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A Schiff base functionalized Cu(II)-based metal-organic framework (MOF) denoted as Cu-L, was developed via a solvothermal method using low-cost starting material, i.e., Schiff base linker, 4,4'-(hydrazine-1,2-diylidenedimethylylidene)dibenzoic acid (L). Good crystallinity and thermal stability of synthesized Cu-L was confirmed by the crystallographic and thermogravimetric studies. An excellent photoluminescent properties of Cu-L ensure their suitability for the ultrafast detection of Fe3+ ions and nitrobenzene via a turn-off quenching response. The remarkable sensitivity of Cu-L towards Fe3+ions and nitrobenzene was certified by the low limit of detection (LOD) of 47 ppb and 0.004 ppm, respectively. With incorporated free azine groups, this MOF could selectively capture Fe3+ions and nitrobenzene in aqueous solution. The plausible mechanistic pathway for the quenching in the fluorescence intensity of the Cu-L in the presence of Fe3+ ions and nitrobenzene have been explained in detail through the density functional theory calculations, photo-induced electron transfer (PET), fluorescence resonance energy transfer (FRET), and competitive energy adsorption. This present study open a new avenue to synthesize novel crystalline MOF-based sensing materials from cheap Schiff base linkers for fast sensing of toxic pollutants.

A water-dispersible Tb(III)-based Metal Organic Framework (TBP) has been produced by diffusion technique using benzene-1,3,5-tricarboxylic acid (BTC) and pyridine as ligands at low-cost and accessible starting materials. The thermal stability, crystalline nature, and rod-shaped morphology of the synthesized TBP have been confirmed by thermogravimetric (TGA), crystallographic (PXRD), and morphological (FE-SEM) studies. Various spectroscopic techniques have been carried out for detailed qualitative, quantitative, and photoluminescence (PL) analyses. For the quick and precise identification of Danofloxacin (DANO), TBP can be used as a sensor in an aqueous medium with significant enhancement compared to various fluoroquinolone antibiotics (levofloxacin (LEVO), ofloxacin (OFLO), norfloxacin (NOR), and ciprofloxacin (CIPRO)) with low detection limit of 0.45 ng/mL (1.25 nM).According to in-depth mechanistic studies of the density functional theory (DFT) calculations and mode of action, hydrogen bonding interactions and photo-induced electron transfer (PET) are the major factors for turn-on enhancement behaviour of TBP to DANO. The advantages of TBP include simple recovery and reuse for at least three cycles without noticeable loss of sensitivity. All of these characteristics profoundly show how beneficial the detection of DANO in aqueous environments is for the security and safety of the public.

Multifunctional Cu (II)-based Metal Organic Framework (MOF) [Cu3(BTC)2] has been synthesized by a facile electrochemical method. Crystallographic and morphological characterizations of synthesized MOF have been done using Powder X-ray Diffractometer and Scanning Electron Microscope (SEM), respectively, whereas Fourier Transform Infrared Spectroscopy (FT-IR), Energy Dispersive X-ray Spectroscopy (EDS), UV-Vis Absorption Spectroscopy and Energy Resolved Luminescence Spectroscopic studies have been used for the detailed qualitative, quantitative as well as optical analyses. Sharp PXRD peaks indicate the formation of highly crystalline MOF with face centered cubic (fcc) structure. Flakes (average length = 0.71µm and width = 0.10 µm) and rods (average aspect ratio = ((0.1:8.3) µm) like morphologies have been observed in SEM micrographs. The presence of C, O and Cu has been confirmed by EDS analysis. Photocatalytic activity potential of the synthesized MOF has been tested using methylene blue dye (MB) as a test contaminant in aqueous media under sunlight irradiation. Selective and sensitive fluorescent sensing of different Nitroaromatic compounds (NACs) like 4-Nitroaniline (4-NA), 2-Nitroaniline (2-NA), 3-Nitroaniline (3-NA), 4-Nitrotoulene (4-NT), 2,4-Dinitrotoulene (2,4-DNT), 1,3-Dinitrobenzene (1,3-DNB), 2,6-Dinitrotoulene (2,6-DNT) has been done by exploring the photoluminescent behaviour of chemically stable Cu3(BTC)2. Synthesized MOF is extremely sensitive towards 4-NA, which is having PL quenching efficiency of 82.61% with highest quenching rate till reported. Indeed, a large quenching coefficient KSV = 34.02 x 10− 7 M− 1 and correlation coefficient R2 = 0.9962 in KSV plot have been elucidated with limit of detection (LOD) = 0.7544 ppb. The possible ways of luminescence quenching are successfully explained by the combination of Photoinduced Electron Transfer (PET) and Resonance Energy Transfer (RET) mechanisms. Additionally, the Density Functional Theory (DFT) calculations have been employed to support the experimental results. Cu3(BTC)2 fully demonstrates the power of a multi component MOF, which provides a feasible pathway for the design of novel material towards fast responding luminescence sensing and photocatalytic degradation of pollutants.

