Uv-Vis Spectroscopy Research Papers - Academia.edu (original) (raw)

Heparin is well-known for its anticoagulant effect and is widely used for a lot of different medical and clinical purposes. There is a high demand in the heparin production market by which the high yield extraction methods is increasing;... more

Heparin is well-known for its anticoagulant effect and is widely used for a lot of different medical and clinical purposes. There is a high demand in the heparin production market by which the high yield extraction methods is increasing; unfortunately, the current extraction yield calculation is not very precise and accurate due to the lack of information about the actual heparin amount in the raw biological material to compare with the extracted amount at the end of the process. In this project, the efficiency of the Charles and Scott’s extraction method and the extraction method using the resin supplied by Leo Pharma was investigated but the yield were low and not promising. The idea of directly monitoring amount of heparin releasing out during raw material digestion using Azure A Chloride solution at 0.00003 M was taken place, this gives a high R2 value (>0.9) to the linearity relationship between heparin and ratio signals produced at 630 nm and 544 nm wavelength of Azure A Chloride chromophores. This provides a very encouraging data in order to reach the aim of the project - quantifying the actual heparin amount in the raw material. The interference effects brought by salts, temperature, alkaline protease, pH, and glycosaminoglycan family members were studied; however, further investigations need carrying out and considering to fully reach the main project theme.

The complexation between folic acid and a typical polyaromatic hydrocarbon, naphthalene, was investigated using FTIR and UV spectra. Appearance of a new IR band at 2376 cm−1 demonstrates that NH2–C=N moiety on pterin ring in folic acid is... more

The complexation between folic acid and a typical polyaromatic hydrocarbon, naphthalene, was investigated using FTIR and UV spectra. Appearance of a new IR band at 2376 cm−1 demonstrates that NH2–C=N moiety on pterin ring in folic acid is protonated when naphthalene is introduced. The emergence of two charge transfer bands at 235 nm and 296 nm in UV difference spectra show the presence of π-π complexation between folic acid and naphthalene. These experiments confirm that naphthalene could combine with the pterin ring of folic acid through π-π donor–acceptor interaction and induce the protonation process in folic acid upon strengthening electron accepting ability of pterin ring. The results suggest that complexation between naphthalene and folic acid necessarily changes their charge distribution and the surroundings. It is inferred that not only biotransformation process of folic acid, but also the toxicity of polyaromatic hydrocarbons could be changed.

The nature of transition from ordinary micelles (of nanometer length scale) of surface active ionic liquid 1-Hexadecyl-3-methylimidazolium chloride, to wormlike micelles (WLM) (micrometer length scale), mediated by hydroxy aromatic... more

The nature of transition from ordinary micelles (of nanometer length scale) of surface active ionic liquid 1-Hexadecyl-3-methylimidazolium chloride, to wormlike micelles (WLM) (micrometer length scale), mediated by hydroxy aromatic π-electron systems 1-Naphthol, 2-Naphthol and 2,3-Dihydroxynaphthalene (2,3-DHN) in salt free condition have been studied under Newtonian as well as non-Newtonian flow regimes. Conductance and tensiometry show that the additives lower the CMC of the ionic liquid. The interaction parameter (β) of the systems at different mole fraction evaluated on basis of Rubingh’s Regular solution approach were negative at all SAIL/Additive compositions. UV-Vis spectroscopy showed that micelle-bound additives formed hydrogen bonds with interfacial water molecules. Increase in steady state fluorescence anisotropic measurements revealed that the additives increasingly partitioned within the micelles. 1H-NMR study confirmed that although the additives reside at the palisade layer, they perturb the micellar core as well. At higher concentration (100mM, 1:1), systems formed transparent viscoelastic gel. Rheological study of the viscoelastic gels showed that their zero shear viscosity is a function of temperature. 2,3-DHN interacted most strongly with the SAIL micelles, both in Newtonian and non-Newtonian regimes. This was corroborated by DFT study of binding energy. Hydrogen bonding of the hydroxy functionality along with strong cation-π interaction between the aromatic moieties and the imidazolium ring are considered as the main driving forces behind the morphology change. The viscosity of C16-3-MeImCl/1-Naphthol increased as function of salt concentration unlike C16-3-MeImCl/NaSal system. A possible mechanism is suggested and discussed. The present study sheds light on understanding the molecular interactions behind the structural change from spherical to elongated micelles, in both microscopic and macroscopic scale, triggered by hydroxy naphthalenes under salt-free condition. The metal tolerance of the gels has huge application prospects as fractured fluids in oil-mining industry.

