Silver Coordination Polymers Based on Newly Designed Bis(cyanobenzyl)bipiperidine Ligand: Synthesis, Anion Exchange, Guest Inclusion, Electrochemical, and Photoluminescence Properties
文摘
A new flexible ligand, bis(cyanobenzyl)bipiperidine (L), has been synthesized and structurally characterized. Nine novel silver(I) coordination polymers (CPs), the dimensionality of which depends on the counteranion, [Ag2(L)(NO3)2]n (1), [Ag2(L)(NO3)2]n (2), {[Ag2(L)(NO3)2)](C16H10)}n (3), {[Ag2(L)(NO3)2)](C20H12)}n (4), [Ag2(L)(ClO4)2]n (5), [Ag2(L)(CF3SO3)2(C4H8O)2]n (6), [Ag2(L)(CF3SO3)2(C3H6O)2]n (7), {[Ag2(L)2]·(BF4)·2(C3H6O)}n (8), and [Ag2(L)3(PF6)2]·x(C3H6O) (9), have been prepared by self-assembly of L with AgX (X = NO3–, ClO4–, CF3SO3–, BF4–, and PF6–) and aromatic guest molecules. Reactions of L with AgNO3 in acetone in either 1:2 or 1:1 stoichiometric ratio occurred rapidly at room temperature, yielding topologically different structural isomers of the three-dimensional (3D) CPs 1 and 2. Additional reactions of linker L with AgNO3 in the presence of aromatic guest molecules (pyrene, perylene) formed CPs of 3 and 4 with the inclusion of the corresponding guest in the crystal lattice associated with the reduction of dimensionality of the self-assembled product from 3D to two-dimensional (2D). Reaction of L with AgTf (Tf = CF3SO3–) in acetone and THF gave two structurally related 2D CPs (6 and 7). Compound 8 represents a one-dimensional (1D) coordination polymer where the BF4 anions are not linked to the silver nodes, while 9 is a discrete coordination complex. Anion exchange accompanying an irreversible structural conversion from 7 to 1 and 7 to 8 was monitored in the crystalline state by IR and PXRD techniques. On the other hand, a reversible anion exchange process was observed between 1 and 8. The electrochemical and solid-state photoluminescence properties of these Ag(I) CPs were also characterized.