Macrocyclic ligand, (7,18-diamino-7,8,17,18-tetrahydrodibenzo[b,j][1,4,9,12]tetraazacyclohexadecine- 6,9,16,19(5H,10H,15H,20H)-tetraone) and its Mn(II) complex was synthesized via sonochemical and conventional methods in nano dimension of 42.29 and 85.63 nm, respectively. The quantitative and qualitative analyses have been done using Fourier Transform Infrared (FTIR), ultraviolet-visible (UV-Vis), mass, electron spin resonance (ESR) spectroscopies and elemental (CHN) analyses. Powder X-ray diffraction (PXRD) and field emission scanning electron microscopy (FE-SEM) have been used for the crystallographic and morphological analyses of the synthesized nano complex, respectively. Based on these studies, octahedral geometry and hexagonal unit cell structure have been proposed for the synthesized Mn(II) nanocomplex. The nano complexes of transition metal can be introduced as the effective nano metal based antimicrobial drugs as they do not require encapsulating or solubilizing chemicals and further offer less side effects and low toxicity as well as improved antimicrobial efficiency. So, it is the need of the hour to work upon such nano based transition metal drugs. The purity, yield and crystallinity of nano complex synthesized by the sonochemical method were found to be far better than those synthesized by the conventional method. The nanocomplex synthesized using two different protocols were screened for in vitro against pathogenic bacteria and fungal species by a two-fold serial dilution method and antioxidant studies were as done using the DPPH scavenging method indicating the better and enhanced performance of the nanocomplex obtained using sonication-assisted method. The sonochemical method enhances the properties of the complex by effectively regulating and reducing the size of the nanocomplex and hindering their agglomeration and has better biomedical applications in comparison to conventional methods.

A novel SnO2@Cu3(BTC)2 composite was synthesized using a quick and affordable bottom-up approach via impregnation of SnO2 nanoparticles into the porous Cu3(BTC)2 metal-organic framework (MOF). The photocatalytic degradation of the methylene blue (MB) dye has been studied for the first time using this novel recyclable SnO2@Cu3(BTC)2 composite. It was found that SnO2@Cu3(BTC)2 composite photo catalytically degrades methylene blue (MB) dye with a degradation efficiency of 85.12% within 80 min under solar irradiation. The most appropriate benefit of this composite is the easy recyclability up to numerous cycles with retention of its photocatalytic activity. Therefore, this cheaper and greener composite photocatalyst is more suitable for large-scale industrial applications than the traditional photocatalysts employed in the degradation of MB dye. Furthermore, this composite has also been investigated as a fluorescence sensor for the detection of nitroaromatic compounds (NACs). It was observed that the 88.2% quenching of the intense fluorescent signal of this composite happens in the presence of 2,4,6-trinitrophenol (TNP) showing it incredibly selectivity towards TNP with no interference of other NACs. With a detection limit of 2.82 µM, this composite exhibits outstanding sensitivity towards TNP. The Stern-Volmer plot for TNP is linearly fitted displays large quenching coefficient, correlation coefficient, and linear ranges KSV = 1.04x104 M-1, R2 = 0.9901, and 0-10 µM, respectively. This quenching response of this composite towards TNP was well-explained by the two mechanisms: one is photo-induced electron transfer (PET), and the other is fluorescence resonance energy transfer (FRET), in addition to theoretical calculations based on density functional theory (DFT). Our findings imply that the synthetic composite can be used as a superior fluorescence sensor and photocatalyst.

Nanoscale complexes of Mn(II), Ni(II), and Cu(II) with 6,15-diamino-1,4,9,12-tetraazacyclohexadecane-5,8,13,16-tetraone were synthesized by ultrasonic sonication method. The Fourier-transform infrared (FTIR) spectroscopy, ultraviolet–visible (UV–vis) spectroscopy, carbon, hydrogen, and nitrogen elemental (CHN) analysis, mass spectrometry (MS), and electron spin resonance (ESR) spectroscopy were used to identify and suggest the structure of the synthesized nanocomplexes. The field emission scanning electron microscopy (FE-SEM) and powder X-ray diffraction (PXRD) revealed that the size of the synthesized nanocomplexes was 44–58 nm. Based on these studies, hexagonal, monoclinic, and cubic unit cell structure has been proposed for the synthesized Mn(II), Ni(II), and Cu(II), respectively. The theoretical calculations of the synthesized nanocomplexes were carried out by a GAUSSIAN 09 program involving geometry optimization and bond parameters using the B3LYP method. Moreover, binding energy, HOMO, and LUMO have been calculated. In addition, hardness, softness, chemical potential, and dipole moment were calculated for ligand and its metal nanocomplexes. The biological efficacy of the synthesized nanocomplexes was examined and found to be better and highly effective drug delivery system (DDS) for the antimicrobial and antioxidative agent.

