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A monoprotected amino acid Bz-Gly-OH assists in the allylic alkylation of a variety of ketones, β-keto esters, aldehydes, etc., during enamine-palladium catalysis. Density functional theory calculations reveal that Bz-Gly-OH assists in the formation of an enamine that attacks the π-allylpalladium complex via an outer sphere mechanism. The preliminary result points to an asymmetric allylic alkylation under a new mode of bifunctional catalysis.

The growth in industrialization worldwide has resulted in continual discharge of organic dyes that contaminate the aquatic ecosystem. Common adsorbents employed for dye removal are often expensive ...

Controlling the product selectivity of a ring-opening hydrolysis reaction remains a great challenge with mineral acids and to an extent with homogeneous catalysts. In addition, even trace amounts of metal impurities in a bioactive product hinder the reaction progress. This has necessitated the development of robust and metal-free catalysts to offer an alternative sustainable route. We report a nitrogen-rich sulfonated carbon as a catalyst derived from an inexpensive precursor for the synthesis of bioactive vicinal diols of spiro-oxindole derivatives. The well-characterized catalyst shows wide generality with different electronic and steric substituents in the substrates under mild reaction conditions. Hot filtration test confirms no leaching of the acid moiety and the catalyst could be reused for four cycles with retention of activities.

An unambiguous and precise method for the synthesis of 3,1-benzoxathiin-4-ones/1,3-benzodioxin-4-ones by the reaction of propargylic alcohols and salicylic/thiosalicylic acids under a catalyst-free and open-air atmosphere is described. This strategy is found to be quite general using various 2-mercapto and 2-hydroxybenzoic acids providing benzoxathiinones/benzodioxinones in good yields.

The facile transformation of the functionalized spiro-cyclopentanones obtained by N-heterocyclic carbenes (NHC) catalyzed homoenolate annulation strategy, leading to the synthesis of indole embedded compounds is described.

The development of high-efficiency and durable bifunctional electrocatalysts is an important and challenging topic in the area of energy storage/conversion. Herein, we prepared metallic cobalt nanoparticle decorated N-doped graphitic sheets (Co@NGr) by adopting facile pyrolysis of a mixed ligand cobalt-based MOF (CoMOF-2) as a sacrificial template displaying good OER and HER activity. The catalytic material harvested at three different pyrolytic temperatures was characterized by various analytical methods such as PXRD, SEM, TEM, Raman, and XPS analyses. The catalytic activity of the obtained hybrid composite materials towards oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) was studied. Co@NGr-900 was found to be an efficient bifunctional electrocatalyst and 10 mA cm−2 current density was afforded at an overpotential of 390 mV for OER and 340 mV for HER respectively. This study provides insight for the development of cost-effective nonprecious element-based electrocatalysts for water splitting which has relevance in energy storage and conversion. Catalytic performance is governed by the synergistic compositional effect of metallic cobalt/nitrogen-doping in the graphitic carbon increasing the electrical conductivity/active sites of the composite material.

Two mixed ligand MOFs, {[Zn2(5NO2-IP)2(L)2](H2O)}n (ADES-1) and {[Cd2(5NO2-IP)2(L)2(H2O)4](L)(H2O)(CH3OH)6}n (ADES-2) (where 5NO2-IP = 5-nitroisophthalate and L = (E)-N′-(pyridin-3-ylmethylene)nicotinohydrazide), have been synthesized and characterized via various analytical methods, including SXRD analysis. SXRD analysis revealed that both MOFs adopt an identical two-dimensional network topology. ADES-1 with bulk phase purity has been synthesized via a conventional reflux method and its potential applications as a functional material for reversible dye adsorption and as an efficient heterogeneous catalyst for the Biginelli reaction were exploited. ADES-1 exhibited the rapid and efficient adsorption of both cationic and anionic dye molecules with a slight preference for methyl violet (86%) compared to the other dyes that were investigated. A separation study involving a mixture of dyes and the application of ADES-1 as a column filler for the separation of organic dyes from water are also demonstrated. Moreover, the catalytic performance of ADES-1 towards a multi-component Biginelli reaction to yield 3,4-dihydropyrimidin-2(1H)-ones (DHPM) derivative has been studied. Finally, studies of the utilization of ADES-1 for dye adsorption and its catalytic activity revealed good stability and reusability, enabling it to be a potential functional material, and possible dye adsorption and Biginelli reaction mechanisms are also proposed.

