Data for Publication "Synthesis and Optical Properties of a Gallium(III) Bis(8-quinolyl)amide Complex"

Complexes of main group elements represent a promising, but underexplored approach in the development of earth-abundant alternatives to precious metal complex photosensitisers. We herein report the synthesis, structural characterisation and optical spectroscopy, supported by DFT and TD-DFT calculations, of a cationic gallium(III) complex, [Ga(BQA)₂]PF₆, expanding the relatively underexplored field of luminophores based on main group elements. Although [Ga(BQA)₂]PF₆ exhibits favourable ligand-based CT absorptions in the visible spectrum, it is only weakly fluorescent and apparently does not undergo intersystem crossing to access the triplet excited state manifold. Computational studies suggest that these unfavourable excited state properties arise from a large singlet-triplet splitting, and accessibility to the central atom by solvent. Our results reinforce recent reports on the need to sterically protect the central element to obtain photoactive earth-abundant metal complexes, extending the concept to main-group complexes where the central element is not electronically involved in the excited state.

主族元素配合物（main group element complexes）是开发贵金属配合物光敏剂（precious metal complex photosensitisers）的地球丰产替代物的一种极具前景但尚未充分探索的途径。本文报道了阳离子型镓(III)配合物[Ga(BQA)₂]PF₆的合成、结构表征及光学光谱研究，并辅以密度泛函理论（DFT, Density Functional Theory）和时间依赖密度泛函理论（TD-DFT, Time-Dependent Density Functional Theory）计算，拓展了主族元素基发光体（luminophores）这一相对未被充分探索的领域。尽管[Ga(BQA)₂]PF₆在可见光谱区表现出有利的配体基电荷转移（CT, charge transfer）吸收，但其荧光较弱，且显然未发生系间窜越（intersystem crossing）以到达三重激发态能级。计算研究表明，这些不利的激发态性质源于较大的单重态-三重态分裂（singlet-triplet splitting）以及溶剂对中心原子的可及性。我们的结果印证了近期关于需通过空间位阻保护中心元素以获得光活性地球丰产金属配合物的报道，并将这一概念拓展至中心元素不参与激发态电子过程的主族元素配合物。