A simple synchronous fluorescent chemosensor 3-hydroxy-2-(4-methoxyphenyl)-4H-chromen-4-one (3-HC) has been synthesized for the selective analysis of Al3+. On the addition of Al3+, 3-HC displayed a redshift with a change in wavelength of emission maximum from 436 to 465 nm along with enhancement in fluorescence intensity, which formed the basis for its sensitive detection. Under optimized conditions, 3-HC was applied for the determination of Al3+ in the concentration range of 1 × 10-7-1 × 10-6 M. The limit of detection (LOD) and limit of quantification (LOQ) values were found out to be 1.69 × 10-8 and 5.07 × 10-8 M respectively. Further, the developed method was applied for the analysis of Al3+ in real water samples (tap water, bottled water, and tube well water) which showed good recovery values in the range of 95-99.7% with RSD less than 4%.

In this study, a new Schiff base, (E)-2-(2-aminophenylthio)-N-(thiophen-2-yl-methylene) benzenamine was synthesized for selective detection of Hg2+. This Schiff base was characterized by proton nuclear magnetic resonance (1HNMR) spectroscopy, carbon-13 nuclear magnetic resonance (13CNMR) spectroscopy, and Fourier-transform infrared (FTIR) spectroscopy. Binding interaction between (E)-2-(2-aminophenylthio)-N-(thiophen-2-yl-methylene)benzenamine and various metal ions has been studied by UV–Vis spectroscopic measurements and shows promising coordination towards Hg2+ and almost no interference from other metal ions ( Ag+, Mn2+, Fe3+, Al3+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Fe2+ and Cr3+).This Schiff base exhibiting detection limit of 3.8 × 10− 8 M. The Schiff base newly synthesized in this study was successfully applied to the determination of Hg2+ in water samples. In addition to the experimental study, a theoretical study was conducted using Gaussian 09 program to support the experimental findings. FTIR, NMR, bond angle, bond length, torsional angles and structural approximation were studied using theoretical consideration.

Organic pollutants (OPs) are of worldwide concern for being hazardous to human existence and natural flora and fauna in view of their contaminating nature, bio-aggregation properties and long range movement abilities in environment. Metal organic frameworks (MOFs) are a new kind of crystalline porous material, composed of metal ions and multi dentate organic ligands with well-defined co-ordination geometry exhibiting promising application respect to adsorptive evacuation of OPs for chromatographic analysis. Applications of MOFs as preconcentration material and column packing material are reviewed. Key analytical characteristics of MOF based preconcentration techniques and coupled chromatographic procedures are summarized in detail. MOF based preconcentration strategies are compared with conventional sorbent based extraction techniques for thorough evaluation of performance of MOF materials.

A facile bottom up technique is opted for the synthesis of novel composite SnO2@Zn-BTC. This synthesized composite is fully characterized by Fourier Transform Infrared (FTIR) Spectroscopy, Powder X-Ray Diffraction (PXRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), and Elemental mapping techniques. Optical analysis is done using UV-Visible absorption spectroscopy and fluorescence studies. Further this composite is utilized for the first time to act as a photocatalyst for degradation of MB dye as a test contaminant under sunlight irradiation. This photocatalyst shows degradation efficiency of 89% within 100 min of exposure of sunlight. In addition to that the synthesized composite can be utilized as a fluorescence probe for detection of NACs via ‘turn-off” quenching response. This composite is extremely sensitive towards 3-NA in aqueous medium with quenching efficiency of 75.42 %, which is highest quenching rate till reported. There occurs no interference for detecting 3-NA in the presence of other NACs. The linear fitting of the Stern-Volmer plot for 3-NA shows large quenching constant (KSV) of 0.0115 ppb-1with correlation coefficient R2 = 0.9943 proves higher sensitivity of composite in sensing process. The outstanding sensitivity of composite for 3-NA is proved by low detection limit (LOD) of 25 ppb (0.18 µM). Photoinduced Electron Transfer (PET) and the Fluorescence Resonance Energy Transfer (FRET) are the mechanisms used for clarification of quenching response of PL intensity by NACs via Density functional theory (DFT) theoretical calculations and extent spectral overlap, respectively. Hence, synthesized composite is verified as multi-component system to act as excellent photocatalyst as well as fluorescent sensor.

In this research, Zn- or Cd-based metal-organic frameworks (coded ZnMOF-1 and CdMOF-1) containing benzene-1,4-dicarboxylic acid (H2bdc) and pyridyl-based Schiff base (4-pyridylcarboxaldehydeisonicotinoylhydrazone (L)) dual ligands were successfully assembled via a conventional solvothermal method. The photoluminescence quenching response of ZnMOF-1 and CdMOF-1 and their sensing sensitivity and selectivity towards various inorganic anions were evaluated in aqueous media. Crystallographic and thermogravimetric studies confirm the formation of both MOFs with good crystallinity and thermal stability.Photoluminescence studies also verify the selectivity of ZnMOF-1 and CdMOF-1 for efficient sensing of inorganic oxyanions (like chromate/dichromate: CrO42− and Cr2O72−). Further, it was noted that only chromate/dichromate (CrO42−/Cr2O72−) anions showed a significant turn-off quenching effect while other anions (like F−, Br−, I−, Cl−, ClO4−, SCN−, SO42−, NO3−, and NO2−) have a low/negligible effect on the photoluminescence intensity of both MOFs. The limit of detection (LOD) of chromate/dichromate by ZnMOF-1 and CdMOF-1 was 9.79/10.94 µM and 2.68/1.48 µM, respectively. A probable mechanism for turn-off quenching response towards chromate and dichromate anions could be attributed to the spectral overlap of both excitation and emission spectra of ZnMOF-1/CdMOF-1 with the absorption spectra chromate/dichromateanions. As a result, the energy transfer from ZnMOF-1 or CdMOF-1 to the target chromate and dichromate anions decreased fluorescence intensity (i.e., fluorescence quenching effect).