UV–visible spectra and color parameters of monovarietal wines with orthogonal partial least squarediscriminant analysis (OPLS-DA) were shown to be practical and rapid methods for classification purposes. Red and white wines from the... more

UV–visible spectra and color parameters of monovarietal wines with orthogonal partial least squarediscriminant
analysis (OPLS-DA) were shown to be practical and rapid methods for classification
purposes. Red and white wines from the 2006–2009 vintages were characterized in terms of color,
anthocyanin content and UV–visible spectra. Syrah and Cabernet Sauvignon wines had high color
density and intensity. Kalecik Karası wines had the highest CIELab parameters and the lowest color
density. Bog˘azkere and O¨ ku¨ zgo¨ zu¨ wines showed similarities with respect to their high red color
parameters and were distinct from other wines. Merlot, Syrah and O¨ ku¨ zgo¨zu¨ wines had the highest
total anthocyanin content (61.9–55 mg/L as median values). White wines made from Chardonnay,
Muscat and Emir grapes were found to have different color characteristics. The vintage-based
discrimination of red wines was mostly apparent in total anthocyanin contents. Different UV
wavelength regions were found to be effective in classification with respect to variety and vintage.
Correct classification rates in the validation set were 100% and 75%, for varietal and vintage
classifications, respectively. This study demonstrated the potential of combination of UV–visible
spectra and color characteristics to be used in the authentication of wines.

The management of contaminants of emerging concern (CECs) in water bodies is particularly challenging due to the difficulty in detection and their recalcitrant degradation by conventional means. In this review, CECs are characterized to... more

The management of contaminants of emerging concern (CECs) in water bodies is particularly challenging due to the difficulty in detection and their recalcitrant degradation by conventional means. In this review, CECs are characterized to give insights into the potential degradation performance of similar compounds. A two-pronged approach was then proposed for the overall management of CECs. Light-driven oxidation processes, namely photo/Fenton, photocatalysis, photolysis, UV/Ozone were discussed. Advances to overcome current limitations in these light-driven processes were proposed, focusing on recent trends and innovations. Light-based detection methodology was also discussed for the management of CECs. Lastly, a cost–benefit analysis on various light-based processes was conducted to access the suitability for CECs degradation. It was found that the UV/Ozone process might not be suitable due to the complication with pH adjustments and limited light wavelength. It was found that EEO values were in this sequence: UV only > UV/combination > photocatalyst > UV/O3 > UV/Fenton > solar/Fenton. The solar/Fenton process has the least computed EEO < 5 kWh m−3 and great potential for further development. Newer innovations such as solar/catalyst can also be explored with potentially lower EEO values.

A recently introduced formulation of time dependent linear response density functional theory within the plane-wave pseudopotential framework 􏰉J. Hutter, J. Chem. Phys. 118, 3928 􏰞2003􏰀􏰁 is n→􏰛* electronic applied to the study of solvent... more

A recently introduced formulation of time dependent linear response density functional theory within the plane-wave pseudopotential framework 􏰉J. Hutter, J. Chem. Phys. 118, 3928 􏰞2003􏰀􏰁 is
n→􏰛* electronic
applied to the study of solvent shift and intensity enhancement effects of the 1A
transition in acetone, treating solute and solvent at the same level of theory. We propose a suitable formalism for computing transition intensities based on the modern theory of polarization, which is applicable to condensed-phase and finite systems alike. The gain in intensity brought about by thermal fluctuations is studied in molecular acetone at room temperature, and in gas-phase ( CH3 ) 2 CO• ( H2 O) 2 at 25 K. The latter system is characterized by the appearance of relatively intense features in the low-energy region of the spectrum, attributable to spurious solvent →solute charge-transfer excitations created by deficiencies in the DFT methodology. The n→􏰛* transition can be partially isolated from the charge-transfer bands, yielding a blueshift of 0.17 eV with respect to gas-phase acetone. This analysis is then carried over to a solution of acetone in water, where further complications are encountered in the from of a solute→solvent charge transfer excitations overlapping with the n→􏰛* band. The optically active occupied states are found to be largely localized on either solute or solvent, and using this feature we were again able to isolate the physical n→􏰛* band and compute the solvatochromic shift. The result of 0.19 eV is in good agreement with experiment, as is the general increase in the mean oscillator strength of the transition. The unphysical charge transfers are interpreted in terms of degeneracies in the spectrum of orbital energies of the aqueous acetone solution.

Abstract: Spectroscopic evidence showed that glycyrrhizin and glycyrrhetinic acid bind DNA and RNA via major and minor grooves as well as the backbone Glycyrrhetinic acid (GA), the main metabolic product of glycyrrhizin (GL) is an aqueous... more

Abstract: Spectroscopic evidence showed that glycyrrhizin and glycyrrhetinic acid bind DNA and RNA via major and minor grooves as well as the backbone Glycyrrhetinic acid (GA), the main metabolic product of glycyrrhizin (GL) is an aqueous extract from licorice root. These compounds are well known for their anti-inflammatory, hepatocarcinogenesis, anti-viral and interferon (IFN)-inducing activity. This study is the first attempt to investigate the binding of glycyrrhizin and glycyrrhetinic acid with DNA and RNA. The effect of the ligand complexation on DNA and RNA aggregation and condensation was investigated in aqueous solution at physiological conditions, using constant DNA and RNA concentration (6.25 mM) and various ligands /polynucleotide (phosphate) ratios of 1/240, 1/120, 1/80, 1/40, 1/20, 1/10, 1/5, 1/2 and 1/1. Fourier transform infrared (FTIR) and UV–visible spectroscopic methods were used to determine the phosphate group with overall binding constants of KGL–DNA=5.7x103 M-1, KGA–DNA=5.1x103 M-1, KGL–RNA=3.03×103 M-1 and KGA–RNA=2.71×103 M-1. The affinity of ligands-DNA and -RNA binding is in the order of glycyrrhizin > glycyrrhetinic acid. DNA remains in the B-family and RNA remains in the A-family structures, while biopolymer aggregation occurred at high triterpenoid concentrations.

