Emission Tuning of Nonconventional Luminescent Materials via Cluster Engineering

Nonconventional Luminescent Materials (NLMs) with distinctive optical properties are garnering significant attention. A key challenge in their practical application lies in precisely controlling their emission behavior, particularly achieving excitation wavelength-independent emission, which is paramount for accurate chemical sensing. In this study, NLMs (Y1, Y2, Y3, and Y4) are synthesized via a click reaction, and it is found that excitation wavelength-dependent emission correlates with molecular cluster formation. Rigid NLMs (Y1, Y2) exhibit excitation-independent emission in dilute solutions with nanoscale clusters but become excitation-dependent at higher concentrations due to larger cluster formation. Flexible NLMs (Y3 and Y4) always show excitation-dependent emission, indicating a tendency for larger cluster formation. While these NLMs exhibit high photoluminescence quantum yields (PLQYs) in dilute solutions (0.1 mg mL^-1) up to 38.0%, they suffer from significant aggregation-caused quenching (ACQ) in the solid state (as low as 0.5%). These findings provide insights into NLM luminescence mechanisms and offer a new approach for tuning their optical properties. With excellent optical properties, facile synthesis, and biocompatibility, these NLMs hold promise for bioimaging and other applications.