A new aluminum-based metal-organic framework (MOF), namelyMIL-53-HNA, was synthesized using low-cost Schiff base linker, 2-(2-hydroxynapthyl-1-imine)terephthalic acid (coded as H2HNA). Because of an excellent fluorescent features of this synthesized MOF, we decided to test its suitability for detecting heavy metal ions in aqueous solution. It is interesting to note that the MIL-53-HNA chemosensor could detect Zn2+ ions in water via turn-on response with good sensitivity and selectivity without being interferedfrom diverse metal ions including Na+, Cd2+, Cu2+, Ni2+, Al3+, Pb2+, Co2+, and Fe3+. The selectivity of this sensortowards Zn2+ ions in aqueous solution could be explained through preferential complexation of these ions via free hydroxyl and imine groups present inside its pore cages. This selective complexation suppressed the photo-induced electron-transfer (PET) process from imine (-CH=N-) double bond to the naphthalene group. This suppression of PET process restored the fluorescence of the naphthalene group in the Zn2+treated MIL-53-HNA chemosensor which ultimatelyled to enhancement of itsfluorescence intensity. Theoreticalcalculations have also been done to provide a thorough explanation of thisturn-on mechanistic response of MIL-53-HNA towards Zn2+ions. Additionally, this sensor showed extremely low limit of detection (LOD), 6.8 µM, demonstrated its exceptional Zn2+ detection capabilities. Low cost, excellent stability, sensitivity, and selectivity are the most promising characteristics of this synthesized chemosensor which make it suitable for wastewater treatment.

A facile bottom up synthesis technique is opted for the preparation of novel composite SnO

A simple pyrazoline-based ‘‘turn off’’ fluorescent sensor 5-(4-methoxyphenyl)-3-(5-methylfuran-2-yl)-1-phenyl-4,5-dihydro-1H-pyrazole (PFM) was synthesized and well characterized by different techniques such as FT-IR, 1H-NMR, 13C-NMR, and mass spectrometry. The synthesized sensor PFM was utilized for the detection of Fe3+ ions. Fluorescence emission selectively quenched by Fe3+ ions compared to other metal ions (Mn2+, Al3+, Fe2+, Hg2+, Cu2+, Co2+, Ni2+, Cd2+, Pb2+, and Zn2+ ) via paramagnetic fluorescence quenching and showed good anti-interference ability over the existence of other tested metals. Under optimum conditions, the fluorescence intensity of sensor quenched by Fe3+ in the range of 0 to 3 μM with detection limit of 0.12 μM. Binding of Fe3+ ions to PFM solution was studied by fluorescent titration, revealed formation of 1:1 PFM-Fe metal complex and binding constant of complex was found to be of 1.3 × 105 M−1. Further, the fluorescent sensor has been potentially used for the detection of Fe3+ in environmental samples (river water, tap water, and sewage waste water) with satisfactory recovery values of 99-101%.

A strongly fluorescent Zn(II)-based azine functionalized MOF was synthesized solvothermally by using inexpensive and readily available starting materials, i.e., benzene-1,3,5-tricarboxylic acid and 1,4-bis(4-pyridyl)-2,3-diaza-2,3-butadiene (4-bpdb). Crystallographic and thermogravimetric studies approved the excellent crystallinity and thermal stability, respectively of the synthesized Zn-MOF. Photoluminescence studies point out that Zn-MOF can be used as a highly sensitive and quickly responsive sensor for the selective identification of Fe3+ ions in water via a significant turn-off quenching response. Herein, accessible Lewis base azine sites originating from 4-bpdb Schiff base ligand within Zn-MOF act as functional sites that can interact favorably with the Fe3+ ions and then lead to obvious variations in the fluorescence spectra. Photo induced electron transfer (PET), fluorescence resonance energy transfer (FRET), and competitive energy adsorption were used to establish the mechanism of action. The detection limit of the Zn-MOF towards Fe3+ was 0.4 µM (25 ppb). The selectivity of Zn-MOF towards Fe3+ ions over other metal ions was certified by competitive test. Easy recoverability and reusability for at least four cycles without significant sensitivity loss are the benefits of the Zn-MOF. All these features clearly demonstrate its great potential of Fe3+ ions detection in aqueous environment for public safety and security.

