Influence of structural changes on photophysical properties of terpyridine derivates: Experimental studies and theoretical calculations

Four terpyridine ligands containing different aryl substituents 4'-(4-quinolinyl)-3,2':6',3 ''-terpyridine (3-qtpy), 4'-(4-quinoliny1)-2,2':6',2 ''-terpyridine (2-qtpy), 4'-(3-methyl-2-thienyl)-4,2':6',4 ''-terpyridine (4-stpy) and 4'-(3-methyl-2-thienyl)-2,2':6',2 ''-terpyridine (2-stpy) were synthesized in a one-pot procedure and characterized by elemental analysis, FT-IR and H-1- and C-13 NMR spectroscopy. Additionally, the 2-stpy structure was confirmed by single crystal X-ray diffraction analysis. The influence of the N-position in the tpy and aryl substituents on the photophysical properties was systematically investigated by spectroscopic methods and simulated by density functional theory (DFT and TD-DFT) calculations. Thermal stability was observed until about 280 degrees C, making these kind of ligands interesting candidates for their use as complex ligands, which are obtained by solvothermal synthesis under temperatures of about 180 degrees C. The electrochemical behavior was also investigated. All molecules show irreversible anodic and cathodic voltammetric peaks in organic medium. (C) 2017 Published by Elsevier B.V.