UV-Visible Spectroscopy

New push–pull (A–D) nickel(II) compounds of general formula [Ni(5-A-5’-D-saltn)] (3a–3l) with unsymmetrically-substituted N2O2 tetradentate Schiff base ligands are reported here. The ligands 5-A-5’-D-saltn2− (H2saltn = N,N’-bis(salicylidene)diaminopropane) possess differently-substituted salicylaldehyde (A/Dsal) moieties condensed to 1,3-diaminopropane (tn), and carry either an electron acceptor (A = H, Br, or NO2) or donor (D = H, Me, or OMe) group in the para position with respect to the coordinated phenoxido oxygen atoms. These compounds could be obtained by template synthesis involving derivatives [Ni(Gsal)2(H2O)2], 1a–e (G = NO2, Br, H, Me and OMe, respectively) and [Ni(GL)2], 2a–d (GL− = (E)-2-((3-aminopropylimino)methyl)-4-G-phenolate, G = NO2, Br, H and Me, respectively). Scrambling of the ligands and condensation to compounds 3 was suitably achieved by refluxing compounds 1 and 2 that carry the G groups suitable for the desired final A–D combination. Dinuclear intermediates [Ni2(μ-GL)2(G’sal)2] (4a,b,e,f,g) were also detected and isolated. The single-crystal X-ray diffraction structures of [Ni(5’-OMe-saltn)]·CHCl3 (3c·CHCl3), [Ni(5-Br-5’-OMe-saltn)]·EtOH (3g·EtOH) and [Ni(5-NO2-saltn)] (3j) show different degrees of distortion around the central core, leading to saddle-like (3c), planar (3g) and step-like (3j) molecular conformations. DFT geometrical optimization of the compounds showed that, for isolated molecules, the saddle-like conformation is slightly more stable with respect to the other conformations. UV-visible absorption spectra showed structured absorption profiles at about 320–440 nm, whose intensity was amplified by the presence of the nitro group, and this was assigned to a convolution of one metal-to-ligand charge transfer and two intra-ligand charge transfer transitions by TDDFT computations. Surprisingly, UV-visible spectra of the derivatives with Br were comparable to the derivatives with Me, suggesting that in this case the behaviour of the halogen was as a weak electron donor group. The experimental investigation (through electric-field-induced second-harmonic and solvatochromic measurements) of the second-order NLO responses of compounds 3, in conjunction with the theoretical calculations, revealed that the observed NLO efficiency is determined by the combined effect of two almost orthogonal charge transfer directions within the molecules, one along the axis approximately bisecting the donor and the accepting moieties and the
other along the A–D axis.

A  simple  UV-Visible  spectrophotometric  method  has  been
developed for the determination of Atorvastatin in its pure form as
well as pharmaceutical dosage form using Methyl Orange reagent.
The  method  is  based  on  the  measurement  of  absorbance  of
Atorvastatin in methanol at 410 nm. The Beer’s law is obeyed
over  the  linear  range  50-300μg  /ml  of  Atorvastatin.  All  the
variables were studied to optimize the reaction conditions. No
interference  was  observed  in  the  presence  of  common
pharmaceutical excipients. The validity of the method was tested
by analyzing the drug in its pharmaceutical preparations. Good
recoveries were also obtained. Assay for the tablet preparation was
performed using UV-Visible spectrophotometric method and the
results were found to be within acceptable limits.

The effect of single and binary solvents on electronic absorption spectra of 1,3-bis[(3-(2-pyridyl) pyrazol-1 ylmethyl)] benzene (1,3-PPB) was examined. 1,3-PPB has two absorption maxima (250 and 280 nm) due to pyridyl pyrazole and benzene systems. In order to explain the obtained results, UV absorption frequencies of the electronic transitions were correlated using a total solvatochromic equation by the Kamlet and Taft. The multiparametric analysis indicates that hydrogen bond donor ability of the solvent (for band I) and non-specific dipolar interactions of the solvents (for band II) play an important role in absorption maxima in pure solvents. Preferential solvation by ethanol (for two bands) was detected in i-PrOH-EtOH solvent mixture. Two spectrophotometric graphical methods were used to estimate the dissociation constant (pK b) with resulting average value of 10.12±0.41.

