Synthesis and Characterization of pH-Responsive Organic–Inorganic Hybrid Material with Excellent Catalytic Activity

Poly(N-isopropylmethacrylamide-co-methacrylic acid) [p(NipAam-Mac)] microgels were synthesized and used as microreactors to fabricate silver nanoparticles. Pure and hybrid microgels were characterized using Ultraviolet–Visible (UV/Vis) spectroscopy, Fourier transform infra-red (FTIR) spectroscopy and transmission electron microscopy (TEM). Catalytic activity of hybrid microgels and mechanism of catalysis by this system was explored using different reaction conditions. At the same temperature, apparent rate constant (k_app) was found to be varied from 0.0414 to 0.7852 min^?1 by increasing the concentration of NaBH₄ from 2.49 to 22.41 mM at constant concentration of substrate and catalyst. However upon extra increase in concentration of NaBH₄ from 22.41 to 37.35 mM reduced the value of k_app to 0.2178 min^?1. Likewise, the value of k_app was found to be increased from 0.1242 to 0.5495 min^?1 with increasing the concentration of 4-nitrophenol [Para-nitrophenol (p-Np)] from 0.063 to 0.079 mM keeping other parameters constant. Further increase in concentration of p-Np caused decline in the value of k_app. Kinetic data reveals that catalytic reduction of p-Np obeys Langmuir–Hinshelwood mechanism and p-Np is converted to p-Ap on the surface of the silver nanoparticles passing through various reaction intermediates.     

An Organic–Inorganic Hybrid Composite as a Coating Agent

An organic–inorganic hybrid composite for use as a coating agent was prepared by mixing linseed oil with hydrophobic octylsilyl titanium dioxide particles having an average diameter of 35 nm (OSI-TIO2-35) in volatile silicone. The weight ratio of linseed oil with OSI-TIO2-35 was varied from 2:8 to 8:2 and the mixture was spread on a glass plate by dragging an applicator across it. After storing in the oven at 60 °C for 2 days, the composite having the weight ratio of OSI-TIO2-35 with linseed oil at 8:2 exhibited very high water-repellent properties having a water contact angle of 148°. Variation of the water contact angle during storage at 60 °C was monitored. It decreased by 10° in the initial 8 h and then increased by 45° over the next 2 days. Composites containing silicone resin, TMSS BY11-018, instead of linseed oil were also prepared. The sample having a weight ratio of OSI-TIO2-35 with TMSS BY11-018 at 8:2 also exhibited very high water-repellent properties with a water contact angle of 152°. The highly hydrophobic surface thus prepared by the coating and drying of those organic-inorganic hybrid composites was easily transferred to highly hydrophilic surfaces by calcination at 500 °C for 3 h.     

Self-Assembled Organic–Inorganic Hybrid Nanocomposite of a Porphyrin Derivative and CdS

A porphyrin derivative, 5-(4-carboxylphenyl)-10,15,20-tris(4-chlorophenyl) porphyrin (PorCOOH), was synthesized and self-assembled as a monolayer thin solid film on the modified surface of a quartz substrate by an ester bond between –COOH groups of PorCOOH molecules and –OH groups of the hydrophilic pretreated SiO₂ surface. An analysis of the spectral change revealed the J-aggregate nature of PorCOOH molecules in the obtained thin solid film. With this thin solid film of PorCOOH as a template, CdS nanoparticles were deposited on it in situ, which were further characterized by electronic absorption, fluorescence, and energy-dispersive X-ray spectroscopy. The morphology of CdS nanoparticles is disklike, and the diameter is ca. 40–60 nm, determined by scanning electronic microscopy. Furthermore, electron transfer between the organic layer and CdS nanoparticles was deduced through fluorescence quenching and theoretical analysis.     

Direct Electrochemistry and Electrocatalysis of Hemoglobin on Bimetallic Au–Pt Inorganic–Organic Nanofiber Hybrid Nanocomposite and Mesoporous Molecular Sieve MCM-41

A glassy carbon electrode modified with MCM-41 and bimetallic inorganic–organic nanofiber hybrid nanocomposite was prepared and used for determination of trace levels of hydrogen peroxide (H₂O₂). The direct electron transfer (DET) and electrocatalysis of hemoglobin (Hb) entrapped in the MCM-41 modified Au–Pt inorganic–organic nanofiber hybrid nanocomposite electrode (Au–PtNP/NF/GCE) were investigated by using cyclic voltammetry in 0.1 M pH 7.0 phosphate buffer solution. Due to its uniform pore structure, high surface area and good biocompatibility, the mesoporous silica sieve MCM-41 provided a suitable matrix for immobilization of biomolecules. The MCM-41 modified Au–Pt inorganic–organic nanofiber hybrid nanocomposite electrode showed significant promotion to DET of Hb, which exhibited a pair of well-defined and quasi-reversible peaks for heme Fe(III)/Fe(II) with a formal potential of ?0.535 V (vs. Ag/AgCl). Additionally, the Hb immobilized on the MCM-41 modified electrode showed excellent electrocatalytic activity toward H₂O₂ reduction.     

