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In this present work, we report the synthesis and structural characterization of a trinuclear Zn(II) complex [{ZnL(N3)}2Zn]·H2O (1), which was derived from a bi-compartmental (N2O4) Schiff base ligand (H2L), synthesized by the 1 : 2 condensation of 1,4-butanediamine and 3-ethoxysalicylaldehyde. The complex was characterized using elemental analysis, IR and UV-Vis spectroscopies, 1H-NMR and single crystal X-ray diffraction studies. The antimicrobial properties of the complex have been investigated. The growing incidence of microbial resistance to available pharmaceuticals has become a major global health concern. The rationale of the study is to evaluate the antibacterial and antibiofilm activities and probable mechanism of action of the novel trinuclear zinc(II) complex. The extent of antibacterial activity was evaluated using the minimal bactericidal concentration method. The anti-biofilm potential of the compound was evaluated using the crystal violet assay and fluorescence microscopy. Radioactively labeled N-acetyl glucosamine, leucine, thymidine, and uridine were used to evaluate the effect of the zinc compound on the cell wall, protein, DNA, and RNA biosynthesis. Our zinc complex showed potential antibacterial activity against most of the tested bacterial samples with a maximum sensitivity against Pseudomonas aeruginosa. The zinc compound dependent inhibition of DNA synthesis and biofilm formation was found in Pseudomonas aeruginosa. Considering the results, we are proposing our novel zinc compound as a promising candidate for the development of antibacterial drugs.

Biogas is one of the promising futuristic renewable energy sources with enormous market potential. However, the presence of CO2 lowers down the calorific value of biogas. Hence, various biogas upgradation technologies are under intense investigation to increase the methane content to the desired level. This study reports on enhancing methane content in biogas through CO2 sequestration into acetic acid via microbial electrosynthesis (MES) process. The previously enriched mixed chemolithoautotrophic microbial culture dominated by Acetobacterium spp. used CO2 present in the biogas as the sole carbon source. After establishing a stable performing biocathode at a fixed cathodic potential of −1 V (vs. Ag/AgCl) through batch mode operation, biogas was fed continuously at different feed rates, viz., 0.5, 0.3, and 0.2 ml/min to the cathode chamber. The highest feed rate of 0.5 ml/min was least effective both for methane content increment (from 61 ± 3% to 86 ± 2%) and acetic acid titer (1.5 ± 0.5 g/L; 0.107 ± 0.02 g/L/d.). In comparison, the lowest flow rate of 0.2 ml/min was the most effective for the intended process (methane upgradation from 62 ± 7% to 93 ± 3% and acetic acid titer 3.4 ± 0.6 g/L produced at 0.24 ± 0.04 g/L/d rate). Both acetic acid bioproduction and biogas upgradation occurred best at an Ecell of 3.3 ± 0.35 V at the low feed rate. A maximum of 84 ± 7%, 57 ± 10% and 29 ± 2% coulombic, carbon and energetic efficiencies, respectively, were achieved in acetic acid. Cyclic voltammograms of biocathodes revealed the decrease in hydrogen evolution potential and increased bioelectrocatalysis, thereby suggesting the contribution of microbes in the process. Acetobacterium, which is known for CO2 fixation, was found to be the dominant microbial genus in biogas fed reactors. The demonstrated approach not only offers the advantage of obtaining two products, one in the bulk phase and the other in the off-gas, it also validates the applicability of the bioelectrochemical biogas upgradation technology.

We report the use of a ditopic molecular probe bispentadecylphenol substituted perylenediimide (PBI–PDP) to examine the molecular level self-assembly of polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) in tetrahydrofuran (THF). A series of complexes were prepared between PS-b-P4VP copolymers with varying lengths of the 4-vinylpyridine chain and PBI–PDP. Light scattering and NMR spectroscopic studies reveal that the self-assembled structures of the solid complexes are not fully disrupted when the complexes are dissolved in THF. NMR experimental parameters measured for the small probe molecule provide detailed insights into the structure of the assemblies in solution as well as the interaction between the small molecule and the block copolymer. Such insights can have important implications in manipulating the nanostructure of block copolymer micelles to suit various application requirements. The dynamics and distribution of the PBI–PDP molecules within the assemblies in solution show a dependence on the leng...

