Solvatochromism, Crystallochromism, and Solid State Structures of Hydrophilically Functionalized Aromatic Amino Ketones Containing Furan and Thiophene Rings

Abstract

[4-Di(2-acetoxyethyl)aminophenyl]-2-furylmethanone [Fur(OAc) 2 ], [4-di(2-hydroxyethyl)-aminophenyl]-2-furylmethanone [Fur(OH) 2 ], and their thiophene analogues, [4-di(2-acetoxy-ethyl)aminophenyl]-2-thienylmethanone [Thi(OAc) 2 ] and [4-di(2-hydroxyethyl)aminophenyl]-2-thienylmethanone [Thi(OH) 2 ], have been synthesized as model compounds for the study of molecular interactions in the solid-state and liquid environments with different polarity. The UV/Vis absorption spectra of these compounds have been studied in 30 solvents of different polarity and hydrogen bonding ability. The solvent dependent UV/Vis spectroscopic band shifts ν max are analyzed using the empirical Kamlet-Taft solvent parameters π* (dipolarity/polarizability), α (hydrogen bond donating capacity), and β (hydrogen bond accepting ability) in terms of the well-established linear solvation energy relationship (LSErs): ν max = (ν max ) 0 + sπ* + aα + bβ. The solvent independent coefficients s, a, and b and (ν max ) 0 have been determined. To evaluate the environmental effects for Fur(OH) 2 and Thi(OH) 2 , the UV/Vis spectroscopic behavior of these compounds was also investigated as pure crystal powders and as a guest in ormosil sol-gel glasses. The solid-state structures of the latter compounds were determined by single-crystal X-ray diffraction techniques. The X-ray investigations confirm the existence of qualitatively different intermolecular hydrogen bonds in Fur(OH) 2 and Thi(OH) 2 , which are additionally reflected by the UV/Vis reflectance absorption spectra and are related to the solvatochromism result.