Luminescent Organic–Inorganic Hybrids of Functionalized Mesoporous Silica SBA-15 by Thio-Salicylidene Schiff Base

Novel organic–inorganic mesoporous luminescent hybrid material N,N′-bis(salicylidene)-thiocarbohydrazide (BSTC-SBA-15) has been obtained by co-condensation of tetraethyl orthosilicate and the organosilane in the presence of Pluronic P123 surfactant as a template. N,N′-bis(salicylidene)-thiocarbohydrazide (BSTC) grafted to the coupling agent 3-(triethoxysilyl)-propyl isocyanate (TESPIC) was used as the precursor for the preparation of mesoporous materials. In addition, for comparison, SBA-15 doped with organic ligand BSTC was also synthesized, denoted as BSTC/SBA-15. This organic–inorganic hybrid material was well-characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy (HRTEM), and photoluminescence spectra, which reveals that they all have high surface area, uniformity in the mesostructure. The resulting materials (BSTC-SBA-15 and BSTC/SBA-15) exhibit regular uniform microstructures, and no phase separation happened for the organic and the inorganic compounds was covalently linked through Si–O bonds via a self-assemble process. Furthermore, the two materials have different luminescence range: BSTC/SBA-15 presents the strong dominant green luminescence, while BSTC-functionalized material BSTC-SBA-15 shows the dominant blue emission.     

Ionothermal Syntheses and Crystal Structures of Two 1D Inorganic–Organic Hybrid Frameworks

Two 1D inorganic–organic hybrid frameworks, namely, [Zn(5-NO₂-bdc)(MIM)₃·H₂O]_n(1) and [Cd(MIM)₂Br₂]_n(2) (5-NO₂-bdcH₂ = 5-nitro-1,3-benzenedicarboxylic acid, MIM = N-methyl imidazole) were synthesized via ionothermal reactions with ionic liquid 1-ethyl-3-methylimidazolium bromide ([EMIM]Br) as solvent and template. Both compounds have been characterized by elemental analyses, spectroscopic analyses, thermogravimetric analysis (TGA) and the single crystal diffraction. The zinc(II) center in compound 1 is a slightly distorted five-coordinate trigonal bipyramid, 5-NO₂-bdc²⁻ anions and MIM moieties effectively bridge Zn centers to result in 1D zigzag chains. While Cd(II) center in compound 2 is in an octahedral coordination environment, and two μ²-bridge bromine link two [Cd(MIM)₂] moieties to form a 1D chain structure. In addition, complex 2 exhibits strong fluorescent emission in the solid state at room temperature.     

Ladder-Like Versus Hexagonal Organic–Inorganic Hybrid Materials in the Extraction of Lead Ions

Meso-structured and ladder organic–inorganic hybrid materials functionalized with ammonium carboxylate groups were prepared. These materials were obtained by the sol–gel process starting from the cyanopropyltriethoxysilane precursor as a building block. Hydrolysis of CN to COOH groups followed by treatment with triethylamine gives rise to cationic exchange materials. These materials exhibit a high chelating capability towards cations and can be used for water treatment. Lead ion (Pb²⁺) was tested as example; and, some tests were made on the meso-structured and ladder material for further comparison in efficacy of extractions.     

Formulation of Mechanochemically Evolved Fly Ash Based Hybrid Inorganic–Organic Geopolymers with Multilevel Characterization

In this research, advanced hybrid inorganic–organic geopolymeric material is developed by environmentally and user friendlier approach. The presented novel approach for geopolymer formation certainly overcomes the existing drawbacks of geopolymerization technology. The effect of rice husk ash and Na₂O/SiO₂ ratios on geopolymer gel formation and mechanical strength has been previously identified via solution chemistry route; however, development of geopolymeric material having hybrid inorganic–organic characters via together mechanochemical grinding of raw materials and effect of mechanochemically activated Na₂SiO₃ on geopolymeric properties via solid state route has never before been explored. Together mechanochemical grinding of raw materials of varying compositions in solid state resulted in the formation of ready to use geopolymeric precursors; which on just addition of water led to development of advanced hybrid inorganic–organic geopolymeric material with considerably enhanced properties. XRD, FTIR and SEM characterization data of developed geopolymeric precursor powder and hybrid inorganic–organic geopolymeric material are reported and discussed in detail. As the results of the investigations, the relationship between geopolymer composition, grinding mechanism and material properties established. The composition which exhibited synergistic effect of both rice husk and SMS is found to be excellent in performance. The study showed that it is practical and better to adopt this greener solid state approach for preparation of geopolymer instead of user-unfriendlier hazardous alkaline solution based approach, to achieve sustainable growth in geopolymers as like Portland cement.     

A Bifunctional Copper Catalyst for the One Pot-One Step Esterification?+?Hydrogenation of Tall Oil Fatty Acids

An efficient copper catalyst for the one-pot one-step hydrogenation?+?esterification of unsaturated free fatty acids is described. The high selectivity in hydrogenation promoted by copper, combined with the high activity in esterification observed with solid mixed oxides allows one to directly obtain stabilized methyl esters.     