Polyaniline supported palladium catalyst was applied in the reductive degradation of organic dyes such as Methylene Blue, Rhodamine B, and Methyl Orange in presence of sodium borohydride as an environmental-friendly approach. Role of pH, catalyst amount, and catalyst support were investigated thoroughly to achieve complete and efficient degradation within few minutes under ambient condition. Heterogeneous nature of the catalyst allowed easy recovery by centrifugation and the catalyst was recycled for five cycles with slightly reduced activity. Recovered catalyst was characterized by ICP-AES and TEM and a slight decrease in the activity of the catalyst was attributed to the agglomeration of the palladium nanoparticles.

In the recent past, many of the deubiquitinases (DUB) were found to modulate mitochondrial clearance or mitophagy and thus they are currently projected as therapeutic targets against neurodegeneration. Among these DUBs, USP14 stands at a distinctive juncture, since it can influence both proteasome complex activity and autophagy process. USP14 interference can enhance mitochondrial clearance and thus can protect Parkinsonian phenotypes in Drosophila model. However, in higher animal models of neurodegenerative disorders, evaluation of the protective role of USP14 is yet to be done. In this perspective, we pointed out a few of the major considerations that should be classified before designing experiments to evaluate the therapeutic potential of this DUB in rodent models of neurodegeneration. These are mainly: level of USP14 in the concerned brain region and how the level alters in the model system. Because USP14 mediated mitophagy is Prohibitin2 dependent, the anticipated impact of this protein in this aspect is also discussed. To illustrate our view, we show that USP14 levels increases in adult rat brain substantia nigra (SN) and cerebellum compared to the young ones. We also depict that rotenone treatment can immediately lead to increased SN specific USP14 levels. Our perception thus portrays USP14 as a therapeutic target, especially for addressing SN specific neurodegeneration in adult rat brain, but may vary with the disease model.

Plants being sessile are always exposed to various stresses including biotic and abiotic stresses. Some of these stresses are genotoxic to cells causing DNA damage by forming lesions which include altered bases, cross-links, and breaking of DNA strands, which in turn hamper the genomic integrity. In order to survive through all these adverse conditions, plants have evolved different DNA repair mechanisms. As seen from the mammalian system and different human diseases, various microRNAs (miRNAs) can target the 3′-untranslated region of mRNAs that code for the proteins involved in DNA repair pathways. Since miRNAs play an important role in plant cells by regulating various metabolic pathways, it can also be possible that miRNAs play an important role in DNA repair pathways too. However, till date, only a handful of plant miRNAs have been identified to play important role in combating genotoxic stresses in plants. Limitation of information regarding involvement of miRNAs in DNA repair as well as in ROS scavenging prompted us to gather information about plant miRNAs specific for these tasks. This mini-review aims to present pertinent literature dealing with different genotoxic stresses that cause genome instability as well as plant specific responses to survive the damage. This is intertwined with the involvement of miRNAs in genotoxic stress in plants, challenges of applying miRNAs as a tool to combat DNA damage along with ways to overcome these challenges, and finally, the future prospective of these understudied aspects.

The present study aimed to demonstrate the utilization of unpurified industrial CO2 with low impurities for acetate production via microbial electrosynthesis (MES) for the first time. In MES experiments with CO2-rich brewery gas, the enriched mixed culture dominated by Acetobacterium produced 1.8 ± 0.2 g/L acetic acid at 0.26 ± 0.03 g/Lcatholyte/d rate and outperformed a pure culture of Clostridium ljungdahlii (1.1 ± 0.02 g/L; 0.138 ± 0.004 g/Lcatholyte/d). The electron recovery in acetic acid was also more for mixed culture (84 ± 13%) than C. ljungdahlii (42 ± 14%). Electrochemical analysis of biocathodes suggested the role of microbial biofilm in improved hydrogen electrocatalysis. In comparative gas fermentation tests, the mixed culture outperformed C. ljungdahlii and produced acetic acid at a similar level with both industrial and pure CO2 feedstocks. These results suggest the robustness and capability of the mixed microbial community for utilizing slightly impure industrial CO2 for bioproduction and presents a major advancement in MES technology.

Allylic amination, directly from alcohols, has been demonstrated without any Lewis acid activators using an efficient and regiospecific molecular iron catalyst. Various amines and alcohols were employed and the reaction proceeded through the oxidation/reduction (redox) pathway. A direct one-step synthesis of common drugs, such as cinnarizine and nafetifine, was exhibited from cinnamyl alcohol that produced water as side product.

