New Tin (IV) and Organotin (IV) Complexes with a Hybrid Thiosemicarbazone/Hydrazone Ligand: Synthesis, Crystal Structure, and Antiproliferative Activity.

Nowadays, the search for new chemotherapeutic agents with low toxicity and high selectivity is a major concern. In this paper, we report the synthesis and characterization of a hybrid thiosemicarbazone/hydrazone ligand in its neutral form (L1H2) and as the chloride salt ([L1H3]Cl)-, three diorganotin (IV) complexes, and one complex with Sn (IV). The compounds have been fully characterized by IR, mass spectra, 1H, 13C, and 119Sn NMR, 119Sn CP/MAS NMR, and by single crystal X-ray diffraction. The organotin compounds have the empirical formula [SnR2L1] (R = Me, Bu, and Ph), but in the solid state, they are polymeric species with seven coordination number due to weak coordination of the pyridine nitrogen, whereas in solution, the polymeric structure is lost to afford hexacoordinate monomeric species. Reaction with SnI4 yields complex [Sn (L1)2]·EtOH, with the metal in a distorted dodecahedral arrangement. We have evaluated the antiproliferative activity of the two forms of the ligands and the four coordination compounds against MDA-MB-231, HeLa, PC3, and HepG2 cancer cell lines, and WI-38 normal cell line, and all the compounds present higher activity than cisplatin, used as the standard control. To investigate the mode of action, we have selected the most active complex, containing phenyl substituents, and used the triple negative breast cancer cell line MDA-MB-231. The results show that the complex induces apoptotic cell death promoted by generation of reactive oxygen species and by disruption of mitochondrial membrane potential.

Exploitation of a 1D coordination polymer as a portable kit for an eye-catching fluorometric response towards sensing of trivalent cations.

The development and utilization of coordination polymers (CPs) have drawn interest for potential applications in different fields. Detection of metal ions in efficient and selective manners is an important field of research. It paves the way to protect human health by balancing toxic metal ions and biologically active metal ions in the atmosphere. In this regard, a new one-dimensional (1D) 4-(1-naphthylvinyl)pyridine (4-nvp) based CP [Cd(NCS)2(4-nvp)2]n (1) was synthesized and characterized structurally by single-crystal X-ray diffraction. Interestingly, this 1D CP underwent supramolecular aggregation via π⋯π stacking interactions, which specifically generated an environment for a potent "turn on" response in the presence of trivalent cations (Fe3+, Al3+, and Cr3+) in the nanomolar range but remained silent in the presence of other metal ions. Density functional theory (DFT) computations and X-ray photoelectron spectroscopy (XPS) were performed to establish the sensing phenomena. Fascinatingly, utilizing the sensitivity of 1 in an aqueous medium, a hands-on portable cotton swab kit was developed for instant identification of these three important trivalent metal cations.

Comparative study on Antibacterial efficacy of a series of chromone sulfonamide derivatives against drug-resistant and MDR-isolates.