Organic–Inorganic Coatings Based on Epoxidised Castor Oil/APTES/TEOS

Two series of organic–inorganic hybrid films were prepared from epoxidised castor oil (ECO) and the inorganic precursor 3-aminopropyltriethoxysilane (APTES), and the combination of APTES with tetraethoxysilane (TEOS) with different organic to inorganic proportions. Films were pre-cured at room temperature under inert atmosphere and subsequently submitted to thermal curing. The macro- and microscopic properties of the films, including adhesion, hardness, microstructure and thermal properties, were determined as a function of the proportion of ECO to inorganic precursors. Morphologic studies showed that the hybrid films were microscopically homogeneous. The hardness and tensile strength of the films increased with increased concentrations of inorganic precursor. All of the films exhibited good adhesion to an aluminium surface and worked as an efficient barrier against corrosion.     

A New 3D Pb(II) Inorganic–Organic Hybrid Framework Based on Terephthalate Acid with the Inorganic Pb–O–Pb Connectivity

Solvothermal reaction of Pb(NO₃)₂ with terephthalate acid afforded one new inorganic–organic hybrid framework, [Pb(PBDC)]_n (1) (H₂PBDC = terephthalic acid). X-ray analysis shows that compound 1 crystallizes in orthorhombic space group Pbca and the two carboxy group of terephthalate acid adopt rare coordination modes. A noticeable point in this paper that compound 1 exhibits preferable catalytic property on degradation of Rhodamine B. The phase purity of the as-synthesized sample was confirmed by powder X-ray diffraction. Moreover, satisfactory elemental analysis, IR spectra, and thermogravimetric analysis were obtained.     

Self-assembly of Mesoporous Ni–P Nanosphere Catalyst with Uniform Size and Enhanced Catalytic Activity in Nitrobenzene Hydrogenation

Mesoporous Ni?CP amorphous alloy nanospheres with controllable sizes and compositions were synthesized by chemical reduction of Ni(OH)₂ colloidal particles co-assembling with surfactant hexadecyl-trimethyl-ammonium bromide in liquid crystal mesophase using hypophosphite as reductant. The effects of the synthesis conditions on the particle size, composition and mesostructure of the mesoporous Ni?CP nanospheres were systematically studied. It was found that the size of the mesoporous Ni?CP nanospheres could be tuned from 35 to 90?nm by changing the reduction temperature, and the phosphorus content of the Ni?CP products could be adjusted in the range of 20.1 to 27.6?% by changing the molar ratio of H₂PO₂ ^?/Ni²⁺. The active surface area and the thermal stability of the mesoporous Ni?CP nanosphere catalyst are much higher than those for the conventional nonporous Ni?CP amorphous alloy. In the liquid phase hydrogenation of nitrobenzene, the typical mesoporous Ni?CP nanosphere catalyst exhibits much higher activity and better selectivity than the conventional nonporous Ni?CP. The correlation between the catalytic performance and the structural properties is discussed based on the results of detailed characterization.     

Pd(II)/Pd(0) Anchored on Magnetic Organic–Inorganic Hybrid Mesoporous Silica Nanoparticles: A Nanocatalyst for Suzuki–Miyaura and Heck–Mizoroki Coupling Reactions

Journal of Inorganic and Organometallic Polymers and Materials - 3-Chloropropyltrimethoxysilane (CPTMS) was grafted on the surface of silica coated Fe3O4 core (Fe3O4@MCM-41) and then condensed with...     

An Efficient and Recyclable Silica Based Inorganic–Organic Hybrid Zinc Catalyst for Transesterification of β-Ketoesters

A new silica based inorganic–organic hybrid zinc catalyst was synthesized and its catalytic activity was investigated for transesterification of β-ketoesters. Polymer supported catalyst was characterized by various techniques such as surface area (BET), elemental and thermogravimetric analyses, FTIR, ¹³C CPMAS spectral studies and atomic absorption spectroscopy (AAS). The reaction proceeded smoothly in the presence of 0.04 mmol of catalyst in toluene at refluxing conditions. The catalyst revealed higher catalytic activity compared to homogeneous catalyst and was reused without appreciable loss in catalytic activity.     

Syntheses and Crystal Structures of Two Inorganic–Organic Hybrid Frameworks Constructed from Pyridine-2,5-Dicarboxylic Acid

Two novel inorganic–organic hybrid frameworks of [Co(2,5-pydc)(4,4′-bipyo)_0.5(H₂O)₃ · 3H₂O] _n (1) and [Cu_1.5Gd(2,5-pydc)₃(2,2′-bipyo)(H₂O)₄ · 2H₂O] _n (2) (2,5-pydc = pyridine-2,5-dicarboxylic acid; 4,4′-bipyo = 4,4′-bipyridine-N,N′-dioxide; 2,2′-bipyo = 2,2′-bipyridine-N,N′-dioxide) were prepared. Both compounds have been characterized by the elemental analyses, IR spectra, TG analysis and the single crystal diffraction. The salient structural feature for both compounds 1 and 2 is that the 1D chain and the mononuclear fragment are connected by strong hydrogen bond interactions to form 2D structure.