A series of non-heme μ-oxo-bridged dinuclear iron(III) complexes of the type [Fe2(μ-O)(L1–L6)2Cl2]Cl2 1–6 have been isolated and their catalytic activity towards oxidative transformation of alkanes into alcohols has been studied using m-choloroperbenzoic acid (m-CPBA) as an oxidant. All the complexes were characterized by CHN, electrochemical, and UV-visible spectroscopic techniques. The molecular structures of 2 and 5 have been determined successfully by single crystal X-ray diffraction analysis and both possesses octahedral coordination geometry and each iron atom is coordinated by four nitrogen atoms of the 4N ligand and a bridging oxygen. The sixth position of each octahedron is coordinated by a chloride ion. The (μ-oxo)diiron(III) core is linear in 2 (Fe–O–Fe, 180.0°), whereas it is non-linear (Fe–O–Fe, 161°) in 5. All the diiron(III) complexes show quasi-reversible one electron transfer in the cyclic voltammagram and catalyze the hydroxylation of alkanes like cyclohexane, adamantane with m-CPBA as an oxidant. In acetonitrile solution, adding excess m-CPBA to the diiron(III) complex 2 without chloride ions leads to intramolecular hydroxylation reaction of the oxidant. Interestingly, 2 catalyzes alkane hydroxylation in the presence of chloride ions, but intramolecular hydroxylation in the absence of chloride ions. The observed selectivity for cyclohexane (A/K, 5–7) and adamantane (3°/2°, 9–18) suggests the involvement of high-valent iron–oxo species rather than freely diffusing radicals in the catalytic reaction. Moreover, 4 oxidizes (A/K, 7) cyclohexane very efficiently up to 513 TON while 5 oxidizes adamantane with good selectivity (3°/2°, 18) using m-CPBA as an oxidant. The electronic effects of ligand donors dictate the efficiency and selectivity of catalytic hydroxylation of alkanes.

A unique α-amination approach using various anilines has been developed for arylacetic acids via adaptation as benzazoles. The reaction proceeds through a single electron transfer mechanism utilizing an iron-based catalyst system to access α-(N-arylamino)acetic acid equivalents. Modification of approved drugs, facile cleavage of the benzazole auxiliary, and tolerance of amide linkage forming conditions constitute the potential applicability of this strategy.

The construction of sophisticated molecular architectures from chemical subunits requires careful selection of the spacers, precise synthetic strategies, and substantial efforts. Here, we report a series of binuclear double-stranded helicates synthesized from different combinations of pyridyl hydrazone-based multidentate ligands (H21, H22, H23) by increasing the methylene spacer and transition metals (Co, Ni, and Zn). The ligands H21 (N′1,N′3-bis((E)-pyridin-2-ylmethylene)malonohydrazide), H22 (N′1,N′4-bis((E)-pyridin-2-ylmethylene)succinohydrazide), and H23 (N′1,N′5-bis((E)-pyridin-2-ylmethylene)glutarohydrazide) and their respective complexes with Co, Ni, and Zn were obtained. Single-crystal X-ray diffraction studies of these binuclear metallohelicates confirm the double-stranded helical structure of the complexes derived from H22. The set of helicates Co-1, Co-2, and Co-3; Ni-1, Ni-2, and Ni-3; and Zn-1, Zn-2, and Zn-3 were investigated for its catalytic activity in the cyclic carbonate formation reaction. Intriguingly, among the synthesized catalyst, Co-1 was found to be better in terms of conversions with the calculated TOF (turnover frequency) of 128/h. The catalytic performance was significantly improved by adding 0.2 mmol of tetrabutylammonium bromide by achieving 76% conversion in 30 min, with the observed TOF of 15,934 h–1/molecule and 7967 h–1/Co center. The results obtained herein show that the double-stranded helicates are effective catalysts for converting both terminal and non-terminal epoxides into their corresponding cyclic carbonates. The striking feature of this catalytic protocol lies in demonstrating the catalytic activity for the conversion of diol to cyclic carbonate, and the detailed kinetic experiments tempted us to propose a tentative reaction mechanism for this conversion.

