pH-induced coordination assembly of mononuclear and dinuclear copper(II) complexes based on a 4,4′-bipyridinium analogue

Upon controlling coordination sites of a new bipyridinium analogue 4′-(N-carboxybenzyl-4-pyridinio)-2,2′:6′,2″-terpyridine chloride (HL·Cl) with different dosage of perchloric acid, two copper complexes with distinct bridging modes, {[Cu(L)Cl]·ClO4·3H2O}n (1) and [Cu2(HL)2Cl2]·4ClO4·H2O (2) have been obtained under hydrothermal condition. Complex 1 features a one-dimensional chain-like structure with mononuclear Cu(II) centers, while 2 is a dichloro-bridged dinuclear Cu(II) complex, which forms one-dimensional supramolecular chain via hydrogen bonding interactions between the carboxylic groups of HL ligands. The magnetic measurement reveals that an antiferromagnetic coupling interaction exists in complex 2.