Solvent‐triggered single‐crystal‐to‐single‐crystal transformation from a monomeric to polymeric copper(II) complex based on an aza macrocyclic ligand

Reversible solvent‐triggered single‐crystal‐to‐single‐crystal (SCSC) transformations are observed between two copper(II) azamacrocyclic complexes: [Cu(C16H38N6)(H2O)2](C12H6O4) (1) and [Cu(C16H38N6)(C12H6O4)] (2). Complex (1) was prepared via self‐assembly of a copper(II) azamacrocyclic complex containing butyl pendant groups, [Cu(C16H38N6)(ClO4)2], with 2,7‐naphthalenedicarboxylic acid. When monomeric compound (1) was immersed in CH3OH, coordination polymer (2) was obtained, indicating a solvent‐triggered SCSC transformation. Furthermore, when (2) was immersed in water, an reverse SCSC transformation from (2) to (1) occurred. Complex (1) presents a 3D supramolecular structure formed via intermolecular hydrogen‐bonding interactions, whereas complex (2) features a 1D zigzag coordination polymer. The reversible SCSC transformation of (1) and (2) was characterized using single‐crystal X‐ray diffraction and in situ powder X‐ray diffraction techniques. Despite its poor porosity, complex (2) displayed interesting CO2 adsorption behaviour under CO2 gas. Reversible solvent‐triggered single‐crystal‐to‐single‐crystal transformations are observed between two copper(II) azamacrocyclic complexes and characterized by single‐crystal X‐ray diffraction and in situ powder X‐ray diffraction.