Coprecipitation of Fe + (III) and Fe + (II) out of FeCl 3 and FeSO 4 ·7H O sources in 2:1 ratio with aqueous 8 MNaOH on heating at 90 °C for 2 h has yielded 85% magnetic (Fe 3 O 4 2 ) nanoparticles (MNPs), and has been characterized by... more

Coprecipitation of Fe

Undoped and Mg doped ZnO nanofibers with different doping concentrations were successfully synthesized using the electrospinning technique. The nanofiber structures were calcined at 300 oC, 400 oC, 500 oC, and 600 oC respectively. It was... more

Undoped and Mg doped ZnO nanofibers with different doping concentrations were successfully synthesized using the electrospinning technique. The nanofiber structures were calcined at 300 oC, 400 oC, 500 oC, and 600 oC respectively. It was observed that the nanofibers turned into a nanoparticular structure at the calcining temperature of 400 oC. The nanoceramic mats were characterized by the Fourier transform infrared-attenuated total reflectance spectroscopy and by the scanning electron microscopy. The electronic band transitions of as-deposited and calcined films were identified by the evaluation of the photoluminescence measurements at room temperature. It was observed that the exitonic transition energy of the ZnO nanostructure blue-shifted to a high energy value with an increasing Mg doping ratio. In order to estimate the decomposition temperature of the nanofibers turning into a nanoparticular structure, the nanofiber structure was calcined at temperatures between 300 oC and 400 oC, the temperature ramp being 20 oC. The evaluation of the emission spectra of the calcined structures show that the decomposition of electrospun nanofibers started at 320 oC. In addition, band gap energies of the samples were determined by the transmittance measurement of the samples and by the UV-VIS spectrophotometer at the room temperature.

Chelation of Co(II) with N,N-Bis(Salicylidene) ethylenediamine (salen type ligand) have been investigated spectrophotometrically and conductometrically in various solvents (methanol, 2-propanol, acetonitrile, and chloroform). By... more

Chelation of Co(II) with N,N-Bis(Salicylidene) ethylenediamine (salen type ligand) have been investigated spectrophotometrically and conductometrically in various solvents (methanol, 2-propanol, acetonitrile, and chloroform). By spectrophotometric measurements, the chelation was performed at 25°C at the wavelengths of the corresponding complex. The stoichiometry of the complexes in each solvent were evaluated using continuous variation method and mole ratio method and the values were found to be 1:1 (M:L). Formation constants (Kf) values were found to be in the order of 10 9-10 10 in the examined solvents. The results show there is no significant difference in formation constant values between the complexes formed in the tested solvents. However, the complex formed in chloroform has a slightly larger values of Kf compared to the other solvents. The stability and stoichiometry of the tested complex in MeOH, PrOH, MeCN and CHCl3 at 25 o C by conductometric method were also evaluated. Conductometric measurements indicate the formation of (1:1) complexes with stability order: CHCl3 > MeCN > PrOH > MeOH and that was in agreement with the spectrophotometric results. The thermodynamics of the complexation reaction in MeOH was also investigated by conductometric measurements. The stability constant values increase with increasing temperature which means that the complexation reaction is an endothermic process. The negative value of ΔG shows the ability of the Salen ligand to form stable complex with Co(II) and the process trend to proceed spontaneously.

In the present work, UV-VIS absorption spectroscopy technique has been used to study the complexation between 1,3-bis (3-(2-pyridyl) pyrazol-1-ylmethyl) benzene (1,3-PPB) and Cu (II), Co (II), Ni (II) ions. The stability and composition... more

In the present work, UV-VIS absorption spectroscopy technique has been used to study the complexation between 1,3-bis (3-(2-pyridyl) pyrazol-1-ylmethyl) benzene (1,3-PPB) and Cu (II), Co (II), Ni (II) ions. The stability and composition of these complexes have been investigated in (1:1) mixed solvent of ethanol and water. The absorption maxima of the Cu(II), Co(II), and Ni(II) complexes have λ max of 294, 290, 293 nm, respectively. The experimental parameters that may affect the complex formation , which include pH, ionic strength, solvent composition, and time, were examined. Job's method was used to evaluate the stoichiometry and formation constant of the complexes. All formed complexes show the formation of 1:1 complexes with stability order of Cu > Co > Ni. Molar absorptivity of the complexes has also been determined.

