurite glass. It is emphasized that even the two stark components of 4S3/2 → 4I15/2 transition may be utilized to monitor the temperature within 300–550 K with its appreciable sensitivity.
Keywords: Upconversion; Stark components; FIR; Sensor; Sensitivity; Ti–sapphire;
Spectroscopic evaluation of Co(II), Ni(II) and Cu(II) complexes derived from thiosemicarbazone and semicarbazone by Sulekh Chandra; Anil Kumar (1410-1415).
Co(II), Ni(II) and Cu(II) complexes were synthesized with thiosemicarbazone (L1) and semicarbazone (L2) derived from 2-acetyl furan. These complexes were characterized by elemental analysis, molar conductance, magnetic moment, mass, IR, electronic and EPR spectral studies. The molar conductance measurement of the complexes in DMSO corresponds to non-electrolytic nature. All the complexes are of high-spin type. On the basis of different spectral studies six coordinated geometry may be assigned for all the complexes except Co(L)2(SO4) and Cu(L)2(SO4) [where L = L1 and L2] which are of five coordinated square pyramidal geometry.
Keywords: Co(II); Ni(II) ;Cu(II); Spectroscopic studies;
Yotta-photonic excitation spectroscopy of salicylidene-m-bromo-aniline by Fuat Bayrakçeken (1416-1420).
The observation of triplet–triplet absorption and emission spectra of salicylidene-m-bromo-aniline in solution, is complicated by the possible colored isomer formation during the optical pumping for yotta-photonic excitation at room temperature. The short-lived (singlet–singlet) and long-lived (triplet–triplet) absorption spectra were recorded phographically by microsecond flash and nano-second laser flash photolysis techniques. Salicylidene-m-bromo-aniline complexes were purified by repeated recrystallization until further recrystallization produced no further changes for X-ray diffraction pattern and optical absorption, emission properties. For yotta-photon excitation system, light could be faster than usual, because of heat and to many photonic collisions in the cavity, slowed down by the molecule, and stopped or frozen in a molecular orbital for a short time from nano-second to atto-second. The physical properties of the absorbed photons, in a very high photon flux density (i.e. in a photon field) are different in photonic character, and the emitted photons by the excited states behaves differently in photon field, no splitting occurs for the absorbed or emitted lines like in electrical or magnetic fields.
Keywords: T–T absorption; Salicylidene-m-bromo-aniline; T–T fluorescence; Entropy change; Activation energy;
Author Index (1421-1424).
Keyword Index (1425-1431).