Sonochemical synthesis of a trinuclear Cu(ii) complex with open coordination sites for the differentiable optical detection of volatile amines

A discrete trinuclear Cu(ii) complex, namely, [Cu-3(pzdc)(2)(dpyam)(2)(H2O)(4)] (1) (H(3)pzdc = pyrazole-3,5-dicarboxylic acid, dpyam = 2,2 '-dipyridylamine) was simply synthesized by the sonochemical process and structurally characterized. The single-crystal X-ray diffraction analysis revealed that three adjacent Cu(ii) centers are linked via two bridging pzdc ligands to form a trinuclear Cu(ii) unit. Each trinuclear Cu(ii) unit contains open coordination sites with two trigonal bipyramidal Cu(ii) centers and one elongated octahedral geometry. Moreover, the open coordination site of 1 was occupied by a small molecule, leading to the guest-induced structural transformation with chromism that was verified by FT-IR, UV-vis diffuse reflectance spectra, elemental analysis, PXRD, and SEM techniques. Compound 1 exhibits color change along with structural transformation in methanol media and after the dehydration process. Also, 1 shows different color responses after exposure to different amine vapors. In addition, compound 1 was conveniently deposited onto a filter paper by a sonochemical method used as a portable test strip for the discriminative qualitative detection of amines.

Automated summary

This study synthesized and structurally characterized a trinuclear copper complex using sonochemical method, finding color changes and structural transformations in different solvents as well as after dehydration, along with different color responses to various amine vapors. Additionally, the compound was conveniently deposited onto filter paper for the discriminative qualitative detection of amines.