Indole compounds are important class of therapeutic molecules, which have excellent pharmaceutical applications. The objective of present research was to investigate the influence of biofield treatment on physical and thermal properties... more

Indole compounds are important class of therapeutic molecules, which have excellent pharmaceutical applications. The objective of present research was to investigate the influence of biofield treatment on physical and thermal properties of indole. The study was performed in two groups (control and treated). The control group remained as untreated, and biofield treatment was given to treated group. The control and treated samples were characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR) spectroscopy and ultraviolet-visible (UV-Vis) spectroscopy. XRD study demonstrated the increase in crystalline nature of treated indole as compared to control. Additionally, the treated indole showed increase in crystallite size by 2.53% as compared to control. DSC analysis of treated indole (54.45ºC) showed no significant change in melting temperature (Tm) in comparison with control sample (54.76ºC). A significant increase in latent heat of fusion (ΔH) by 30.86% was observed in treated indole with respect to control. Derivative thermogravimetry (DTG) of treated indole showed elevation in maximum thermal decomposition temperature (Tmax) 166.49ºC as compared to control (163.37ºC). This was due to increase in thermal stability of indole after biofield treatment. FT-IR analysis of treated indole showed increase in frequency of N-H stretching vibrational peak by 6 cm-1 as compared to control sample. UV spectroscopy analysis showed no alteration in absorption wavelength (λmax) of treated indole with respect to control. The present study showed that biofield has substantially affected the physical and thermal nature of indole.

Black-brown needle-shaped single crystals of [Co 2 (en) 4 (O 2)(OH)][C 4 O 4 ] 1.5 4H 2 O (en = ethylenediamine) have been prepared in aqueous solution at room temperature. Space group P (no.2) with a = 800.20(8), b = 1225.48(7), c =... more

Black-brown needle-shaped single crystals of [Co 2 (en) 4 (O 2)(OH)][C 4 O 4 ] 1.5 4H 2 O (en = ethylenediamine) have been prepared in aqueous solution at room temperature. Space group P (no.2) with a = 800.20(8), b = 1225.48(7), c = 1403.84(9) pm, alpha= 100.282(5), beta= 94.515(7), gamma= 95.596(6)°. The Co 3+ cations [Co(1), Co(2)] are coordinated in an octahedral manner by four nitrogen atoms stemming from the ethylenediamine molecules and two oxygen atoms each from a hydroxo group and a peroxo group, respectively. Both Co 3+ coordination polyhedra are connected by a common corner and by the peroxo group leading to the binuclear [(en) 2 Co(O 2)(OH)Co(en) 2 ]3+ cation. The squarate dianions, not bonded to Co 3+ , and the [(en) 2 Co(O 2)(OH)Co(en) 2 ] 3+ cations are linked by hydrogen bonds forming a three-dimensional supramolecular network containing water molecules. Magnetic measurements reveal a diamagnetic behaviour indicating a low-spin electron configuration of Co 3+. The UV-Vis spectra shows two LMCT bands (pi*(O2 2-) ->d (Co 3+)) at 274 and 368 nm and the d-d transition (1A1g-> 1T1g) at 542 nm. Thermoanalytical investigations in air show that the compound is stable up to 120 °C. Subsequent decomposition processes to cobalt oxide are finished at 460 °C.

In this study, the interaction of clomiphene (CLO), a non-steroidal and ovulatory stimulant drug employed in the treatment of infertility, with human serum albumin (HSA), the most abundant plasma transport protein, was investigated using... more

In this study, the interaction of clomiphene (CLO), a non-steroidal and ovulatory stimulant drug employed in the treatment of infertility, with human serum albumin (HSA), the most abundant plasma transport protein, was investigated using spectrofluorometric, FT-IR, UV-Vis, and molecular modeling methods. The obtained results indicated that the binding of CLO to HSA led to intense fluorescence quenching of HSA via a static quenching mechanism, and that the process of CLO binding to HSA was enthalpy driven. By using experimental and theoretical methods, it was confirmed that as a result of binding CLO, slight conformational changes in HSA occurred. Also, the negative DH of interaction indicated that the binding of CLO with HSA was mainly enthalpy driven. The experimental and computational results suggested that hydrogen bonds and van der Waals interactions played a major role in the binding, with overall binding constants of K ¼ 3.67 Â 10 9 M À1 at 286 K and 6.52 Â 10 5 mol L À1 at 310 K. Moreover, the results of molecular modeling showed that Asp234, Phe228, Leu327, and Arg209 in HSA had the highest interaction energies with the ligand.

ZnS nanoparticles (NPs) 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... more

ZnS nanoparticles (NPs) 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.

A Simple, selective, precise and rapid absorption correction Spectrophotometric method has been developed and validated as per ICH guideline for the simultaneous estimation of Ranitidine Hydrochloride and Dicyclomine Hydrochloride in... more

A Simple, selective, precise and rapid absorption correction Spectrophotometric method has been developed and validated as per ICH guideline for the simultaneous estimation of Ranitidine Hydrochloride and Dicyclomine Hydrochloride in tablet dosage form. Method is base on UV Spectrophotometric for determination of two drug, by using Methanol as a solvent and diluted the same with 0.1N NaOH, solution. In this UV method, the two wavelength were selected, 311.4 nm and at 217 nm for RANTD and DICY, respectively. this method was validated according to ICH guideline and Linearity range, was found to be 7.5-37.5 µg/ml and 1-5 µg/ml for RANTD and DICY, respectively. The method was successfully applied to assay drugs in tablet.

