Covalently linked pyrene antennas for optically dense yet aggregation-resistant light-harvesting systems

In this study we present a novel energy transfer material inspired by natural light-harvesting antenna arrays, zinc(ii) phthalocyanine-pyrene (ZnPcPy). The ZnPcPy system facilitates energy transfer from 16 covalently linked pyrene (Py) donor chromophores to the emissive central zinc(ii) phthalocyanine (ZnPc) core. Nearly 98% energy transfer efficiency is determined from the changes in emission decay rates between free MePy to covalently linked Py, supported by comparisons of photoluminescence quantum yields using different excitation wavelengths. A comparative analysis of ZnPcPy and an equivalent mixture of ZnPc and MePy demonstrates the superior light-harvesting performance of the covalently linked system, with energy transfer rates 9705 times higher in the covalently bound system. This covalent strategy allows for very high loadings of absorbing Py chromophores to be achieved while also avoiding exciton quenching that would otherwise arise, with the same strategy widely applicable to other pairs of Forster resonance energy transfer (FRET) chromophores. Inspired by natural light-harvesting antenna arrays, intramolecular energy transfer in zinc(ii) phthalocyanine-pyrene is vastly accelerated compared to equivalent mixtures of its free component chromophores.

Automated summary

In this study, a new energy transfer material called zinc(ii) phthalocyanine-pyrene (ZnPcPy) is presented, inspired by natural light-harvesting antenna arrays. The ZnPcPy system facilitates efficient energy transfer from covalently linked pyrene (Py) donor chromophores to the emissive central zinc(ii) phthalocyanine (ZnPc) core. Comparative analysis shows that the covalently linked ZnPcPy system has a superior light-harvesting performance, with energy transfer rates 9705 times higher than an equivalent mixture of ZnPc and MePy.