Synthesis,characterization and application of a novel nanorod-structured organic–inorganic hybrid material as an efficient catalyst for the preparation of aminouracil derivatives

Research on Chemical Intermediates - In this work, a novel nanorod-structured organic–inorganic hybrid material namely nanorod-[SiO2-Pr-Im-SO3H][TFA] (N-[SPIS][TFA]) has been synthesized, and...     

Photoregulated uptake and release of drug by an organic–inorganic hybrid sol–gel material

A photo-responsive molecularly imprinted sol–gel organic-inorganic hybrid material prepared by covalent imprinting of the template-functional monomer complex formed between 4,4′-dihydroxylazobenzene and ibuprofen was developed to explore the photo-regulated uptake and release of drug by a silicate-based smart molecularly imprinted materials. After imprinting, the template molecules (ibuprofen) were removed via hydrolysis in acid, and accurate cavities were left, which could be used as the receptor recognition sites for ibuprofen. The new organic–inorganic hybrid material shows specific affinity to ibuprofen and reversible uptake and release of ibuprofen upon alternate irradiation at 365 and 440 nm, respectively. The favorable binding strength of the imprinted receptor sites in the molecularly imprinted polymer (MIP) for ibuprofen is found to be 2.28 × 10³ M⁻¹. Density of receptor sites in the MIP material was 4.0 μmol/g—MIP.     

Naked eye detection of cadmium using inorganic–organic hybrid mesoporous material

A novel and low-cost optical sensor for the naked eye detection of Cd²⁺in aqueous media based on mesoporous silica containing 4-(2-pyridylazo)resorcinol (PAR) as a probe molecule anchored by N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride (TMAC) was prepared. The effects of various factors such as pH, solvent volume, temperature, reaction time, amount of the material, and the presence of various ions were studied in order to optimize operating conditions. The detection was based on the color change of PAR from orange-yellow to purple as a result of complexation with Cd²⁺. The intensity of the Cd-PAR complex varies linearly with the Cd²⁺concentration, from zero to 1.78×10⁻⁷ mol dm⁻³. The detection and quantification limits for the method when determining Cd²⁺ were 1.75×10⁻⁸ and 5.77×10⁻⁸ mol dm⁻³, respectively, with a correlation coefficient of 0.99. Good chemical stability of the material was observed for a period of five months. The developed sensor was applied to the analysis of various industrial effluents and tap water samples. Electronic supplementary material Supplementary material is available for this article at     

Highly enantioselective Henry reaction catalyzed by a new chiral C2-symmetric N,N′-bis(isobornyl)ethylenediamine–copper complex

A new chiral C₂-symmetric N,N′-bis(isobornyl)ethylenediamine–copper complex is found to be an efficient catalyst in the enantioselective Henry reaction between nitromethane and various aldehydes to provide β-hydroxy nitroalkanes with high chemical yield (up to 95%) and high enantiomeric excess (up to 90%).     

Green and efficient oxidation of benzylic alcohols with hydrogen peroxide catalyzed by an inorganic–organic hybrid catalyst

Inorganic–organic hybrid catalysts 1-POM(M) were prepared by electrostatic interaction between transition metal-substituted polyoxometalates, {[PW₁₁MO₃₉]^4? [M?=?Cr(III), Fe(III)], [PW₁₁MO₃₉]^5?, [M?=?Mn(II), Co(II), Ni(II), Cu(II), Zn(II)], [PW₁₁VO₄₀]^4?}, and branched organic polyammonium, (tris[2-(dimethylammonium)ethyl]-1,3,5-benzenetricarboxylate), and characterized by elemental analyses, UV–vis and FT IR spectroscopic techniques, XRD, SEM, and Thermogravimetric-Differential thermogravimetric analyses. The hybrid material 1-POM(Zn) was an efficient and selective heterogeneous catalyst in the oxidation of benzylic alcohols to their corresponding carbonyl compounds with hydrogen peroxide. The catalyst was reused several times without significant loss of catalytic activity.     

One-pot preparation of N,N′-alkylidene bisamide derivatives catalyzed by silica supported polyphosphoric acid (SiO2-PPA)

Silica supported polyphosphoric acid (SiO₂-PPA) as an efficient heterogeneous catalyst was found to be effective for the one-pot three-component condensation reaction of phenyl acetylene/1-hexyne, aromatic aldehyde and benzamide/acetamide to produce a series of N,N′-alkylidene bisamides. The desired products were obtained in good to high yields. The assistance of alkynes has been confirmed by using thin layer chromatographic (TLC) studies. All the reactions were done at 100 °C using 0.025 g of catalyst. The developed method is valid for either substituted aldehyde, thus it constitutes a general synthetic method for these kinds of compounds. In all the cases aromatic aldehydes containing electron-withdrawing groups gave shorter time than that with electron-donating groups. Additionally, the reaction of butyraldehyde with benzamide failed to have any product in the presence of phenyl acetylene but with 1-hexyne the product was formed in moderate yield.     

