Concomitant Crystallization of Genuine Supramolecular Isomeric Rhombus Grid and Ribbon

Abstract

Two genuine Co(II) supramolecular isomers, a two-dimensional (2-D) rhombus grid 1 and a one-dimensional (1-D) ribbon 2, that have the same metal fragment and ligand conformations, were crystallized from the same reaction bath under hydro(solvo)thermal conditions. The formation of supramolecular isomers in this system is dominated by the bridging orientation of InMe-4-py ligands, which is mainly influenced by reaction temperature but also weakly swayed by pH value, reaction time, and counteranion. The major rhombus grid 1 is the thermodynamically favored product, and the minor ribbon 2 is the kinetically favored product under controlled conditions, as supported by their relative abundances in functions of temperature and time. Both polymeric networks of supramolecular isomers 1 and 2 display a high thermal stability over 350 °C. Magnetic studies of 1 and 2 indicate that the Co(II) centers in the 2-D and 1-D networks are essentially magnetically insulated. The magnetic behavior demonstrates depopulation of higher energy Kramers doublets to the ground state, which results from a spin–orbit contribution, of the high-spin Co(II) center in Oh configuration upon a decrease of temperature.