Coordination-driven [2+2] metallo-macrocycles isomers: conformational control and photophysical properties

Abstract

In recent years, fluorescent supramolecular materials have received significant attention due to their wide application prospects. However, the relationship between the conformation of supramolecules and their photophysical properties remains an open question. In this study, two rhomboidal metallacycle isomers, SA and SB, self-assembled with trans- and cis-isomers of tetraphenylethylene-based ditopic pyridyl ligands (LA and LB), and a 120° di-platinum (II) acceptor were prepared. Compared with metallacycle SB constructed by cis- tetraphenylethylene (TPE)-based ligand LB, the curved rhomboidal metallacycle SA constructed with trans-TPE-based ligand LA can restrict molecular motions of the aromatic groups on TPE and exhibits better light-emitting properties. Moreover, curved SA also exhibited better fluorescence stability than isomer SB towards molecules with strongly electron-withdrawing groups. This work provides a new platform to explore the relationship between conformation and the corresponding photophysical properties.

Keywords

Supramolecular self-assembly / metallacycles / isomer / conformational control / coordination-induced emission

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