Linker-Induced Structural Diversity and Photophysical Property of MOFs for Selective and Sensitive Detection of Nitroaromatics

The linker [1,1′:3′,1″-terphenyl]-4,4′,4″,6′-tetracarboxylic acid (H4L) was used to construct two three-dimensional (3D) metal–organic frameworks (MOFs), namely, {[Cd2(L)(L1)(DMF)(H2O)](2DMF)(3H2O)}n (1) and {[Cd4(L)2(L2)3(H2O)2](8DMF)(8H2O)}n (2) (DMF = N,N′-dimethylformamide) in the presence of colinkers 4,4′-bipyridine (L1) and 2-amino-4,4′-bipyridine (L2), respectively, under solvothermal condition. A small change in the colinker leads to significant differences in the overall structure of the MOFs. Topological analysis reveals that the framework 1 exhibits 6,4-connected forbidden sub-configuration (FSC) topology, while the framework 2 exhibits twofold interpenetrated and (3,4,4)-connected new network topology with Schlafli point symbol {4.62}{4.64.8}{42.62.82}. The crystallographic investigation reveals the framework 2 having single helix structure, which is further coiled through noncovalent interaction, afforded a double-helix structure similar to DNA. These double helices are further connected thr...