Accessing a Long-Lived 3LC State in a Ruthenium(II) Phenanthroline Complex with Appended Aromatic Groups

• DOI: 10.1021/acs.inorgchem.0c02102
• Publication Date: 2020-11-11T17:54:11Z
• Authors: Georgina E. Shillito; Samantha E. Bodman; Joseph I. Mapley; Christopher M. Fi...; Keith C. Gordon
• Keywords: Chemical Sciences not elsewhere classified; emissive 3 MLCT states; archetypal parent; R group; Biophysics; 40 μ; Biochemistry; 01 natural sciences; Sociology; Space Science; resonance Raman spectroscopy; Environmental Sciences not elsewhere classified; Genetics; ground state; Long-Lived 3 LC State; photophysical properties; Cancer; Pharmacology; naphthalene substituents; Ecology; 3 LC; Ru; emission spectroscopy; 0104 chemical sciences; emissive 3 MLCT state; Medicine; Appended Aromatic Groups; Physical Sciences not elsewhere classified

The photophysical properties of a series of heteroleptic Ru(II) complexes of the form [Ru(phen)2(phen-5,6-R2)]2+, where phen = 1,10-phenanthroline and R = phenyl (Ph), p-tert-butylbenzene (p-Ph-tBu), p-methoxybenzene (p-Ph-OMe), and 2-naphthalene (2-naph), have been measured. Variation of the R group does not greatly perturb the electronic properties of the ground state, which were explored with electronic absorption and resonance Raman spectroscopy and are akin to those of the archetypal parent complex [Ru(phen)3]2+. All complexes were shown to possess emissive 3MLCT states, characterized through transient absorption and emission spectroscopy. However, an additional, long-lived excited state was observed in the Ru(II) naphthalene complex. The naphthalene substituents facilitate population of a 40 μs dark state which decays independently to that of the emissive 3MLCT state. This state was characterized as 3LC in nature, delocalized over the naphthalene substituted ligand.