The compound 17β-oestradiol (E2) is a steroidal oestrogen used extensively in food processing and animal husbandry. As E2 is well-known as a typical endocrine disrupting chemical, its release, penetration, and exposure create serious environmental concerns. Carbon dots (CDs) have attracted great attention due to their excellent fluorescent and non-toxic properties. To help improve the selectivity of CDs, they can be combined with molecularly-imprinted polymers (MIPs). In light of the limitations involved in the fabrication of MIP layer on CDs (e.g., time consumption and low controllability of imprinted layer), the mussel inspired dopamine self-polymerization can be considered as an alternative option. As functional monomer in molecular imprinted technology, dopamine can be used efficiently to polymerize in weak alkaline condition (e.g., formation of polydopamine). In this research, a new method was developed for selective and sensitive fluorescent detection of E2 based on self-polymerization of dopamine (functional monomer) on fluorescent carbon dots (CDs@MI-PDA). The developed sensor selectively binds with E2 to quench the fluorescence intensity of CDs by photo-induced electron transfer. The sensor showcases a detection limit of E2 as 0.34 ng/mL with a linearity over 1-50 ng/mL. Furthermore, the probe was successfully applied to water (tap and river water) and milk samples with recoveries of 96.4-102.2 %. This study is expected to open a new path for the development of a simple and convenient detection approach for E2 present in complex matrices.

Continuous release of pollutants into the environment poses serious threats to environmental sustainability and human health. For trace-level analysis of pollutants, layered double hydroxide (LDH) is an attractive option to impart enhanced sorption capability and sensitivity toward pollutants because of its unique layered structure, tunable interior architecture, high anion-exchange capacities, and high porosity (e.g., Zn/Cr LDH/DABCO-IL, Ni/Al LDH, CS-Ni/Fe LDH, SDS-Fe

A molecularly imprinted polymer (MIP) of carbamazepine (CBZ) was synthesized so as to facilitate the selective extraction of CBZ from aqueous and bio-samples by using a non-covalent imprinting approach. Synthesized materials were characterized with Fourier-transform infrared spectroscopy and scanning electron microscopy studies. The imprinted polymer was evaluated and applied as a sorbent for solid-phase extraction (SPE) coupled with HPLC-UV to detect CBZ and its metabolite oxcarbazepine (OXC). The optimal conditions for molecularly imprinted SPE (MISPE) consist of the cartridge conditioning using methanol followed by triply distilled water, loading the aqueous sample and elution by methanol-acetic acid (9 : 1, v/v). The selectivity and sensitivity for pre-concentration and separation of the target analytes were studied in details, in order to build a simple and sensitive method which can act as a potential analytical strategy to monitor CBZ and OXC in the environmental and biological samples. The developed method exhibited a wide linear range (1–500 μg/L), good linearity (R2 > 0.990), and relative standard deviation

A simple, fast, and sensitive analytical protocol using fabric-phase sorptive extraction followed by high performance liquid chromatography with ultraviolet detection has been developed and validated for the extraction of five parabens including methylparaben, ethylparaben, propylparaben, butylparaben, and benzylparaben. In the present work, sol-gel polyethylene glycol coated fabric-phase sorptive extraction membrane is used for the preconcentration of parabens (polar) from complex matrices. The use of fabric-phase sorptive extraction membrane provides a high surface area which offers high sorbent loading, shortened equilibrium time, and overall decrease in the sample preparation time. Various factors affecting the performance of fabric-phase sorptive extraction, including extraction time, eluting solvent, elution time, and pH of the sample matrix, were optimized. Separation was performed using a mobile phase consisting of water:acetonitrile (63:37; v/v) at an isocratic elution mode at a flow rate of 0.9 mL/min with wavelength at 254 nm. The calibration curves of the target analytes were prepared with good correlation coefficient values (r2 > 0.9955). The limit of detection values range from 0.252 to 0.580 ng/mL. Finally, the method was successfully applied to various cosmetics and personal care product samples such as rose water, deodorant, hair serum, and cream with extraction recoveries ranged between 88 and 122% with relative standard deviation

Multidentate 1,3,5-benzenetricarboxylic acid (organic linker), Zn (II) based Zn-BTC has been synthesized via electrochemical method. Quantitative and Qualitative analyses of synthesized metal-organic framework (MOF) have been done using Fourier Transform Infrared (FTIR) Spectroscopy, Energy Dispersive X- Ray Spectroscopy (EDS) and Photoluminescence (PL). Powder X-Ray Diffraction (PXRD) and Scanning Electron Microscopy (SEM) have been used for crystallographic and morphological & topographical analyses, respectively. Crystallographic studies confirm the formation of face-centered cubic (fcc) crystal structure with good crystallinity. Photo-catalytic activity of synthesized MOF has been tested using Methylene Blue (MB) dye as a test contaminant in aqueous media under sunlight irradiation. Recorded results reveal that the synthesized MOF efficiently degrade MB dye upto 96% under sunlight exposure after 270 min. Photoluminescence studies indicate that Zn-BTC could be used as an efficient material for sensing of nitroaromatic compounds (NACs): 4-Nitroaniline (4-NA), 2-Nitroaniline (2-NA), 3- Nitroaniline (3-NA), 2,4-Dinitrotoulene (2,4-DNT), 4-Nitrotoulene (4-NT) in N,N’-Dimethylformamide (DMF) by fluorescence quenching and shows maximum quenching efficiency towards 3-NA (72.80%). Notably, the variation in luminescence intensity of 3-NA@Zn-BTC shows a linear relationship over its different concentrations from 0-1000 ppb range with KSV = 2.7 x 104 M-1 and R2 = 0.9924 with limit of detection 0.889 ppb (6.43µM) (LOD). The possible ways of luminescence quenching are successfully explained by the combination of Photoinduced Electron Transfer (PET) and Resonance Energy Transfer (RET) mechanisms. Additionally, the Density Functional Theory (DFT) calculations have been employed to support the experimental results. Zn-BTC fully demonstrates the power of a multi component MOF, which provides a feasible pathway for the design of novel material towards fast responding luminescence sensing and photocatalytic degradation of pollutants.

