Reversible Luminescence Vapochromism and Crystal-to-Amorphous-to-Crystal Transformations of Pseudopolymorphic Cu(I) Coordination Polymers

Four solvent-responsive one-dimensional copper­(I) coordination polymers (CPs), namely, {[Cu₄I₄<b>L</b>(MeCN)₂]­·CH₂Cl₂}_<i>n</i> (<b>1</b>), {[Cu₄I₄<b>L</b>(MeCN)₂]­·CHCl₃}_<i>n</i> (<b>2</b>), {[Cu₄I₄<b>L</b>(MeCN)₂]­·0.5<i>p</i>-xylene}_<i>n</i> (<b>3</b>), and [Cu₄I₄<b>L</b>­(MeCN)₂]_<i>n</i> (<b>4</b>), were prepared by reaction of CuI with <i>N</i>,<i>N</i>′-bis­[2-(cyclohexylthio)­ethyl]­pyromellitic diimide (<b>L</b>) via self-assembly under varying solvent conditions. CPs <b>1</b>–<b>4</b>, which are pseudopolymorphic supramolecular isomers derived from solvent molecules, are composed of Cu₄I₄ cubane clusters. The ligands in CPs <b>1</b>–<b>3</b> adopted a <i>syn</i>-conformation, whereas in CP <b>4</b> they were observed in the <i>anti</i>-conformation. This occurred via <i>syn</i> to <i>anti</i> transitions upon heating, followed by exposure to MeCN vapor. In addition, a reversible <i>anti</i> to <i>syn</i> transition was achieved by agitating in mixed organic solvents. It was shown that ligand transition from the <i>syn-</i> to the <i>anti</i>-conformation occurred through crystal-to-amorphous-to-crystal transformations. Furthermore, CPs <b>1</b>–<b>3</b> exhibited reversible solvent exchange and crystal transformation by exposure to vapors from volatile organic compounds

Controlled Reversible Crystal Transformation of Cu(I) Supramolecular Isomers

Four copper­(I) coordination polymers (CPs), {[CuI<b>L</b>]·CH₃CN]}_<i>n</i> (<b>1</b>), {[CuI<b>L</b>]·CHCl₃}_<i>n</i> (<b>2</b>), {[CuI<b>L</b>]·CH₂Cl₂}_<i>n</i> (<b>3</b>), and [CuI<b>L</b>]_<i>n</i> (<b>4</b>), were prepared by self-assembly reactions between CuI and (2-pyrazinylcarbonyl)­thiomorpholine (<b>L</b>). CPs <b>1</b>–<b>4</b> are interconnected by rhomboid Cu–I₂–Cu units. CPs <b>1</b> and <b>4</b> have one-dimensional loop-chain structures, and <b>2</b> and <b>3</b> adopt two-dimensional network structures. CPs <b>1</b>–<b>4</b> are pseudopolymorphic supramolecular isomers. CPs <b>2</b>′ and <b>3</b>′ are prepared by removal of solvate molecules from CPs <b>2</b> and <b>3</b>, which are polymorphic supramolecular isomers with CP <b>4</b>. Reversible crystal-to-crystal transformations were observed under appropriate conditions such as solvent or heat