Sulfonamide derivatives have numerous pharmaceutical applications having antiviral, antibacterial, antifungal, antimalarial, anticancer, and antidepressant activities. The structural flexibility of sulfonamide derivatives makes them an excellent candidate for the development of new multi-target agents, although long-time exposure to sulfonamide drugs results in many toxic impacts on human health. However, sulfonamides may be functionalized for developing less toxic and more competent drugs. In this work, sulfonamides including Sulfapyridine (a), Sulfathiazole (b), Sulfamethoxazole (c), and Sulfamerazine (d) are used to synthesize Schiff bases of 7-hydroxy-4-methyl-2-oxo-2H-chromene-8-carbalde-hyde (1a-1d). The synthesized compounds were spectroscopically characterized and tested against hospital isolates of three Gram-positive (Methicillin-resistant Staphylococcus aureus PH217, Ampicillin-resistant Coagulase-negative Staphylococcus aureus, multidrug-resistant (MDR) Enterococcus faecalis PH007R) and two Gram-negative bacteria (multidrug-resistant Escherichia coli, and Salmonella enterica serovar Typhi), compared to the quality control strains from ATCC (S. aureus 29213, E. faecalis 25922, E. coli 29212) and MTCC (S. Typhi 734). Two of the four Schiff bases 1a and 1b are found to be more active than their counterpart 1c and 1d; while 1a have showed significant activity by inhibiting MRSA PH217 and MDR isolates of E. coli at the minimum inhibitory concentration (MIC) of 150 µg/mL and 128 µg/mL with MBC of 1024 µg/mL, respectively. On the other hand, the MIC of 1b was 150 µg/mL against both S. aureus ATCC 29213 and Salmonella Typhi MTCC 734, compared to the control antibiotics Ampicillin and Gentamycin. Scanning electron microscopy demonstrated the altered surface structure of bacterial cells as a possible mechanism of action, supported by the in-silico molecular docking analysis.

Correlation in Structural Architecture toward Fabrication of Schottky Device with a Series of Pyrazine Appended Coordination Polymers.

Energy is the center of importance for the survivability of civilization. Use of fossil fuel is going to be suspended, and renewable energy is technologically costlier. In the quest for new energy sources and to minimize fuel expenditure, the design of energy efficient devices is one of the solutions. Toward this objective, highly delocalized π-acidic N-hetreocycle pyrazine bridged Cd(II)-based coordination polymers (CPs), [Cd(tppz)(adc)(MeOH)] (1), [Cd(tppz)(trep)] (2), and [Cd(tppz)(2,6-ndc)] (3; tppz = 2,3,5,6-tetrakis(2-pyridyl)pyrazine) are synthesized in combination with π-accessible dicarboxylato linkers (acetylene dicarboxylic acid (H2adc), terephthalic acid (H2trep), and 2,6-naphthalene dicarboxylic acid (2,6 H2ndc)). The structures of the compounds, 1-3, have been confirmed by single-crystal X-ray diffraction measurements. Analysis of electrical property demonstrates that light irradiation enhances the conductivity and follows the order 3 > 2 > 1; compound 3 possesses the highest conductivity (1.93 × 10-3 (light), 1.12 × 10-4 S m-1 dark)), than 2 (1.80 × 10-4 (light), 1.10 × 10-4 S m-1 (dark)) and 1 (5.06 × 10-5 (light), 4.72 × 10-5 S m-1 (dark)). This light-induced electrical conductivity can pave the way toward fabrication of an active electronic device by using the discussed materials.

Pyridyl-Isonicotinoyl Hydrazone-Bridged Zn(II) Coordination Framework with Thiophenedicarboxylato Link: Structure, Biological Activity, and Electrical Conductivity.

Multidimensional applicability of functional materials is one of the focal attractions in today's scientific research. Highly stable and crystalline coordination polymers served as one of the active members in the club of multifunctional materials. Toward this concept, a 3-dimensional (3D) coordination framework, {[Zn2(tdc)2(pcih)2]n} (1) (tdc2-, 2,5-thiophene dicarboxylate; pcih, pyridine-4-carboxaldehyde isonicotinoyl hydrazine), is designed and has been structurally well characterized by single crystal X-ray crystallography. One of the carboxylate groups of tdc2- chelates to Zn(II), while the other carboxylato group (-COO) acts as bridging-O to neighboring Zn(II); the pcih serves as pyridyl-N bridging motif to two Zn(II) centers. The optical band gap, 3.83 eV (Tauc's plot), implies probable semiconducting ability of the material. Interestingly, the device fabricated using compound 1 measures the electrical conductivity, 2.21 × 10-5 S cm-1, and series resistance (Rs), 807 Ω, at the dark phase, which are improved significantly to 6.36 × 10-5 S cm-1 and 460 Ω, respectively, under illumination conditions. Isoniazid, used to synthesize pcih and hence the Zn(II) compound 1, is a medicine; so, the medicinal efficiency of 1 is checked by measuring the anticancer activity against MDA-MB-231, HeLa, HCT-116, and HepG2 cells. It is observed that drug efficacy is highest on MDA-MB-231 cells (IC50: 19.43 ± 1.36 µM) than other cancer cells [IC50: 24.43 ± 2.02 µM (HeLa), 26.06 ± 3.48 µM (HCT-116), and 44.28 ± 3.04 µM (HepG2)]. Therefore, the material has significant contribution in the area of energy and health toward the sustainable development goals.

