White light emission from a two-component hybrid gel via an energy transfer process

Abstract

A two-component light-harvesting organogel containing a naphthalimide-based gelator (1) as a donor and a phosphorescent Ir(III) complex [Ir(bt)₂(acac)] (bt = 2-phenylbenzothiazole and acac = acetylacetone) (Ir) as an acceptor was used to produce white-light-emitting organogels. The addition of complex Ir to the gel 1 had a certain effect on the self-assembly behaviour of molecule 1, but did not affect the gelation ability, mechanical strength and structure surface wettability of the gel. The optical properties of the two-component gel 1–Ir could be tuned via high intermolecular energy transfer efficiency between 1 and complex Ir, which was confirmed by geometry optimizations and harmonic vibrational analyses. The white-light-emitting organogel was obtained with the molar ratio of complex Ir in the range of 0.3–1.0. In particular, the gel 1–Ir with the addition of 0.5 equivalent of Ir could emit white-light with the Commission Internationale de L' eclairage (CIE) coordinates of 0.33 and 0.31 under the excitation of 374 nm light.