Microwave-assisted,methanesulfonic acid-catalyzed synthesis of 3,3′-(arylmethylene)bis(4-hydroxy-2H-chromen-2-ones)

Efficient synthesis of 3,3′-(arylmethylene)bis(4-hydroxy-2H-chromen-2-ones) has been achieved by methanesulfonic acid-catalyzed, microwave-assisted reaction of 4-hydroxycoumarin and aromatic aldehydes in ethanol. The procedure has the advantages of high yield, short reaction time, low energy consumption, and convenient work-up. Compound structures were confirmed by IR, ¹H NMR, and ¹³C NMR spectroscopy and by elemental analysis.     

Formation of hybrid nano-crystals in organic–inorganic films from a basic sol

Organic–inorganic films containing hybrid nanocrystals have been prepared by sol–gel processing in controlled conditions. We have systematically changed the temperature and the aging time of a precursor sol containing an organically modified alkoxide bearing an epoxy group, 3-glycidoxypropyltrimethoxysilane, to obtain a controlled crystallization of hybrid layered structures in hybrid films. The precursor sol has been aged at different temperatures, from 5 to 60 °C, and for 1, 2 or 3 days; the films have been deposited from the aged sol and immediately after characterized by X-ray diffraction, Fourier transform infrared spectroscopy and Raman spectroscopy. We have observed that the formation of the hybrid crystals can be obtained only when at least 50% of the epoxies are opened and a larger silica condensation is achieved. These conditions are reached after aging at 60 °C for 1 day, or at longer aging times when the sol is aged at lower temperatures. Transmission electron microscopy and optical polarized images have confirmed the formation of the hybrid crystals.     

Synthesis of 3,3-bis(2-haloethyl) and 3,3,3′-tris(2-haloethyl) derivatives of 1,1′-[methylenebis(oxy)]bis(triaz-1-ene 2-oxides)

Synthetic procedures towards 3,3-bis(2-haloethyl) and 3,3,3′-tris(2-haloethyl) derivatives of 1,1′-[methylenebis(oxy)]bis(triaz-1-ene 2-oxides) via halogenation of the corresponding 2-hydroxyethyl derivatives of 1,1′-[methylenebis(oxy)]bis(triaz-1-ene 2-oxides) and iodination of the corresponding 2-bromoethyl derivatives were elaborated. The synthesized compounds are promising NO donors in the living organisms.     

Synthesis and characterization of a novel organic–inorganic hybrid supramolecular recognition material and its selective adsorption for cesium

To separate Cs(I) from highly active liquid waste, a macroporous silica-based 25, 27-bis(iso-propyloxy)calix[4]arene-26,28-crown-6 (BiPCalix[4]C6) supramolecular recognition material, BiPCalix[4]C6/SiO₂–P, was synthesized and characterized by SEM, FT-IR, and TG-DSC. The adsorption properties of BiPCalix[4]C6/SiO₂–P and a macroporous polymer-based supramolecular recognition composite, BiPCalix[4]C6/XAD-7, were compared. It was found that BiPCalix[4]C6/SiO₂–P exhibited better adsorption ability and faster adsorption dynamics than BiPCalix[4]C6/XAD-7. The adsorption isotherm of Cs(I) onto BiPCalix[4]C6/SiO₂–P was studied at 298 K and it was well described by Langmuir isotherm model. The complex composition between BiPCalix[4]C6/SiO₂–P and Cs(I) was determined as 1:1 type by investigating the effect of the concentrations of BiPCalix[4]C6, Cs(I), and H⁺ on the adsorption. Meanwhile, the selectivity of BiPCalix[4]C6/SiO₂–P towards Na(I), K(I), Rb(I), Cs(I), Sr(II), Ba(II), Ru(III), Mo(VI), La(III), and Y(III) was investigated.     

Synthesis and spectral properties of 3,3′-bis(dipyrrolylmethene)

Bis(2,4,7,8,9-pentamethyldipyrrolylmethene-3-yl)(4′-methoxyphenyl)methane dihydrobromide was synthesized and its spectral properties were studied. It was found that the basicity of the ligand 3,3′-bis-(dipyrrolylmethene) decreases upon insertion of the methoxyphenyl group in the 3,3′-spacer.     

