Blue Emissive Zn (II) Conjugated 1D Coordination Polymers: Fluorescent Probe for Ultra-Low Level Accurate Detection...

For this easy detection of organochlorine pesticides (OCPs), we have constructed two Zn(II)-based 1D coordination polymers (CPs) JU70 [Zn(II)(phen)(H₂O)(5-HIPA)]_∞ and JU73 [Zn(II)(bpy)(5-HIPA)]_∞ under the solvothermal reaction conditions, where 5-HIPA is the 5-hydroxy isopthalic acid and bpy is 2,2' bipyridyl and phen is 1,10-Phenanthroline. The single crystal X-ray diffraction study (SCXRD) reveals that in JU70, the metal centers occupy a hexacoordinated distorted octahedral geometry, while JU73 bears a pentacoordinate distorted square bipyramidal geometry, exhibiting a 1D network with an infinite zigzag pattern. Both compounds exhibit deep blue color fluorescence at ∼425 nm. One interesting fact that the developed CPs exhibit excellent thermal and aqueous phase stabilities. The CPs showcase exceptional detection capabilities for 2,6-dichloro-4-nitroaniline (DCN), a widely used and most important chemical of OCPs, via a fluorescence "turn-off" response, enabling rapid and sensitive monitoring in pure aqueous medium with an ultralow level detection limit of 50-60 nm. The sensing mechanism involves a synergistic combination of photoinduced electron transfer, resonance energy transfer, and intermolecular charge transfer (PET-RET-ICT), accompanied by noncovalent π-π interactions, as supported by density functional theory (DFT) studies. As a real time application, the sensors can be successfully use to fabricate a CPs@cotton-swab kit, and a paper strip.