Construction and structural transformation of two coordination sphere supramolecular isomers based on Co(ii) and 4-(2-pyridyl)-NH-1,2,3-triazole via one-pot synthesis

Abstract

Two coordination sphere supramolecular isomers based on Co(II) and 4-(2-pyridyl)-NH-1,2,3-triazole, namely [Co(HL)₂Cl₂]·2H₂O (Co–Cl, HL = 4-(2-pyridyl)-NH-1,2,3-triazole) and [Co(HL)₂(H₂O)₂]Cl₂ (Co–H₂O), have been obtained via one-pot synthesis and structurally characterized by single-crystal X-ray diffraction analysis. The construction of supramolecular isomers in this system is mainly influenced by reaction temperature and reaction time. ESI-MS spectra revealed that the single crystals of both isomers possess identical mass fragments and similar distribution in positive mode. Theoretical calculations indicated that there was very little difference in total energy between the two isomers. However, the thermodynamically favored Co–Cl possesses stronger coordination bonds and the kinetically favored Co–H₂O has stronger hydrogen bonds.