Silver Coordination Polymers Based on Newly Designed Bis(cyanobenzyl)bipiperidine Ligand: Synthesis, Anion Exchange, Guest Inclusion, Electrochemical, and Photoluminescence Properties

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, [Ag 2 ( L )(NO 3 ) 2 ] n ( 1 ), [Ag 2 ( L )(NO 3 ) 2 ] n ( 2 ), {[Ag 2 ( L )(NO 3 ) 2 )](C 16 H 10 )} n ( 3 ), {[Ag 2 ( L )(NO 3 ) 2 )](C 20 H 12 )} n ( 4 ), [Ag 2 ( L )(ClO 4 ) 2 ] n ( 5 ), [Ag 2 ( L )(CF 3 SO 3 ) 2 (C 4 H 8 O) 2 ] n ( 6 ), [Ag 2 ( L )(CF 3 SO 3 ) 2 (C 3 H 6 O) 2 ] n ( 7 ), {[Ag 2 ( L ) 2 ]·(BF 4 )·2(C 3 H 6 O)} n ( 8 ), and [Ag 2 ( L ) 3 (PF 6 ) 2 ]· x (C 3 H 6 O) ( 9 ), have been prepared by self-assembly of L with AgX (X = NO 3 –, ClO 4 –, CF 3 SO 3 –, BF 4 –, and PF 6 – ) and aromatic guest molecules. Reactions of L with AgNO 3 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 AgNO 3 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 = CF 3 SO 3 – ) in acetone and THF gave two structurally related 2D CPs ( 6 and 7 ). Compound 8 represents a one-dimensional (1D) coordination polymer where the BF 4 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.