Emissive silver(i) cyclic trinuclear complexes with aromatic amine donor pyrazolate derivatives: way to efficiency

3-Trifluoromethyl-pyrazoles containing strong fluorophore groups: triphenylamine (TPAPz) and carbazole (CarbPz), and their trinuclear silver(i) complexes are found to be emissive in solution and the solid state, giving the first example of silver pyrazolate adducts emissive in solution at room temperature. The electronic coupling was observed for pyrazole with a structurally flexible triphenylamine substituent, determining the intraligand charge-transfer (ILCT) nature of the excited states. The association-dissociation of the trinuclear complex core with the heavy atom effect leads to the intense phosphorescence of the triphenylamine-containing complex. The structural rigidity of the N-ethyl carbazole substituent allows only twisting via the bond to the pyrazolate core leading to typical carbazole-centered (LC) fluorescence in solution. In the solid-state, aggregation plays the primary role in emission properties. The observed behavior is in good agreement with the theoretical calculations.

Automated summary

This study investigates the fluorescence properties of 3-trifluoromethyl-pyrazoles containing triphenylamine and carbazole groups, as well as their silver complexes, in both solution and solid state. The results show that the electronic coupling between triphenylamine substituent and pyrazole leads to fluorescence emission in solution, while the rigid structure of the N-ethyl carbazole substituent results in typical carbazole-centered fluorescence. Aggregation plays a major role in determining the emission properties in the solid state.