In Situ Oxidation of Pyridyl-Dihydrobenzoimidazoquinazoline and the Synthesis of a Highly Luminescent Cd(II) Coordination Polymer: A Promising Candidate for Mutagenic Nitroaromatic Detection and Device Fabrication.

Pyridyl-substituted imidazoquinoline, a potent fluorescent framework, is advantageous to architect multifunctional coordination networks for sensing and fabricating emergent electrical conductors. In this work, a Cd(II)-based one-dimensional (1D) coordination polymer (1D CP), [Cd(glu)2(pbiq)2(H2O)]n (1), [H2glu = glutaric acid and pbiq = 4-(6-(pyridin-4-yl)benzo[4,5]imidazo[1,2-c]quinazoline)], has been structurally confirmed by single-crystal X-ray crystallography. The H-bonding and π···π interactions built a three-dimensional (3D) supramolecular structure that strongly emits at 416 nm in acetonitrile suspension. Potentially intrusive nitroaromatics (NAs) and trinitrophenol (TNP) selectively quench the strong emission of 1, and the highest quenching is noted in the case of TNP. A detection limit (limit of detection (LOD)) of 1.51 × 10-7 M for TNP is determined. The band gap (3.31 eV) of 1 recognizes semiconducting behavior, and an electronic device is fabricated. The correlation of current vs voltage (I-V plot) reveals a substantial non-ohmic electrical conductivity of 1 (Λ: 1.10 × 10-5 S m-1) along with a low energy barrier (ΦB: 0.69), and the series resistance (Rs) becomes 6.21 kΩ.

Aminoisophthalate Bridged Cd(II)-2D Coordination Polymer: Structure Description, Selective Detection of Pd2+ in Aqueous Medium, and Fabrication of Schottky Diode.

Photoluminescence activity of coordination polymers (CPs) has evoked intricate applications in the field of materials science, especially sensing of ions/molecules. In the present study, 2,3,5,6-tetrakis(2-pyridyl)pyrazine (tppz) and 5-aminoisophthalate (HAIPA-) coordinated to Cd(II) to architect a coordination polymer, {[Cd(HAIPA)(tppz)(OH)]·3H2O}n (CP1) which unveils blue emission in an aqueous acetonitrile (98% aqueous) suspension. The emission is selectively quenched by Pd2+ only without interference in the presence of as many as 16 other cations. The structure of CP1 shows the presence of a free -COOH group, and the interlayer (-CO)O(2)···O(7) (OC-) distance, 4.242 Å, along with the π···π interactions (3.990, 3.927 Å), may make a cavity which suitably accommodates only Pd2+ (van der Waal's radius, 1.7 Å) through the Pd(II)-carboxylato (-COO-Pd) coordination. The stability of the composite, [CP1 + Pd2+] may be assessed from the fluorescence quenching experiment, and the Stern-Volmer constant (KSV) is 7.2 × 104 M-1. Therefore, the compound, CP1, is a promising sensor for Pd(II) in a selective manner with limit of detection (LOD), 0.08 µM. The XPS spectra of CP1 and [CP1 + Pd2+] have proven the presence of Pd2+ in the host and the existence of a coordinated -COO-Pd bond. Interestingly, inclusion of Pd2+ in CP1 decreases the band gap from 3.61 eV (CP1) to 3.05 eV ([CP1 + Pd2+]) which lies in the semiconducting region and has exhibited improved electrical conductivity from 7.42 × 10-5 (CP1) to 1.20 × 10-4 S m-1 ([CP1 + Pd2+]). Upon light irradiation, the electrical conductivities are enhanced to 1.45 × 10-4 S m-1 (CP1) and 3.81 × 10-4 S m-1 ([CP1 + Pd2+]); which validates the highly desired photoresponsive device applications. Therefore, such type of materials may serve as SDG-army (sustainable development goal) to battle against the environmental issues and energy crisis.