This study focused work-exposure to particulate matter ≤ 10 µm (PM10), volatile organic compounds (VOCs) and biological monitoring of major VOCs (BTEX) to observe the significant effects of traffic related pollutants on respiratory and hematological systems of workers engaged in two occupational settings, petrol pumps and traffic areas of Kolkata metropolitan city, India. PM10 was assessed by personal sampling and particle size distribution by 8-stage Cascade Impactor. VOCs were analysed by gas chromatography-flame ionization detector (GC-FID) and five urinary metabolites, trans trans- mercapturic acid (tt-MA), S-phenyl mercapturic acid (SPMA), hippuric acid (HA), mandelic acid (MA) and methyl hippuric acid (MHA) of VOCs, benzene, toluene, ethyl benzene and xylenes (BTEX) by reverse phase high performance liquid chromatography (HPLC). Pulmonary functions test (PFT) was measured Spirometrically. ∂-aminoleavulinic acid (ALA) and porphobilinogen (PBG) in lymphocytes were measured spectrophometrically following column chromatographic separation. High exposure to PM10, having 50% of particles, ≤ 5.0 µm in both the occupational settings. Exposure to toluene was highest in petrol pumps whereas benzene was highest (104.6 ± 99.0 μg m-3) for traffic police personnel. Workplace Benzene is found many fold higher than the National ambient standard. Air-benzene is correlated significantly with pre- and post-shift tt-MA (p < 0.001) and SPMA (p < 0.001) of exposed workers. Blood cell counts indicated benzene induced hematotoxicity. ALA and PBG accumulation in lymphocytes indicated alteration in heme-metabolism, especially among traffic police. Significant reduction of force exploratory volume in one second (FEV1) and forced vital capacity (FVC) of fuel fillers are observed with increased tt-MA and SPMA. Study revealed PFT impairments 11.11% (6.66% restrictive and 2.22% obstructive and combined restrictive and obstructive type, each) among petrol pumps and 8.3% obstructive type among traffic police.

We have designed seven organic diradicals with polyacene couplers to show the effect of the configuration, aromaticity [estimated with the help of Nucleus Independent Chemical Shift (NICS(0) and NICS(I)), and Harmonic Oscillator Model of Aromaticity (HOMA)] and HOMO–LUMO gap of the couplers on the exchange coupling constant of the diradicals. It has been observed that the linear polyacenes are less aromatic compared to the corresponding angular ones. We have correlated aromaticity indexes NICS and HOMA to explain the change of aromaticity for structures having the same number of carbon and hydrogen atoms and rings. The diradicals with linear couplers manifest stronger exchange coupling constants compared to those with angular couplers. It has been found that the NICS value cannot adequately address the aromaticity of the polyacenes, whereas the HOMA value can reliably account for the observations. Here, we have found the HOMO–LUMO gap is the determining factor for the extent of the magnetic exchange coupling constant in the diradicals. It has been found that not only the energy value of the LUMO, but also its occupation number and spatial position, play an important role in magnetic exchange in diradicals. Thus, the role of the LUMO in magnetic exchange has been firmly established through this work. The magneto-structural correlation has also been studied to establish the mechanism of magnetic interaction.

Allylic amination, directly from alcohols, has been demonstrated without any Lewis acid activators using an efficient and regiospecific molecular iron catalyst. Various amines and alcohols were employed and the reaction proceeded through the oxidation/reduction (redox) pathway. A direct one-step synthesis of common drugs, such as cinnarizine and nafetifine, was exhibited from cinnamyl alcohol that produced water as side product.

The sulfonoquinovosyldiacylglyceride (SQDG) isolated from the leaves of Azadirachta indica showed significant anti-leukemic activity in human leukemic cell lines U937 and K562 with IC50 of 9 μg/ml. SQDG treated leukemic cells showed chromatin condensation, apoptotic body formation, and increased caspase 3 production indicating apoptosis. Cell cycle study revealed that the treated leukemic cells accumulated in the sub-G1 phase; the cell cycle was halted in this phase and the DNA content decreased in other phases.

Chloromethylated polystyrene supported ionic liquid is used as catalyst in the aldol-type coupling of a variety of aldehydes with ethyl diazoacetate in water. Moderate to excellent yields of the corresponding α-diazo-β-hydroxy esters were obtained. The catalyst was separated by filtration and reused in five consecutive cycles without any appreciable loss of activity.

Oxidative Heck reactions of arylboronic acids and alkenes are carried out in the presence of polyaniline-supported palladium catalysts using air as a co-oxidant to afford the Heck products with excellent yields and selectivities under base- and ligand-free conditions. The catalyst was recovered by simple filtration and used for several cycles with consistent activity.

