Metal–Organic Dimerization of Dissymmetrical Ligands toward Customized Through-Space Chromophore Interactions

The pursue of good photophysical properties for organic
optoelectronic
materials requires a well understanding of through-space chromophore
interactions, which further requires a well control over the spatial
arrangement of chromophores. However, it remains a challenge to precisely
customize the positioning of chromophores in their aggregating form
such as in a simplest cofacially stacked dimer. Herein, this work
provides a customizable molecular design based on dissymmetrical ligands
that can enable a precise control over chromophore interactions through
the formation of metal–organic dimers. Anti-paralleled stacking
of two dissymmetrical ligands in the metal–organic dimers results
in a lateral shifting of chromophore stacking, whose spacing is determined
and adjusted by the degree of ligand dissymmetry. Three metal–organic
dimers with a variation in chromophore spacing exhibited unique photophysical
properties in both solution and solid states and displayed high-efficient
luminescence against quenching in their aggregating states. This strategy
thereby offers a universally applicable way to construct chromophore
dimers with fixed cofacial spacing and determinate through-space interactions.

为获取有机光电材料（organic optoelectronic materials）的优良光物理性能，需要充分理解空间间生色团（chromophore）相互作用，而这又要求对生色团的空间排布进行精准调控。然而，目前仍存在一项挑战：难以精准定制生色团在聚集态下的定位，例如最简单的共面堆叠二聚体（cofacially stacked dimer）结构。为此，本工作提出一种基于不对称配体（dissymmetrical ligands）的可定制分子设计策略，可通过构建金属有机二聚体（metal–organic dimers）实现对生色团相互作用的精准调控。金属有机二聚体中两个不对称配体的反平行堆叠（anti-paralleled stacking），会使生色团堆叠产生侧向位移（lateral shifting），其间距可通过配体的不对称程度进行确定与调节。三款生色团间距存在差异的金属有机二聚体，在溶液与固态下均展现出独特的光物理性能，且在聚集态下可抵御猝灭，实现高效发光。该策略由此提供了一种普适性方法，可用于构建具有固定共面间距与确定空间间相互作用的生色团二聚体。