Environmental remediation, particularly in the context of water pollution, has been at the centre of a range of research domains over the past few decades. Metal organic frameworks (MOFs) or coordination polymers (CPs) are a relatively new class of infinite materials comprising metal nodes and linkers as repeat units. Exclusive merits of these materials such as tuneable porosity, and physical and chemical properties reflect in their extensive applications in fields such as sensing, adsorption, separation, catalysis, etc. In the present study, we evaluate the application of Zn(II)/Cd(II) based mixed ligand luminescent MOFs/CPs towards addressing the concerns related to water pollution. Firstly, the origin of photoluminescence in MOFs/CPs is discussed, which underlines the merits of Zn(II) and Cd(II) metal ions, mixed linker systems as well as the delicate host–guest interactions between the framework and analyte. The hydrolytic and chemical stability of the luminescent MOFs/CPs is prerequisite for their in-field sensing applications, which are critically studied in the context of Cd(II)/Zn(II) and mixed linker based luminescent MOFs/CPs. Subsequent sections separately underscore the important studies on sensing of organic pollutants viz., nitroaromatics, acetone, acetylacetone and paraquat as well as inorganic pollutants including di- and trivalent metal cations viz, Hg2+, Cu2+, Pb2+, Pd2+, Al3+, Fe3+ and Cr3+; and inorganic anions such as cyanide, iodide, chromate, dichromate, manganate etc. Efforts to develop paper strip based versatile sensors for noxious ions are also highlighted.

The synthesis and characterization of a mixed ligand metal–organic framework (MOF) with good thermal and chemical stability, {[Co(BDC)(L)·2H2O]·xG}n (CoMOF-2), involving an aromatic dicarboxylate (H2BDC = 1,4-benzenedicarboxylic acid) and an acyl-decorated N-donor linker [L = (E)-N′-(pyridin-4-ylmethylene) isonicotinohydrazide] by various physicochemical techniques, including Single crystal X-Ray Diffraction (SXRD), are reported. The MOF showed a good affinity for CO2 capture, and Grand Canonical Monte Carlo simulation studies exposed strong interactions of CO2 with the functionalized N-donor ligand of the framework. CoMOF-2 and KI act as an efficient binary catalyst for the sustainable utilization of CO2 with spiro-epoxy oxindole to spirocyclic carbonate under ambient conditions. Notably, herein we report MOF-based catalysis for the cycloaddition of oxindole-based epoxides with CO2 for harvesting new spirocyclic carbonates. Interestingly, we could isolate and crystallize six of the spirocyclic carbonate ...

An efficient photocatalytic method was developed for the remote C5-H bond carboxylation of 8-aminoquinoline amide and sulfonamide derivatives. This methodology uses in situ generated •CBr3 radical as a carboxylation agent with alcohol and is further extended to a variety of arenes and heteroarenes to synthesize the desired carboxylated product in moderate-to-good yields. The reaction proceeding through a single electron transfer pathway was established by a control experiment, and a butylated hydroxytoluene-trapped aryl radical cation intermediate in high-resolution mass spectrometry was identified.

The ligand L1 of 4-methyl-2,6-diformylphenol and L2 of 4-tert-butyl-2,6-diformylphenol are synthesized through Schiff base condensation with rac-, (R)-(+), or (S)-(−)-1,1′-binaphthyl-2,2′-diamine (...

Synthesis of 2,6-disubstituted pyridines from pyridotriazoles through palladium-catalyzed aerobic oxidative denitrogenative reactions has been described. Denitrogenation of arylated pyridotriazoles generates metal-carbene intermediates in situ and provides selectively 6-aryl-2-benzoylpyridines. The same conditions have been extended to regioselective C-3 and C-8 diarylation of several imidazo[1,2-a]pyridines.

