Bifunctional Chemosensor Research Articles

Inserting auxiliary ligand to construct a Cd(II)-based salamo-like coordination polymer as bifunctional chemosensor for detecting picric acid and S2−

A tailored Cd(II) coordination polymer [Cd(HL)2(1,4-pbyb)]n (Cd(II)-CP), has been synthesized successfully by using the host ligand H2L (4‑chloro-4ʹ‑bromo-6‑bromo-6ʹ‑tert‑butyl‑2,2ʹ-[ethylenedioxybis(nitrilomethylidyne)]diphenol) and auxiliary ligand 1,4-di(pyridin-4-yl)benzene (1,4-pbyb) under the room temperature volatilization method. Single crystal X-ray diffraction experiment showed that Cd(II) atoms possess a slightly twisted hexa-coordinated octahedron configuration and Cd(II)-CP forms an infinite 1D zigzag-like chain configuration. The structural diversity of Cd(II)-CP is mainly attributed to the introduction of auxiliary ligand. The Cd(II)-CP is a highly selective and sensitive luminescent bifunctional chemosensor toward nitroaromatic compounds (NACs) and anions, which exhibits turn-off fluorescence effect on picric acid (PA) and turn-on fluorescence effect for sulfide ions (S2−). The sensing mechanisms were also carefully investigated. This study provides new conceptions for the design of CPs for detecting pollutants from surroundings, potentially mitigating health risks to humans and natural ecosystems.

Synthesis and structural analysis of push-pull imidazole-triazole based fluorescent bifunctional chemosensor for Cu2+ and Fe2+ detection

Fluorescent imidazole-triazole based ligands L1 and L2 have been designed as chemical push-pull chemosensors for divalent metal ions and synthesized through palladium-catalyzed cross-coupling reactions using indium organometallics and click chemistry. The novel ligands exhibit intense absorption in the ultraviolet region with high molar extinction coefficients, and strong fluorescence emission with large Stokes displacements. On the basis of UV–Vis absorption spectroscopy and fluorescence emission data in acetonitrile, L1 is shown as a bifuncional chemosensor with differential response for Fe2+ and Cu2+ over a range of selected 3d divalent and other metal ions. The binding site of the ligand was established by single-crystal X-ray diffraction and 1H NMR spectroscopy studies. The association constants, determined by spectrofluorimetric titrations, show a steady binding affinity of L1 for Cu2+ and Fe2+ in comparison with other previously reported fluorescent bidentate chemosensors, offering the lowest limit of detection (LOD) with Cu2+. DFT calculations provide a rationale properly understanding and interpreting the experimentally observed results. Indeed, a mechanism of the different optical responses of L1 towards 3d divalent metal ions is proposed.

Rational design of dual-functional peptide-based chemosensor for sequential detection of Ag+ (AgNPs) and S2− ions by fluorescent and colorimetric changes and its application in live cells, real water samples and test strips

A novel bifunctional chemosensor L with excellent fluorescent group FITC labelled at tetrapeptide (CysProGlyHis-NH2) was designed and developed. L exhibited fluorescent quenching response and unique visual color change for Ag+ and AgNPs in aqueous solution. The stoichiometry between L and Ag+ was confirmed to be 1:1 based on fluorescent titration, Job's plot, ESI-HRMS and theoretical calculation studies. In particular, the limit of detection (LOD) of L for the detection of Ag+ and AgNPs were calculated as 3.35 nM and 4.57 nM, respectively. In addition, the L-Ag complex as a new relay chemosensor could be highly selective detection of S2−via obvious color and fluorescence changes, which could be monitored by the naked eye. The LOD for S2− was as low as to be 28.17 nM with high sensitivity. Furthermore, L indicated a rapid response (within 50 s), exciting circularity (more than 10 times) and wide pH response range (6 ∼ 12). Moreover, in view of excellent stability, low cytotoxicity and biocompatibility, we further successfully applied L for Ag+, AgNPs and S2− detection and imaging in living cells, real water samples and test strips.

A novel bifunctional chemosensor for bioimaging in living cells with highly sensitive colorimetric and fluorescence detection of CN− and Al3+

A novel colorimetric/fluorescent chemosensor (1o) was designed and synthesized for the detection of CN− and Al3+.

