Solvatochromism and Theoretical Studies of Dicyanobis(phenylpyridine)iridium(III) Complex Using Density Functional Theory

Luminescent cyanometallate [Ir(ppy)(2)(CN)(2)](-) (ppy = C6H5C5H4N) has recently gained attention due to its desired photophysical properties. Our research group reported that the [Ir(ppy)(2)(CN)(2)](-) has shown a negative solvatochromism like [Ru(bipy)(CN)(4)](2-), resulting in a blue-shift of the UV-Vis absorption bands in the water. Therefore, to gain insight into the specific solvent-solute interaction governed by the hydrogen bond in the solvation hydration shell, density functional theory (DFT) calculations were performed on the singlet ground state of the [Ir(ppy)(2)(CN)(2)](-) and its solvent environment in the water at B3LYP level theory. It was demonstrated, seven water molecules provided a good description of the relevant spectra: IR and UV-Vis. The calculation reproduced the positions and intensities of the observed v(C N) bands at 2069 and 2089 cm(-1). The calculated MLCT transition wavelength was 366 nm vs. a measured value of 358 nm, differing by 8 nm. The study revealed the water molecules interacted with cyanide ligands through CN center dot center dot center dot H-OH type hydrogen bonds and water-water interactions (HO-H center dot center dot center dot OH2 type hydrogen bonds) were involved in the solvation hydration shell around the [Ir(ppy)(2)(CN)(2)](-).

Automated summary

Through density functional theory calculations, the research team demonstrated specific solvent-solute interactions of [Ir(ppy)(2)(CN)(2)](-) and its solvent environment in water, revealing the mechanism of water molecules interacting with cyanide ligands through hydrogen bonding.