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In this work, ammonia intercalated zinc hydroxide chloride hydrate (ZHC-NH3), Zn5(OH)8Cl2.4[(H2O)x(NH3)1-x)] was synthesised using precursor, [ZnCl2.2{HONC(CH3)2}] by sol-gel method in presence of ...

Spray pyrolytic deposition (SPD) of titania films on borosilicate glass substrates has been carried out using oxime-modified titanium(IV) isopropoxide, [Ti(OiPr)2{ONC(CH3)2}2]. Thermal study of the...

In this study, mullitisation at low temperature was observed in an oxime-modified aluminosiloxane precursor [(CH3)2CNO}2Al{OSi(Ph)2O}Al{ONC(CH3)2}2]. Oxime-modified aluminosiloxane was synthesised ...

Decadence of metals is often due to several environmental factors. To prevent the deterioration of metals, a durable epoxy layer of metal oxides is utilized, that provide ultimate resistance and protection against corrosion. These metal oxides can be a monomer or a hybrid polymerized mixture of different components. This paper includes the study of epoxy film on steel to fight against corrosion using metal oxides of cerium ions, titanium dioxide, zinc oxide and graphene oxide and to describe the efficacy of these primers. Different techniques would be used with time monitored process such as Electrochemical studies, salt spray studies, FT-IR, XRD, TEM and XPS analyses that would reveal comparable results.

Synthesis of nanoparticles through biological pathway especially using fungal extracts is gaining attention in the field of nanotechnology due to its economic and ecofriendly nature with wide-ranging antimicrobial performance. In the present study, ZnO nanoparticles were synthesized from white-rot fungus Phanerochaete chrysosporium, using 0.01 M ZnSO4·7H2O and 0.1 N NaOH as precursors. P. chrysosporium is an efficient wood degrading fungus that has majorly two types of extracellular peroxidases; lignin peroxidase (Lip) and manganese peroxidase (MnP). These oxidoreductase enzymes play a major role in the synthesis of ZnO nanoparticles. Glycerol acted as a stabilizer that also regulated the shape and size of the ZnO nanoparticles at room temperature. Addition of glycerol transformed the shape of the ZnO nanoparticles from hexagonal (average size 83.9 nm) to spherical (average size 59.5 nm). These nanoparticles were further characterized by Fourier Transform Infrared spectrum, scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction analysis. ZnO nanoparticles also demonstrated eficient antibacterial activity against Staphylococcus aureus and Escherichia coli under the experimental conditions. Thus, the present study explores the fungal mediated biosynthesis and antibacterial application of ZnO nanoparticles.

Cellulose/PVA/TiO2 nanocomposite (CPT) film was synthesized by the sol-gel method and compared with cellulose/PVA (CP) film. To get CPT film, TiO2 sols was prepared by acetoxime modified titanium (IV) isopropoxide and are blended with cellulose and polyvinyl alcohol (PVA) suspensions in fixed ratios. After drying in a preheated oven, CPT film was obtained. CP film was also prepared by the same procedure in absence of TiO2 sol. Both films were characterized by SEM-EDX, XRD, and FT-IR analysis. SEM images of CPT showed a homogenous distribution of TiO2 particles throughout the film. Both thin films have dense and nonporous morphologies as shown in the SEM images. Thermal studies suggest that CPT film is thermally stable than CP film. The photocatalytic activity of CPT film was assessed by photo-oxidation of methylene blue (MB) under sunlight. The results revealed enhanced photocatalytic activity performance of CPT film, 98.10% MB degradation within 120 min under sunlight.

This analysis is concerned with the investigation of the capability of alumina coating deposited by spray coating method using oxime-modified aluminum(III) isopropoxide as a sol–gel precursor to improve vibration damping and anti-corrosion properties of aluminum alloys. Coating microstructures, thickness and roughness were investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies, respectively. To this end, the quality of the coating was determined by the corrosion rate which was analyzed by mean of electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The vibration and noise technique were applied to measure comparison of vibration and noise damping of bare and alumina coated samples. The results indicate the alumina coating deposited over aluminum alloy by spray coating method is uniform, homogenous, crack free, having high vibration damping and anti-corrosive behavior.