A mixed ligand three-dimensional neutral porous framework, {[Co(OBA)(L)]xG}n (CoMOF-1) (H2OBA = 4,4′-oxybis(benzoic acid); L = (E)-N′-(pyridin-4-ylmethylene)isonicotinohydrazide; G = DMF, EtOH, MeOH, H2O), was successfully synthesized via a hydrothermal and reflux method. The activated MOF (CoMOF-1′) not only showed good affinity toward CO2 molecules, but also exhibited a good catalytic performance for CO2 conversion with a variety of terminal and internal epoxides. Grand Canonical Monte Carlo (GCMC) simulation proved the strong interactions of CO2 molecules with the amide functional groups of the MOF. The Lewis acidity of the Co(II) centers endowed by the weakly chelated carboxylate from the OBA ligand and Lewis basicity originating from the acylamide functionality of the pyridyl-based Schiff base ligand L favored the efficient solvent-free cycloaddition reaction of CO2 with different epoxides. Strikingly, CoMOF-1′ exhibited good catalytic efficiency for CO2 coupled with various terminal epoxides at ambient temperature and pressure (1 bar, 60 °C, 12 h) and with a variety of internal epoxides at moderate reaction conditions (30 bar, 100 °C, and 8 h) with good yield and recyclability. Further, the binary heterogeneous catalyst showed good chemical stability, easy separation and recyclability (6 cycles) without a noticeable decrease in activity. To the best of our knowledge, this is the first investigation on a neutral porous MOF as a potential heterogeneous solvent-free catalyst toward CO2 utilization for internal epoxide under moderate reaction conditions. Based on the structural evidence, a plausible mechanism for the cycloaddition reaction was proposed, which is further reinforced by the relative energy of each stage obtained from periodic Density Functional Theory (DFT) calculations.

A series of mononuclear copper(II) complexes of the type [Cu(L)Cl2] 1–6, where L is a tridentate 3 N ligand such as N-methyl-N′-(pyrid-2-ylmethyl)ethylenediamine (L1), N-ethyl-N′-(pyrid-2-ylmethyl)ethylenediamine (L2), N-phenyl-N′-(pyrid-2-ylmethyl)ethylenediamine (L3), N,N-dimethyl-N′-(pyrid-2-ylmethyl)ethylenediamine (L4), N,N-diethyl-N′-(pyrid-2-ylmethyl)-ethylenediamine (L5) and N-methyl-N′-(pyridin-2-ylmethyl)benzene-1,2-diamine (L6), has been isolated and studied as functional models for catechol oxidase enzymes in different aqueous micellar media. The X-ray crystal structures of 2 and 5 contain a CuN3Cl2 chromophore with a trigonal bipyramidal based coordination geometry. Interestingly, all the complexes form cationic [Cu(L)(DBC)(H2O)]+ adduct species in which DBC2− acts as a monodentate ligand, and the adduct species interacts strongly with anionic SDS micelles. The rates of the oxygenase reaction follow the trend SDS > TX-100 ∼ water > CTAB, revealing that the rate of the reaction in micellar media are higher than those in aqueous solution and that the nature of biomimetic microenvironments of the micellized copper(II) catalyst and also the ligand stereoelectronic factors like donor atom basicity and steric bulk of ligand N-alkyl substituents, determine the catecholase-like activity.

A series of non-heme μ-oxo-bridged dinuclear iron(iii) complexes of the type [Fe

Water is vital for the sustenance of all forms of life. Hence, water pollution is a universal crisis for the survival for all forms of life and a hurdle in sustainable development. Textile industry is one of the anthropogenic activities that severely pollutes water bodies. Inefficient dyeing processes result in thousands of tons of synthetic dyes being dumped in water bodies every year. Therefore, the efficient removal of synthetic dyes from wastewater has become a challenging research field. Owing to their tuneable structure–property aspects, metal–organic frameworks (MOFs) have emerged as promising adsorbents for the adsorptive removal of dyes from wastewater and textile effluents. In this perspective, we highlight recent studies involving the application of MOFs for the adsorptive removal of hazardous dye molecules. We also classify the developed MOFs into cationic, anionic, and neutral framework categories to comprehend their suitability for the removal of a given class of dyes.