In the present work, analytical methods, UV Spectrophotometry and Liquid Chromatography (HPLC), were developed and validated for quantification of cefpirome, a broad-spectrum fourth-generation cephalosporin, in raw material and powder for... more

In the present work, analytical methods, UV Spectrophotometry and Liquid Chromatography (HPLC), were developed and validated for quantification of cefpirome, a broad-spectrum fourth-generation cephalosporin, in raw material and powder for injectable preparation. The UV spectrophotometric method was performed at 271 nm, using 0.1 M hydrochloric acid as solvent. The HPLC was carried out using Techsphere ODS column and mobile phase consisted of methanol-water (30:70, v/v) with flow rate 0.8 mL/min and UV detection at 265 nm. The validation method yielded good results demonstrated statistically that the methods were linear, precise, accurate, specific and robust. A preliminary stability study of cefpirome showed that the UV Spectrophotometry and Liquid Chromatography methods were specific for the determination cefpirome in the presence of its degradation products. No statistically difference was observed between the proposed methods. The UV Spectrophotometry and Liquid Chromatography methods allow the quantitation of cefpirome in pharmaceutical dosage form and raw material and can be used for the drug analysis in routine quality control.

p-Chlorobenzaldehyde (p-CBA) is used as an important chemical intermediate for the preparation of pharmaceuticals, agricultural chemicals, dyestuffs, optical brighteners, and metal finishing products. The study aimed to evaluate the... more

p-Chlorobenzaldehyde (p-CBA) is used as an important chemical intermediate for the preparation of pharmaceuticals, agricultural chemicals, dyestuffs, optical brighteners, and metal finishing products. The study aimed to evaluate the effect of biofield energy treatment on the physicochemical and spectroscopic properties of p-CBA. The study was accomplished in two groups i.e. control and treated. The control group was remained as untreated, while the treated group was subjected to Mr. Trivedi’s biofield energy treatment. Finally, both the samples (control and treated) were evaluated using various analytical techniques. The surface area analysis showed a substantial increase in the surface area by 23.06% after biofield treatment with respect to the control sample. The XRD analysis showed the crystalline nature of both control and treated samples. The X-ray diffractogram showed the significant alteration in the peak intensity in treated sample as compared to the control. The XRD analysis showed the slight increase (2.31%) in the crystallite size of treated sample as compared to the control. The TGA analysis exhibited the decrease (10%) in onset temperature of thermal degradation form 140°C (control) to 126°C in treated sample. The Tmax (maximum thermal degradation temperature) was slightly decreased (2.14%) from 157.09°C (control) to 153.73°C in treated sample of p-CBA. This decrease in Tmax was possibly due to early phase of vaporization in treated sample as compared to the control. The FT-IR spectrum of treated p-CBA showed the increase in wavenumber of C=C stretching as compared to the control. The UV spectroscopic study showed the similar pattern of wavelength in control and treated samples. Altogether, the surface area, XRD, TGA-DTG and FT-IR analysis suggest that Mr. Trivedi’s biofield energy treatment has the impact to alter the physicochemical properties of p-CBA. This treated p-CBA could be utilized as a better chemical intermediate than the control p-CBA for the synthesis of pharmaceutical drugs and organic chemicals.

In this study, simultaneous and competitive removal of methylene blue (MB) and malachite green (MG) dyes was performed by employing nanostructure Zr-SBA-15, once using solid-phase extraction method (SPE) and again using ultrasonic bath,... more

In this study, simultaneous and competitive removal of methylene blue (MB) and malachite green (MG) dyes was performed by employing nanostructure Zr-SBA-15, once using solid-phase extraction method (SPE) and again using ultrasonic bath, followed by second-order derivative spectrophotometric method in order to resolve the corresponding overlapped spectra. Zr-SBA-15 characterized by FT-IR, XRD, BET, SEM and EDX techniques. Using the proposed procedure, removal of the mentioned dyes was carried out in the minimum time. Moreover, some of the most influential parameters including the initial concentration of MB and MG, dosage of the absorbent, sonication time and pH of the medium were optimized using central composite design (CCD) in response surface methodology (RSM). Desirability scores demonstrated the optimal conditions as follows: sonication time of 4.78 min, adsorbent dosage of 6.66 mg, pH of 7.15 and initial concentrations of 10.21 and 5.48 mg L−1 for MB and MG, respectively. Under optimum conditions, maximum adsorption capacities of 310.88 and 140.61 mg g−1 were achieved for MB and MG, respectively. Kinetic studies and calculation of relevant equations from kinetic graphs and isotherm exhibited simultaneous adsorption of the desired dyes, followed by pseudo-second order spectrophotometric method and Langmuir isotherm.

Ab initio molecular dynamics simulations on 1-nm thick slabs of amorphous silica have been carried out in order to mimic the local properties of mesoporous materials framework. A number of defects have been considered, both with closed... more

Ab initio molecular dynamics simulations on 1-nm thick slabs of amorphous silica have been carried out in order to mimic the local properties of mesoporous materials framework. A number of defects have been considered, both with closed and open shell electronic structure, and their spectroscopic properties analyzed and compared with experiments. The “strained siloxane bridge” defect has been studied in detail and its possible radical nature highlighted.

