Construction of 1,3,5-Triazine-Based Prisms and Their Enhanced Solid-State Emissions

Abstract

In this study, two trigonal prisms based on the 1,3,5-triazine motif (SA and SB), distinguished by hydrophobic groups, were prepared by the self-assembly of tritopic terpyridine ligands and Zn(II) ions. SA and SB exhibited high luminescence efficiencies in the solid state, overcoming the fluorescence quenching of the 1,3,5-triazine group caused by π–π interactions. Notably, SA and SB exhibited different luminescence behaviors in the solution state and aggregation state. SB with 12 alkyl chains exhibited extremely weak fluorescence in a dilute solution, but its fluorescence intensity and photoluminescence quantum yield (PLQY) were significantly enhanced in the aggregated state (with the increase in the water fraction), especially in the solid state. Different from the gradually enhanced efficiency of SB, the PLQY of SA gradually decreased with the increase in aggregation but still maintained a high luminescence efficiency. These two complexes exhibited different modes to solve the fluorescence quenching of 1,3,5-triazine in the solid state. The hierarchical self-assembly of SB exhibited nanorods owing to the hydrophobic interactions of alky chains, while SA aggregated into spheres under the influence of π–π interactions.