This investigation is concerned with the mechanical property enhancement of the steel alloy by deposition of alumina coating using dip coating method. Alumina coatings were deposited using oxime-modified aluminum(III) isopropoxide as a sol–gel precursor. The Scanning electron microscopy (SEM) images of the coated samples suggest deposition of uniform alumina coatings and alumina composition over steel alloy. The mechanical property of the bare, dip coated steel alloy samples were investigated by the slow strain rate test (SSRT). The SSRT indicates that dip coated steel alloy shows higher ultimate tensile strength as compare to the bare samples.

This work is concerned with the investigation of the capability of alumina coatings, deposited over aluminum alloy by dip coating methods to improve mechanical properties. Alumina coatings were deposited using oxime-modified aluminum (III) isopropoxide as a sol-gel precursor. The Scanning electron microscopy (SEM-EDX) images of the coated samples suggest deposition of uniform and crack free alumina coatings. The mechanical property of the bare, and dip coated aluminum alloy were investigated by the slow strain rate test in 3.5% of NaCl solution. The coated sample indicate higher ultimate tensile strength, it’s reflect the protective behavior of coating.

Dense alumina coatings were fabricated over aluminum alloy via dip coating method using oxime-modified aluminum(III) isopropoxide as a sol–gel precursor. The influence of important dip coating parameter; withdrawal rates on quality, thickness, uniformity and corrosion resistivity of coatings were investigated. Structural characterization of coated substrates were done by X-ray diffraction patterns (XRD), scanning electron microscopy (SEM) and atomic force microscopy studies (AFM). Corrosion tests by electrochemical studies indicated that corrosion resistive alumina coatings can be achieved by using withdrawal rate of 25 mm min–1 and 04 cycles of coatings in 3.5% aqueous NaCl solution.

Alumina coatings are widely used to enhance the wear, abrasion, and corrosion resistance of metal components. This investigation aims at studying the alumina sol-gel coating on the anodized aluminum alloy surface using a dip coating technique. A stable alumina coating was deposited over the anodized aluminum surface using oxime-modified aluminum(III) isopropoxide as sol-gel precursor. The scanning electron microscopy image of the coated anodized sample suggests deposition of a uniform and crack-free aluminum coating. The corrosion resistances of bare, anodized, and coated anodized aluminum alloy samples were investigated by electrochemical impedance spectroscopy and potentiodynamic polarization in 3.5 wt % aqueous NaCl solution. An appreciable shifting was observed in the equilibrium corrosion potential (Ecorr) and the corrosion current density (icorr) values of both anodized and coated anodized samples: i.e. Ecorr: from –1377.11 mV (anodized) to –711.54 mV (coated anodized) and icorr: from 80.37 μA/cm2 (anodized) to 0.090 μA/cm2 (coated anodized). The results clearly indicate the corrosion resistive behavior of nano-alumina coatings.

Zinc(II)/acetoxime system, [ZnCl2.2{HONC(CH3)2}] has been synthesized and studied by single-crystal X-ray diffraction and thermogravimetric analyses. This coordinated complex has been utilized as a potential precursor for photocatalytic and antibacterial zinc oxide nanoparticles (ZnO NPs) by sol–gel method. The powder XRD patterns of the formed ZnO particles suggest formation of a hexagonal phase with an average crystallite size of ~15 nm, which corroborates with TEM analysis. The photocatalytic activity of the synthesized ZnO NPs was examined for the degradation of methylene blue and methyl orange dyes under sunlight. In total, 99.8% of MB and 55.42% of MO were degraded within 160 min of irradiation. The formed ZnO was also explored for its potential to reduce the viability of the Gram-negative bacteria, Escherichia coli and Gram-positive bacteria, Staphylococus aureus. ZnO was found to be a promising antibacterial agent against both the bacteria; however, in the case of E. coli, higher concentration was required (2.5 mg·mL−1) as compared with the S. aureus, where inhibition occurred at low concentration (0.005 mg·mL−1).

Modification of germanium(IV) alkoxides with haloacetic acids in different molar ratios yielded, germanium(IV) alkoxo-halocarboxylates of the type [Ge(OR)4-n(OOCCX3)n] [1-4] [where R = Pri;...

