Solvatochromism of a Novel Ruthenium Complex, [Ru(acac)2(N-(2-Methylsulfonylphenyl)formamido)]: A Correlation between the Electronic Structure and Spectroscopic Properties

Abstract

Solvatochromism is commonly used in many fields of chemical and biological research to study bulk and local polarity in macro systems (membranes, etc.), or even the conformation and binding of proteins. Despite its wide use, solvatochromism still remains a largely unknown phenomenon due to the extremely complex coupling of many different interactions and dynamical processes which characterize it. In this work the spectroscopic characterization of the Ru(acac)2(L) complex (1) [HL = N-(2-methylsulfonyl-phenyl)formamide] are presented. Gas- and solution-phase structural and electronic features of (acac)2Ru(L) have been investigated using density functional theory. The molecular structure underscores the flexibility of the formyl fragment in the metal complex. Time-dependent density functional theory has been used to investigate the excited states and solvatochromic properties of Ru(acac)2(L). The calculated vertical excitation energies in solution are consistent with the experimental data, showing that the ligand-to-metal charge-transfer transitions, in both the visible and UV regions, dominate over the ligand based π–π* transitions.