Anti-HSV nucleoside and non-nucleoside analogues: spectroscopic characterisation of naphthyl and coumarinyl amides and their mode and mechanism of antiviral action.

Nucleoside analogues acyclovir, valaciclovir, and famciclovir are the preferred drugs against human Herpes Simplex Viruses (HSVs). However, the viruses rapidly develop resistance against these analogues which demand safer, more efficient, and nontoxic antiviral agents. We have synthesized two non-nucleoside amide analogues, 2-Oxo-2H-chromene-3-carboxylic acid [2-(pyridin-2-yl methoxy)-phenyl]-amide (HL1) and 2-hydroxy-1-naphthaldehyde-(4-pyridine carboxylic) hydrazone (HL2). The compounds were characterized by different physiochemical methods including elementary analysis, FT-IR, Mass spectra, 1H-NMR; and evaluated for their antiviral efficacy against HSV-1F by Plaque reduction assay. The 50% cytotoxicity (CC50), determined by MTT test, revealed that HL1 (270.4 µg/ml) and HL2 (362.6 µg/ml) are safer, while their antiviral activity (EC50) against HSV-1F was 37.20 µg/ml and 63.4 µg/ml against HL1 and HL2 respectively, compared to the standard antiviral drug Acyclovir (CC50 128.8 ± 3.4; EC50 2.8 ± 0.1). The Selectivity Index (SI) of these two compounds are also promising (4.3 for HL1 and 9.7 for HL2), compared to Acyclovir (49.3). Further study showed that these amide derivatives block the early stage of the HSV-1F life cycle. Additionally, both these amides make the virus inactive, and reduce the number of plaques, when infected Vero cells were exposed to HL1 and HL2 for a short period of time. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-023-03658-0.

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.

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.

Spectrophotometric Determination of Trace Amount of Total FeII/FeIII and Live Cell Imaging of a Carboxylato Zn(II) Coordination Polymer.

The coordination polymer, (Zn(II)-CP, 1), {[Zn(2,6-NDC)(4-Cltpy)](H2O)4} (1) (2,6-H2NDC = 2,6-naphthalene dicarboxylic acid and 4-Cltpy = 4'-chloro-[2,2';6',2″]terpyridine) is structurally characterized by single crystal X-ray diffraction measurement and other physicochemical studies (PXRD, FTIR, thermal analysis, microanalytical data). 4-Cltpy acts as end-capping ligand, and NDC2- is a carboxylato bridging motif to constitute ZnN3O2 distorted trigonal bipyramid core that propagates to construct 1D chain. The coordination polymer, 1, detects total iron (Fe3+ and Fe2+) in aqueous solution by visual color change, colorless to pink. Absorption spectrophotometric technique in aqueous medium measures the limit of detection (LOD) 0.11 µM (Fe2+) and 0.15 µM (Fe3+), and binding constants (Kd) are 6.7 × 104 M-1 (Fe3+) and 3.33 × 104 M-1 (Fe2+). Biocompatibility of 1 is examined in live cells, and intracellular Fe2+ and Fe3+ are detected in MDA-MB 231 cells. Zn(II) substitution is assumed upon addition of FeIII/FeII solution to the suspension of the coordination polymer, 1, in water-acetonitrile (41:1) (LZnII + FeIII/II → LFeIII + ZnII, where L is defined as coordinated ligands), which is accompanied by changing from colorless to pink at room temperature. The color of the mixture may be assumed to the charge transfer transition from carboxylate-O to Cltpy via Fe(II/III) bridging center (carboxylate-O-Fe-CltPy). The product isolated from the reaction is finally characterized as Fe(III)@1-CP. It is presumed that product Fe(II)@1-CP may undergo fast aerial oxidation to transform Fe(III)@1-CP. The FeIII exchanged framework (Fe(III)@1-CP) has been characterized by PXRD, IR, TGA and energy dispersive X-ray analysis (EDX)-SEM. The MTT assay calculates the cell viability (%), and the tolerance limit is 100 µM to total Fe2+ and Fe3+.

