Charge transfer interactions and nonlinear optical properties of push–pull chromophore benzaldehyde phenylhydrazone: A vibrational approach

Experimental and theoretical studies on o-, m- and p-chlorobenzylideneaminoantipyrines

Corrosion inhibition of mild steel by two new S-heterocyclic compounds in 1 M HCl: Experimental and computational study

A theoretical study of the complexes formed by hypohalous acids (HOX, X = F, Cl, Br, I, and At) with three nitrogenated bases (NH3, N2, and NCH) has been carried out by means of ab initio methods, up to MP2/aug-cc-pVTZ computational method. In general, two minima complexes are found, one with an OH···N hydrogen bond and the other one with a X···N halogen bond. While the first one is more stable for the smallest halogen derivatives, the two complexes present similar stabilities for the iodine case and the halogen-bonded structure is the most stable one for the hypoastatous acid complexes.

Competition of Hydrogen Bonds and Halogen Bonds in Complexes of Hypohalous Acids with Nitrogenated Bases

Surface-enhanced Raman spectroscopy (SERS) as a powerful analytical tool has gained extensive attention. Despite of many efforts in the design of SERS substrates, it remains a grand challenge for creating a general substrate that can detect diverse target analytes. Herein, we report our attempt to address this issue by constructing a novel metal-graphene oxide nanostructured film as SERS substrate. Taking advantages of the high affinity of graphene oxide (GO) toward aromatic molecules and the SERS property of nanostructured metal, this structure exhibits great potential for diverse aromatic molecules sensing, which is demonstrated by using crystal violet (CV) with positive charge, amaranth with negative charge, and neutral phosphorus triphenyl (PPh(3)) as model molecules.

Functionalizing Metal Nanostructured Film with Graphene Oxide for Ultrasensitive Detection of Aromatic Molecules by Surface-Enhanced Raman Spectroscopy

Spectroscopic analysis and DFT calculations of a food additive Carmoisine

Combretastatin-A2 (CA2), a potential anticancer drug in advanced preclinical development, is extracted from the medicinal plant Combretum caffrum. The NIR-FT Raman and FT-IR spectral studies of the molecule were carried out and ab initio calculations performed at the B3LYP/6-31G(d) level to derive the equilibrium geometry as well as the vibrational wavenumbers and intensities of the spectral bands. The vibrational analysis showed that the molecule has a similar geometry as that of cis-stilbene, and has undergone steric repulsion resulting in twisting of the phenyl ring with respect to the ethylenic plane. Vibrational analysis was used to investigate the lowering of the stretching modes, and enhancement of infrared band intensities of the C–H stretching modes of Me2 may be attributed to the electronic effects caused by back-donation and induction from the oxygen atom. Analysis of phenyl ring modes shows that the CA2 stretching mode 8 and the aromatic C–H in-plane bending mode are equally active as strong bands in both IR and Raman spectra, which can be interpreted as the evidence of intramolecular charge transfer (ICT) between the OH and OCH3groups via conjugated ring path and is responsible for bioactivity of the molecule. Copyright © 2008 John Wiley & Sons, Ltd.

Density functional study on the structural conformations and intramolecular charge transfer from the vibrational spectra of the anticancer drug combretastatin‐A2

The FT-IR and FT-Raman spectra of sodium salt of 4-hydroxy-3[1-(4-nitrophenyl)-3-oxobutyl]-2H-1-benzopyran-2-one (acenocoumarol sodium salt) in solid phase have been recorded and analyzed. The optimization geometry, intramolecular hydrogen bonding, and harmonic vibrational wavenumbers of acenocoumarol sodium salt have been investigated with the help of B3LYP density functional theory (DFT) methods. The infrared and Raman spectra were predicted theoretically from the calculated intensities. Natural bond orbital (NBO) analysis indicates the presence of CH···O hydrogen bonding in the molecule. The first static hyperpolarizability of the molecule has been computed. Copyright © 2009 John Wiley & Sons, Ltd.

Theoretical and vibrational spectral investigation of sodium salt of acenocoumarol

Amaranth (E123, Food Red 9, FD & C Red 2) is a sulfonated azo dye used as a color additive in foodstuffs, pharmaceuticals and cosmetics. FT-IR and FT-Raman spectra of amaranth were recorded and analyzed. Density functional theory (DFT) calculations were performed to derive the equilibrium geometry, vibrational wavenumbers, intensities and first hyperpolarizability. The results of the optimized molecular structure gave clear evidence for the intramolecular charge transfer (ICT) and intramolecular hydrogen bonding in the molecule. Azo stretching wavenumbers are lowered owing to conjugation and π-electron delocalization. Time-dependent density functional theory (TD-DFT) calculations of the electronic spectra were performed on the optimized structure and compared with the experimental UV-visible spectrum. Vibrational spectra, natural bonding orbitals (NBO) analysis and optimized geometry indicate CH·N hydrogen bonding in the molecule. The first hyperpolarizability of the molecule was calculated. The optical nonlinearity of the dye is due to the donation of the electron density from the hydroxyl group of the conjugated system via naphthalene (2) ring into π*-orbital of the azo moiety. Copyright © 2008 John Wiley & Sons, Ltd.

C. Ravikumar

Papers

Charge transfer interactions and nonlinear optical properties of push–pull chromophore benzaldehyde phenylhydrazone: A vibrational approach

Spectroscopic analysis and DFT calculations of a food additive Carmoisine

Density functional study on the structural conformations and intramolecular charge transfer from the vibrational spectra of the anticancer drug combretastatin‐A2

Theoretical and vibrational spectral investigation of sodium salt of acenocoumarol

FT‐Raman, IR and UV‐visible spectral investigations and ab initio computations of a nonlinear food dye amaranth