Tin Oxide Nanoparticles and SnO2/SiO2Hybrid Materials by Twin Polymerization Using Tin(IV) Alkoxides

Novel electroblowing synthesis of tin dioxide and composite tin dioxide/silicon dioxide submicron fibers for cobalt(ii) uptake

Nanoscale SnO2 has many important properties ranging from sorption of metal ions to gas sensing. Using a novel electroblowing method followed by calcination, we synthesized SnO2 and composite SnO2/SiO2 submicron fibers with a Sn : Si molar ratio of 3 : 1. Different calcination temperatures and heating rates produced fibers with varying structures and morphologies. In all the fibers SnO2 was detected by XRD indicating the SnO2/SiO2 fibers to be composite instead of complete mixtures. We studied the Co2+ separation ability of the fibers, since 60Co is a problematic contaminant in nuclear power plant wastewaters. Both SnO2 and SnO2/SiO2 fibers had an excellent Co2+ uptake with their highest uptake/K d values being 99.82%/281 000 mL g-1 and 99.79%/234 000 mL g-1, respectively. Compared to the bare SnO2 fibers, the SiO2 component improved the elasticity and mechanical strength of the composite fibers which is advantageous in dynamic column operation.

Stabilizing γ-Alkyltin-Oxo Keggin Ions by Borate Functionalization

We report a hierarchical self-assembly engineering of tin-oxo clusters from nanosized hydrophobic clusters to a single-layer film of assembled clusters. These clusters are derivatives of the previously reported Na-centered butyltin Keggin ions, but they are bicapped with butyltin and with borate ligands. The formulas γ-[( n-BuSn)₁₄(OCH₃)₁₀(OH)₃O₉(NaO₄)(HBO₃)₂] and γ-[( n-BuSn)₁₄(OCH₃)₁₀(OH)₃O₉(NaO₄)(PhBO₂)₂] were determined from single-crystal X-ray diffraction and bulk solution characterization including small-angle X-ray scattering, electrospray ionization mass spectrometry, and multinuclear and multidimensional NMR (¹¹⁹Sn, ¹³C, and ¹H). Solution characterization confirms that borate functionalization inhibits the solution-phase β-γ Keggin isomer interconversion that was recognized prior for uncapped butyltin clusters, and in this case, the γ isomer is favored. The assembly of the γ-NaSn₁₄BO₃ clusters into a homogeneous Langmuir-Blodgett monolayer is the first step toward creating nanopatterned films for microelectronic devices.

Spirocyclic tin salicyl alcoholates - a combined experimental and theoretical study on their structures, 119Sn NMR chemical shifts and reactivity in thermally induced twin polymerization

The spirocyclic tin salicyl alcoholate, 4H,4'H-2,2'-spirobi[benzo[d][1,3,2]dioxastannine] (1), and its 6,6'-dimethoxy (2) and 8,8'-di-tert-butyl-6,6'-dimethyl derivative (3) were synthesized and thermally induced twin polymerization of precursor 2 was performed to give a SnO2-containing hybrid material. Studies on the molecular structures of 1-3 were carried out using 119Sn{1H} CP MAS NMR spectroscopy and DFT calculations. Crystallization of compound 3 from dimethyl sulfoxide solution provided the Lewis acid-base adduct 3(dmso)2 exhibiting a hexacoordinated tin atom in the solid state, in agreement with the results of the spectroscopic and DFT calculation data. 119Sn NMR spectroscopy of the compounds 1-3 and 3(dmso)2 revealed equilibria among the diverse oligomers in solution phase pointing at hexacoordinated tin atoms.

Chiral molecular fluoridosilicates and their twin polymerization for the preparation of fluorine-doped mesoporous silica and microporous carbon

The synthesis of organic–inorganic hybrid materials, microporous carbon and fluorine-doped mesoporous silica by the twin polymerization of pentacoordinated fluoridosilicates is reported.

Electronic Structure Calculations and Experimental Studies on the Thermal Initiation of the Twin Polymerization Process

Presented here is a combined computational and experimental study on the thermal initiation process of the twin polymerization. Although thermally initiated twin polymerization offers a versatile scheme for obtaining hybrid organic/inorganic nanocomposite materials, the mechanism for its initiation is very different from the proton-initiated twin polymerization. In this study, the basic mechanism of the early steps of the polymerization process of 4 H,4 H'-2,2'-spirobi[benzo[d][1,3,2]dioxasiline] was investigated by using electronic structure calculations in conjunction with experimental differential scanning calorimetry studies. This way, the influences on the thermally initiated twin polymerization process could be analyzed in detail. The previous mechanistic hypotheses are systematically assessed herein to show that, based on the results, a new hypothesis for an initiation mechanism can be formulated that is in agreement with all experimental observations. These results suggest that, before the formation of the polymer networks, the thermal initiation starts with the formation of low-molecular-weight fragments that react to yield acidic groups. If a sufficient amount of these form, the reaction is ultimately funneled into a mechanism similar to that of proton-initiated twin polymerization.

