One-dimensional chains consisting of copper(II) ions and an orthogonal anthracene-pyrimidine derivative: hierarchical formation of high-dimensional networks and their magnetic properties

Abstract

Recrystallization of 9-(5-pyrimidinyl)anthracene (1) with copper(II) nitrate trihydrate formed three kinds of complexes: 1·Cu(NO₃)₂·H₂O (2), 1·Cu(NO₃)₂·MeOH·H₂O (3) and 1·Cu(NO₃)₂·2EtOH (4) by changing the recrystallization solvent. The crystal structure of the three complexes showed cooperation of metal coordination, hydrogen bonding, and aromatic stacking interactions in the hierarchical formation of one-, two- and three-dimensional networks. Complexes 2 and 3 formed zigzag one-dimensional chains consisting of 1 and Cu²⁺ ions by coordination of pyrimidine to Cu²⁺ ion in equatorial trans fashion. Complex 4 formed a spiral one-dimensional chain by coordination in equatorial cis fashion. The magnetic behavior of 2, 3, and 4 were measured on a SQUID susceptometer to reveal that there existed strong antiferromagnetic interactions between Cu²⁺ ions. The magnetic data of one-dimensional antiferromagnetic chains were analyzed by the Bonner–Fisher model. The antiferromagnetic interaction between Cu²⁺ ions was around −55 K, which is the largest value observed in pyrimidine-bridged Cu²⁺ ions.