The present paper review the drug-DNA interactions, their types and applications of experimental techniques used to study interactions between DNA and small ligand molecules that are potentially of pharmaceutical interest. DNA has been known to be the cellular target for many cytotoxic anticancer agents for several decades. Understanding how drug molecules interact with DNA has become an active research area at the interface between chemistry, molecular biology and medicine. In this review article, we attempt to bring together topics that cover the breadth of this large area of research. The interaction of drugs with DNA is a significant feature in pharmacology and plays a vital role in the determination of the mechanisms of drug action and designing of more efficient and specifically targeted drugs with lesser side effects. Several instrumental techniques are used to study such interactions. In the present review, we will discuss UV-Visible spectroscopy, fluorescence spectroscopy and cyclic voltammetry. The applications of spectroscopic techniques are reviewed and we have discussed the type of information (qualitative or quantitative) that can be obtained from the use of each technique. Not only have novel techniques been applied to study drug-DNA interactions but such interactions may also be the basis for the development of new assays. The interaction between DNA and drugs can cause chemical and conformational modifications and, thus, variation of the electrochemical properties of nucleobases.Copyright © 2013 Elsevier B.V. All rights reserved.

(for co-autors, please see the pdf). The whole Annual Report of DNC (FNSPE, CTU) 2011/2012 is available at the website of the Department - http://www.jaderna-chemie.cz/data/documents/vyrocni_zpravy/AR2011-2012.pdf

The UO2(2+) - SO4(2-) - H2O system is important for uranium
mining studies, safety studies of radioactive waste repository, geochemical modelling and several other fields.
Aim of our work was to obtain parameters of the speciation
(log β° for the individual uranyl-sulfate complexes and SIT
coefficients ε(i, j) where i is an uranyl specie) by factor
analysis based fit of the spectral data.

Please, see also IAA 2014 Proceedings paper -
(The IAA 2014 Proceedings contribution cite part of this research, compare it with TRLFS based speciation studies of both uranyl-sulfates and uranyl-selenates and further discuss the uranyl-sulfates stability constant data overestimation in this work - the need for a precise preceding uranyl hydrolytic study under similar conditions is stressed there).

In the present study, two simple, precise and economical UV methods have been developed for the estimation of Amodiaquine Hydrochloride in bulk formulation using methanol. Method A involved the measurement of UV absorbance in zero order derivative at 343 nm, while Method B involved the measurement of UV absorbance in first order derivative at 217.5 nm. Both methods, A and B followed Beer-Lambert's law with the drug in the concentration range of 10-70 μg/ml and correlation coefficient (r2) 0.9998 and 0.9997, respectively. The limit of detection for zero order and first order was found to be 0.032 and 2.716 respectively. The limit of quantification for zero order and first order was found to be 0.097, 8.231 respectively. Outcomes of the experiments were found appropriate on statistical confirmation. Hence, suggested procedures can be effectively utilized for the assessment of Amodiaquine hydrochloride in regular analytical studies.

Homemade brews and the raw materials used can be a major source of nitrate and nitrite in human diet. Because of the potential health hazards result in. high intake of nitrate and nitrite, determination of these ions content in Homemade brews and the raw materials used. Sources of nitrites include vegetables, fruit, and processed meats The aim of this research was to determine the concentration of nitrite in Homemade brews and the raw materials sampled from eleven stations in Nairobi County - Kenya. So, a total of one hundred and thirty two (132) home-made alcoholic beverages, forty eight (48) water and eighteen (18) raw materials samples were analyzed for nitrite. These were analyzed using, a SHADZU (Model No. UV-2550) UV-Visible spectrophotometer. The measurement was based on ISO Method (N0.6635). The detection limit and analitation limit of nitrite determination were found to be 0.93 μg/ml and 2.82 μg/ml respectively. The recommended maximum contamination levels set by Kenya Bureau of Standards/World Health Organization for nitrate in alcohols is nitrite 0.003 mg/l Data has been analyzed with p value and ANOVA. According to the results, the average of nitrite content in all of the samples was more than standard limits. Homemade brews and the raw materials used had significantly higher nitrite differences (p<0.05).

Solar cell absorber Copper Zinc Tin sulfide (CZTS) thin films have been prepared by chemical bath deposition (CBD) method using Triethanolamine as stabilizing agent in 60 ml precursor solution at different time interval on a pre-cleaned glass substrate. CZTS is a good absorber material for low cost and non-toxic. The prepared CZTS thin films were scrutinized by UV-Visible spectroscopy revealed that optical energy gaps decreases with increase in deposition time intervals and it contain the direct energy band gap is ~ 1.6 eV.

