http://nopr.niscpr.res.in/handle/123456789/35750 2026-10-11T07:02:10Z http://nopr.niscpr.res.in/handle/123456789/35757 Title: Charge transfer interaction of 8-hydroxyquinoline with DDQ: Spectrophotometric, thermodynamic and molecular modeling studies Authors: Naveen, Baindla; Arunapriya, Lakkadi; Parthasarathy, Tigulla Abstract: The charge transfer complex of the donor, 8-hydroxyquinoline (8HQ) with the π-acceptor 2,3-dichloro-5,6-dicyano<i>-p</i>-benzoquinone (DDQ) in acetonitrile medium has been studied spectrophotometrically at different temperatures. The 8HQ reacts instantaneously with DDQ to form reddish brown charge transfer complex. Absorption spectra of the complex shows multi-charge transfer bands at 456, 548 and 588 nm. The high values of the formation constant and molecular extinction coefficient, calculated from the Benesi-Hildebrand equation, show the high stability of the CT complex. Enthalpy and entropy of CT complex formation have been estimated by using van’t Hoff equation where the more negative value of Δ<i>H</i>° confirms strong bonding between donor and acceptor. The signs of Δ<i>H</i>°, Δ<i>S</i>° and Δ<i>G</i>° reveal that the CT complex formation process is exothermic and a spontaneous process. The experimental studies are complemented by quantum chemical calculations at DFT (B3LYP/6-31G) level of theory, including bond lengths, bond angles, Mulliken electron charge on atoms and molecular electrostatic potential maps which are helpful in assigning the CT route. In addition, GAMESS interface computations are performed to characterize the highest occupied molecular orbital and lowest unoccupied molecular orbital surfaces of the complex. A good consistency was found between experimental and theoretical results. Page(s): 1209-1215 2016-10-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/35756 Title: Quantum mechanical study of carbon nanotubes functionalized with drugs, pentoxifylline and lysofylline Authors: Jalayeri, Elham; Morsali, Ali; Bozorgmehr, Mohammad R Abstract: The noncovalent interactions of drug pentoxifylline (PTX) with (5, 5) pristine and COOH functionalized-carbon nanotube and the mechanisms of covalent functionalization of the drug, lisofylline (LSF) with (5, 5) COOH and COOCl functionalized carbon nanotube have been studied by density functional theory calculations. Quantum molecular descriptors for four configurations of noncovalent interaction are calculated. It is found that binding of PTX with COOH functionalized CNT is thermodynamically favorable. COOH and COCl functionalized CNT can bind to lysofylline via OH (COOH mechanism) and Cl (COCl mechanism ) groups, respectively. The barrier energies of two mechanisms have been evaluated and compared with each other. It was found that the COOH mechanism has activation energy higher than the COCl mechanism, and hence the reason for suitability of COCl pathway for covalent functionalization. Page(s): 1202-1208 2016-10-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/35755 Title: Experimental and theoretical studies on the structure, electronic and vibrational spectra of <i>o/p</i>-hydroxybenzylidene-<i>o/p</i>-toluidines Authors: Suna, P; Hota, P; Misra, P K Abstract: The experimental and theoretical analyses of the electronic and vibrational spectra of four biologically active aldimines, i. e., <i>o/p</i>-hydroxybenzylidene-<i>o/p</i>-toluidines, using experimental techniques and semiempirical calculations are reported. Theoretical geometry optimization, and vibrational and electronic spectral studies have been computed in the gaseous phase at the PM3 and AM1 levels. The theoretical vibrational frequency data obtained from PM3 and AM1 level calculations are close to the experimental values. Geometrical optimization reveals that the two benzene rings of the aldimines are out-of-plane with respect to azomethine linkage (–C=N-). The electronic transitional energies of highest occupied molecular orbital and the lowest unoccupied molecular orbital energies calculated by FMO analysis predict the high reactivity of the molecules. The possible bonding sites of aldimines have been predicted by molecular electrostatic potential analysis. Various characteristics parameters such as electron affinity, ionization energy, hardness, softness, chemical potential and electrophilicity index of the focused aldimines are determined. Page(s): 1192-1201 2016-10-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/35753 Title: Molecular adsorption study of nicotine on the nitrogen doped TiO₂ anatase nanoparticles: Insights from van der Waals corrected DFT computations Authors: Abbasi, Amirali; Sardroodi, Jaber Jahanbin Abstract: The interaction of nicotine with undoped and nitrogen-doped TiO₂ anatase nanoparticles is investigated by density functional theory studies. The results indicate that the interaction between nicotine and N-doped TiO₂ nanoparticles is stronger than that between nicotine and pristine TiO₂ nanoparticles, which suggests nitrogen doping helps to strengthen the interaction of nicotine with TiO₂ nanoparticles. In other words, the doping of nitrogen atom promotes the interaction of nicotine with TiO₂ nanoparticles. It is found that the nitrogen atom of nicotine molecule tends to be strongly adsorbed on the five-fold coordinated titanium site of N-doped anatase nanoparticles. By including van der Waals interactions between nicotine molecule and TiO₂, it is found that the adsorption on the N-doped TiO₂ is energetically more favorable than that on the pristine one. The projected density of states analysis indicates the formation of chemical bond between nitrogen atom of nicotine and titanium atom of nanoparticle. These results offer a theoretical basis and general understanding of the interaction of TiO₂ nanoparticles with nicotine, suggesting potential applications of N-doped TiO₂ nanoparticles in designing of novel sensors and removers for nicotine detection. Page(s): 1182-1191 2016-10-01T00:00:00Z