Rational synthesis of a pyridyl-imidazoquinazoline based multifunctional 3D Zn(II)-MOF: structure, luminescence, selective and sensitive detection of Al3+ and TNP, and its semiconducting device application.

In the age of sustainable development, the exploration of multifunctional materials is of high priority due to their economic benefits and environmental suitability. A stable luminescent coordination polymer, [Zn2(tdc)4(pdiq)3] (1), (pdiq = pyridyl-imidazoquinazoline; H2tdc = 2,5-thiophenedicarboxylic acid) has been prepared and structurally confirmed by single-crystal X-ray diffraction analysis. The 3D framework consists of a distorted octahedral geometry with a ZnO4N2 coordination sphere where four carboxylato-O donations come from two tdc2- as bridging ligands and two pyridyl-Ns come from two pdiq. The π⋯π interactions between the imidazolium and phenyl groups bestow robustness on the architecture. The compound is chemically stable to water, shows tolerance to acid/base aqueous solutions (pH = 2-12), and is stable to the impact of organic solvents. The high dispersibility of Zn-MOF (1) in acetonitrile may enhance the fluorescence intensity compared to that in water, which prompted fluorescence measurements in the former solvent and it is used for the efficient and selective turn-off ratiometric sensing of Al3+ ions (LOD, 1.39 × 10-7 M). In addition, the fluorescence emission of 1 is instantly quenched by trinitrophenol (TNP) and the LOD is 1.54 × 10-7 M. The Tauc's plot is used to measure the semiconducting band gap (3.33 eV) and the electrical conductivity is significantly increased upon illumination (Λ: 1.14 × 10-3 S m-1 (dark), 5.35 × 10-3 S m-1 (light)) and the energy barrier declines marginally (FB: 0.57 (dark), 0.49 (light)). Transit time (τ) and diffusion length (LD) at the quasi-Fermi level were analyzed to offer information on the charge transport mechanism of the compound. The better performance on photo-irradiation signifies the enhanced charge transfer kinetics of a Zn-MOF coated thin-film device (TFD 1), which encourages its application in semiconductor devices.

A Dual Functional 2D MOF Exhibiting Rare Photosalient Effect as well as Selective Pd(II) Sensing in Aqueous Medium.

A Zn(II) based two-dimensional metal-organic framework (2D MOF) [Zn2(suc)2(4-nvp)2] (1) [H2suc = succinic acid and 4-nvp = 4-(1-naphthylvinyl)pyridine] exhibits a "photosalient effect" under UV light as well as sunlight along with the release of a stereoselective cyclobutane ligand, 1,3-bis(4'-pyridyl)-2,4-bis(naphthyl)cyclobutane (rctt-4-pncb). Photolysis of in situ generated MOF in solution also leads to the formation of rctt-4-pncb crystals. Interestingly, compound 1 shows a high selectivity for Pd(II) sensing in aqueous medium.

Sunlight-Induced In Situ Isomerization of Both Ligands in a Mixed-Ligand Coordination Polymer: From Photosalient to Photoinert Crystals.