A brief introduction into computational methodology and preliminary results for spectroscopic (excitation energies, vibrational frequencies in ground and excited electronic states) and thermodynamic (stability constants, standard enthalpies and enthropies of complexation reactions) properties of some 1:1, 1:2 and 1:3 uranyl sulphato-and selenato-complexes in aqueos solutions will be given. The relativistic effects are included via Effective Core Potential (ECP), electron correlation via (TD)DFT/B3LYP (dispersion interaction corrected) and solvatation is described via explicit inclusion of one hydratation sphere beyond the coordinated water molecules. We acknowledge limits of this approximate description – more accurate calculations (ranging from semiphenomenological two-component spin-orbit coupling up to four-component Dirac-Coulomb-Breit hamiltonian) and Molecular Dynamics simulations are in preparation. The computational results are compared with the experimental results from Time-resolved Laser-induced Fluorescence Spectroscopy (TRLFS) and UV-VIS spectroscopic studies (including our original experimental research on this topic). In case of the TRLFS and UV-VIS speciation studies, the problem of complex solution spectra decomposition into individual components is ill-conditioned and hints from theoretical chemistry could be very important. Qualitative agreement between our quantum chemical calculations of the spectroscopic properties and experimental data was achieved. Possible applications for geochemical modelling (e.g. safety studies of nuclear waste repositories, modelling of a future mining site) and analytical chemical studies (including natural samples) are dissucussed.

Quantum chemistry calculations of energies, geometries, electronic structures, polarizabilities, and hyperpolarizabilities of organic dye sensitizer 2-aminopyrimidine-5-carbonitrile were studied based on ab initio HF and Density Functional Theory (DFT) using the hybrid functionalsB3LYP. Ultraviolet-visible (UV-Vis) spectrum was investigated by Time Dependent DFT (TDDFT). Features of the electronic absorption spectrum in the visible and near-UV regions were assigned based on TDDFT calculations. The absorption bands are assigned to π→π* transitions. Calculated results suggest that the three excited states with the lowest excited energies in 2-aminopyrimidine-5-carbonitrile is due to photo induced electron transfer processes. The interfacial electron transfer between semiconductor TiO2 electrode and dye sensitizer2-aminopyrimidine-5-carbonitrile, is due to an electron injection process from excited dye to the semiconductor's conduction band. The role of amine and nitrile group in 2-aminopyrimidine-5-carbonitrile geometries, electronic structures, and electronic absorption spectra were analyzed in Dye sensitizer solar cell (DSSC) give a good conversion efficiency.

Azithromycin and metal interaction are successfully found thereafter, interaction result. Also, the antimicrobial activity of the drug and the metals complexes were determined. This has been seen that Azithromycin interacts along with metal at pH 7.4. The different essential metal intricate of the azithromycin has been synthesized and characterized by techniques like NMR, UV, atomic absorption, FT-IR, and elemental analysis. Spectroscopic, IR Spectroscopic, disk diffusion method, Biological assay studies of complexes. On the other hand, there is metals complex in this interaction, which is interaction with the drug into our body. And have been using there various types of bacteria for finding a zone of inhibition. Some paper there uses methanol and ethanol for disk diffusion results clearly showing. If we use Azithromycin in a single way, it has a high bioavailability and proportionally increases the absorption with concentration. But if we use its interaction with metals, then bioavailability and absorption decrease and less half-life. Using a variety of methods and studies such as Antifungal study, Antibacterial study, Biological study with different types of spectroscopic analysis, Conductrometric, IR spectrometric, and Disk-diffusion methods its shows, that's less pharmacological action. After all discussion, it's concluded that if we have taken Azithromycin, we will use the metals complex before two hours and after one hour. There is or will no interaction and in this, we say well and get the best bioavailability and high pharmacological action.