A molecularly imprinted fluorescence sensor built as a mesoporous structured silica imprinted layer on the surface of carbon dots (CDs@m-MIP) was employed for the selective detection of triclosan (TRI). The fluorescence of this CDs@m-MIP was affected sensitively and selectively by TRI via an electron transfer-induced fluorescence quenching mechanism with a detection limit of TRI at 1.08 nM (range 1.72-138 nM) under the optimum setup (e.g., pH, response time, and CDs@m-MIP dose). This approach was used successfully to detect TRI in real water samples (e.g., sewage, river, and tap water). The recoveries of TRI were satisfactory in spiked river and tap water (in 94.7-99.5 %). The outcome of this research is thus expected to help develop highly efficient fluorescent sensing systems towards diverse hazardous compounds including TRI.

Multidentate 1,3,5-benzenetricarboxylic acid (organic linker), Zn (II) based Zn-BTC has been synthesized via electrochemical method. Quantitative and Qualitative analyses of synthesized metal-organic framework (MOF) have been done using Fourier Transform Infrared (FTIR) Spectroscopy, Energy Dispersive X- Ray Spectroscopy (EDS), and Photoluminescence (PL). Powder X-Ray Diffraction (PXRD) and Scanning Electron Microscopy (SEM) have been used for crystallographic and morphologicaltopographical analyses, respectively. Crystallographic studies confirm the formation of face-centered cubic (fcc) crystal structure with good crystallinity. Photo-catalytic activity of synthesized MOF has been tested using Methylene Blue (MB) dye as a test contaminant in aqueous media under sunlight irradiation. Recorded results reveal that the synthesized MOF efficiently degrade MB dye upto 96% under sunlight exposure after 270 min. Photoluminescence studies indicate that Zn-BTC could be used as an efficient material for sensing of nitroaromatic compounds (NACs): 4-Nitroaniline (4-NA), 2-Nitroaniline (2-NA), 3- Nitroaniline (3-NA), 2,4-Dinitrotoulene (2,4-DNT), 4-Nitrotoulene (4-NT) in N,N'-Dimethylformamide (DMF) by fluorescence quenching and shows maximum quenching efficiency towards 3-NA (72.80%). Notably, the variation in luminescence intensity of 3-NA@Zn-BTC shows a linear relationship over its different concentrations from 0-1000 ppb range with K

Amine/hydrazone functionalized dual ligand Cd(II)/Zn(II) based metal-organic frameworks (MOFs) denoted as CdMOF- and ZnMOF-NH

A Schiff base bis(thiophen-2-yl-methylene)benzene-1, 4-diamine (L) was synthesized and used for selective and sensitive detection of Fe

A simple fluorescent chemosensor 5-(4-methylphenyl)-3-(5-methylfuran-2-yl)-1-phenyl-4, 5-dihydro-1H-pyrazole (PY) has been synthesized for the detection of Cd

Scientific pieces of evidence indicate that the polymorphism in the ALR2 regulatory gene favors the susceptibility to diabetic complications (DCs). Previous studies have uncovered several single nucleotide polymorphisms (SNPs) in the ALR2 regulatory sites that negatively modulate the activity of this enzyme and eventually increase the risks of DCs. In view of this, the current study aimed at investigating whether the mutation as a resultant of missense SNPs in the regulatory site of ALR2 enzyme can also hamper the interactions of ALR2 inhibitors with the key amino acid residues in the ALR2 binding site. Around 202 SNPs in the ALR2 gene were reported in the dbSNP database. Out of these, eighteen SNPs that are responsible for point mutations in the regulatory sites of ALR2 enzyme were identified and considered for the study. Identified SNPs were then categorized as stabilizing or destabilizing using various in silico tools and webservers. The resulting mutational constructs of ALR2 were further probed for their influence on the binding affinities and binding modes with well-known ALR2 inhibitors using structure-based analyses. This study identified three destabilizing SNPs, i.e., rs779176563 (C298S), rs1392886142 (G16A), and rs1407261115 (A245T), that lead to the compromised response to most of the ALR2 inhibitors which are in clinical trials. On the other hand, treatment with these ALR2 inhibitors may benefit the population which carries missense SNPs rs748119899, rs1402962430, and rs1467939858 that code for W219S, Q183V, and S214A, respectively. Overall findings of the study suggest that one SNP in the inhibitor site and two SNPs in the co-factor site of ALR2 may be responsible for the low efficacy and unsuccessful journey of ALR2 inhibitors in the clinical trials.

