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An anion-mediated preorganization approach was used to design and synthesize the benzimidazolium-based calix compound R1 ∙2ClO 4 - . X-ray crystallography analysis revealed that the hydrogen bonding interactions between the benzimidazolium cations and N,N-dimethylformamide (DMF) helped R1 ∙2ClO 4 - encapsulate DMF molecule(s)A nanoreactor, with R1 ∙2ClO 4 - and L -histidine ( L -His) as the components, was fabricated using a neutralization method. The nanoreactor could detoxify paraoxon in 30 min. L -His played a vital role in this process. Paraoxonase is a well-known enzyme used for pesticide degradation. The Ellman's reagent was used to determine the percentage inhibition of the acetylcholinesterase (AChE) activity in the presence of the nanoreactor. The results indicated that the nanoreactor inhibited AChE inhibition.

A tripodal receptor R1 with a combination of nitrogen and oxygen-based binding sites was designed and used for the selective determination of Cu2+. The fluorescence emission profile of R1 in the presence of Cu2+ showed a marked enhancement in fluorescence intensity, indicating high selectivity among other metal ions. The R1–Cu2+ complex was further explored as a sensor for anion detection. Upon addition of Br−, switching to a fluorescence “off” state was observed. The Br− selectivity of the complex over a wide range of concentrations was observed via titrimetric analysis through changes in the emission spectra.

A one-pot procedure for the synthesis of hydrazine derivatives from aldehydes via radical addition reactions was developed. Lewis acids promoted both the condensation between aldehydes and benzhydrazide, and the alkyl radical addition to the Cdbnd N bond of hydrazones, affording moderate-to-high yields of hydrazine derivatives. The present process provides a tin-free radical, sustainable, and eco-friendly synthetic method.

A radical "on water" addition to the C═N bond of hydrazones has been described. Hydrazone, diphenylsilane, alkyl iodide, and triethylborane afforded the corresponding addition products "on water" in good yields. A significant solvent effect was observed from the water. The developed protocol can be applied to the synthesis of 3-substituted isoindolinone derivatives. Moreover, the process offers environmentally benign tin-free radical reaction conditions.

A benzothiazole-based azo compound was synthesized and evaluated as a probe for the selective sensing of cations and anions. The probe (PA) could detect Cu2+ ions in aqueous media selectively, without interference from other cations and with a limit of detection of 0.43 μM. The resultant complex, PA-Cu2+, could be used as a secondary probe for detecting S2− ions in aqueous media in the presence of other interfering anions through a cation displacement process.

An efficient protocol for the synthesis of 4H-chromene derivatives via a one-pot multicomponent reaction was developed using a self-assembled catalyst system. The self-assembling nature of the fabricated catalyst is unique, consisting of carbon-quantum dots (CQDs) and ionic liquids (ILs). At the critical micelle concentration (CMC), the ILs organize themselves as micelles and the CQDs are trapped inside, forming a CQD-colloidal reaction system (CRS). The reactions of naphthols with aromatic aldehydes and malononitrile in the CQD-CRS system gave excellent yields of 4H-chromene derivatives at room temperature in 15 min upon sonication. The present method provides a high EcoScale score and a low E-factor, validating the greenness of the procedure. The self-aggregating nature of the catalyst is highly advantageous as it can be recycled and reused provided the CMC is maintained. To the best of our knowledge, this is the first example of a self-assembled CQD-based catalyst in aqueous media. CQD-CRS can be considered a designer’s catalyst, as by changing the ILs/CQDs components, multiple variants could be produced under different solvent conditions.

Reaction of 2-formylbenzoates with hexamethyldisilazane and diethyl phosphite in the presence of Yb(OTf) 3 proceeded smoothly at room temperature to afford addition adducts, which were readily cyclized to 3-phosphonate phthalides by adding trifluoroacetic acid (TFA). The reactions employing Sc(OTf) 3 instead of Yb(OTf) 3 produced 3-phosphonate isoindolinones without addition of TFA.

We synthetized a sulfonamide-based dipodal receptor capable of recognizing Ag + selectively in water in the presence of other possible competing cations through color change. The resultant Ag-complex showed suitability as a chemosensor for the sensing of I − ions in water in the presence of other anions through a cation displacement process. The detection limits of the receptor for Ag + and of the resultant complex for I − were identified as 2.43 and 5.31 μM, respectively.