Time-dependent density functional theory 􏰂TD-DFT􏰁 calculations of the electronic response of molecular and bulk liquid water based on a very accurate orbital-dependent ground-state exchange-correlation potential, the statistical average of 􏰂model􏰁 orbital potentials 􏰂SAOP􏰁, and on the adiabatic local density approximation 􏰂ALDA􏰁 for the exchange-correlation kernel are described. The quality of the calculated excitation energies, both in the molecule and in the liquid, is assessed by comparison to hybrid TD-DFT calculations and experimental data. A combination of classical molecular dynamics simulations and TD-DFT calculations sampling several disordered configurations of a small liquid sample is then used to simulate the optical absorption spectrum in the region of 0–15 eV. The resulting room-temperature absorption profile is discussed in connection with previous TD-DFT calculations as well as with results from Green’s function theory and experiment.

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TiO2 is an effective and extensively employed photocatalyst, but its practical use in visible-light-mediated organic synthesis is mainly hindered by its wide band gap energy. Herein, we have discovered that Rh-photodeposited TiO2 nanoparticles selectively dehydrogenate N-heterocyclic amines with the concomitant generation of molecular hydrogen gas in an inert atmosphere under visible light (λmax = 453 nm) illumination at room temperature. Initially, a visible-light-sensitive surface complex is formed between the N-heterocycle and TiO2. The acceptorless dehydrogenation of N-heterocycles is initiated by direct electron transfer from the HOMO energy level of the amine via the conduction band of TiO2 to the Rh nanoparticle. The reaction condition was optimized by examining different photodeposited noble metals on the surface of TiO2 and solvents, finding that Rh0 is the most efficient cocatalyst, and 2-propanol is the optimal solvent. Structurally diverse N-heterocycles such as tetrahydroquinolines, tetrahydroisoquinolines, indolines, and others bearing electron-deficient as well as electron-rich substituents underwent the dehydrogenation in good to excellent yields. The amount of released hydrogen gas evinces that only the N-heterocyclic amines are oxidized rather than the dispersant. This developed method demonstrates how UV-active TiO2 can be employed in visible-light-induced synthetic dehydrogenation of amines and simultaneous hydrogen storage applications.

The samples of CR-39 polymer (TASTRAK, Bristol, England) were annealled thermally at various temperatures ranging from 100°C to 180°C for 1 hour, in air. FTIR spectroscopy reveals the structural degradation of CR-39 polymer due to thermal annealing above its glass transition temperature. Optical band gap of pristine and thermally annealed samples has been determined using UV-Visible absorption spectra. It has been observed that the optical band gap decreases continuously as a result of annealing.

With the view of extracting gold out of waste, the ethanolic extract of weed (Bidens biternata) (EEBb) was explored for its inhibitory efficacy towards acid corrosion of AA6063 (aluminium alloy) in 0.5 M HCl. The experimentations were carried out employing chemical method at room and elevated temperatures and various corrosion parameters were calculated. The inhibitory efficacy was found to be 88.09 % at 1.04 g/L of EEBb. The adsorption of the inhibitor onto the metal surface was further endorsed by carrying out Quantum Chemical Analysis (QCA), spectroscopic (UV-Visible Spectroscopy) and surface morphological studies (SEM). The adsorptive nature of EEBb was investigated and found to best fitted in Langmuir adsorption isotherm. The high inhibition efficiency was attributed to the adsorption of active molecules leading to the formation of a protective layer on the AA6063 surface. The results were very promising and indicate that toxic weed Bidens biternata can be very effectively to combat acid corrosion of aluminium. Moreover, these can be a good replacement for most of the hazardous chemicals used to inhibit metal corrosion.

This study was carried out to determine the levels of nitrate in homemade brews, spirits and the used raw materials using the UV-Visible spectroscopy. These were analyzed using, a SHADZU (Model No. UV-2550) UV-Visible spectrophotometer. The measurement was based on ISO Method (N0.6635). This was done by reducing the nitrate to nitrite in the presence of Zn/NaCl. Nitrite produced was subsequently diazotized with sulphonilic acid then coupled with anthranilate to form an azo dye which was then measured at 493 nm. Four hundred and forty (440) home - made alcoholic beverages, one hundred and ten (110) tap water and eighteen (18) raw materials (maize, millet, for sorghum, honey, jaggery and muratina) samples obtained from various parts of Nairobi slums and its environs were analyzed. Some samples contained high levels of nitrate though slightly lower than the limits. The concentrations of nitrate varied from non detectable (ND) to 46.3 ± 1.404 mg/l (the detection limit and analitation limit of nitrite determination were found to be 0.93 μg/ml and 2.82 μg/ml respectively). The recommended maximum contamination levels set by Kenya Bureau of Standards/World Health Organization for nitrate in alcohols is nitrate 50 mg/l. Most of the homemade brews and spirits analyzed in this study had values slightly lower than the levels recommended by the World Health Organization. Values of nitrate were observed to be generally high in the brews/spirits and the raw materials used. These raw materials may have contributed in elevating the levels of these pollutants in the brews. The results indicate that the UV-Visible spectroscopy method is suitable for analyzing the presently studied samples. This is a reliable and cheap method for routine analysis of a large number of homemade brews/spirits samples.