An atom-economical and efficient route for the direct amidation and amination of aryl C-H bonds using our synthesized recyclable heterogeneous Cu-MnO catalyst is reported here. The direct C-H amidation was carried out using a simple amide without any preactivated coupling partner, and simple air was used as the sole oxidant. The reaction proceeds very smoothly with a broad range of substrates containing numerous functional groups in very good to excellent yields. Direct C-H aminations with a secondary amine were carried out under base-, ligand-, and external oxidant-free conditions in very good to excellent yields in very mild conditions. Both the amidation and amination can be scaled up on a gram scale with similar yields. The major advantage is that our catalyst is recyclable and reused several times without any significant loss of reactivity.

Base assisted divergent reactivity of isatins and allenoates has been achieved, which afforded diastereoselective spirofuran oxindoles and γ-functionalized allenoates. The DBU mediated Morita–Baylis–Hillman (MBH) reaction followed by the cascade annulation through the stabilized β-ammonium enolate intermediate led to the spiro-framework, wherein DABCO furnished the γ-functionalized allenoates. The protocol offers access to biologically relevant functionalized oxindole scaffolds with an excellent substrate scope under mild reaction conditions.

Crystalline two-dimensional organic nanosheets (2D-ONs) having atomic or near-atomic thickness with infinite lateral dimensions are of crucial significance for their possible application as a material for energy storage. The presence of nanofluidic channels with a designed array of molecular interlayers in such 2D-ONs, for a favorable lithium-ion transport, has special significance for improving the efficacy of lithium-ion batteries. However, the rational design of crystalline 2D-ONs remains a challenge because of the lack of appropriate monomers and convenient preparation methods. Herein, we report a unique lithium-ion conducting behavior of zwitterionic 2D-ONs, formed through self-assembly of a small organic molecule AM-1. Different microscopic studies confirm the near-atomic thickness (∼3.5 nm) of these 2D-ONs. Results of the single-crystal X-ray diffraction studies confirm the presence of a one-dimensional (1D) channel in crystalline 2D-ONs, which was generated during the self-assembly process of the zwitterionic monomer scaffold. The presence of immobilized ionic centers with well-defined directional channels in the 2D-ONs favors the transportation of lithium ions with a room-temperature lithium-ion conductivity of 5.14 × 10-5 S cm-1, which is rather unique for self-assembled 2D-ONs.

Two new entangled Cu­(II)-based metal–organic frameworks (MOFs) have been synthesized, namely [Cu­(BDC)­(BPDB)0.5]n (PNU-25) and [Cu­(NH2-BDC)­(BPDB)0.5]n (PNU-25-NH2), using a H2O–MeOH solvent mixture. Both the PNU-25 and PNU-25-NH2 MOF materials were characterized by various analytical techniques, and their potential for catalyzing CO2 fixation into cyclic carbonates at an atmospheric pressure, at a low reaction temperature, and in the neat conditions was demonstrated. The amine-functionalized PNU-25-NH2 exhibited a significantly high conversion of epichloro­hydrin (ECH) at 1 bar of CO2 pressure, at 55 °C, and with a moderate catalyst amount (1 mol%), with over 99% selectivity toward the corresponding cyclic carbonate of ECH. The superior catalytic activity of PNU-25-NH2 may be attributed to its high amount of acidic–basic sites and large BET surface area in comparison with the PNU-25. The PNU-25-NH2 catalyst could be reused up to four cycles without compromising its structural integrity and the ECH conversion. The reaction mechanism of the CO2 and ECH cycloaddition reaction mediated by PNU-25-NH2 was investigated in detail, based on the experimental inferences and periodic calculations of density functional theory (DFT). The energy barrier of the rate-determining step of the PNU-25-NH2/TBAB-catalyzed reaction was significantly lower than the barriers of the rate-determining steps of non-catalyzed and TBAB-catalyzed reactions.

