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.

Theoretical investigation of the substituent effects on the electronic and optical properties of 6-substituted coumarin derivatives

“…It is found that time-dependent density functional theory (TD-DFT) at the B3LYP/6-311+G (d, p) level correctly reproduced the absorption wavelength and intensity of many organic molecules [33][34][35][36]. And as you can see in our previous work, in the case of 6-fluoro coumarin, the calculated absorption and emission spectrum at this level were found to be in good agreement with the experimental values [37].…”

Stereoselective polymerization of methyl methacrylate and rac-lactide mediated by iminomethylpyridine based Cu(ii) complexes

“…The bands assigned to n(C]N) of the azomethine group and n(C]N)py shied to higher wavenumber in the spectra of all complexes, indicating the possibility of back donation and the participation of nitrogen atoms in bonding. 54,55 Elemental analysis for all complexes was consistent with the proposed structures in Scheme 1. All the synthesized Cu(II) complexes were soluble in common organic solvents.…”

Solvatochromism and pH effect on the emission of a triphenylimidazole-phenylacrylonitrile derivative: experimental and DFT studies

“…Based on our previously reported the strong electron withdrawing feature of the phenylacrylonitrile/pyridylacrylonitrile based chromophore that act as a good acceptor and to show an enhancement of emission in the solid state but some case its weak. [38][39][40] Hence it exhibited an important effect on the optical and electronic properties. [41][42][43] Herein we report the synthesis of a novel imidazole derivatives containing the phenylacrylonitrile (half of the a-cyanostilbene) unit using a simple route.…”