Layered-double-hydroxide-supported nanorhodium catalyst (LDHRh(0)) was employed in the Heck-type coupling of alkenes 1 with arylboronic acids 2 to afford the corresponding substituted alkenes 3 in good to high yields (Table 1). The catalyst was separated by simple filtration and reused for five cycles with consistent activity.

Polyaniline supported CuI catalyst was prepared, characterized and effectively used in the N -arylation of N (H)-heterocycles and benzylamines with aryl halides and arylboronic acids and in aza-Michael reaction of amines with activated alkenes. The catalyst was recovered by simple filtration and reused for several cycles with consistent activity.

Silica-supported tetramethylguanidine catalyst was prepared and effectively used in the aldol-type coupling of aldehydes with ethyl diazoacetate to afford the corresponding α-diazo-β-hydroxy esters in good to excellent yields. The catalyst was quantitatively recovered from the reaction by a simple filtration and reused for a number of cycles with almost consistent activity.

Glycation-modified hemoglobin in diabetes mellitus has been suggested to be a source of enhanced catalytic iron and free radicals causing pathological complications. The present study aims to verify this idea in experimental diabetes. Pelargonidin, an anthocyanidin, has been tested for its antidiabetic potential with emphasis on its role against pathological oxidative stress including hemoglobin-mediated free radical reactions. Male wistar rats were grouped as normal control, streptozotocin-induced diabetic control, normal treated with pelargonidin and diabetic treated with pelargonidin. Pelargonidin-treated rats received one time i.p injection of the flavonoid (3 mg/kg bodyweight). Biochemical parameters were assayed in blood samples of different groups of rats. Liver was used for histological examinations. Pelargonidin treatment normalized elevated blood glucose levels and improved serum insulin levels in diabetic rats. Glucose tolerance test appeared normal after treatment. Decreased serum levels of SOD and catalase, and increased levels of malondialdehyde and fructosamine in diabetic rats were reverted to their respective normal values after pelargonidin administration. Extents of hemoglobin glycation, hemoglobin-mediated iron release, iron-mediated free radical reactions and carbonyl formation in hemoglobin were pronounced in diabetic rats, indicating association between hemoglobin glycation and oxidative stress in diabetes. Pelargonidin counteracts hemoglobin glycation, iron release from the heme protein and iron-mediated oxidative damages, confirming glycated hemoglobin-associated oxidative stress in diabetes.

Pd/C is used as an efficient catalyst for the copper-free Sonogashira coupling of acid chlorides and terminal alkynes to afford ynones in high yields (Tables 1 and 3). Cyclization of (2-methoxyaryl)-substituted ynones induced by I2/ammonium cerium(IV) nitrate (CAN) at room temperature gave 3-iodochromenones (=3-iodo-4H-1-benzopyran-4-ones) in excellent yield (Table 4).

Layered double hydroxides supported rhodium(0) catalyst was prepared, characterized and effectively used as a catalyst in the Heck, Suzuki and Stille cross-coupling of haloarenes. The catalyst can easily be removed by simple filtration and reused for several cycles with consistent activity.

Polyaniline supported palladium catalysts were prepared from different palladium precursors and all the catalysts are well characterized using ICP-AES, FTIR, TGA–DTA, SEM-EDX and XPS analysis. All the catalysts were tested for Suzuki–Miyaura coupling of bromo- and chloroarenes in water and the catalyst prepared from PdCl2 precursor was found to be the most effective catalyst. The catalyst can easily be recovered by simple filtration and reused for several cycles with almost consistent activity.

Silica tethered copper complexes are effectively used as reusable catalysts in the N-arylation of N(H)-heterocycles and benzyl amines with aryl halides and arylboronic acids. N-Arylated products were isolated in good to excellent yields, demonstrating the versatility of the protocol. Moreover the Cat2 was easily recovered by simple filtration and reused for several cycles with consistent activity.

Polyaniline supported indium(III) trichloride (PANI-In) catalyst was prepared and thoroughly characterized by using FTIR, XPS, scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX) and ICP-AES. Thus, the synthesized catalyst was efficiently used in the aza-Michael reaction of amines with electron-deficient olefins and aza-Diels-Alder reaction of cyclic enol ethers with aromatic amines in water. Moreover, the catalyst was easily recovered by simple filtration and reused for several cycles with consistent activity.

