Ground state and photophysical properties of Ru(phen)2quo+: a strong excited state electron donor

Electronic Tuning of Ruthenium Complexes by 8‐Quinolate Ligands

“…This finding is consistent with the thermal accessibility of nonemissive low‐lying ligand‐field (LF) dd state(s) from the lowest energy 3 MLCT state that is typical of Ru(II) complexes, including 1 (2). In addition, the emission maximum observed for 2 is similar to those reported previously for related Ru(II) complexes containing quo − , which range from 757 to 783 nm for [Ru(L) 2 (quo)] + (L = phen, 4,7‐dimethyl‐1,10‐phenantroline, 3,4,7,8‐tetramethyl‐1,10‐phenanthroline) in water (11,12). The excitation spectrum of 2 overlays well with the absorption spectrum (Fig.…”

“…The strong binding of 8‐quinolate (quo − ) to metals has long been known, and transition metal complexes of these and related ligands have been used in a variety of applications (11–33). For example, the use of quo − in the sensing of closed‐shell transition metal and heavy ions has proved useful, since the tris‐homoleptic species are strongly luminescent (25–33).…”

“…In particular, the photophysical properties and dynamics of [Ru(bpy) 3 ] 2+ (1, bpy = 2,2¢-bipyridine) and related complexes have been investigated extensively including the effect of structural modifications to the bidentate ligands on their ground and excited state redox chemistry (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14). For example, the presence of oxygen in the ligation sphere of the ruthenium center dramatically affects the energy of the lowest energy transitions assigned as metal-to-ligand charge transfer, MLCT (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22). It has also been shown that, with careful selection of ligands, it is possible to tune the redox chemistry of the metal center (23,24).…”

“…In addition, the electroluminescence of Al(quo) 3 and Ga(quo) 3 has been useful in organic light emitting diodes (26,33). Although the complexation of quo ) and its derivatives with many metals has been extensively investigated, there are a limited number of reports of their ruthenium complexes (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22). Of these, little is known about the effect of the ligation sphere on the redox and optical properties of these complexes.…”

“…Previous work by this group focused on the [Ru(L) 2 (quo)] + series of complexes, where L represents bpy, 1,10‐phenanthroline, 4,7‐dimethyl‐1,10‐phenanthroline and 3,4,7,8‐tetramethyl‐1,10‐phenanthroline (11,12). The molecular structures of these ligands are shown in Fig.…”