Solvent-introduced two novel copper(II)–letrozolate compounds: Solvothermal synthesis, crystal structures and photoluminescence property

A well-known antifungal agent letrozole was selected in this work to react with CuCl2·2H2O under solvothermal conditions. Two novel supramolecular coordination compounds, namely, [Cu(LTZ)3Cl2] (1) and [Cu(LTZ)4Cl2]·H2O (2) (LTZ = letrozole = 1-[bis(4-cyano-phenyl)methyl]-1,2,4-triazole), have been successfully obtained by changing the solvent. The utilization of ethanol/water solvent led to the formation of 1, which crystallizes in the monoclinic system, space group P2(1)/c. When the methanol/water solvent was used instead under the similar conditions, we got compound 2, space group C2/c. The Cu(II) center is a five-coordinated [CuN3Cl2] square pyramidal geometry in 1, but six-coordinated [CuN4Cl2] octahedral environment in 2, which maybe mainly introduced by the solvent molecule. These two large mononuclear compounds both are packed into complex three-dimensional supramolecular frameworks via the hydrogen bonds and interesting π⋯π interactions. The photoluminescence measurements show that two compounds both show strong blue emissions ascribed to the intraligand and/or ligand to metal charge transfer.