Ultra-strong through-space conjugation enabled by robust molecular skeleton and flexible aggregate

Manipulating the electronic structure of organic functional materials by through-space conjugation (TSC) to achieve high photophysical performances has been a longstanding research focus. Although the working mechanisms of TSC have been demonstrated, the fundamental roles of the intrinsic molecular skeleton and extrinsic aggregates remain unclear. Herein, four trinaphthylmethanol (TNMOH) isomers and four trinaphthylmethane (TNM) isomers with varying connecting sites of naphthalene were synthesized, and their photophysical properties were systematically investigated. The strength of TSC gradually enhanced from 222-TNM to 111-TNM with the increased number of 1-naphthalene units, resulting in long-wavelength clusteroluminescence with an absolute quantum yield of 57% of 111-TNM. Experimental and theoretical results revealed that the inherent attribute of robust intramolecular interactions within individual molecules is fundamental for ultra-strong TSC, and intermolecular interactions play an auxiliary role in fortifying and stabilizing intramolecular interactions. This work demonstrates the intrinsic and extrinsic factors of manipulating TSC and provides a reliable strategy for constructing nonconjugated luminogens with efficient clusteroluminescence.