Isomerism in 1D coordination polymers of Cu(II) complexes of N-(2-hydroxybenzyl)-L-valine: Influence of solvent and coordination sphere on the conformation

Abstract

The reaction of the deprotonated N-(2-hydroxybenzyl)-L-valine ligand ("Sval") with Cu(II) salts afforded [Cu2(Sval) 2(H2O)3]n, 1, which has a 1D coordination polymeric structure cross-linked by strong hydrogen bonds to give 2D hydrogen-bonded coordination polymer in the solid state. Compound 1 can lose all the water molecules bonded to Cu(II) below 110°C. However, recrystallization from aqueous solution of anhydrous 1 gave a supramolecular isomer, [Cu2(Sval)2(H2O)]n· 2nH2O, 2. Interestingly, the thermal dehydration behavior of 2 is very similar to that of 1. Pseudo-supramolecular isomeric compounds of [Cu 2(Sval)2(H2O)n·0.5nC 3H7OH, 3, and [Cu4(SVal)4(H 2O)2(C4H9-OH)n· nC4H9OH, 4, were obtained when anhydrous 1 was recrystallized from 2-proponal and 1-butanol, respectively.