Reaction of Zn(NO3 )2 ⋅ 6H2 O, maleic acid (H2 mal) and trans-4-(1-naphthylvinyl)pyridine (trans-nvp) in the dark results in the formation of a one-dimensional coordination polymer (1D CP) [Zn(mal)(trans-nvp)] (1), which is photosalient in nature. The crystals of 1 pop violently under UV light and moderately in sunlight, and generate cyclobutane ligands. However, the same reaction mixture kept in visible light exhibits the rare example of in situ isomerization of both ligands: cis-trans transformation of maleate and trans-cis isomerization of the nvp ligands, and subsequent formation of another 1D CP [Zn(fum)(cis-nvp)2 (H2 O)2 ] (2, H2 fum=fumaric acid), which is found to be photoinert. Thus, altering the reaction condition from dark to visible light gives rise to photosalient to photoinert crystals.

Idiosyncatic recognition of Zn2+ and CN- using pyrazolyl-hydroxy-coumarin scaffold and live cell imaging: depiction of luminescent Zn(II)-metallocryptand.

Multi-responsive and selective sensor design is one of the stimulating research areas in the sensors field. We have designed a pyrazolyl-hydroxy-coumarin scaffold, 7-hydroxy-4-methyl-8-(((5-phenyl-1H-pyrazol-3-yl)imino)methyl)-2H-chromen-2-one (H2L) and characterized it by spectroscopic techniques (1H NMR, 13C NMR, ESI-MS, IR). The single crystal X-ray diffraction measurement confirms the molecular structure of the probe. It shows the selective sensing of Zn2+ in the presence of sixteen other cations with 'Turn On' approach through the enhancement of green florescence ((λem = 499 nm; λex = 390 nm) in CH3CN/H2O (99 : 1, v/v; HEPES buffer, pH 7.5) medium with the limit of detection (LOD) of 34.76 nM. The structural depiction of the isolated Zn2+ complex reveals cage like metallocryptand cyclic hexamer, [Zn6L6] with 30.9% void of cavity along the crystallographic c axis of approximate dimension of 7.502 × 7.050 × 7.068 Å3. The diffusion NMR study reveals only one type of complex in the solution, having 1 : 1 composition, i.e., Zn2+ : H2L, which affirms the isolated form of the complex. On the other hand, the receptor, H2L, recognizes the very noxious anion CN- out of sixteen anions. The product identification using spectroscopic techniques supports the nucleophilic addition of CN- across the exocyclic imine (CN) bond, which shows blue emission ((λem = 447 nm; λex = 390 nm), and the LOD was 19.91 nM. The composition of [H2L-Zn2+] and [H2L-CN-] was established by 1H NMR titration, Job's method, ESI-MS, and FTIR spectra. The efficacy of the probe was further studied using MTT assay in MDA-MB 231 and WI-38 cell line as well as for the intracellular imaging of Zn2+ and CN- using a fluorescence microscope. Flow Cytometry was further performed for the quantitative analysis of Zn2+ distribution in MDA-MB 231 cells.

Molecular modeling of potent novel sulfonamide derivatives as non-peptide small molecule anti-COVID 19 agents.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent for the COVID-19. The Sulfonamides groups have been widely introduced in several drugs, especially for their antibacterial activities and generally prescribed for respiratory infections. On the other hand, imidazole groups have the multipotency to act as drugs, including antiviral activity. We have used a structure-based drug design approach to design some imidazole derivatives of sulfonamide, which can efficiently bind to the active site of SARS-CoV-2 main protease and thus may have the potential to inhibit its proteases activity. We conducted molecular docking and molecular dynamics simulation to observe the stability and flexibility of inhibitor complexes. We have checked ADMET (absorption, distribution, metabolism, excretion and toxicity) and drug-likeness rules to scrutinize toxicity and then designed the most potent compound based on computational chemistry. Our small predicted molecule non-peptide protease inhibitors could provide a useful model in the further search for novel compounds since it has many advantages over peptidic drugs, like lower side effects, toxicity and less chance of drug resistance. Further, we confirmed the stability of our inhibitor-complex and interaction profile through the Molecular dynamics simulation study. Our small predicted moleculeCommunicated by Ramaswamy H. Sarma.