Synthesis of 4,4′-bis(dichloroamino)- and 4,4′-bis(chloroamino)-3,3′-azofurazans,the first representatives of dichloroamino- and chloroaminofurazans

First representatives of dichloroamino- and chloroaminofurazans, viz., 4,4′-bis(dichloroamino)- and 4,4′-bis(chloroamino)-3,3′-azofurazans, were synthesized by the chlorination of 4,4′-diamino-3,3′-azofurazan with sodium hypochlorite in the CH₂Cl₂—H₂O mixture.     

Synthesis,characterisation and ion exchange properties of hybrid organic–inorganic composite material: polyacrylamide zirconium (IV) iodosulphosalicylate

ABSTRACT

Contamination of groundwater by heavy metal is one of the most emerging and serious environmental problems. There are so many methods which are available to overcome these problems. Among various available methods, hybrid organic–inorganic ion exchange resin has become more popular due to certain advantages over other available conventional methods; hence, in the present proposed work, we synthesised a hybrid organic–inorganic composite material polyacrylamide zirconium (IV) iodosulphosalicylate by using the sol-gel technique. Synthesised resin was characterised by various methods like Infrared spectroscopy and Thermogravimetric analysis-Differential thermal analysis. Various samples of this ion exchange resin are prepared by changing the condition of synthesis, i.e. concentration of acrylamide to rationalise the ion exchange capacity of the synthesise hybrid organic–inorganic ion exchange resins. A mixture of 0.1 M potassium iodate, 0.1 M sulphosalicylic acid and 0.1 M acrylamide was added dropwise to 0.4 M zirconium oxychloride accompanied by constant stirring for 8 h using magnetic stirrer at 70°C to yield polyacrylamide zirconium (IV) iodosulphosalicylate with maximum ion exchange capacity. Ion exchange capacity of synthesised resin was determined by column method and the maximum ion exchange capacity was found for Pb(II). Determination of k_d values shows that the resin was highly selective for Pb (II).The selectivity for Pb was also evaluated by using certain binary mixture separation such as Ni (II)-Pb(II), Cu(II)-Pb(II), Cd(II)-Pb(II), Sr(II)-Pb(II), Ba(II)-Pb(II),Zn(II)-Pb(II) and Mg(II)-Pb(II).     

Assembly of two novel inorganic–organic hybrid solids based on 3-(aminomethyl)pyridine ligand

Two new inorganic–organic hybrids, (Hampy)Zn₂(PO₄) (HPO₃) (1) and (ampy)Zn₂(HPO₃)₂ (2), where ampy = 3-(aminomethyl)pyridine, have been solvothermally prepared and structurally characterized. Compound 1 exhibits an unusual two-dimensional layer structure, which possesses a central 4.8² zincophosphate sheet wrapped by infinite zincophosphite chains. Left- and right-handed helical chains participate in the formation of the zincophosphate layer. Compound 2 features a three-dimensional pillared-layer structure, in which two-dimensional Zn^II(HPO₃) inorganic sheets were cross-linked by ampy ligands. The simultaneous occurrence of zinc-amine helical chains in 2 is unique and, to the best of our knowledge, firstly encountered in phosphite/phosphate hybrid materials. Different coordination modes and roles of the same ampy ligand were observed in the formation of the hybrid structures.     

Sol–gel synthesis,characterization and water vapor adsorption properties of 1,1′-(1,6-hexanediyl)-bis(imidazolium)dichloride-silica hybrid material

1,1′-(1,6-hexanediyl)-bis(imidazolium)dichloride-silica hybrid material was prepared in 90 % yield by ammonia catalyzed sol–gel condensation of 1,1′-(1,6-hexanediyl)-bis[3-(3-triethoxysilylpropyl)-imidazolium]dichloride in aqueous ethanol. This novel ionic liquid-silica hybrid material can adsorp 27 % w/w water vapor in 90 min at room temperature and atmospheric pressure. This is a higher water adsorption capacity and rate than commercial desiccant Drierite which showed only 16 % w/w of water vapor adsorption and required 10 h to reach the maximum adsorption under identical conditions. The new adsorbent could be reused for five cycles without any significant loss in activity after regeneration by heating at 110 °C, for 24 h.     

