Stepwise coordination isomerism of 2D networks: Adsorption of diiodomethane into crystals and recognition in SCSC mode

Reaction of CdI2 with C2-symmetric multidentate N-donor (L) in a mixture of ethanol and dichloromethane produces single crystals of 3(dichloromethane)·2(ethanol)@[CdI2L] (23.26 Å thickness layer) with a new 2D topology of {43·62·8}. These single crystals in tetrahydrofuran are isomerized into new single crystals of 4(tetrahydrofuran)@[CdI2L] (9.15 Å thickness layer) with a 2D topology of sql {44·62}. The tetrahydrofuran solvate molecules of 4(tetrahydrofuran)[CdI2L] are fully replaced by adsorption of dihalomethane molecules in the single-crystal-to-single-crystal (SCSC) mode. The most interesting feature is that both 3(dichloromethane)·2(ethanol)@[CdI2L] and 4(tetrahydrofuran)@[CdI2L] crystals are integral to an efficient and tolerant matrix for recognition of diiodomethane (CH2I2) in the SCSC mode, even though the adsorption rate of 4(tetrahydrofuran)@[CdI2L] crystals is much faster than that of 3(dichloromethane)·2(ethanol)@[CdI2L]. That is, their blue photoluminescence is significantly quenched in the presence of diiodomethane, and recovered by removal of the diiodomethane.