Modified ZnO NPs were synthesized through a sol–gel route with an aromatic capping agent to provide a highly efficient catalyst, NS-5, for the one-pot multicomponent synthesis of various pyrimidine derivatives using a solvent-free ball milling technique. Greenness of the present method was evaluated by calculating an Ecoscale score and E-factor. Characteristics of the method include use of a recyclable catalyst, scale-up to a multigram scale, and ease of product isolation.

A benzimidazole-based dipodal receptor was designed and synthesized. The receptor recognized Cu2+ ions selectively in an aqueous medium in the presence of other metal ions. The resultant complex displayed selective sensing ability toward H2PO4− via a metal displacement process. The detection limits of the receptor to Cu2+, and the resultant complex to H2PO4−, were calculated to be 9.76 and 1.41 μM, respectively. These values are sufficiently low indicating that this system shows good potential for application in biological and environmental sample analyses.

A benzothiazole-based receptor conjugated with an imidazolium cation, receptor N1, was synthesized. Receptor N1 is capable of selectively binding Hg(II) in the presence of other metal ions in water, with a large enhancement in fluorescence intensity at 380 nm via a PET mechanism. The resulting Hg(II) complex of receptor N1 showed a selective ratiometric response upon addition of Br− ions. The Hg(II) complex of receptor N1 was used to determine the concentration of Br− ions in the presence of other anions, with a detection limit of 22 nM. 1H NMR studies showed that the imidazolium hydrogen in the Hg(II) complex of receptor N1 participates in the recognition of Br− ions. In the absence of Hg(II), receptor N1 did not recognize Br− ions.

Herein, radical addition to the C N bond in hydrazone derivatives of α-ketoesters under “on-water” conditions has been described. The present method provides a route to synthesize α,α-dialkyl α-amino esters, which are difficult to obtain using other methods because of their intrinsically low activity. The radical addition reaction is more efficient when performed under “on-water” conditions than when performed in an organic solvent, showing the prominent solvent effect of water. In the present process, the (Z)-hydrazone derivatives of α-ketoesters show higher reactivity than their corresponding (E)-hydrazones. The process provides tin-free, green reaction conditions.

We synthesized a dinuclear Cu(II) paddle-wheel complex R1 containing a benzimidazolium ligand and explored using it as a fluorescence turn-ON sensor for detecting phosphates in water. The sensor exhibited both fluorescence and electrochemical responses to phosphates with high selectivity and sensitivity over other anions, which makes it useful for the detection of harmful organophosphates.

A direct reductive amination procedure for the efficient preparation of tertiary amines (II) under mild reaction conditions employing (Tms)2NH as nitrogen source is developed.

A solvent-free selective green synthesis of 1,2-disubstituted benzimidazoles was developed using a ball-milling technique. Recyclable ionic liquid-coated ZnO-nanoparticles (ZnO-NPs, catalyst 5) were employed as a catalyst, which produced high yields, turnover number and turnover frequency because of the synergetic catalytic properties of the ionic liquid and ZnO-NPs. The present method was successfully employed in the synthesis of various 1,2-disubstituted benzimidazole derivatives in excellent yields with high selectivity. The reaction could also be performed on a multi-gram scale with the same efficiency. A high eco-scale score and a low E-factor emphasize the ecofriendly nature of the present method.

A series of tricyclic dihydropyrimidine derivatives were synthesized using a one-pot, three-component Traube–Schwarz reaction in the presence of catalyst Zn(ClO4)2·6H2O. All the purified compounds were evaluated for their in vitro anticancer activity against three different cancer cell lines such as prostate cancer cells (PC3), lung cancer cells (NCI-H1299) and colon cancer cells (HCT116). In vitro DNA-intercalation ability of the compounds was investigated by UV–vis absorption spectroscopy, showing the insertion of compound into the DNA base pairs and a strong interaction with the DNA double helix.

Imidazole and imine-linked dipodal receptors were decorated on the surface of ZnO nanoparticles. Cation binding assays of these chemosensors showed that receptors 5 and 6 had high selectivity for Al(III) and Zn(II) ions, respectively. The detection limit for Al(III) with receptor 5 was 11 nM, and the detection limit for Zn(II) ion with receptor 6 was 23 nM.