Luminescent binuclear Zinc(II) organic framework as bifunctional water-stable chemosensor for efficient detection of antibiotics and Cr(VI) anions in water

To achieve the ultrastable LMOFs with predominant luminescent sensing performances, the aromatic π-electron mixed ligands strategy was introduced, and the ternary LMOF of {[Zn2(HDDB)(bib)1.5]·3H2O}n (1), was fabricated based on 3,5-di(2′,4′-dicarboxylphenyl)benozoic acid (H5DDB) and the N-donor of meta-bis(imidazol-1-yl)benzene (bib) under mixed solvothermal condition. LMOF 1 features the first reported 3D 3,4,4-c {62.83.10}{62.8}2{63.82.10}2 framework with 21.2 % porosity as well as high thermal and chemical stability. Further luminescent sensing showed that LMOF 1 as a bifunctional chemosensor possessing predominant detectability for sensitive detect the hexavalent chromates and nitroimidazoles/nitrofurans antibiotics in water through strong luminescent quenching effects, with excellent reusability as well as trace detection limits. Moreover, luminescent quenching mechanisms were further investigated from electron transfer and energy transfer viewpoints.

Highly Selective and Sensitive Benzimidazole Based Bifunctional Sensor for Targeting Inedible Azo Dyes in Red Chilli, Red Food Color, Turmeric Powder, and Cu(Ii) in Coconut Water.

In this study, a simple Benzimidazole based bifunctional chemosensor 4-(2-(3,4-dimethoxyphenyl)-1H-benzo[d]imidazol-6-yl) benzene-1,2-diamine, L was synthesized and characterized. The sensor proved to be selective and sensitive towards detecting banned azo dyes Sudan Dye I, II, and Metanil Yellow via fluorescence turn-off response. The proposed mechanism of fluorescence quenching was the inner filter effect. LODs for Sudan I, II, and Metanil Yellow were found to be 0.009µM, 0.012µM, and 0.0073µM, respectively. The developed chemosensor also showed a colorimetric response towards Cu (II) ions via an apparent color change from yellow to pink. LOD for Cu (II) ions was found to be 1.2µM. The synthesized benzimidazole based bifunctional chemosensor was adequately tested to determine Sudan I in Red chili powder and red Food color samples, Metanil yellow in turmeric powder, and Cu(II) packaged coconut water.

A stable cationic Cd(II) coordination network as bifunctional chemosensor with high sensitively and selectively detection of antibiotics and Cr(VI) anions in water

A stable Cd(II) based luminescence coordination polymer, {[Cd(tib)2](NO2)2·0.5DMA·H2O}n (CdCP, tib ​= ​1,3,5-tris(1-imidazolyl)benzene), containing the 2D {4^3}2{4^6.6^6.8^3}-kgd cationic sheet, has been successfully obtained and applied as an efficient and versatile chemical sensor. Fluorescence sensing experiments revealed that CdCP displays high sensitivity and selectivity for detecting inorganic Cr(VI) anions and nitrofuran/nitroimidazole antibiotics (ABXs) in aqueous solutions via luminescence quenching effects. In addition, the mechanisms of fluorescent quenching were discussed based on optical spectroscopy and quantum chemical calculation, which indicated that the quenching mechanisms involving internal filter effect (IFE) and photo-induced electron transfer (PET). This work provides a meaningful strategy for design multi-responsive cationic MOFs/CPs as chemical sensor in the detection of pollutants in water.

A Zn-based metal–organic framework as bifunctional chemosensor for the detection of nitrobenzene and Fe3+

In this report, three metal-organic frameworks (MOFs) were synthesized by hydrothermal reactions with 4,4′,4″-nitrilotribenzoic acid (H3NTB), 1,10-phenanthroline (phen) and water by introducing Zn(Ⅱ), Mn(Ⅱ) and Cu(Ⅱ) center ions, namely, [Zn(HNTB)(phen)]n (Ⅰ), [Mn(HNTB)(phen)•H2O]n (Ⅱ) and {[Cu(HNTB)(phen)•H2O]•H2O}n (Ⅲ). Single-crystal X-ray diffraction data analyses demonstrate that Ⅰ-Ⅲ are assembled into three-dimensional frameworks based on the building blocks of {ZnO4N2}, {MnO3N2} and {CuO4N2} through the connections of HNTB2−, intermolecular hydrogen bonds and the π … π interactions between pyridine rings, respectively. The fluorescent properties of Ⅰ-Ⅲ have been systematically studied in different solutions containing certain metal ions and organic molecules. As a result, Zn-MOF (I) exhibits a dual-responsive fluorescent sensor toward nitrobenzene (NB) and Fe3+ with high selectivity, stability and anti-interference ability at the existence of other corresponding analytes originating from its excellent fluorescent quenching efficiency. Moreover, the possible sensing mechanisms for the above analytes have also been elucidated, which are testified by PXRD analysis, ICP-AES, UV–vis spectra, XPS and the density functional theory (DFT).

