Bio-Inspired Artificial Light-Harvesting Arrays Based on Boron(III)-Chelates

Abstract

Many diverse natural systems use sunlight to drive critical chemical reactions. To harvest sufficient photon densities, natural organisms have developed highly sophisticated light absorbing antennae rather than rely on direct illumination of a single chromophore. Attempts to develop artificial analogues have resulted in the synthesis and spectroscopic characterisation of elaborate molecular assemblies and here we consider the case for using boron(III) chelates as the primary light absorb-ers. Such entities make attractive modules for the creation of multi-component arrays with individual units sited in a logical sequence for long-range electronic energy transfer. Alternatively, certain boron(III) chelates can be synthesised in high yield by simple strategies that avoid time-consuming purification. These latter materials are appealing as components for large-scale light harvesters. The use of photonic crystals avoids the need to position individual molecules at the catalyst but presents severe design challenges. Interrupting, or redirecting, the flow of excitons within the array requires the introduction of novel switches that can be activated by selective illumination. Protecting the array against adventitious photofading is a major objective that has yet to be achieved. artificial light-harvesting array built by attaching disparate BOBIPY derivatives to a functionalized C60 residue. At high concentration in a thin plastic film, electronic energy migration proceeds between adjacent particles decorated with the yellow dye and exciton trapping occurs at the blue dye. This is a rare example of long-range energy transfer between particles. Reprinted with permission from [18]. Copyright (2012) American Chemical Society.