A convenient solvent-free method for the synthesis of benzothiazole, benzimidazole, and benzoxazole derivatives has been developed using recyclable ZnO-NPs via a ball-milling strategy. The method affords environmentally friendly reaction conditions that score high on the ecoscale with the low E-factor. The process is also highly efficient even on a multi-gram scale and provides easy product isolation.

A simple and selective chemosensor, A, was developed for recognizing Cu2+. The emission spectra of receptor A showed a fluorescence quenching response upon addition of Cu2+ with a low detection limit of 4.51 nM, significantly less than the WHO recommended guideline for drinking water. In addition, the formed A∙Cu2+ complex was examined for secondary sensing of anions. The A∙Cu2+ complex showed selectivity for CN– via a recovering emission profile of A.

A benzimidazole-based Co3+ complex was synthesized and evaluated as a sensor for I− and HSO 4 - in aqueous media. The complex showed electrochemical changes with I− over other anions, whereas it had a ratiometric response to HSO 4 - with UV–visible spectroscopy even in the presence of other anions.

An azo dye-coupled benzimidazole-based receptor 1 was synthesized and investigated as a receptor for metal ions in semi-aqueous medium. The receptor recognizes Cu2+ with high selectivity over other metal ions. The resultant complex 1·Cu2+ was found to selectively bind oxalic acid via counter ion displacement.

A three-component reaction that involved a carbonyl compound, benzoylhydrazine, allyl bromide, and indium in the presence of readily available Zn(ClO4)2·6H2O was developed for the syntheses of secondary and tertiary homoallylic hydrazides. Excellent chemoselectivities and diastereoselectivies were observed. Aldehydes as well as acyclic and cyclic ketones were well-suited to the reaction conditions and provided secondary and tertiary homoallylic hydrazides in excellent yields.

A benzthiazole-based multifunctional chemosensor was designed with siderophores like binding sites for recognition of Fe3+ and both hydrogen bond donor and acceptor binding sites for oxyanion HSO 4 − . The sensor recognizes Fe3+ selectively through enhancement of fluorescence emission intensity at 440 nm and recognizes HSO 4 − through a bathochromic shift in UV–vis spectra from 315 nm to 365 nm with clear isosbestic points at 345 nm and 395 nm. The recognition of both Fe3+ and HSO 4 − is free from the interference from the other cations and anions, respectively.

A benzimidazole-based receptor that selectively recognized Cr3+ without interference from other metal ions was synthesized in this study. The resultant Cr-complex recognized HSO4− and F− via two approaches. HSO4− ions bound to the metal center, causing changes in the fluorescent spectra at different wavelengths, whereas F− ions displaced Cr3+, thereby switching ON the fluorescent spectra at the same wavelength.

An efficient method for the asymmetric synthesis of highly optically pure 2-substituted piperidines and 6-substituted piperidine-2-ones from aldehydes was developed by a sequence of enantioselective hydrazone allylation and ring closing metathesis. This method was found to be effective for a variety of substrates, showing substrate generality. The method's synthetic utility was illustrated in concise synthesis of the alkaloid (R)-(−)-coniine.

A new benzimidazole-based receptor was developed with potential functional groups for excited state proton transfer (ESPT) through keto–enol tautomerism. The enol form of the receptor selectively recognizes Zn2+, allowing it to be used as a ratiometric fluorescence sensor in DMSO/CH3CN (1:9, v/v). The binding event triggers a blue-shifted band through the modulation of charge transfer transitions. The sensor is applicable for recognizing Zn2+ in the cytoplasm of Saccharomyces cerevisiae.

A benzimidazole-based imine linked receptor was synthesized for fluorescent recognition of Cu 2+ in a CH 3 CN/H 2 O (8:2, v/v) solvent system. The receptor offers an opportunity for the selective estimation of Cu 2+ in the presence of another metal ion at equimolar concentration. The Cu 2+ complex with the receptor acted as a sensor for a phosphate anion, and the phosphate recognition event restored the fluorescence intensity of the receptor.

We synthesized an imine-linked, benzimidazole-based chemosensor that can be used for chromogenic recognition of Mg 2+ and fluorescent recognition of Cr 3+ . The chemosensor shows sensitive, selective, and ratiometric recognition of Cr 3+ through concurrent quenching at one wavelength and enhancement of fluorescence intensity at another wavelength. It can also be used to detect Mg 2+ via UV–vis absorption spectroscopy. DFT calculations support these phenomena. The sensor can be used to strain microbe cells without breakage.