A highly emissive Zn(II)-pyridyl-benzimidazolyl-phenolato-based chemosensor: detection of H2PO4-via "use" and "throw" device fabrication.

2-Ethoxy-6-[1-(phenyl-pyridin-2-yl-methyl)-1H-benzoimidazol-2-yl]-phenol (HL) selectively serves as a sensitive 'turn on' Zn2+ sensor in 9 : 1 (v/v) DMSO/H2O (HEPES buffer, pH = 7.4) medium in the presence of sixteen other cations at the limit of detection (LOD) of 3.2 nM. The strong blue emission of the complex, {[Zn(L1)OAc]} (HL1 = benzimidazolyl ring-opening structure of HL) (λem, 461 nm), is quenched by H2PO4- in the presence of eighteen other anions and the LOD is 0.238 µM. The emission of the complex is due to restricted intramolecular rotation (RIR) followed by chelation-enhanced fluorescence (CHEF). The quenching of the emission of [Zn(L1)OAc] by H2PO4- (in the presence of other PVs (inorganic and biological) as well as additional anions) is due to the 'turn off' fluorescence via the demetallation and release of the nonfluorescent ligand, HL, and [Zn(H2PO4)]+. An INHIBIT logic gate memory circuit of the probe HL was devised with Zn2+ and H2PO4- as two consecutive inputs. The percentage of H2PO4- recovery was excellent and was obtained from distilled, tap, and drinking water sources. The bright blue emission of [Zn(L1)OAc] further triggered the fabrication of ready-made portable thin films of the Zn-complex, which executed a cost-effective 'on-site' solid-state contact mode detection of H2PO4- with selectivity at the picogram level (10.97 pg cm-2) by monitoring the intensities of quenched spots under UV light upon varying the analyte concentration from 10-8 to 10-3 M. Finally, taking advantage of reversible fluorescence switching, a simple and definite ion-responsive security feature was successfully embedded into a "use" and "throw" solution-coated paper strip of the Zn(II)-pyridyl-benzimidazolyl-phenolato-based chemosensor, which efficiently detected H2PO4- in water by a successive 'ON-OFF' fluorescence switching-driven security activity without any exhaustion of the emission phenomenon.

A Reusable Efficient Green Catalyst of 2D Cu-MOF for the Click and Knoevenagel Reaction.

[Cu(CPA)(BDC)]n (CPA = 4-(Chloro-phenyl)-pyridin-4-ylmethylene-amine; BDC = 1,4-benzenedicarboxylate) has been synthesized and structurally characterized by single crystal X-Ray diffraction measurement. The structural studies establish the copper (II) containing 2D sheet with (4,4) square grid structure. The square grid lengths are 10.775 and 10.769 Å. Thermal stability is assessed by TGA, and subsequent PXRD data establish the crystallinity. The surface morphology is evaluated by FE-SEM. The N2 adsorption-desorption analysis demonstrates the mesoporous feature (∼6.95 nm) of the Cu-MOF. This porous grid serves as heterogeneous green catalyst with superficial recyclability and thermal stability and facilitates organic transformations efficiently such as, Click and Knoevenagel reactions in the aqueous methanolic medium.

Two-Dimensional MOF Modulated Fiber Nanogenerator for Effective Acoustoelectric Conversion and Human Motion Detection.