From molecular germanates to microporous Ge@C via twin polymerization

Four molecular germanates based on salicyl alcoholates, bis(dimethylammonium) tris[2-(oxidomethyl)phenolate(2-)]germanate (1), bis(dimethylammonium) tris[4-methyl-2-(oxidomethyl)phenolate(2-)]germanate (2), bis(dimethylammonium) tris[4-bromo-2-(oxidomethyl)phenolate(2-)]germanate (3) and dimethylammonium bis[2-tert-butyl-4-methyl-6-(oxidomethyl)phenolate(2-)][2-tert-butyl-4-methyl-6-(hydroxymethyl)phenolate(1-)]germanate (4), were synthesized and characterized including single crystal X-ray diffraction analysis. In the solid state, compounds 1 and 2 exhibit one-dimensional hydrogen bonded networks, whereas compound 4 forms separate ion pairs, which are connected by hydrogen bonds between the dimethylammonium and the germanate moieties. The potential of these compounds for thermally induced twin polymerization (TP) was studied. Germanate 1 was converted by TP to give a hybrid material (HM-1) composed of phenolic resin and germanium dioxide. Subsequent reduction with hydrogen provided a microporous composite containing crystalline germanium and carbon (Ge@C -C-1, germanium content ∼20%). Studies on C-1 as an anode material for Li-ion batteries revealed reversible capacities of ∼370 mA h gGe@C(-1) at a current density up to 1384 mA g(-1) without apparent fading for 500 cycles.

New sterically hindered tin(iv) siloxane precursors to tinsilicate materials: synthesis, spectral, structural and photocatalytic studies

A series of sterically hindered tin(iv) siloxanes (1–8) were synthesized and characterized. The single-source precursors1and3were well suited for producing tinsilicate materials and it act as a photocatalyst for degradation of methylene blue.

Mesoporous SnO2–SiO2 and Sn–silica–carbon nanocomposites by novel non-hydrolytic templated sol–gel synthesis

A novel non-hydrolytic sol–gel (NHSG) synthesis of mesoporous tin silicate xerogels is presented.

Twin Polymerization--a New Principle for Hybrid Material Synthesis

Twin polymerization is a novel modular approach for the synthesis of hybrid materials. Using this strategy two distinct polymers of either inorganic or organic nature are produced from a single source monomer in a mechanistically coupled process. Twin polymerization is an elegant way for producing nanostructured organic-inorganic hybrid materials of composition and morphology on demand. The main objective of this Review is the explanation of the principle of various twin polymerization processes and their appropriate terminologies. Different types of twin polymerization are classified with respect to the underlying processes as described in individual examples, demonstrating its potential in material synthesis. Prospects of the synthetic methodology of twin polymerization are demonstrated for different molecular structures of twin monomers and the resulting hybrid materials. A comparison with other scenarios for the synthesis of two different polymers within one procedure is included.

Zirconium and Hafnium Twin Monomers for Mixed Oxides

The synthesis of Zr and Hf twin monomers of type [M(2-OCH₂ ^c C₄ H₃ O)₄ (x HOCH₂ ^c C₄ H₃ O)] (3, M=Zr, x=0; 4, M=Hf, x=1) and M[(2-OCH₂ -C₆ H₄ O)₂ (2-HOCH₂ -C₆ H₄ OH)] (5, M=Zr; 6, M=Hf) by reacting M(OR)₄ (M=Zr, R=ⁿ C₃ H₇ , 1; M=Hf, R=ⁿ C₄ H₉ , 2) with 2-furylmethanol or 2-hydroxybenzyl alcohol is discussed. Complexes 3-6 were homopolymerized under acidic conditions. Additionally, 5 and 6 were copolymerized with 2,2'-spirobi[4 H-1,3,2-benzodioxasiline] (SBS). Under acidic conditions SBS forms a phenolic resin/SiO₂ nanostructured material. The resulting hybrid materials from the homopolymerization of 3-6 and the copolymerized materials from 5 and 6 were characterized by standard solid-state analytics. The inorganic lattice of the MO₂ materials from the homopolymerized complexes 3-6 and SiO₂ /MO₂ from the copolymerization of 5 and 6 with SBS was obtained by air oxidation. The oxide materials were characterized by X-ray powder diffraction (XRPD) and energy-dispersive X-ray analysis, which proved their identity. The inner surface area was determined by N₂ adsorption/desorption studies, which revealed surface areas of 100 m²  g^-1 for MO₂ . The mixed oxides SiO₂ /MO₂ were additionally investigated by differential scanning calorimetry and variable-temperature XRPD to study the thermal behavior. It was found that crystallization of tetragonal MO₂ nanoparticles is characteristic within the SiO₂ matrix, but higher sintering temperatures caused crystallization of the SiO₂ lattice.