A simple synchronous fluorescent chemosensor 3-hydroxy-2-(4-methoxyphenyl)-4H-chromen-4-one (3-HC) has been synthesized for the selective analysis of Al

By using Schiff base tricarboxylate ligand 5-(4-carboxybenzylideneamino)isophthalic acid (H 3 CIP), a new imine functionalized copper metal organic framework (MOF) has been synthesized solvothermally. It was fully characterized by Fourier Transform Infrared (FTIR) Spectroscopy, Powder X-Ray Diffraction (PXRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), and elemental mapping techniques. The as-synthesized MOF has been utilized as fluorescent probe for detection of nitro aromatic explosives (NAEs). The results show that the copper MOF can be developed into highly selective and sensitive sensor for detection of TNP in the aqueous medium via the “turn-off” quenching response. The linear fitting of the Stern-Volmer plot for TNP offered large quenching constant of 1.07 × 10 4 M −1 for Cu-MOF indicating the high sensitivity of the sensing process. Outstanding sensitivity of prepared material towards TNP detection was further validated by the low detection limit of 80 ppb (0.35 µM). The detailed mechanistic studies for their mode of action and density functional theory (DFT) calculations reveals that photo-induced electron transfer (PET) and fluorescence resonance energy transfer (FRET) processes, as well as electrostatic interactions ( i.e. H-bonding) are the key factors for the turn-off response toward TNP by this fluorescent sensor. Thus, this new LMOF owing to their high water stability and remarkable functional features are potential candidates which can be developed into selective and sensitive TNP detection devices.

Various forms of α-amino nitrile molecules are found to exert strong impacts on the synthesis of multiple organic compounds such as pharmaceuticals, amino acids, agrochemical agents, and pesticides. Spherical ZnO nanoparticles (NPs) prepared by a simple co-precipitation method are an efficient heterogeneous catalyst for the synthesis of vital intermediate α-amino nitriles. The present protocol was investigated via one-pot synthesis of α-amino nitriles over ZnO NPs using a three-component coupling reaction of aldehydes, amines, and trimethylsilyl cyanide in acetonitrile. The feasibility of our synthesis approach was assessed with respect to the purity and yield of synthesized products in relation to several controlling variables (e.g., ZnO molar ratio, reaction time, amines/aldehydes types, and solvent). The qualitative characteristics of α-amino nitrile products were evaluated by Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR), and mass spectroscopic analysis. A high yield (81–95%) of pure α-amino nitriles within a short reaction time (45–75 min) along with good recyclability of the catalyst (e.g., without significant loss in performance over five cycles) was confirmed as the distinctive merits of this new eco-friendly synthetic method. This study confirms that various amines including sterically crowded secondary amines should react efficiently with benzenoid plus non-benzenoid aldehyde to yield α-amino nitriles. The selected route is very fast as well as economical. Hence, this method can be used for large-scale production of a variety of biologically important molecules through α-amino nitriles.

Exposure to volatile organic compounds (VOCs) can exert serious impacts on human health. The detection and identification of VOCs are, therefore, important both in outdoor and indoor (whether workplace or residential) environments. The use of colorimetric and optical sensing techniques for VOCs is expected to offer new ways to overcome many limitations in traditional gas sensing systems. In this work, a classification of colorimetric and optical sensing devices was made and discussed with respect to the sensing mechanisms, principles, and sensing materials for common VOCs (e.g., alcohols, aldehydes, alkenes, aromatic compounds, halogenated VOCs, ketones, and polycyclic aromatic hydrocarbons). The performances of these sensing approaches were also evaluated in terms of sensitivity relative to other available detection methods. Furthermore, this paper offers an extensive review of recent progresses in this area with a discussion on the future challenges associated with the expansion of colorimetric/optical sensing techniques.

Schiff bases and their metal complexes have become well-known for catalytic (e.g., in various synthetic processes) and biological properties (e.g., antifungal, antibacterial, anti-malarial, and antiviral characteristics) since their discovery by Hugo Schiff in 1864. As synthetic compounds, they are employed as versatile tools in numerous applications such as fluorescent turn-on/turn-off sensors for the determination of diverse analytes (e.g., metallic components). As such, they can offer a way to identify toxic ions and/or to provide their speciation in environmental media. This review covers a broad range of Schiff bases that are used in sensing applications for metallic cations and anions in various kinds of environmental and biological media.