The real-time application of piezoelectric nanogenerators (PNGs) under a harsh environment remains a challenge due to lower output performance and poor durability. Thus, the development of flexible, sensitive, and stable PNGs became a topic of interest to capture different human motions including gesture monitoring to speech recognition. Herein, a scalable approach is adapted where naphthylamine bridging a [Cd(II)-µ-I4] two-dimensional (2D) metal-organic framework (MOF)-reinforced poly(vinylidene fluoride) (PVDF) composite nanofibers mat is prepared to fabricate a flexible and sensitive composite piezoelectric nanogenerator (C-PNG). The needle-shaped MOF was successfully synthesized by the layering and diffusion of two different solutions. The incorporation of single-crystalline 2D MOF ensures a large content of electroactive phases (98%) with a resultant high-magnitude piezoelectric coefficient of 41 pC/N in a composite nanofibers mat due to the interfacial specific interaction with -CH2-/-CF2- dipoles of PVDF. As an outcome, C-PNG generates high electrical output (open-circuit voltage of 22 V and maximum power density of 24 µW/cm2) with a very fast response time (tr ≈ 5 ms) under periodic pressure imparting stimuli. Benefiting from bending and twisting functionality, C-PNG is capable of scavenging biomechanical energy by mimicking complex musculoskeletal motions that broaden its application in wearable electronics and fabric integrated medical devices. In addition, C-PNG also demonstrates an efficient acoustic vibration to electric energy conversion capability with an improved power density and acoustic sensitivity of 6.25 µW and 0.95 V/Pa, respectively. The overall energy conversion efficiency is sufficient to operate several consumer electronics without any energy storage unit. This acoustic observation is further validated by the finite element method-based theoretical simulation. Overall, the 2D MOF-based device design strategy opens up a new possibility to develop a human-motion compatible energy generator and a self-powered acoustic sensor to power up electronic gadgets as well as low-frequency noise detection.

Sunlight assisted SCSC dimerization of a 1D coordination polymer impacts the selectivity of Pd(II) sensing in water.

A one-dimensional coordination polymer (1D CP) [Cd(4-nvp)2(5-ssa)]·(4-nvp) (1) [4-nvp = 4-(1-naphthylvinyl)pyridine and 5-ssa = 5-sulfosalicylic acid] undergoes topochemical [2+2] cycloaddition by sunlight irradiation to generate a two-dimensional (2D) CP [Cd(rctt-4-pncb)0.5(4-nvp)(5-ssa)]·(4-nvp) (1') [rctt-4-pncb = 1,3-bis(4'-pyridyl)-2,4-bis(naphthyl)cyclobutane] in a single-crystal to single-crystal manner. Interestingly, 1' can be reverted back to 1 by heating and both the CPs selectively recognize Pd2+ in aqueous medium; however, the limit of detection is improved after photodimerization.

X-ray structure of two Schiff bases: TURN-ON sensing of Fe3+ and Al3+ in the HepG2 cell line.

The efficiency of the fluorescence sensitivity of a sensor may be tuned by the modulation of the steric and electronic parameters in the structure. In this study, the thiophenyl Schiff base (E)-N1-(phenyl(pyridin-2-yl)methyl)-N2-(thiophen-2-ylmethylene)benzene-1,2-diamine (HL') exhibited very high selectivity and a sensitive fluorescence enhancement towards Fe3+ with violet emission (λem, 385 nm; LOD, 3.8 nM). On the other hand, the naphthyl Schiff base (E)-1-(((2-((phenyl(pyridin-2-yl)methyl)amino)phenyl)imino)methyl)naphthalen-2-ol (H2L'') exhibited fluorescence sensitivity towards Al3+, showing blue emission (λem, 502 nm; LOD, 3.3 nM) in H2O (HEPES buffer, pH 7.4) medium. The emission enhancement of HL' upon binding to Fe3+ may be considered to be due to the restriction of intramolecular rotation, while the selectivity of H2L'' towards Al3+ may be due to the turn on emission through the restriction of excited state intramolecular proton transfer (ESIPT) and the introduction of chelation enhanced fluorescence (CHEF). Furthermore, DFT computation supported the sensing strategy and the probes were applied for intracellular detection of Fe3+ and Al3+ in HepG2 cell lines.