A photochromic diarylethene-functionalized fluorescent probe for Cd2+ and Zn2+ detections

Abstract A novel bifunctional chemosensor 1O constructed with diarylethene and pyridazine unit has been designed and synthesized with excellent photochromic properties upon UV/Vis radiation. The chemosensor 1O shows prominent selectivity and high sensitivity for Cd2+ and Zn2+ by obvious fluorescent enhancement with a low detection limit in water-acetonitrile solution (v(water):v(acetonitrile) = 1:9). The chemosensor 1O could be utilized as a fluorescent sensor for Cd2+ with a limit of detection (LOD) of 2.3 × 10−6 M. With the presence of Zn2+, the fluorescence of the generated zinc complex enhances remarkably and the limit of detection (LOD) for Zn2+ is calculated to be 1.1 × 10−5 M by Job’s plot titrations. A logic circuit of this chemosensor 1O has been constructed with the input signals of UV and visible light, Cd2+ (or Zn2+) and EDTA and the output signal of the emission intensity. In addition, the concentrations of Cd2+ or Zn2+ in real water are detected quickly and conveniently by this chemosensor.

A Heterocyclic-based Bifunctional Sensor for Detecting Cobalt and Zinc Ion.

A new bifunctional chemosensor HBP ((E)-2-(2-((5-bromopyridin-2-yl)methylene)hydrazinyl) quinoline) based on heterocyclic compounds was designed and studied. The HBP showed successful detecting ability toward cobalt ion with a UV-visible red-shift and a color change of colorless to pink. Moreover, toward zinc ion, the HBP showed an obvious fluorescence turn-on response. The binding ratio of the HBP to cobalt and zinc was a 2 to 1 for both ions. The detection limits were found to be 10 nM for Co2+ and 18 nM for Zn2+. Based on UV-vis and fluorescent spectral variations, Job plots, ESI-MS, FT-IR and calculations, the binding mechanisms of the HBP toward cobalt and zinc ions were proposed.

A Zn-Based Fluorescent Coordination Polymer as Bifunctional Sensor: Sensitive and Selective Aqueous-Phase Detection of Picric Acid and Heavy Metal Ion

In contrast to the traditionally exploited cages, organic chromophores and metal organic frameworks (MOFs) as a sensing model, the chemistry of 1D coordination polymers as promising sensors is still under explored and needs special attention. Herein, a zinc 1D coordination polymer, {[Zn(HPydc)2]·2H2O}n (1) has been synthesized using 2,3-Pyridinedicarboxylic acid (H2Pydc) and characterized employing FT-IR, single crystal X-ray, PXRD, TG, CV, spectral studies, time resolved fluorescence and Hirshfeld surface analysis. The 1 displayed intermolecular O⋯H, Cl⋯H and others interactions, which create a supramolecular network. These interactions have been substantiated by Hirshfeld surface analyses. 1 exhibit promising dual functional sensing behaviour for recognition of picric acid (PA) and Pd2+ ions over other nitroaromatic compounds (NACs) and metal ions via fluorescence quenching with high selectivity and sensitivity in the aqueous phase. The unique properties of 1 as a potential bi-functional chemosensor for the detection of both PA and Pd2+ in the aqueous medium has been estabilished as confirmed by its high quenching efficiency, selectivity and superior detection limit. The sensing mechanism is explored by spectral titrations, time decay and also by the DFT (B3LYP/def2-SVP) studies. The present investigation adds to the advancement of MOF or CP materials research, particularly in their application as biological and environmental fluorescent chemosensors.

