Multi‐emissive 1D Cd(II) polymers with a biphenyl bridged bisazamacrocycle for ratiometric discrimination of nitroaromatics and selective visual detection of picric acid

Abstract

Three one‐dimensional ladder‐like coordination polymers consisting of Cd6 metalloring as the building unit, {[Cd4LCl4]·3H2O}n (1), {[Cd3L(ClO4)(H2O)]ClO4·3H2O}n (2), and {[Cd6(L)2(NO3)2(CH3OH)(H2O)](NO3)2·2CH3OH·5H2O}n (3), were solvothermally constructed from a carboxylic functionalized bisazamacrocyclic ligand 4,4′‐bis((4,7‐bis(2‐carboxyethyl)‐1,4,7‐triazacyclonon‐1‐yl)methyl)‐1,1′‐biphenyl (H4L). These compounds dispersed in ethanol show the multiple emissions originating from the monomeric and intramolecularly overlapping biphenyl moieties which could be sensitively quenched by picric acid (PA) and 4‐nitrophenol (4‐NP) through the effective fluorescence resonance energy transfer process. The differential fluorescent responses of each compound on exposure to PA and 4‐NP individually make the convenient ratiometric discrimination of two analytes based on the fluorescent intensity ratio (I320/I360) attainable, and 1 and 2 as ratiometric chemosensors for PA present a broad linear detection range from 4 to 300 μM with detection limits of 0.84 and 0.93 μM, respectively. Furthermore, the blue light emission of 1 under an ultraviolet lamp could be selectively quenched by PA even in the presence of all other interfering nitroaromatic pollutants, which empowers the fast visual detection of PA by naked eye.

Zn(ii) and Co(ii) coordination polymers based on semi-rigid bis-pyridyl-bis-amide and angular dicarboxylate ligands: synthesis, structures and properties

“…25 A notable red and blue shift of the wavelengths of 1 and 2 in comparison with those of L 1 , L 2 and dicarboxylic acid may be ascribed to the different ligand conformations and coordination mode upon coordination to the Zn( ii ) ions. 26…”

Fluorescent water‐stable Zn (II) coordination polymers for selective aqueous detection of nitrophenols

“…[31][32][33] With this in mind, over the past few years, bis/tris-tacn derivatives (tacn = 1,4,7-triazacyclononane) carrying fluorescent spacers have been utilized as compartmental ligands by our group to achieve either a heterometallic metalorganic cage or 1D Cd (II) CPs, which can be used as recyclable sensors for selective and sensitive detection of nitroaromatic explosives and even the visual discrimination of these structural-like analytes. [34,35] As a continuation of our work on the design and synthesis of stable coordination assemblies with fluorescent polyazamacrocyclic ligands for NACs detection, two fluorescent cyclen-derived ligands with different aromatic carboxylate side-arms (Scheme 1) were selected as the multidentate scaffolds to coordinate with Zn (II) to afford two water-stable Zn (II)-based CPs (Zn-1 and Zn-2). With increasing conjugation of the side-arm aromatic groups, the ligand-based fluorescence emission of these CPs shifts from UV towards visual region.…”

“…[ 31–33 ] With this in mind, over the past few years, bis/tris‐tacn derivatives (tacn = 1,4,7‐triazacyclononane) carrying fluorescent spacers have been utilized as compartmental ligands by our group to achieve either a heterometallic metal–organic cage or 1D Cd (II) CPs, which can be used as recyclable sensors for selective and sensitive detection of nitroaromatic explosives and even the visual discrimination of these structural‐like analytes. [ 34,35 ]…”

Chemodosimetric Mechanistic Insight through Trapping Intermediate for Selective Detection of Picric Acid in Aqueous Medium by a Dinuclear CdII Complex

“…For application purposes, it is highly desirable that a fluorescent probe can be synthesized easily, sufficiently soluble in water and effective as sensor in aqueous medium with high selectively. So far, a considerable number of fluorescent materials have been utilized for selective detection of PA. Those sensors include small organic molecules, [10–21] organic polymers including conjugated polymers, [22–26] discrete metallo‐organic coordination compounds [27–41] including macrocycles/cages [30–32] or AIEgens [40,41] coordination polymers including MOFs, [42–73] nanoaggregates [74–76] and carbon or quantum dots [77,78] . However, apart from their complicated multistep preparation procedures, these sensor materials are found to be efficient in organic medium, which is not feasible for their practical application.…”

“…In order to get a clear and deeper insight into the sensing behaviour, various signalling mechanisms (e. g. photoinduced electron transfer (PET), intramolecular charge transfer (ICT), förster resonance energy transfer (FRET), inner filter effect (IFE) and chemodosimetry) along with various supramolecular interactions (e. g. hydrogen bonding, metal‐ligand coordination, electrostatic interactions) are rationally considered. It is evident from previous studies that detection of PA by considering all above mentioned signalling mechanisms [10,12–37,42–78] except chemodosimetry [11,38] have been well explored. Clearly, fluorescent chemodosimetric approach to detect PA needs special attention.…”