Single crystals of cyclodimeric zinc(ii) complexes containing 9,10-bis((isoquinolin-5-yloxy)methyl)anthracene: reversible adsorption of target molecules and recognition of CH2I2 in an SCSC mode

Self-assembly of ZnCl2 with a new C2-symmetric bidentate N-donor ligand gives rise to stable crystals consisting of 46-membered metallacyclodimers, [ZnCl2L]2·5C4H8O. The tetrahydrofuran solvates of the single crystals are replaced by o-, m-, and p-xylene isomers within 5 min in a single-crystal-to-single-crystal (SCSC) mode, by which this system serves as a tolerant template for reversible adsorption/desorption of target molecules. Further, the equimolar mixture of o-X, m-X, and p-X was adsorbed onto the crystals in the 1 : 1 : 2 mole ratio at room temperature. The photoluminescence (PL) spectra of the single crystals efficiently show the on–off switching nature on adsorption of CH2I2 in the SCSC mode. Moreover, the [ZnCl2L]2·5C4H8O crystals in an aniline medium transform into crystals of ligand-exchanged species [Zn2Cl4L(C6H5NH2)2]·2C6H5NH2 in the SCSC mode.