Coordination-Driven Self-Assembly of Carbazole-Based Metallodendrimers with Generation-Dependent Aggregation-Induced Emission Behavior.

Abstract

A new family of 120° carbazole-based dendritic donors D1-D3 have been successfully designed and synthesized, from which a series of novel supramolecular carbazole-based metallodendrimers with well-defined shapes and sizes were successfully prepared by [2+2] and [3+3] coordination-driven self-assembly. The structures of newly designed rhomboidal and hexagonal metallodendrimers were characterized by multinuclear NMR ((1) H and (31) P) spectroscopy, ESI-TOF mass spectrometry, FTIR spectroscopy, and the PM6 semiempirical molecular orbital method. The fluorescence emission behavior of ligands D1-D3, rhomboidal metallodendrimers R1-R3, and hexagonal metallodendrimers H1-H3 in mixtures of dichloromethane and n-hexane with different n-hexane fractions were investigated. The results indicated that D1-D3 featured typical aggregation-induced emission (AIE) properties. However, different from ligands D1-D3, metallodendrimers R1-R3 and H1-H3 presented interesting generation-dependent AIE properties. Furthermore, evidence for the aggregation of these metallodendrimers was confirmed by a detailed investigation of dynamic light-scattering, Tyndall effect, and SEM. This research not only provides a highly efficient strategy for constructing carbazole-based dendrimers with well-defined shapes and sizes, but also presents a new family of carbazole-based dendritic ligands and rhomboidal and hexagonal metallodendrimers with interesting AIE properties.