A tripodal receptor bearing phenol as a hydrogen bond donor site and azo dye as the signaling subunit was synthesized. The receptor had a high binding affinity for CN− as signaled by the change in the color of a solution of sensor 4 upon addition of CN−. Using UV–Vis spectroscopy, the system can be used to quantify 0–19 × 10−5 mol L−1 of CN−, and the sensor was found to successfully function in the presence of other anions.

We synthesized a benzthiazole-based chemosensor with mixed S,N donor sites. The binding units are incorporated in a highly flexible tripodal framework which facilitates the complexation of the binding of larger-sized metals. The chemosensor resulted in the sensitive and selective recognition of Ba2+ through the enhancement of the fluorescence intensity when studied in a THF/H2O (8:2, v/v) solvent mixture. The sensor offers an interesting opportunity to monitor Ba2+ in biological samples including the cytoplasm of microbes such as Saccharomyces cerevisiae.

We synthesized a novel 1,3,5-substituted triethylbenzene derivative with a benzimidazole moiety as a binding and signalling subunit. The triethylbenzene platform was judiciously incorporated into the receptor design such that all the fluorophores are in close proximity to each other in order to facilitate stacking. The advantage of this approach lies in the fact that the receptor will offer a dual channel emission for the multiple ratiometric determination of metal ions. The sensor was tested in a CH 3 CN/H 2 O (7:3, v/v, pH 7.1) HEPES buffered solution and successfully developed for the ratiometric and simultaneous estimation of Fe 3+ and Cu 2+ ions in aqueous samples.

A novel 1,3,5-substituted triethylbenzene derivative with a 2-aminobenzimidazole moiety as a binding and signaling subunit was synthesized. The sensor was tested in a buffered CH(3)CN/H(2)O (99:1, v/v) solution and found to be selective for iodide as demonstrated by the photophysical properties obtained through UV-vis absorption and fluorescence spectroscopy analyses.

We synthesized a novel benzimidazole-based, anthracene-coupled fluorescent receptor capable of recognizing and estimating the concentrations of Fe3+ in semi-aqueous solution by ratiometric estimation. Our sensor can be made highly selective for Fe3+ over other metal ions by changing the solvent composition.

Various carboxylic acids were converted into acyl fluorides in excellent yields by treatment with trichloroacetonitrile, triphenylphosphine, and TBAF(t-BuOH) 4 at room temperature. The reaction was applicable to the preparation of acid-sensitive amino acid fluorides without deprotection or rearrangement.

We synthesized a novel receptor with a unique combination of sp2 nitrogen (–CH N–) and carbonyl groups from amide linkages. These two moieties are judiciously incorporated into the receptor design such that these sites simultaneous binding a metal ion may generate a stable five-member ring. The receptor has been used to selectively detect Zn2+ through changes in the fluorescence spectra. Upon Zn2+ binding with the receptor, the fluorescence band shifted to enhance fluorescence intensity, allowing ratiometric determination of Zn2+ concentration.

We developed a simple, practical, and catalytic method for the N-formylation of a wide variety of amines in the presence of molecular iodine as a catalyst under solvent-free conditions. This reaction is applicable to the chemoselective N-formylation of amino groups and α-amino acid esters without epimerization.

A novel receptor, designed with a combination of oxygen and nitrogen-binding sites for metal ions and hydrogen bond donor sites for anion binding, was synthesized. The receptor has been explored for the selective detection of I− against a range of physiologically relevant anions and cations through changes in its UV–vis spectra. On the other hand, receptor-binding selectivity for Fe3+ over a wide linear concentration range was observed through changes in the emission spectra. This is the first Letter of a sensor capable of detecting both I− and Fe3+ using two different detection modes.

We have developed a simple, mild method for N-formylation of a wide variety of amines in the presence of indium metal as a catalyst under solvent-free conditions. This reaction is applicable to the chemoselective N-formylation of amino groups and α-amino acid esters without epimerization.

We synthesized a novel fluorescent receptor based upon a benzimidazole moiety in a dipodal framework. The receptor exhibited a dual fluorescence emission which is quenched upon addition of Cu 2+ or Fe 3+ . Interestingly, the receptor offers a ratiometric property and an ‘OR’ logic gate property to Cu 2+ and Fe 3+ .

