Four solvent-responsive one-dimensional copper(I) coordination polymers (CPs), namely, {[Cu 4 I 4 L(MeCN) 2 ]·CH 2 Cl 2 } n (1), {[Cu 4 I 4 L(MeCN) 2 ]·CHCl 3 } n (2), {[Cu 4 I 4 L(MeCN) 2 ]·0.5p-xylene} n (3), and [Cu 4 I 4 L(MeCN) 2 ] n (4), were prepared by reaction of CuI with N,N′-bis[2-(cyclohexylthio)ethyl]pyromellitic diimide (L) via self-assembly under varying solvent conditions. CPs 1−4, which are pseudopolymorphic supramolecular isomers derived from solvent molecules, are composed of Cu 4 I 4 cubane clusters. The ligands in CPs 1−3 adopted a synconformation, whereas in CP 4 they were observed in the anticonformation. This occurred via syn to anti transitions upon heating, followed by exposure to MeCN vapor. In addition, a reversible anti to syn transition was achieved by agitating in mixed organic solvents. It was shown that ligand transition from the syn-to the anti-conformation occurred through crystal-to-amorphous-to-crystal transformations. Furthermore, CPs 1−3 exhibited reversible solvent exchange and crystal transformation by exposure to vapors from volatile organic compounds.C oordination polymers (CPs) have recently received a great amount of attention, with studies focusing on the control of geometric structures of compounds formed by coordination between well-designed ligands and metal cations. Furthermore, the production of compounds exhibiting useful functionalities has also been investigated. CPs have the potential for use in various fields, such as catalysis, 1−3 ion exchange, 4,5 selective adsorption, 6−8 hydrogen storage, 9,10 sensors, 11,12 and magnetism-based applications. 13,14 Moreover, a number of studies are currently underway regarding the crystal transformation of CPs by control of anionic, solvent, ligand, and metal cationic molar ratios. Predicting such structural changes is not easy; hence, many chemists have invested effort in identifying and controlling the influences of the factors that induce structural changes. Our aim was to focus on reversible/nonreversible structural transformations in copper(I) CPs by variation of temperature and solvent. Furthermore, we wished to investigate their emission changes under the above conditions. We expect that a number of structural transformations will be related to conformational changes of the sulfur-containing organic ligands and the labile Cu−S coordination bond. 15−17 We investigated the preparation of four CPs by reaction of CuI with a dithioether ligand bearing a pyromellitic diimide spacer. We found that by varying the ligand to metal ratio, complexes with different structures were formed, including rhomboid dimers and stair-step polymers. Although acetonitrile and dichloromethane were used as solvents and structural transformations were induced by controlling the ligand/metal ratio, some reversible crystal transformations were also observed. 15 We later reported the preparation of four CPs containing Cu 2 I 2 clusters by reaction of CuI with a ligand bearing both pyrazine and sulfur moieties. In addition, we reported a contr...

The controlled self-assembly of CuI and an asymmetric ligand with mixed N/S donors, 2-(tert-butylthio)-N-(pyridin-3-yl)acetamide (L), afforded three Cu(I) coordination polymers (CPs), [Cu4I4L2(MeCN)2]n (1), [Cu4I4L2]n (2), and {[Cu4I4L2]⋅MeOH}n (3). X-ray analyses showed that CPs 1-3 are supramolecular isomers with 1, 2, and 3D structures, respectively. CP 1 adopts a stairstep Cu4I4 cluster, whereas CPs 2 and 3 are composed of cubane-like Cu4I4 clusters. Crystal-to-crystal transformations of 1 to 2 and 3 showed reversible transformations between different Cu4I4 clusters using heat or solvent (acetonitrile or methanol) vapor. CP 2 was reversibly transformed to 3 by the addition of methanol and heat. Therefore, the transformations between supramolecular isomers 1, 2, and 3 are completely reversible.

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

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