Substituent Influence on Structural and Luminescent Diversities of Cu3(pyrazolate)3-CunIn Coordination Supramolecular Isomers

Three photoluminescent isomeric complexes [Cu 3 ( L4 ) 3 ] 2 [CuI] 2 (labeled as complexes 1, 2, and 3 ) were prepared from the same bifunctional organic ligand H L4 (3-(4-pyridyl)-5-methyl-1 H -pyrazole) and CuI by careful manipulation of the reaction conditions. Planar trinuclear Cu 3 ( L4 ) 3 and CuI/Cu 2 I 2 units are integrated via N–Cu coordination bonds into Cu 3 Pz 3 -Cu n I n systems (Pz = pyrazolate). Complex 1 is a discrete supramolecular aggregate via cooperative π-acid···base (Cu 3 ···I) and Cu···Cu interactions. Complexes 2 and 3 are 2-fold interpenetrated three-dimensional frameworks. The small size of the Cu n I n ( n = 1 or 2) units and structural diversities in such Cu 3 Pz 3 -Cu n I n systems were realized by preinstalling a methyl group on pyrazole at the 5-position of the ligand. The three complexes exhibit subtly different yellow emissions under UV irradiation in their solid states, originating from their respective triplet excited states of the supramolecular coordination luminophores. These results demonstrate that the structural and luminescent diversities of the Cu 3 Pz 3 -Cu n I n -based complexes can be regulated by substituents.