Single crystals of Diglycine Sulphate monohydrate (DGSM) have been grown by slow evaporation solution growth technique. The size of the grown crystals is 20x10x10mm3 with the duration of 25 days. To identify the cell parameter, space... more

Single crystals of Diglycine Sulphate monohydrate (DGSM) have been grown by slow evaporation solution growth technique. The size of the grown crystals is 20x10x10mm3 with the duration of 25 days. To identify the cell parameter, space group and planes indexing the grown crystals were subjected to single & powder XRD. The different modes of vibrations present in the crystal were identified with FT- IR spectrum. The optical transmission, absorbance, extinction coefficient, Reflectance and refractive index have been studied to find its linear properties by UV-Vis spectroscopy. Band gap energy was calculated to be 4.71 eV. The dielectric constant, dielectric loss and AC conductivity has been measured as a function of frequency and temperature.

Blue single crystals of Cu[µ2-OOC(CH2)PO3H]*2H2O (1) and Cu1.5[µ3-OOC(CH2)PO3]*5H2O (2) have been prepared in aqueous solution. 1: Space group C2/c (no. 15) with a = 1623.3(2), b = 624.0(1), c = 1495.5(2) pm, beta = 122.45(1)°. Cu is... more

Blue single crystals of Cu[µ2-OOC(CH2)PO3H]*2H2O (1) and Cu1.5[µ3-OOC(CH2)PO3]*5H2O (2) have been prepared in aqueous solution. 1: Space group C2/c (no. 15) with a = 1623.3(2), b = 624.0(1), c = 1495.5(2) pm, beta = 122.45(1)°. Cu is coordinated by three oxygen atoms stemming from the hydrogenphosphonoacetate dianion and three water molecules to form a distorted octahedron. The Cu-O bonds range from 190.4(3) to 278.5(3) pm. The connection between the Cu2+ cations and the hydrogenphosphonoacetate dianions leads to a two-dimensional structure with layers parallel to ( 01). The layers are linked by hydrogen bonds. 2: Space group (no. 2) with a = 608.2(1), b = 800.1(1), c = 1083.6(1) pm, alpha = 94.98(1)°, beta = 105.71(1)°, gamma = 109.84(1)°. There are two crystallographically independent Cu2+ cations coordinated in a square pyramidal and an octahedral fashion, respectively. The Cu-O bonds range from 192.9(2) to 237.2(2) pm. The coordination of the phosphonoacetate trianion to Cu(1) results in infinite polyanionic chains parallel to [100] with a composition of {Cu(H2O)[OOC(CH2)PO3]}nn. Hydrated Cu(2) cations are accommodated between the chains as counter ions. 1 and 2 show structural features of cation exchangers. Magnetic measurements reveal a paramagnetic Curie-Weiss behaviour. Compound 2 shows antiferromagnetic coupling between Cu2+ ions due to a super-superexchange coupling. The UV/Vis spectra of 1 suggests three d-d transition bands at 763 nm (2B1 -> 2E), 878 nm (2B1 -> 2B2), and 1061 nm (2B1 -> 2A1). Thermoanalytical investigations in air show that compound 1 is stable up to 165 °C, whereas the decomposition of 2 begins at 63 °C.

We describe a unified formulation of time-dependent Hartree-Fock (TD-HF) and time-dependent density-functional theory (TD-DFT) for the accurate and efficient calculation of the optical response of infinite (periodic) systems. The method... more

We describe a unified formulation of time-dependent Hartree-Fock (TD-HF) and time-dependent density-functional theory (TD-DFT) for the accurate and efficient calculation of the optical response of infinite (periodic) systems. The method is formulated within the linear-response approximation, but it can easily be extended to include higher-order response contributions, and, in TD-DFT, it can treat with comparable computational efficiency purely local, semi-local or fully non-local approximations for the ground-state exchange-correlation (XC) functional and for the response TD-DFT XC kernel in the adiabatic approximation. At variance with existing methods for computing excitation energies based on the diagonalisation of suitable coupling matrices, or on the inversion of a dielectric matrix, our approach exploits an iterative procedure similar to a standard self-consistent field calculation. This results in a particularly efficient treatment of the coupling of excitations at different k points in the Brillouin zone. As a consequence, our method has the potential to describe completely from first principles the optically induced formation of bound particle-hole pairs in wide classes of materials. This point is illustrated by computing the optical gaps of a series of representative bulk semiconductors, (non-spin polarised) oxides and ionic insulators.

The complexation between folic acid and typical polyaromatic hydrocarbons (Acenaphthylene and Acenaphthene) was studied by using FTIR and UV spectra with pH changing. The experiments confirmed that combination was through π-π... more

The complexation between folic acid and typical polyaromatic hydrocarbons (Acenaphthylene and Acenaphthene) was studied by using FTIR and UV spectra with pH changing. The experiments confirmed that combination was through π-π donor–acceptor interaction and inducing the protonation process in folic acid upon strengthening electron accepting ability of the acid so the changing of their charge distribution and the surroundings became necessarily. In another words, this inferred that not only biotransformation process of folic acid, but also the toxicity of polyaromatic hydrocarbons could be more understood.

A model linear oppositely charged polyelectrolyte complex exhibits phase separation upon heating consistent with lower critical solution temperature (LCST) behavior. The LCST coexistence curves narrow with increasing monovalent salt... more

A model linear oppositely charged polyelectrolyte complex exhibits phase separation upon heating consistent with lower critical solution temperature (LCST) behavior. The LCST coexistence curves narrow with increasing monovalent salt concentration (Cs) that reduces the polymer concentration (Cp) in the polymer-rich phase. The polymer-rich phase exhibits less hydration with increasing temperature, while an increase in Cs increases the hydration extent. The apparent critical temperature, taken as the minimum in the phase diagram, occurs only for a narrow range of Cs. Mean field theory suggests an increasing Bjerrum length with temperature can lead to an electrostatic-driven LCST; however, the temperature dependence of the Flory-Huggins interaction parameter and solvation effects must also be considered.