Ranitidine lies under the group of drugs called H2
blockers. Ranitidine reduces the quantity of acid
produced by the stomach. It’s used in the treatment and
prevention of ulcers in stomach and in intestine like
GERD & Zollinger-Ellison syndrome. Ranitidine is also
coupled with enhance the risk of developing pneumonia.
Assay was done by different brands available in market
of ranitidine. Different dilutions were made and check
out their linearity and regression was found to be linear.
Absorbance was measured by UV Spectrophotometer
and statistically one way ANOVA was implemented to
analyze the comparison b/w groups and within groups.

In this experiment, the effect of annealing at 400 o C and gamma irradiation  with the rate of 2.4 Gy/s[1] and then annealing as post treatments on optical properties and dimension of Ag Nano clusters were investigated. Ag Nano clusters were formed by ion-exchange process during which SLS substrates immersed in to the AgNO3 salt bath at 400 o C.it eventually led to planer wave guide [1]. Grazing incidence x-ray diffraction analysis demonstrated the presence of Ag on Ag-ion exchanged substrates. The ion-exchanged substrates were then annealed and gamma irradiated and then annealing as post treatments. The effect of post treatments on optical properties of samples including absorption spectra and linear refractive index, examined by analyzing optical density as a function of wavelength curves and Brewster angle determination. The results of absorption spectra indicated broadening and shift of ionic (Ag ୒ ା), and neutral (Ag ୒ ଴) silver nanocluster peaks after post treatments. It was revealed about peak displacement as blue shift in annealed and red shift in gamma irradiated and blue shift in annealed samples. Calculation of Ag Nano cluster dimensions and refractive index of substrates revealed that post treatments procedures and especially gamma irradiation process caused nonlinear reduction in both of their values.

ZnS nanoparticles have been synthesized by the facile chemical route with a narrow size distribution in the MA/octene-1 copolymer matrix and effect of reaction time has been discussed. X-ray diffraction pattern confirms the pure cubic phase of ZnS with 5-7 nm average crystal sizes which are in good agreement with the AFM and UV-Vis measurements. Absorption spectra exhibit a strong blue shift from the bulk with the 3.98 eV optical band gap which clearly indicates the strong size confinement effect. Thermogravimetric analyses show increased thermal stability of the nanocomposite compared to the copolymer. The possible growth mechanism of the particles formation and stabilization has been discussed.

This paper presents some copper(II) complexes of salen analogues in which the two salicylaldehyde moieties carry different (electron donor, D, and acceptor, A) substituents in position 5, producing a push-pull charge asymmetry. The X-ray structures of some compounds show the presence of pairs of stacked molecules with head-to-tail intermolecular associations. The geometries of all complexes have been optimized through density functional theory (DFT) studies, which have shown that a major influence on the coordination bond lengths is given by the presence of the electron acceptor NO2 group. Such an influence operates mainly on the Cu-phenolato bonds: elongation of the Cu-O distance of the 5-nitrosalicylaldehyde moiety, with a concomitant decrease of the other Cu-O distance; the Cu-N bonds are less affected. The D groups have only a minor influence. The nonlinear optical responses, mugxbetavec, of some molecules have been determined by EFISH measurements, and the betavec values have been obtained using the DFT-calculated íg values because solubility problems hampered the experimental measurements of mug of some derivatives; the former, however, have been found to be in agreement with the experimental values that could be obtained. Deconvolution of the absorption bands in the near-UV region has allowed recognition of the charge-transfer (CT) transition, assigned to a ligand-to-metal CT (LMCT) by time-dependent DFT computations;
we have then used the solvatochromism of this transition to obtain beta0 and betaCT values using the two-state model. These values were compared with those obtained by computational studies, which have also allowed evaluation of the influence of the substituents on the directions of íg and betatot.