A Gelation-Induced Enhanced Emission Active Stimuli Responsive and Superhydrophobic Organogelator: “Turn-On” Fluorogenic Detection of Cyanide and Dual-Channel Sensing of Nitroexplosives on Multiple Platforms

Abstract

A pyrene-based highly emissive low-molecular-weight organogelator, [2-(4-fluorophenyl)-3-(pyren-1-yl)­acrylonitrile] (F1), is presented, which divulges thixotropic and thermochromic fluorescence switching via reversible gel-to-sol transition and tremendous superhydrophobicity (mean contact angles: 149–160°), devoid of any gelling and/or hydrophobic units. The rationale for the design strategy reveals that the restricted intramolecular rotation (RIR) in J-type self-assembly promotes F1 for the prolific effects of aggregation- and gelation-induced enhanced emission (AIEE and GIEE). Meanwhile, hindrance in charge transfer via the nucleophilic reaction of cyanide (CN–) on the CC unit in F1 facilitates the selective fluorescence “turn-on” response in both solution [9:1 (v/v) DMSO/water] and solid state [paper kits] with significantly lower detection limits (DLs) of 37.23 nM and 13.4 pg/cm2, respectively. Subsequently, F1 discloses CN– modulated colorimetric and fluorescence “turn-off” dual-channel response for aqueous 2,4,6-trinitrophenol (PA) and 2,4-dinitrophenol (DNP) in both solution (DL = 49.98 and 44.1 nM) and solid state (DL = 114.5 and 92.05 fg/cm2). Furthermore, the fluorescent nanoaggregates of F1 in water and its xerogel films permit a rapid dual-channel “on-site” detection of PA and DNP, where the DLs ranged from nanomolar (nM) to sub-femtogram (fg) levels. Mechanistic insights reveal that the ground-state electron transfer from the fluorescent [F1-CN] ensemble to the analytes is responsible for anion driven sensory response, whereas the unusual inner filter effect (IFE) driven photoinduced electron transfer (PET) was responsible for self-assembled F1 response toward desired analytes. Additionally, the nanoaggregates and xerogel films also detect PA and DNP in their vapor phase with reasonable percentage of recovery from the soil and river water samples. Therefore, the elegant multifunctionality from a single luminogenic framework allows F1 to provide a smart pathway for achieving environmentally benign real-world applications on multiple platforms.

Metal–Organic Coordination Polymers: A Review of Electrochemical Sensing of Environmental Pollutants

“…The detection of nitro group based aromatic compounds (NACs) has received substantial attention for domestic security and environmental safety . For instance, there are vital security needs for a quick and subtle recognition of homemade and commercial explosive materials for supporting numerous counter-terrorism surveillance events.…”

“…The detection of nitro group based aromatic compounds (NACs) has received substantial attention for domestic security and environmental safety. 132 For instance, there are vital security needs for a quick and subtle recognition of homemade and commercial explosive materials for supporting numerous counter-terrorism surveillance events. These materials always threaten agencies such as the Ministry of Home Affairs (MHA), Ministry of Defense (MOD), Crime Bureau of Intelligence (CBI), Ministry of Environment, Forest and Climate Change (MOEFCC), etc.…”

Aggregation induced emission and volatile acid vapour sensing in acridine appended poly (aryl ether) based low molecular weight organogelator

“…Organogels form hierarchical architectures by self-assembly 13,14 through H-bonding, π–π stacking, van der Waals and electrostatic interactions 15 and metal ion coordination 16 with a gelator that exhibits an AIE property, which is often termed gelation induced emission enhancement (GIEE). 17–20 The three-dimensional porous network structure of a gel with a high surface-to-volume ratio enhances the adsorption, accumulation and diffusion of gaseous molecules, which enhance the sensitivity of the response. 21–23 Various organogels have been used to detect volatile acids, amines and explosives in their gel as well as xerogel states.…”