The efficacy and mechanism of flaxseed lignan secoisolariciresinol diglucoside (SDG) on glucose hemostasis in obese mice were examined. Male C57BL/6J mice fed on a high-fat diet (60 kcal% fat) for 15 weeks were divided into four groups and treated by oral gavage with 0, 10, 100, or 1000 mg/kg/d of SDG dissolved in water for 6 weeks. Age-matched mice fed with a low-fat diet (10% kcal fat) were used as the normal control. SDG lowered fasting blood glucose, insulin, and free fatty acid levels and improved oral glucose tolerance, insulin response, and homeostatic model assessment-estimated insulin resistance index in mice fed the high-fat diet. Flaxseed SDG also increased GLUT4 expression and tended to increase phosphorylated AKT to total AKT ratio in the muscle tissue. The data demonstrated that flaxseed SDG improved glycaemic control, at least in part, by enhancing insulin signalling and sensitivity in diet-induced obese mice.

Nanocrystalline magnesium oxide supported palladium(0) catalyst [NAP-Mg-Pd(0)], prepared by the counter-ion stabilization of PdCl 4 2- followed by reduction with hydrazine hydrate, was effectively used in the Heck olefination of haloarenes (chloro, bromo, and iodo) to afford good to excellent yields of substituted olefins. This ligand-free heterogeneous NAP-Mg-Pd(0) catalyst was quantitatively recovered from the reaction by a simple filtration and reused for a number of cycles with almost no loss of activity. Moreover, NAP-Mg-Pd(0) efficiently catalyzed the Sonogashira coupling of haloarenes with terminal alkynes without any copper co-catalyst under milder conditions to afford excellent yields of substituted alkynes.

Polyaniline-supported Sc, In, Pd, Os and Re catalysts were prepared by using a simple protocol and the thus prepared catalysts were well characterized using FTIR, XPS, UV-Vis/DRS, TGA-DTA. All the catalysts were successfully employed in a wide range of organic transformations such as cyanation and allylation of carbonyl compound, Suzuki coupling of aryl halides and boronic acids, and, most importantly, in asymmetric dihydroxylation of olefins to afford optically active vicinal diols. All the catalysts were separated from the reaction mixture by simple filtration and reused with consistent activity for five cycles without noticeable leaching of metal from the support.

Layered double hydroxide (LDH)-supported nanoplatinum(0) and nanopalladium(0) catalysts were prepared by a simple ion exchange technique and subsequent reduction with hydrazine hydrate and used for the allylation of aldehydes to give moderate to good yields of homoallylic alcohols. Detailed mechanistic studies of LDH-Pd(0)-catalyzed allylation using XPS and TGA-MS reveal that a monoallyl-palladium complex is the key intermediate for the catalytic cycle.

A nanocrystalline magnesium oxide-stabi- lized palladium(0) catalyst is prepared by counterion stabilization of PdCl4 2 � with nanocrystalline MgO fol- lowed by reduction. This ligand-free heterogeneous nanocrystalline MgO-stabilized nanopalladium (NAPMgPd(0)) catalyst using the basic MgO in place of basic ligands exhibits excellent activity in Su- zuki and Stille cross-coupling of haloarenes (chloro, bromo and iodo) to afford the unsymmetrical biaryls. The catalyst is quantitatively recovered by simple fil- tration and reused for four cycles with almost consis- tent activity.

Layered double hydroxides (LDH) supported nanoplatinum catalyst was prepared and employed for Suzuki cross coupling of aryl halides (iodides and bromides) with a broad range of arylboronic to afford the corresponding biaryls in good to excellent yields without using any external ligand. The catalyst is reused for several cycles with consistent activity.

New bifunctional catalysts composed of PdCl 4 2- , OsO 4 2- and OsO 4 2- , WO 4 2- designed and prepared by a counterionic stabilization technique involving the reactions of Na 2 PdCl 4 -K 2 OsO 4 and K 2 OsO 4 -Na 2 WO 4 with nanocrystalline MgO are well characterized. These bifunctional catalysts, NAP-Mg-PdOs and NAP-Mg-OsW perform tandem Heck asymmetric dihydroxylation and asymmetric dihydroxylation-N-oxidation reactions, respectively, in the presence of the chiral ligand 1,4-bis(9-o-dihydroquinidinyl)phthalazine [(DHQD) 2 PHAL] in a single pot. It is quite impressive to note that H 2 O 2 is used as a terminal oxidant to provide N-methylmorpholine N-oxide (NMO) in situ by the oxidation of N-methylmorpholine (NMM) in the asymmetric dihydroxylation-N-oxidation catalyzed by NAP-Mg-OsW.

