Polytorsional-amide/carboxylates-directed Cd(ii) coordination polymers exhibiting multi-functional sensing behaviors

Abstract

By rational assembly of polytorsional-amide [N,N′-bis(4-methylenepyridin-4-yl)-1,4-naphthalene dicarboxamide (L)] and polytorsional-carboxylates [H₂ADI = adipic acid, H₂PIM = pimelic acid, H₂SUB = suberic acid], three new Cd-based coordination polymers (CPs) C₃₀H₃₀CdN₄O₇ (1), C₃₁H₃₂CdN₄O₇ (2) and C_31.03H_30.55CdCl_0.24N₄O_5.52 (3) were successfully synthesized. CPs 1–2 and 3 are 2D networks and a 3D framework, which all display 3,5-connected topologies with different structural details. The effects of carboxylates with different carbon chains on the structure of the complexes were studied. Fluorescence experiments show that CPs 1–3 have good multi-functional sensing ability for metal cations (Fe³⁺), anions (MnO₄⁻, CrO₄²⁻, Cr₂O₇²⁻) and organochlorine pesticides (2,6-dichloro-4-nitroamine) with good anti-interference and recyclable characteristics. The possible sensing mechanism is also investigated in detail.