Spectrochemical analysis is a scientific technique that deals with light and its absorption and emission by solutions and other material substance. In this investigation, spectrophometric method is developed for the determination of... more

Spectrochemical analysis is a scientific technique that deals with light and its absorption and emission by solutions and other material substance. In this investigation, spectrophometric method is developed for the determination of phosphate in the various commercial detergent samples. Although there are multiple detergent samples, this particular investigatory report focuses on a single brand sample. The amount of phosphate is determined by molybdenum blue method in conjugation with UV-visible spectrophotometer. The principle of this method involves the formation of molybdophosphoric acid, which is reduced to the intensely colored complex, molybdenum blue. This is an extremely sensitive analytical method and is reliable down to concentrations of 0.1mg/L of water. The analytical method is standardized by multiple standardization strategies, the external standardization and standard addition method using 5ppm standard as assigned. The system obeys the Beer-Lambert's Law at 337nm in the concentration of range 1.0-25.0ppm.

Titanium acts as a Lewis acid relative to bases adsorbed in zeolites, attaining a coordination number of up to six. The red-shift of the Ligand to Metal Charge Transfer (LMCT) electronic transitions detected by UV/Vis studies on titanium... more

Titanium acts as a Lewis acid relative to bases adsorbed in zeolites, attaining a coordination number of up to six. The red-shift of the Ligand to Metal Charge Transfer (LMCT) electronic transitions detected by UV/Vis studies on titanium zeolites upon hydration is investigated using a DFT-based computational approach which takes into account the full periodicity of the crystalline phase.

The absorption spectrum of fluorenone in zeolite L is calculated from first-principles simulations. The broadening of each band is obtained from the explicit treatment of the interactions between the chromophore and its environment in the... more

The absorption spectrum of fluorenone in zeolite L is calculated from first-principles simulations. The broadening of each band is obtained from the explicit treatment of the interactions between the chromophore and its environment in the statistical ensemble. The comparison between the simulated and measured spectra reveals the main factors affecting the spectrum of the chromophore in hydrated zeolite L. Whereas each distinguishable band is found to originate from a single electronic transition, the bandwidth is determined by the statistical nature of the environment of the fluorenone molecule. The K+⋯O[double bond, length as m-dash]C motif is retained in all conformations. Although the interactions between K+ and the fluorenone carbonyl group result in an average lengthening of the C[double bond, length as m-dash]O bond and in a redshift of the lowest energy absorption band compared to gas phase or non-polar solvents, the magnitude of this shift is noticeably smaller than the total shift. An important factor affecting the shape of the band is fluorenone's orientation, which is strongly affected by the presence of water. The effect of direct interactions between fluorenone and water is, however, negligible.

Volcano surveillance in Colombia was formally initiated just after reactivation of Nevado del Ruiz volcano, when over 23,000 people were killed and approximately 5,000 were injured by four thick lahars that raced down river valleys on the... more

Volcano surveillance in Colombia was formally initiated just after reactivation of Nevado del Ruiz volcano, when over 23,000 people were killed and approximately 5,000 were injured by four thick lahars that raced down river valleys on the volcano0s flanks. The Armero tragedy was the second-deadliest volcanic disaster in the 20th century, being surpassed only by the 1902 eruption of Mount Pelée, and is the fourth-deadliest volcanic eruption in recorded history.
Gas monitoring on Colombian volcanic fumaroles started as in situ sampling with chemical lab analyses, later a gas telemetry system was developed and finally, from year 2007 and onwards, we are using optical remote sensing instruments for volcanic gas monitoring developed in the European projects DORSIVA and NOVAC.
NOVAC (Network for Observation of Volcanic and Atmospheric Change) today encompasses 64 scanDOAS (plus mobileDOAS) systems at 24 active volcanoes in four continents. SO2 data from NOVAC technology at active Colombian volcanoes, will be presented together with all cases of explosive eruptions from 2007 until 2012.
Special attention will be given on periods of volcanic eruptions, when magma body is transported from the deep to the surface and a clear increase of sulphur dioxide is detected at NOVAC stations located at 4 - 8 km distance from the volcanic fumaroles.

