Second‐order nonlinear optical responses switching of N∧N∧N ruthenium carboxylate complexes with proton‐electron transfer

In this article, the nonlinear optical (NLO) switching action of Ru(III/II) carboxylate complexes was investigated by density functional theory (DFT). Among the studied complexed, Ru(III)PhCOO− has the largest β value of 4972 × 10−30 esu. Through the proton transfer (PT) process, the COOH group of Ru(III)PhCOOH and Ru(III)COOH complexes can form the COO− group. Then, COO− group acts as a strong donor and Ru(III) acts as an acceptor, which may be the most favorably used in the development of metal complexes NLO material. The redox NLO switching and PT NLO switching of Ru(III)PhCOO−, Ru(III)PhCOOH, Ru(II)PhCOO−, and Ru(II)PhCOOH complexes have been studied. The β value of Ru(III)PhCOO− complex is ∼36 and ∼48 times larger than those of reduced Ru(II)PhCOO− and Ru(II)PhCOOH, respectively. Note that the β value of deprotonated Ru(III)PhCOO− is ∼215 times larger than that of Ru(III)PhCOOH. The molecular electrostatic potential analysis also confirms that Ru(III)PhCOOH may have poor performance in the second-order NLO response. In addition, the TDDFT calculations show that the ligand to metal charge transfer transition lead to the largest β value of the Ru(III)PhCOO− complex. This investigation provides important insight into the remarkably large NLO properties and NLO switching of Ru(III/II) carboxylate complexes. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem 000: 000–000, 2011