A study on the electronic spectra of vinylpyridines and 1,2‐(dipyridyl)ethylenes. Molecular orbital calculations

Abstract

The electronic absorption spectra of 2-, 3-, and 4-vinylpyridines and 1,2-(2,3-dipyridyl), 1,2-(2,4-dipyridyl), 1,2-(3,4-dipyridyl), and 1,2-(4,4-dipyridyl) ethylenes have been investigated in polar and nonpolar solvents. A correlation has been made between the geometry of the molecule and the observed spectrum. Molecular orbital calculations have been carried out using the INDO/ s-CI procedure and a limited geometry optimization. The solvent effect at the MO level has been calculated. MO calculations predicted the existence of n -r * transitions that were not observed experimentally. The wave functions of the different CI states were calculated. The experimental transition energy as well as oscillator strength corresponded satisfactorily with the calculated ones. The observed transitions were assigned according to the results of MO calculations.

Contribution of the Charge Transfer Mechanism to the Surface-Enhanced Raman Scattering of the Binuclear Ion Complex [Fe2((Bpe)(CN)10]6- Adsorbed on a Silver Electrode in Different Solvents

“…According to molecular orbital calculations the first excited state of the BPE is C(1)−C(2) antibonding and C(3)−C(2) and C(3‘)−C(1) bonding in character. Therefore, one would expect that the transfer of one electron to the LUMO of BPE would cause a decrease on the C(1)−C(2) bond order and an increase in the C(3)−C(2) and C(3‘)−C(1) bond orders.…”

Probing atomic level structural transformation in O–H⋯N heterosynthon crystal

“…This makes it extremely difficult to monitor the complete conversion as both the crystal size and crystal quality (as characterized by the width of the reflections) decreases continuously with conversion so that at a certain level, the crystals were no longer suitable for single crystals X-ray analysis. Upon irradiation at the maximum absorption of the bpe chromophore (300 nm) 18 (cf. Fig.…”

“…The splitting of the absorption band is attributed to five different transitions in the bpe monomer 18. One n-p* and other p-p* transitions.…”