The NOVAC project, funded by European Union, was started in October 2005 with the aim to establish a global network of stations for the quantitative measurement of volcanic gas emissions. The network is based on a novel type of... more

The NOVAC project, funded by European Union, was started in October 2005 with
the aim to establish a global network of stations for the quantitative measurement
of volcanic gas emissions. The network is based on a novel type of instrument, the
Scanning Dual-beam mini-DOAS. Primarily the instruments will be used to provide
new parameters in the toolbox of observatories for gas emission estimates, geophysical
research and hazard assessment. In addition, data are exploited for other scientific
purposes, e.g. global estimates of volcanic gas emissions, regional to global statistical
analysis, and studies of atmospheric chemistry. In particular large scale validation of
satellite measurements of volcanic gas emissions will be possible, bringing spaceborne
observation volcanoes a significant step forward.
The Scanning Dual-beam Mini-DOAS instrument is capable of real-time automatic,
unattended measurement of the total emission fluxes of SO2 and BrO from a volcano
with better then 5 minutes time resolution during daylight. The high time-resolution
of the data enables correlations with other geophysical data, e.g. seismicity, thus significantly
extending the information available for real-time hazard assessment and research.
By comparing high time resolution gas emission data with emissions from
neighboring volcanoes on different geographical scales, or with other geophysical
events (earthquakes, tidal waves) mechanisms of volcanic forcing may be revealed.
The spectra recorded by the instrument will also be used to derive data that complement
global observation networks related to climate change and stratospheric ozone
depletion research.
The consortium encompasses observatories of 19 volcanoes from five continents, including
some of the most active and strongest degassing volcanoes in the world.

A simple salicylic acid selective fluorescence receptor 1 was designed by combining 1-pyrenecarboxaldehyde and 1-(3-aminopropyl)imidazole. The selective sensing of salicylic acid resulted in a significant increase in monomer emissions... more

A simple salicylic acid selective fluorescence receptor 1 was designed by combining 1-pyrenecarboxaldehyde
and 1-(3-aminopropyl)imidazole. The selective sensing of salicylic acid resulted in a significant
increase in monomer emissions due to the p–p interactions between the benzene and pyrene rings. The
nature of the interactions between receptor 1 and salicylic acid was investigated further by 1H NMR
spectroscopy, and the energy minimised structure of the complex between receptor 1 and salicylic acid
was optimised. Receptor 1 showed the highest binding constant with 5-nitrosalicylic acid (Ka = 7.18 
104 M1) among all the aromatic carboxylic acids tested. 5-Nitrosalicylic acid formed a complex with
receptor 1 at a 1 : 1 ratio in EtOH.

In the recent past, the pharmaceutical modification of drug molecules by complexation with biologically relevant metals to improve their properties such as stability, dissolution rate, absorption and bioavailability has been extensively... more

In the recent past, the pharmaceutical modification of drug molecules by complexation with biologically relevant metals to improve their properties such as stability, dissolution rate, absorption and bioavailability has been extensively studied. In order to achieve better and enhanced medicinal activity, vanadyl complexes of the widely used lincomycin (Lin-van) and neomycin (Neo-van) have been synthesized and their physico-chemical properties examined. The UV-Vis absorption properties of these complexes were determined and their antimicrobial activities were tested against some pathogenic organisms viz: Proteus vulgaris, Klebsiella pneumonae, Escherichia coli and Staphylococcus aureus. In all cases, Neo-van showed better antimicrobial activity than Lin-van while both complexes showed better activity than the antibiotic lincomycin and the previously reported Cu-Lin.

We present the chemical synthesis of silver sulfide nanocrystals (NCs) in PVA matrix and the extended characteristics of the obtained nanocomposites with fullerene. The samples were prepared with the different concentration of fullerene... more

We present the chemical synthesis of silver sulfide nanocrystals (NCs) in PVA matrix and the extended characteristics of the obtained nanocomposites with fullerene. The samples were prepared with the different concentration of fullerene and PVA for compression of their fraction relation with the optical and phase properties. UV–vis spectra of Ag 2 S show sharp excitonic features and a large blue shift from the bulk material. The NCs grain size was determined about 10–15 nm which is confirmed by different techniques such as Scanning electron microscopy (SEM), UV–visible absorption and X-ray Diffractometer (XRD). The SEM images demonstrate that the nanoparticles overlapped and stabilized with a polymer matrix. The EDAX result indicates that the prepared nanocomposites are composed of pure phase Ag, S, C and any other irrelevant mixtures have not been detected.

Molecular crystals of meso-(5-((4-formylphenyl)ethynyl)thiophen-2-yl)-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene 4a and meso-(4-((4-formylphenyl)ethynyl)phenyl)-4,4-difluoro-4-bora-3a,4a-diaza-s-inda-cene 4b were synthesized using... more

Molecular crystals of meso-(5-((4-formylphenyl)ethynyl)thiophen-2-yl)-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene 4a and meso-(4-((4-formylphenyl)ethynyl)phenyl)-4,4-difluoro-4-bora-3a,4a-diaza-s-inda-cene 4b were synthesized using palladium(0)-catalyzed Sonogashira cross coupling reactions and characterized using an experimental-theoretical approach. The crystal structures of F-BODIPYs 4a-b are structurally analogous, yet their crystal packing motifs displayed remarkable differences due to contrasting hydrogen-bonding interactions. A CASTEP study of the unit cell for each compound provided the theoretical band structure and density-of-states (DOS) diagrams for each molecular crystal, suggesting a semiconductor character for both solids. Analysis of the computed electron density with Bader's QTAIM describes the intermolecular-contact network within each periodic system, while Natural Bonding Or-bitals (NBO) display in-phase overlap between stacked units, denoting intermolecular delocalization of the electron density via stacking. TDDFT analysis of solution UV-Vis spectra gives insight into the nature of the observed excitations along with the effects derived from the relative rotation of p-subsystems in solution.