Two-dimensional ZnII /CdII -based dual ligand metal-organic frameworks (MOFs) {[M(CHDC)(L)]⋅H2 O}n involving 4-pyridyl carboxaldehyde isonicotinoylhydrazone (L) in combination with flexible 1,4-cyclohexanedicarboxylic acid (H2 CHDC) as linkers have been synthesized by adaptable synthetic protocols including a green mechanochemical (grinding) method. Characterization, chemical/thermal stability, phase purity, and solid-state luminescent properties of both MOFs have been established by various analytical methods. Structural analysis revealed dimeric metal clusters composed of [M2 (CHDC)2 ]n loops doubly pillared with L, generating a 2D framework. Both MOFs can be used as highly active solvent-free binary catalysts for CO2 cycloaddition with epoxides in the presence of the co-catalyst tetrabutylammonium bromide (TBAB) with good catalytic conversion in up to six catalytic cycles without significant loss of activity. The present investigation demonstrates the application of MOFs as efficient heterogeneous catalysts for CO2 utilization under moderate reaction conditions. Based on the single-crystal X-ray data, a probable mechanism for the cycloaddition reaction has also been proposed.

Three previously undescribed dihydro-β-agarofuran sesquiterpenoids (1–3) along with eight known sesquiterpenoids (4–11) were isolated from the seeds of C. paniculatus. The structures of these compounds were determined on the basis of UV, IR, HR-MS (ESI), 1D and 2D NMR data obtained, and their absolute configurations were further confirmed by single-crystal X-ray diffraction. All these compounds were evaluated for their α-glucosidase and α-amylase inhibition, and antiglycation properties. Compounds 1, 3, 4, 5, 7 and 11 showed good α-glucosidase inhibition with IC50 values, 39.56 ± 0.761, 35.60 ± 0.843, 36.54 ± 0.173, 44.83 ± 0.453, 42.58 ± 0.209 and 45.84 ± 0.356 μM respectively. Molecular docking studies revealed that these compounds bind effectively to the active sites of the protein 3A4A, which supports the observed α-glucosidase inhibitory activity.

1,2,4-Trisubstituted-(1H)-imidazoles have been synthesized by the Cu(OTf)2- and I2-catalyzed unusual C–C bond cleavage of chalcones and benzylamines. After the α,β-unsaturated C–C bond cleavage, the β-portion is eliminated from the reaction. Various aryl- and heteroaryl-substituted chalcones and benzylamines were well tolerated in this unusual transformation to yield the trisubstituted-(1H)-imidazoles.

A series of intramolecularly hydrogen-bonded zwitterionic compartmental ligands HL1-HL4, containing a pendent diamine arm that is monoprotonated and an aldehyde functionality at two different ortho-positions of a 4-halophenoxide, is reported herein. Single-crystal X-ray diffraction (SXRD) provides persuasive evidence for the identification of this class of proton-transferred zwitterions at room temperature. The solid-state photoluminescent nature of these zwitterions remains intact in aqueous and organic solutions. Grinding of HL1 and HL2 with Cu2+ /Ni2+ salts develop turn-on probes 1-4. Compounds 1 and 4 are dinuclear CuII and NiII species, respectively. Compound 2 is a tetranuclear CuII complex. Interestingly, compound 3 is a mononuclear NiII species in which both nitrogen atoms in the pendant diamine arm are protonated and, therefore, not coordinated to the NiII center. All these probes (1-4) display an instant response to the poison gas hydrogen cyanide (HCN) and cyanide salts present in both solid matrices and aqueous (100 % water) solution. Selective and rapid sensing of HCN gas and cyanide salts in solid/soil/water phases, without any interference, by the mechanosynthesized complexes 1-4 can be perceived easily by the naked eye under a hand-held UV lamp.

