Anion- and Solvent-Induced Assembly and Reversible Structural Transformation of d(10)-Metal Coordination Architectures Containing N-(4-(4-Aminophenyloxy)phenyl)-isonicotinamide

摘要

We set out studies on anion-and solvent-induced assembly based on the ligand N-(4-(4-aminophenyloxy)phenyl) isonicotinamide (papoa), which is synthesized to show a bent and flexible backbone. Reactions of papoa with ZnX2 (X=Cl, Br, and I) gave the dinuclear macrocycles ([ZnX2(papoa)](2); X=Cl (1a), Br (2a), I (3)), the structure of which was determined by X-ray diffraction. Notably, the less bulky Cl and Br compounds afforded the coordinated imine in acetone (i.e., [ZnX2(papoi)](2), papoi = N-(4-(4-(propan-2-ylideneamino) phenoxy)phenyl) isonicotinamide; X=Cl (1b), Br (2b)), whereas the iodine one only gave the coordinated amine compound 3 under the same reaction condition. In fact, the coordinated imine can return to the amine analogue upon exposure to air or in DMSO, which has been monitored by H-1 NMR spectroscopy and powder X-ray diffraction. Both the dinuclear [Zn(papoa)(NO3)(2)](2) (4a) and the 1D [Zn(papoa)(2)(NO3)(2)](n) (4b) were formed from the reaction of Zn(NO3)(2) and papoa in mixed solvents with acetone and acetonitrile, respectively. In addition, Cd(ClO4)(2) can react with papoa to give the 1D framework {[Cd(-papoa)(2)(CH3CN)(2)](ClO4)(2)}(n) (5a) and the 2D framework [Cd(-papoa)(2)(ClO4)(2)](n) (5b), depending on the solvent used, that is, MeOH and CH3CN, respectively. Importantly, the 1D framework with axially coordinated CH3CN molecules and the 2D framework with axially coordinated ClO4- ions can be inter-converted by heating and grinding in the presence of CH3CN, respectively. Such a reversible structural transformation process was proven by PXRD studies.