Structure and solvatochromism of heteroaromatic aminoketones containing thiophene moieties

A series of N-substituted phenyl-2-thienyl ketones including 2-(4-fluorobenzoyl)thiophene (FLBT, 1a), 2-(4-piperidinobenzoyl)thiophene (PIBT, 1b), 2-(4-morpholinobenzoyl)thiophene (MOBT, 1c), 2-(4-thiomorpholinobenzoyl)thiophene (THBT, 1d), 2-(4-phenylpiperazinobenzoyl)thiophene (PHBT, 1e), 2-(4-pyrrolidinobenzoyl)thiophene (PYBT, 1f), 2-(4-hydroxyethylpiperazinobenzoyl)thiophene (HYBT, 1g), 1,4-bis(4-benzoyl-2-thienyl)piperazine (BBTP, 2) and 1,6-bis(4-benzoyl-2-thienyl)-N,N'-dimethylhexamethylenediamine (BBDA, 3) have been investigated regarding solvatochromism and solid-state structure. Solvatochromic properties have been analyzed using the Kamlet-Taft linear solvation energy relationship. The influence of the dipolarity/polarizability (pi*) and hydrogen-bond acidity (a) of the solvent, respectively, on the portions of the bathochromic UV-Vis band shift as a function of substituent is discussed. The solid-state structures of 1b (C16H17NOS), 1C (C15H15NO2S) and 1f (C15H15NOS) have been determined by single-crystal x-ray structure analysis. Crystallochromic effects are discussed comparatively with regard to the linear solvation energy relationships and the results of the solid-state structures. Copyright (c) 2005 John Wiley & Sons, Ltd.