title: Theoretical and experimental spectroscopic analysis of  cyano-substituted styrylpyridine compounds.
abstract: A combined theoretical and experimental study on the structure, infrared,  UV-Vis and 1H NMR data of trans-2-(m-cyanostyryl)pyridine, trans-2-[3-methyl-(m-cyanostyryl)]pyridine and trans-4-(m-cyanostyryl)pyridine is presented. The synthesis was carried out with an efficient Knoevenagel condensation using green chemistry conditions. Theoretical geometry optimizations and their IR spectra were carried out using the Density Functional Theory (DFT) in both gas and solution phases. For theoretical UV-Vis and  1H NMR spectra, the Time-Dependent DFT (TD-DFT) and the Gauge-Including Atomic Orbital (GIAO) methods were used, respectively. The theoretical characterization matched the experimental measurements, showing a good correlation. The effect of cyano- and methyl- substituents, as well as of the N-atom position in the pyridine ring on the UV-Vis, IR and NMR spectra, was evaluated. The UV-Vis results showed no significant effect due to electron-withdrawing cyano- and electron-donating methyl-substituents. The N-atom position, however, caused a slight change in the maximum absorption wavelengths. The IR normal modes were assigned for the cyano- and methyl-groups. 1H NMR spectra showed the typical doublet signals due to protons in the trans position of a double bond. The theoretical characterization was visibly useful to assign accurately the signals in IR and  1H NMR spectra, as well as to identify the most probable conformation that could be present in the formation of the styrylpyridine-like compounds.
authors: Chemistry Center, Institute of Sciences, Autonomous University of Puebla, Complex of Sciences, ICUAP, 103H, 22 Sur y San Claudio, University City, Puebla City, Pue.-72570, Mexico. francisco.melendez@correo.buap.mx.
authors: Maria Eugenia
authors: ME
authors: Castro
authors: Maria Judith
authors: MJ
authors: Percino
authors: Victor M
authors: VM
authors: Chapela
authors: Margarita
authors: M
authors: Ceron
authors: Guillermo
authors: G
authors: Soriano-Moro
authors: Jorge
authors: J
authors: Lopez-Cruz
authors: Francisco J
authors: FJ
authors: Melendez