Bifunctional chemosensor based on a dye-encapsulated metal-organic framework for highly selective and sensitive detection of Cr2O72− and Fe3+ ions

A three-dimensional protonated proflavin (PF) encapsulated metal-organic framework, formulated as [Zn(NIPH)2(HPF)2] (1), has been successfully synthesized under hydrothermal conditions using the familiar and cheap ligand 5-nitroisophthalic acid (5-H2NIPH). The as-synthesized compound 1 exhibits an intense green emission in solution, whereas strong red fluorescence is observed in the crystal form. The strong green emission of 1 could be highly and selectively quenched by Fe3+ ions, even in the presence of other competing metal ions such as Ag+, Al3+, Ca2+, Cd2+, Co2+, K+, Mg2+, Mn2+, Na+ and Zn2+. In addition, 1 exhibits superior selectivity and sensitivity towards Cr2O72− ions over other anions including Br−, CH3COO−, Cl−, F−, H2PO4−, HCO3−, HPO42−, NO3−, PO43− and SO42−. The possible luminescence quenching mechanisms were investigated. This work revealed that a dye-encapsulated MOF can be used as one of the most fascinating multi-response luminescence materials for selective chemical sensing.

Salen-based bifunctional chemosensor for copper (II) ions: Inhibition of copper-induced amyloid-β aggregation

Disruption of copper homeostasis is associated with a number of severe diseases including Alzheimer’s disease (AD), Parkinson’s disease (PD), Wilson’s disease, and Menkes syndrome. Given this association, the detection and capture of Cu2+ in biological fluids and tissues may provide a new direction for the diagnosis and treatment of related disorders. The current analytical approaches, however, are challenging due to the high cost, complexity, and long time required to prepare and analyze samples. Here, we report a novel salen ligand, namely N,N’-(1,2-phenylene)bis(1-(1H-imidazol-4-yl)methanimine) (pimi), which can readily detect and concurrently capture Cu2+ from aqueous as well as biological mediums. Pimi can selectively and specifically detect Cu2+ from biofluid and cellular samples with rapid ccresponse time (<3 s) and an ultra-sensitive detecting limit (2.7 nM). More importantly, pimi showed excellent environmental tolerance and had a very wide pH range for detecting Cu2+ in a variety of biological samples. Attributed to the strong binding affinity and selectivity towards Cu2+, pimi was found to capture Cu2+ ions from Cu-Aβ complexes, thus inhibiting copper-induced aggregation of Aβ and protecting neuronal cells from the toxicity of aggregated Aβ. These results provide a compelling starting point for further fine-tuning of salen-based chemosensor for the diagnosis and treatment of diseases associated with the hyperaccumulation of copper.

A bifunctional rhodamine derivative as chemosensor for recognizing Cu2+ and Hg2+ ions via different spectra

A new simple bifunctional chemosensor 1 based on rhodamine was synthesized by hydrazide and formylformic acid, which could detect Cu2+ and Hg2+via different detecting methods in CH3CN-HEPES buffer solution (20 mmol/L, pH 7.4) (1:9, v/v) respectively. When sensor 1 bound with Cu2+, it showed a colorimetric change, while a selective enhancement in fluorescence occurred upon 1 binding with Hg2+, resulting from the spirolatam-ring opening process. The binding modes of 1 with Cu2+ and Hg2+ were investigated based on UV, fluorescence change, ESI-Mass and Job’s Plot data. Moreover, sensor 1 could selectively detect target ion in a mixed solution of Cu2+ and Hg2+, and the two metal ions do not interfere with each other in the process of detecting Cu2+ or Hg2+ with 1.

Execution of julolidine based derivative as bifunctional chemosensor for Zn2+ and Cu2+ ions: Applications in bio-imaging and molecular logic gate.

A simple julolidine based chemosensor (JT) was designed and synthesized by single condensation step. JT displayed excellent selectivity and sensitivity with on-off responses towards Zn2+ and Cu2+ over other biologically relevant metal ions in aqueous media. Upon addition of Zn2+ ions, JT exhibited a significant blue shift in emission followed by turn-on enhancement while with Cu2+, the fluorescence intensity of JT was completely vanished. The 1:1 binding affinity between JT and Zn2+/Cu2+ was proposed by Job's plot analysis. The detection limit for Zn2+ and Cu2+ ions reached at 3.5 × 10-8 M and 1.46 × 10-6 M, respectively. The sensing mechanism of JT with Zn2+/Cu2+ was supported by DFT calculations. Based on photophysical studies and its reversibility environment with EDTA, molecular logic gates were fabricated. Furthermore, JT was successfully established to detect intracellular Zn2+ ions in live cells by turn-on response.