Flaxseed Lignan Secoisolariciresinol Diglucoside Improves Insulin Sensitivity through Upregulating GLUT4 Expression in Diet-Induced Obese Mice Yanwen Wang1, Bourlaye Fofana2, Moumita Roy1, and Kaus...

Silica-supported copper catalysts were effectively used in the three-component coupling of aldehydes, amines and alkynes to afford the corresponding propargylamines in moderate to excellent yields. The catalyst was quantitatively recovered from the reaction by a simple filtration and reused for a number of cycles with almost consistent activity.

A layered double hydroxide-supported nanoplatinum catalyst is employed in the Heck and Stille cross-coupling of a wide range of iodoarenes to give the corresponding cross-coupled products in good to excellent yields. The catalyst is recovered by centri-fugation and reused over a number of cycles with consistent activity.

Layered double hydroxide-supported nanopalladium (LDH-Pd°) is an effective catalyst for Suzuki cross-coupling of a wide range of aryl iodides and bromides with arylboronic acids at room temperature. The catalyst is reused for four cycles with consistent activity.

Objectives Glycyrrhizin is the main water-soluble constituent of the root of liquorice (Glycyrrhiza glabra). The study investigates the effect of glycyrrhizin on streptozotocin (STZ)-induced diabetic changes and associated oxidative stress, including haemoglobin-induced free iron-mediated oxidative reactions. Methods Male Wistar rats were grouped as normal control, STZ-induced diabetic control, normal treated with glycyrrhizin, diabetic treated with glycyrrhizin and diabetic treated with a standard anti-hyperglycaemic drug, glibenclamide. Different parameters were studied in blood and tissue samples of the rats. Key findings Glycyrrhizin treatment improved significantly the diabetogenic effects of STZ, namely enhanced blood glucose level, glucose intolerant behaviour, decreased serum insulin level including pancreatic islet cell numbers, increased glycohaemoglobin level and enhanced levels of cholesterol and triglyceride. The treatment significantly reduced diabetes-induced abnormalities of pancreas and kidney tissues. Oxidative stress parameters, namely, serum superoxide dismutase, catalase, malondialdehyde and fructosamine in diabetic rats were reverted to respective normal values after glycyrrhizin administration. Free iron in haemoglobin, iron-mediated free radical reactions and carbonyl formation in haemoglobin were pronounced in diabetes, and were counteracted by glycyrrhizin. Effects of glycyrrhizin and glibenclamide treatments appeared comparable. Conclusion Glycyrrhizin is quite effective against hyperglycaemia, hyperlipidaemia and associated oxidative stress, and may be a potential therapeutic agent for diabetes treatment.

Layered-double-hydroxide-supported nanorhodium catalyst (LDHRh(0)) was employed in the Heck-type coupling of alkenes 1 with arylboronic acids 2 to afford the corresponding substituted alkenes 3 in good to high yields (Table 1). The catalyst was separated by simple filtration and reused for five cycles with consistent activity.

Oxidative Heck reactions of arylboronic acids and alkenes are carried out in the presence of polyaniline-supported palladium catalysts using air as a co-oxidant to afford the Heck products with excellent yields and selectivities under base- and ligand-free conditions. The catalyst was recovered by simple filtration and used for several cycles with consistent activity.

Silica-supported tetramethylguanidine catalyst was prepared and effectively used in the aldol-type coupling of aldehydes with ethyl diazoacetate to afford the corresponding α-diazo-β-hydroxy esters in good to excellent yields. The catalyst was quantitatively recovered from the reaction by a simple filtration and reused for a number of cycles with almost consistent activity.

A 3-aminopropyl-functionalized silica-supported rhodium(0) catalyst (SiO2–Rh0) was prepared and employed in the Heck-type coupling of arylboronic acids and alkenes, affording good-to-excellent yields of substituted alkenes; the catalyst was recovered by filtration and reused for several cycles.

Polyaniline supported palladium catalysts were prepared from different palladium precursors and all the catalysts are well characterized using ICP-AES, FTIR, TGA–DTA, SEM-EDX and XPS analysis. All the catalysts were tested for Suzuki–Miyaura coupling of bromo- and chloroarenes in water and the catalyst prepared from PdCl2 precursor was found to be the most effective catalyst. The catalyst can easily be recovered by simple filtration and reused for several cycles with almost consistent activity.

A 3-aminopropyl-functionalized silica-supported rhodium(0) catalyst (SiO2–Rh0) was prepared and employed in the Heck-type coupling of arylboronic acids and alkenes, affording good-to-excellent yields of substituted alkenes; the catalyst was recovered by filtration and reused for several cycles.