Two Stable Bifunctional Zinc Metal–Organic Frameworks with Luminescence Detection of Antibiotics and Proton Conduction

Abstract

Functionalized crystalline solids based on metal–organic frameworks (MOFs) enable efficient luminescence detection and high proton conductivity, making them crucial in the realms of environmental monitoring and clean energy. Here, two structurally and functionally distinct zinc-based MOFs, [Zn(TTDPa)(bodca)]·H 2 O ( 1 ) and [Zn(TTDPb)(bodca)]·H 2 O ( 2 ), were successfully designed and synthesized using 3,6-di(pyridin-4-yl)thieno[3,2- b ]thiophene (TTDPa) and 2,5-di(pyridin-4-yl)thieno[3,2- b ]thiophene (TTDPb) as ligands, in the presence of bicyclo[2.2.2]octane-1,4-dicarboxylic acid (H 2 bodca). Both 1 and 2 display a three-dimensional (3D) structure with 5-fold interpenetration, and notably, 2 forms a larger one-dimensional pore measuring 17.16 × 10.81 Å 2 in size. Fluorescence experiments demonstrate that 1 and 2 can function as luminescent sensors for nitrofurantoin (NFT) and nitrofurazone (NFZ) with low detection limits, remarkable selectivity, and good recyclability. A comprehensive analysis was conducted to investigate the differing sensing effects of compounds 1 and 2 and to explore potential sensing mechanisms. Additionally, at 328 K and 98% relative humidity, 1 and 2 exhibit proton conductivity values of 2.13 × 10 –3 and 4.91 × 10 –3 S cm –1, respectively, making them suitable proton-conducting materials. Hence, the integration of luminescent sensing and proton conductivity in monophasic 3D Zn-MOFs holds significant potential for application in intelligent multitasking devices.