New Bifunctional Diarylethene Sensor for Multianalyte Detection and Al3+ Imaging in Live Cells

A novel photochromic diarylethene bifunctional chemosensor with a hydroxybenzylidene-2-naphthohydrazide group was synthesized with multicontrollable and photoswitchable properties, induced by UV–vis light, acid/base, and metal ions in acetonitrile. The deprotonated derivative of the compound showed good photochromism and notable fluorescence enhancement. It could serve as a “naked-eye” colorimetric sensor for Ni2+. Moreover, its fluorescence was enhanced by 75-fold, turning from dark to bright jade green, upon the addition of Al3+. The compound formed complexes with Ni2+ and Al3+ in a 1:1 stoichiometry and could detect these metal ions at concentrations as low as 1.67 × 10–5 and 9.45 × 10–8 mol L–1, respectively. Additionally, it can penetrate into HeLa cells and can be used for the detection of intracellular Al3+.

Synthesis and Photo- and Ionochromic and Spectral-Luminescent Properties of 5-Phenylpyrazolidin-3-one Azomethine Imines

Photochromic 5-phenylpyrazolidin-3-one-based azomethine imines containing 2-((1H-imidazol-2-yl)methylene) 1, 2-(pyridin-2-ylmethylene) 2, 2-(quinolin-2-ylmethylene) 3, and 2-((8-hydroxyquinolin-2-yl)methylene) 4 substituents were synthesized. All the compounds exist in the ring-opened O forms. Under irradiation with light of 365 nm, compounds 1–4 undergo thermally reversible isomerization into ring-closed bicyclic diaziridine isomers C. Azomethine imines 1–3 exhibit properties of ion-active molecular “off-on” switches of fluorescence when interacting with F− or AcO− anions. Compound 4 represents a bifunctional chemosensor demonstrating a colorimetric “naked-eye” effect for Ni2+ cation and complete fluorescence quenching in the presence of H+, F−, and CN− ions.

Detection of Ga3+ and Cu2+ by a Simple Quinoline-Based Bifunctional Chemosensor

Detection of Ga³⁺ and Cu²⁺ by a Simple Quinoline-Based Bifunctional Chemosensor

Dicarboxylate-induced structural diversity of luminescent ZnII/CdII coordination polymers derived from V-shaped bis-benzimidazole

Six ZnII/CdII CPs (1–6), derived from V-shaped bbib and dicarboxylates, have been synthesized; complex 2 is a good bifunctional chemosensor for the detection of Fe3+ and MnO4−.

Zn/Cd/Cu- frameworks constructed by 3,3′-diphenyldicarboxylate and 1,4-bis(1,2,4-triazol-1-yl)butane: Syntheses, structure, luminescence and luminescence sensing for metal ion in aqueous medium

Three metal-organic frameworks (MOFs), [M(dpdc)(btb)0.5]n (M = Zn 1, Cd 2; dpdc = 3,3′-diphenyldicarboxylate and btb = 1,4-bis(1,2,4-triazol-1-yl)butane) and [Cu3(dpdc)3(btb)2]n (3) were prepared and structurally determined. 1 is a 2D structure with the topology of {33·47·54·6}, while 2 possesses a 3D framework with the {312·429·514} topology. Complex 3 displays a 3D framework with the topology of {315.435.55}2{36.48.512.6.7}. 1–2 exhibit intense blue luminescence and high stability in water, which make them highly promising candidates as sensors using in aqueous medium. Complex 1 is a potential bi-functional chemosensor for Fe3+ and Al3+ ions while 2 displays a selective sensing ability to Fe3+ ion. Quenching mechanism of Fe3+ on the luminescence of 1–2 is attributed to the charge transfer process LMCT. 1 and 2 have same compositions but have different structures, thermally stabilities and different luminescence sensing functions. The relationship between MOF structures and luminescence sensing toward metal ions are further discussed.