Anion-Directed Assemblies of Cationic Metal–Organic Frameworks Based on 4,4′-Bis(1,2,4-triazole): Syntheses, Structures, Luminescent and Anion Exchange Properties

Three cationic metal–organic
frameworks (MOFs), Ag­(btr)·​PF6·​0.5CH3CN (1), Ag2(btr)2­(H2O)·​2CF3SO3·​H2O (2), and Ag2(btr)2­(NO3)·​NO3 (3), were prepared
from reaction of 4,4′-bis­(1,2,4-triazole) (btr) with silver
salts containing different anions. Complex 1 is a three-dimensional
(3-D) framework constructed from tetrahedral-shaped nanoscale coordination
cages with PF6– as counteranions. 2 and 3 are 3-D architectures containing 1-D
channels, in which charge-balancing CF3SO3– and NO3– are located
in their respective channels. Luminescent emission of 1–3 shows an obvious red shift compared with the
btr ligand. Anion exchange studies show that 1 is able
to selectively exchange MnO4– in aqueous
solution with a modest capacity of 0.56 mol mol–1; the luminescent emission of 1 is quickly quenched
upon MnO4– exchange.