Tetraphenylethene-Based Supramolecular Coordination Frameworks with Aggregation-Induced Emission for an Artificial Light-Harvesting System

Supramolecular coordination is an efficient strategy to construct supramolecular coordination frameworks with predesigned structures, assembled shapes, and specific function. In this work, we report the synthesis, structural characterization, and photophysical property of two tetraphenylethene-based supramolecular coordination frameworks 1a and 1b formed from 1,1,2,2-tetrakis(4-(pyridin-4-yl)phenyl)ethene (2a) or 1,1,2,2-tetrakis(4-((E)-2-(pyridin-4-yl)vinyl)phenyl)ethene (2b) and a linear difunctional platinum(II) ligand (3a) via coordination-driven self-assembly. Controlled by the specific angularity and geometry of tetraphenylethene (with 60° and 120°) and difunctional Pt(II) linker (with 180°), these supramolecular coordination frameworks possess a well-defined and two-dimensional (2D) rhombic network-type topology with good periodicity and porosity. Given the aggregation-induced emission (AIE) property of tetraphenylethene units and the porosity of frameworks, 1a and 1b have been successfully used as fluorescent platforms and energy donors to fabricate efficient artificial light-harvesting materials with two fluorescent acceptors (Nile Red and Sulforhodamine 101) via noncovalent interactions in aqueous solution. Furthermore, these light-harvesting materials have been applied for promoting cancer cell imaging with a full shift of imaging channels from blue/green channels to the red channel. Thus, this study provides an effective approach to fabricate functional frameworks as fluorescent platforms for developing more fluorescent materials.