Sensing and adsorption of hazardous and explosive nitroaromatic compounds using metal–organic frameworks (MOFs) have been a promising research field in the current scenario due to environmental concerns and homeland security. Here, we report two mixed ligand MOFs {[Co2(SDB)2(TIB)(H2O)](H2O)(1,4-dioxane)2}n (CP1) and {[Cd3(SDB)3(TIB)](H2O)2(1,4-dioxane)(G)x}n (CP2) (where SDB = 4,4′-sulfonyldibenzoate, TIB = 1,3,5-tris(imidazol-1-ylmethyl) benzene, and G = guest solvent molecules) synthesized by a hydrothermal method and the application of CP2 as an adsorbent and sensing material for 2,4,6-trinitrophenol (TNP). Both MOFs are characterized by various physicochemical techniques including single crystal X-ray analysis, and the crystal structures of CP1 and CP2 revealed that both MOFs are 3D frameworks composed of trimeric metal clusters linked by SDB ligand further coordinated through the imidazole nitrogen of the TIB moiety. Taking advantage of d10 transition metal present in the case of CP2, the recognition...

Dye capture and separation through coordination polymers (CPs) has been a promising research field in recent times due to the toxic and nondegradable nature of organic dyes released into the environment from various industries as well as the reusability of CPs for the said purpose. Here, we report the synthesis and characterization of two mixed ligand CPs {[Zn2(HBTC)2(L)(H2O)2](C2H5OH)3}n (CP1) and {[Zn5(BTC)2(L)3(OH)4(H2O)2](H2O)4(CH3OH)11}n (CP2) (where H3BTC = 1,3,5-benzene tricarboxylic acid and L = 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene) by the stoichiometric variation of the precursors. The crystal structure analysis revealed that CP1 is a 2D network composed of a [Zn2(HBTC)2(H2O)2]n motif linked via terminal nitrogen atoms of L and CP2 is a 3D framework in which symmetrically disposed two-dimensional {[Zn5(BTC)2(L)3(OH)4(H2O)2]}n sheets composed of pentanuclear [Zn5(RCO2)6(μ3-OH)2(μ2-OH)2(H2O)2] SBUs are pillared by L ligands. Adsorption and separation of cationic dyes by CP1 and the solid-state fluorescence properties of both CPs have been investigated. Cationic dyes (RhB, MB, and MV) can be effectively adsorbed by CP1 from their aqueous solution (61%, 90%, and 97%, respectively) while the anionic dye methyl orange (MO) remains uncaptured. Dye desorption studies and CP1 as a column chromatographic filler for the separation of cationic dyes in water have also been demonstrated.

Herein, a zinc(ii)-based 3D mixed ligand metal organic framework (MOF) was synthesized via versatile routes including green mechanochemical synthesis. The MOF {[Zn(ATA)(L)·H2O]}n (ZnMOF-1-NH2) has been characterized by various physico-chemical techniques, including SCXRD, and composed of the bipyridyl-based Schiff base (E)-N'-(pyridin-4-ylmethylene)isonicotinohydrazide (L) and 2-aminoterephthalic acid (H2ATA) ligands as linkers. The MOF material has been explored as a multifunctional heterogeneous catalyst for the cycloaddition of alkyl and aryl epoxides with CO2 and sulfoxidation reactions of aryl sulfides. The influence of various reaction parameters is examined to optimize the performance of the catalytic reactions. It is found that solvent-free catalytic reaction conditions offer good catalytic conversion in the case of cyclic carbonates, and for sulfoxide, good conversion and selectivity are achieved in the presence of DCM as a solvent medium under ambient reaction conditions. The chemical and thermal stability of the catalyst are excellent and it is active for up to four catalytic cycles without significant loss in activity. Furthermore, based on the catalytic activity and structural evidence, a plausible mechanism for both catalytic reactions is proposed.

The BF3·Et2O catalyzed reaction of nitrosobenzenes and an excess amount of propargylic alcohols was investigated to synthesize highly-substituted indole-3-carbinols. This reaction involves formal [3 + 2]-cycloaddition and the subsequent 1,3-rearrangement in a tandem manner via 3-alkylidene-3H-indole N-oxides. This methodology involves the sequential addition of propargylic alcohols and inexpensive Lewis acid catalyst, occurs in an open-air environment and is atom economical. The highly-substituted indole-3-carbinols were obtained in short time and the operational simplicity allows for a large scale experiment.

