Isomerism in 1D Coordination Polymers of Cu(II) Complexes of <i>N</i>-(2-Hydroxybenzyl)-<scp>l</scp>-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 [Cu 2 (Sval) 2 (H 2 O) 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, [Cu 2 (Sval) 2 (H 2 O)] n ·2 n H 2 O, 2 . Interestingly, the thermal dehydration behavior of 2 is very similar to that of 1 . Pseudo-supramolecular isomeric compounds of [Cu 2 (Sval) 2 (H 2 O)] n ·0.5 n C 3 H 7 OH, 3, and [Cu 4 (Sval) 4 (H 2 O) 2 (C 4 H 9 OH)] n · n C 4 H 9 OH, 4, were obtained when anhydrous 1 was recrystallized from 2-proponal and 1-butanol, respectively.