Phase-transfer enantioselective monoalkylation of prochiral nickel(ii) complexes catalyzed by 3,3′-bis[hydroxy(diphenyl)methyl]-1,1′-binaphthyl-2,23′-diol (BIMBOL) as a route to α-amino acids

An achiral nickel complex with a Schiff base derived from glycine was alkylated with alkyl halides under conditions of asymmetric phase-transfer catalysis. The chiral tetraol (R)-BIMBOL was employed as a catalyst. The enantiomeric purity of the alkylation products was up to 88%. Subsequent decomposition of the complexes afforded the corresponding a-amino acids.     

Synthesis and spectral analysis of alkyl-substituted 3,3′-bis(dipyrrolylmethenes)

Four new alkyl-substituted 3,3′-bis(dipyrrolylmethene) dihydrobromides containing from 4 to 10 alkyl substituents were synthesized. In a highly alkylated ligand of these substances one of the hydrogen atoms of the 3,3′-methylene spacer was substituted with a phenyl group. The compounds obtained were studied by IR, ¹H NMR, electron absorption, and fluorescent spectroscopy. The increased alkylation degree of pyrroles and the introduction of an aryl substituent in the 3,3′-spacer causes a significant high-frequency shift of the N-H stretching vibrations in the IR spectra, an upfield shift of the NH-proton signals in 1H NMR spectra, a decrease in the auxochromic effects of protons on the aromatic system of chromophore in the composition of salts. The red shift of maximum of the strong band in electron absorption spectra and the emission spectra of compounds in DMF, DMSO, C₅H₅N, C₆H₆, and CHCl₃ was established. The salts obtained are stable in benzene and chloroform, while in electron-donor solvents the irreversible processes of solvolytic dissociation of salts to free organic base and HBr take place.     

Synthesis and characterization of organic–inorganic hybrid materials prepared by sol–gel and containing CdS nanoparticles prepared by a colloidal method using poly(N-vinyl-2-pyrrolidone)

This paper describes the synthesis and characterization of CdS nanoparticles (NPs) stabilized with poly(N-vinyl-2-pyrrolidone) and their further immobilization on a hybrid organic–inorganic matrix produced by the sol–gel process. The production of the hybrid matrix doped with CdS NPs was carried out in two steps. In the first step a precursor, designated diureasil precursor, was synthesized from the reaction between the terminal amine groups of α,ω-diamine-poly(oxyethylene-co-oxypropylene) and the isocyanate group of 3-isocyanatopropyltriethoxysilane. The next step involved the hydrolysis and condensation reactions of ethoxy groups attached to silicon, this step resulting in the formation of a crosslinked siliceous network linked through urea bonds to a poly(oxyethylene)/poly(oxypropylene) chain. The NPs were added to the diureasil precursor before the gelation process to allow a homogeneous dispersion of the NPs within the matrix. The developed method allowed the transfer of colloidal NPs to a solid matrix without the need of exchange the capping agents or the solvent. The materials were characterized by absorption, steady-state photoluminescence spectroscopy and by TEM. The results obtained showed the presence of CdS NPs with quantum size effect dispersed within the diureasil matrix. The obtained nanocomposites show a high transparency in the visible range accounting for the good dispersion of the NPs within the matrix. The TEM analysis confirmed that the NPs are uniformly dispersed within the diureasil matrix.     

Synthesis and characterization of two new inorganic–organic hybrid cobalt molybdenum(V) phosphates

Two new inorganic–organic hybrid cobalt phosphomolybdates (Hdien)₂[Co(dien)]₂[Co(dien)(H₂O)]₂[CoMo₁₂O₂₄(HPO₄)₂(H₂PO₄)₂(PO₄)₄(OH)₆]?···?5H₂O (1) and (H₂dien)₂[Co(dien)]₂[Co(H₂O)₂]₂[CoMo₁₂O₂₄(HPO₄)₄(PO₄)₄(OH)₆]?···?7H₂O (2) (dien?=?diethylenetriamine), involving molybdenum in the V oxidation state and covalently bonded transition metal complexes, have been prepared under mild hydrothermal conditions and structurally characterized by elemental analyses, IR spectra, TG analyses, and single-crystal X-ray diffraction. Compound 1 exhibits a one-dimensional (1D) chain framework, in which dien molecules adopt two kinds of coordination modes. Compound 2 shows a two-dimensional (2D) layer framework with three types of unusual tunnels. To the best of our knowledge, it is the first time [Co(dien)] units are directly incorporated into 1D and 2D skeletons of reduced molybdenum phosphates. The electrochemical properties of the two compounds were studied via the method of bulk-modified carbon paste electrodes. Furthermore, the magnetic properties of compound 2 are reported.