We developed a simple, efficient, and selective method for preparing organic carbamates and carbonates using a catalytic amount of indium. A wide range of carbamates and carbonates were synthesized in high yields. The method is also applicable to the selective protection of amino groups under mild conditions.

A convenient and efficient method was developed for the synthesis of alkyl phenyl selenides, sulfides, and selenoesters in one-pot reaction by using indium metal. The reaction showed the selectivity for tert-alkyl, benzylic, and allylic halides over primary and secondary alkyl halides. For the reaction of primary and secondary alkyl iodides and bromides, the yields of selenides were improved by the addition of a catalytic amount of iodine.

A novel benzthiazole-based fluorescent receptor was synthesized, and its anion recognition properties were compared with those of similarly designed benzimidazole-based receptors. The selectivity of this receptor for the recognition of dihydrogen phosphate is enhanced by employing hydrogen bonding, in which cooperative polarization effect to the carbonyl group of amide linkages is lacking.

A Cu(II) complex of a tripodal receptor bearing an anthracene moiety on one pod as a fluorophore was synthesized. The anion recognition behavior of the Cu(II) complex was evaluated in CH3CN/H2O (95:5, v/v), resulting in an extremely high selectivity for iodide over other anions such as F−, Cl−, Br−, NO 3 - , CH3COO−, and H 2 PO 2 - . The Cu(II) complex acts as a selective probe for estimating iodide even in the presence of other anions without any interference.

Cl3CCONH2/PPh3 was a versatile reagent to convert carboxylic acids into their corresponding acid chlorides. This intermediate was clearly confirmed by spectroscopic methods (IR, 1H, 13C NMR). This one-pot reaction of in situ acid chloride generated with various alcohols successfully furnished the corresponding esters in moderate to excellent yields.

We synthesized a novel benzimidazole-based fluorescent receptor bearing imine linkages with two sets of sp 2 nitrogens, and investigated its binding properties toward various metal ions. The receptor exhibited a shift in emission band upon binding with Fe 3+ ions, and no such significant response was noticed in other metal ions. The receptor shows a property of selective ratiometric fluorescent probe of Fe 3+ ions without interferences of the background metal ions.

We synthesized a novel hybrid receptor bearing an array of hydrogen bond donors from benzimidazole and thiourea moieties. The recognition behavior of the receptor toward various anions has been evaluated in a DMSO/H2O (8:2, v/v) solvent system. The receptor showed changes in fluorescent intensity only with PO43-, and it showed no such significant response to any of the other anions such as F−, Cl−, Br−, I−, CN−, ClO4-, H2PO4-, HPO42-, AcO−, NO2-, CO32-, HCO3-, SO42-, and HSO4-. The receptor is highly selective in recognizing PO43-even in the presence of other anions in aqueous DMSO.

p-tert-Butylcalix[4]arene-based dipodal receptor has been synthesized in cone conformation. The binding affinity of this receptor was evaluated with some aliphatic diacetates such as malonate, succinate, glutarate, adipate, pimelate, and suberate in CH3CN. The receptor has the highest binding affinity for pimelate by making a 1:1 complex. This receptor was used to estimate pimelate in the presence of other dicarboxylates.

We have established the optimal conditions for the Wittig reaction for synthesizing α-bromoacrylates with a high selectivity, and developed a simple and efficient one-pot procedure for preparing various conjugated acetylenic carboxylates in moderate to high yields.

We investigated an imine-linked fluorescent receptor bearing both the hydrogen bond donor and the hydrogen bond acceptor motifs as recognition sites in the design of the receptor. The recognition behavior of the receptor toward various nucleobases was evaluated in CH 3 CN/H 2 O (95:5, v/v) solution. The receptor showed significant changes in fluorescent intensity with adenine, but it showed no such changes on the addition of other nucleobases.

A novel fluorescent receptor bearing benzimidazole moieties as recognition sites was synthesized. The recognition behaviour of the receptor towards various anions has been evaluated in CH3CN. The receptor showed ratiometric fluorescent changes only with CH3COO−, and it showed no significant response to any of other anions such as Cl−, Br−, I−, HSO 4 - , NO 3 - , C6H5COO− and H 2 PO 4 - .