Dual ligand MOFs {[Zn(ADA)(L)]·2H2O}n (1) and {[Cd(ADA)(L)]·2H2O}n (2) involving Zn(II)/Cd(II) metal centres and flexible 1,3-adamantanediacetic acid (H2ADA)/pyridyl based Schiff base ligand, 4-pyridylcarboxaldehydeisonicotinoylhydrazone (L) as linkers have been efficiently synthesized including green mechanochemical methods and characterised using various analytical methods. Crystal structures of both MOFs, and luminescence and semiconducting properties have also been investigated. Both materials were exploited for efficient catalytic activity in the Knoevenagel condensation reaction for a variety of substrates with good yields and recyclability under ambient reaction conditions in aqueous media. Probably the Lewis acidic metal centre and the presence of amide functionality in the L of the MOFs are cooperatively involved in the efficient condensation reaction by these catalytic materials.

Light-emitting materials are of significant interest owing to their potential applications in electroluminescent devices/displays and sensors. Herein, light-emitting metallogel systems are developed using self-assembled Ln(III)-complexes (Ln(III) = Eu(III) and Tb(III)) of 4′-p-fluorophenyl-2,2′:6′,2′′-terpyridine (L-F) and 4′-p-chlorophenyl-2,2′:6′,2′′-terpyridine (L-Cl) ligands. The luminescence of these metallogels could be tuned over a wide spectrum. Near-white light emission (CIE coordinates: (0.31, 0.36) and (0.34, 0.36)) was achieved by controlling the [L-X] (X = F, Cl)/[Eu(III)]/[Tb(III)] stoichiometry. Adopting an alternate strategy, near white light emission was also achieved using metallogels derived from Eu·L-F-Ir (CIE coordinates: 0.28, 0.35) and Eu·L-Cl-Ir (CIE coordinates: 0.31, 0.35). For this, a blue emissive [IrIII(F2ppy)2(biimid)]PF6 complex was used along with Eu(III)-terpyridine gel systems (red emissive component). Eu·L-F, Tb·L-F and Eu·L-F-Ir (1 wt%) could also be incorporated into a poly(methyl methacrylate) (PMMA) polymer matrix for developing transparent red, green and white luminescent PMMA films with excellent UV-shielding properties. Being colourless to the naked eye and luminescent on exposure to UV-irradiation, such metallogels have the potential to be used as an invisible security ink. Moreover, the dynamic nature of Ln–N(terpyridine) coordination bonds was utilized for demonstrating the chemo/vapor-responsive behaviour of the lanthanide-based gel systems, which could offer a suitable pathway for future engineering of stimuli-responsive gel materials.

An unprecedented three component reaction involving arylidene oxazolone, enal and NHC, leading to the synthesis of fully substituted cyclopentanone derivatives with three contiguous stereocenters, is reported. This reaction illustrates the rare example of a multicomponent process involving NHCs, where the NHC-bound enolate is isolated by the interception of the NHC-homoenolate with arylidene oxazolone.

Mechanochemistry provides a fast, convenient, clean, and atomefficient route to one-pot two-step synthesis of a series of copper-specific turn-on chemosensors (L1–L5), directly from solid reactants and without bulk solvents. Comparison of powder XRD, FTIR-ATR, and SEM data with the solution-route prepared compounds indicated mechanosynthesis of pure receptors and the results are reproducible. Single crystal X-ray structure determination confirmed the identities of the mechanosynthesized ionophores (L1–L5). The probes with limit of detection in the range 8–0.1 μM behave reversibly and bind one equivalent of Cu2+ with association constants ranging 1 × 104–1.5 × 104 M−1. Excepting L5, the selective responses of other ionophores (L1–L4) toward Cu2+ altered considerably in presence of other ions. Superior sensory properties of L5 have also been utilized for selective “dip-in” recognition of Cu2+ in pure aqueous solution upon fabricating cellulose acetate bio-polymer with L5 yielding an optode (optical membrane). The L5-optode showed a naked eye observable colour change from faint peach to rosy pink (in visible light) and blue-pink to green (under UV lamp) on addition of 10 μM and 1 μM aqueous solutions of Cu2+, respectively.