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

Area of Science:

• Coordination Chemistry
• Supramolecular Chemistry
• Materials Science

Background:

• The 1,3,5-triazine motif often suffers from fluorescence quenching due to π-π interactions.
• Developing luminescent materials that overcome this quenching is crucial for applications.

Purpose of the Study:

• To synthesize and characterize two trigonal prisms, SA and SB, based on the 1,3,5-triazine core.
• To investigate their luminescence properties in solution and aggregated states.
• To understand the structure-property relationships governing their luminescence behavior.

Main Methods:

• Self-assembly of tritopic terpyridine ligands with Zn(II) ions.
• Preparation of two distinct trigonal prisms (SA and SB) differing in hydrophobic groups.
• Spectroscopic analysis (luminescence, PLQY) in solution and aggregated states.
• Structural characterization of aggregated forms (nanorods, spheres).

Main Results:

• Both SA and SB exhibit high luminescence efficiencies in the solid state, mitigating π-π stacking quenching.
• SB shows weak fluorescence in dilute solution but enhanced luminescence upon aggregation, especially in solid state.
• SA's photoluminescence quantum yield decreases with aggregation but maintains high efficiency.
• SB self-assembles into nanorods via hydrophobic interactions, while SA forms spheres via π-π interactions.

Conclusions:

• SA and SB effectively overcome 1,3,5-triazine fluorescence quenching in the solid state through different self-assembly mechanisms.
• Hydrophobic interactions in SB promote aggregation-induced emission, while π-π interactions in SA lead to sphere formation with sustained luminescence.
• These findings provide strategies for designing robust luminescent materials based on the 1,3,5-triazine core.