A rapid extraction and cleanup method using selective fabric phase sorptive extraction combined with gas chromatography and mass spectrometry has been developed and validated for the determination of broad polarity spectrum emerging pollutants, ethyl paraben, butyl paraben, diethyl phthalate, dibutyl phthalate, lidocaine, prilocaine, triclosan, and bisphenol A in various aqueous samples. Some important parameters of fabric phase sorptive extraction such as extraction time, matrix pH, stirring speed, type and volume of desorption solvent were investigated and optimized. Calibration curves were obtained in the concentration range 0.05-500 ng/mL. Under the optimum conditions, the limits of detection were in the range 0.009 -0.021 ng/mL. This method was validated by analyzing the compounds in spiked aqueous samples at different levels with recoveries of 93 to 99% and relative standard deviations of

A new ion-selective polyvinyl chloride membrane electrode based on Schiff base [N,N′-bis(1-hydroxynaphthalene-2-carbaldehyde)-o-phenylenediamine] as an ionophore is successfully worked out as sensor for Zn(II) ions. The electrode shows excellent potentiometric response characteristics and displays a linear emf versus log[Zn2+] response over a wide concentration range of 1.0 × 10–7‒0.1 M with nernstian slope of 29.0 ± 0.1 mV/decade with the detection limit of 1.8 × 10–8 M. The sensor exhibits the advantages of fast response time (

In the present work, a high-efficiency and solvent minimized microextraction technique, fabric phase sorptive extraction followed by gas chromatography and mass spectrometry analysis is proposed for the rapid determination of four organophosphorus pesticides (terbufos, malathion, chlorpyrifos, and triazofos) in vegetable samples including beans, tomato, brinjal, and cabbage. Fabric phase sorptive extraction combines the beneficial features of sol-gel derived microextraction sorbents with the rich surface chemistry of cellulose fabric substrate, which collectively form a highly efficient microextraction system. Fabric phase sorptive extraction membrane, when immersed directly into the sample matrix, may extract target analytes even when high percentage of matrix interferents are present. The technique also greatly simplifies sample preparation workflow. Most important fabric phase sorptive extraction parameters were investigated and optimized. The developed method displayed good linearity over the concentration range 0.5-500 ng/g. Under optimum experimental conditions, the limits of detection were found in the range of 0.033 to 0.136 ng/g. The relative standard deviations for the extraction of organophosphorus pesticides were

In this research, the adsorptive performance of a starch-magnesium/aluminum layered double hydroxide (S-Mg/Al LDH) composite was investigated for different organic dyes in single-component systems by conducting a series of batch mode experiments. S-Mg/Al LDH composite showed preferential adsorption of anionic dyes than cationic dyes. The marked impact of key process variables (e.g., contact time, adsorbent dosage, pH, and temperature) on its adsorption was investigated. Multiple isotherms, kinetics, and thermodynamic models were applied to describe adsorption behavior, diffusion, and uptake rates of the organic dyes over S-Mg/Al LDH composite. A better fitting of the non-linear Langmuir model reflects the predominance of monolayered adsorption of dye molecules on the composite surface. Partition coefficients (mg g−1 μM−1) for S-Mg/Al LDH were observed in the following descending order: Amaranth (665) > Tartrazine (186) > Sunset yellow (71) > Eosin yellow (65). Furthermore, comparative evaluation of the adsorption enthalpy, entropy, and Gibbs free energy values indicates that the adsorption process is spontaneous and exothermic. S-Mg/Al LDH composite maintained a stable adsorption/desorption recycling process over six consecutive cycles with the advantages of low cost, chemical/mechanical stability, and easy recovery. The results of this study are expected to expand the application of modified LDHs toward wastewater treatment.

Molecularly imprinted polymers (MIPs) are promising materials for analytical applications because of their structural predictability and recognition specificity. However, the applications of conventional MIPs suffer in a practical sense due to several defects (e.g., deeply embedded cavities, incomplete removal of the template, non-uniform distribution of binding sites, and slow rebinding kinetics). Core-shell nanoparticles coated with MIPs can be an attractive alternative to overcome such limitations. The core-shell structure offers a high surface area with a uniform distribution of binding sites to facilitate the removal of the template molecule and subsequent rebinding of the target molecule at high mass transfer efficiency. This work provides a comprehensive review of the classes of core-shell MIPs such as solid single, solid composite, and hollow core forms. The utility of novel and emerging core-shell MIPs is described for applications in optical, electrochemical, and piezoelectric sensors along with the associated challenges and opportunities.

Using a co-precipitation method, starch-Mg/Al layered double hydroxide (S-Mg/Al LDH) composites were synthesized. Their physicochemical properties were assessed by Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and thermo-gravimetric analysis. The quantification of six non-steroidal anti-inflammatory drugs (NSAIDs) was conducted using real samples (e.g., hospital waste water, river water, sewage treatment plant water, and tablet formulations) by gas chromatography-mass spectrometry. For the development of this method, the system was optimized in terms of several key variables (e.g., pH, flow rate, and eluent type/volume). The developed method for NSAIDs exhibited good resolution, sensitivity, reproducibility, and specificity even in complex matrices with limits of detection between 4 and 20 pg/mL. Hence, S-Mg/Al LDH composites were proven to be efficient and fast solid phase extraction (SPE) sorbents for NSAIDs. In addition, each LDH-SPE cartridge showed good reusability without a noticeable change in performance (e.g., up to 30 cycles) and target recoveries between 99.5 – 82.9 %. This work should open up new opportunities for a sesnsitive and sustainable quantitative method for the determination of NSAIDs in complex samples.