An economic, eco-friendly and efficient synthesis route for Zinc oxide (ZnO) nanoparticles (NPs) using fungus Phanerochaete chrysosporium has been explored along with the single-step impregnation of these nanoparticles on cellulose fibers. The transmission electron microscopy confirmed 50 nm as an average size of ZnO NPs and showed the presence of hexagonal phases. ZnO NPs–cellulose composite was fabricated by amending sugarcane bagasse-extracted cellulose in the reaction mixture during the nanoparticle synthesis. The composite was characterized using Fourier transform infrared, X-ray diffraction patterns, Scanning electron microscopy, and Energy dispersive spectroscopy, thermogravimetric analysis, and also evaluated for its antimicrobial potential. The analyses revealed that well-dispersed hexagonal wurtzite ZnO NPs were present on the surface of the cellulose fibers. ZnO NPs–cellulose demonstrated antibacterial activity against Staphylococcus aureus and Escherichia coli, and antifungal activity against Aspergillus niger, Geotrichum candidum, and Phanerochaete chrysosporium. Thus, the study demonstrated an environmental friendly synthesis of ZnO NPs–cellulose composite using an economic and efficient method, which can be used for developing antimicrobial cellulosic fabric for numerous applications.

In-situ synthesis of zinc oxide modified graphitic carbon nitride composite (in-situ ZnO-g-C3N4) was carried out via a one-step thermal condensation method where [ZnCl2.2{HONC(CH3)2}] was used as a precursor for zinc oxide while urea was taken as a source of g-C3N4. In another synthesis process, urea was also decomposed with ZnO nanoparticles to yield ZnO-g-C3N4 composite and urea alone decomposed to g-C3N4. The in-situ ZnO-g-C3N4 has a higher surface area, 128.68 m2/g as compared to ZnO-g-C3N4 (88.99 m2/g) and g-C3N4 (87.22 m2 /g). The enhanced photocatalytic activity performance of materials against MB i.e. in-situ ZnO-g-C3N4, 99.37%; ZnO-g-C3N4, 97.02% and g-C3N4, 92.12% degradation within 90 minutes in sunlight. The adsorption capacities towards Pb2+, Cd2+ and Cr3+ heavy metal ions on in-situ ZnO-g-C3N4 is 48.144 mg.g-1, 48.883 mg.g-1 and 40.108 mg.g-1; on ZnO-g-C3N4 is 43.043 mg.g-1, 45.005 mg.g-1 and 37.766 mg g-1;and ong-C3N4 is 39.057 mg.g-1, 41.495 mg.g-1 and33.855 mg.g-1.

Волокна целюлози були вилучені з жому цукрової тростини і потім модифіковані наночастинками (НЧ) ZnO за допомогою золь-гель процесу з використанням оксим-модифікованого прекурсора Zn [ZnCl2.2{HONC(CH3)2}] у різних вагових співвідношеннях, щоб зробити їх антимікробними. Модифіковані ZnO волокна целюлози додатково характеризувались інфрачервоною спектроскопією з перетворенням Фур'є (FTIR), рентгенівською дифракцією (XRD) та скануючою електронною мікроскопією (SEM). Отримані результати підтвердили наявність добре диспергованих НЧ гексагонального вюрцита ZnO на поверхні целюлози. Більш низькі значення ширини забороненої зони (2,87-2,48 еВ) спостерігалися в модифікованій ZnO целюлозі в порівнянні з чистими НЧ ZnO (~ 3,3 еВ). Антибактеріальну активність досліджували щодо Staphylococcus aureus і Escherichia coli при різних співвідношеннях (1:1, 1:2 і 1:3) і концентраціях (1,5·200 мг·мл – 1) модифікованої ZnO целюлози. Протигрибкову активність модифікованої ZnO целюлози (1:1) оцінювали щодо Aspergillus niger, Phanerochaete chrysosporium і Geotrichum candidum. Співвідношення 1:1 модифікованої ZnO целюлози при випробуваній концентрації помітно інгібувало ріст міцелію гриба. Протигрибкова ефективність модифікованої ZnO целюлози залежала від концентрації досліджуваного зразка, тому максимальне інгібування росту міцелію відбувалося при найвищій концентрації (5 мг). Cellulose fibers were extracted from sugarcane bagasse and then modified with ZnO nanoparticles (NPs) by a sol-gel process using an oxime modified Zn precursor [ZnCl2.2{HONC(CH3)2}] in different gram ratios to make them antimicrobial. ZnO modified cellulose fibers were further characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) studies. Obtained results confirmed well-dispersed hexagonal wurtzite ZnO NPs onto the surface of cellulose. Lower band gaps (2.87-2.48 eV) were observed in ZnO modified cellulose as compared to pure ZnO NPs (~ 3.3 eV). Antibacterial activities were examined against Staphylococcus aureus and Escherichia coli in different ratios (1:1, 1:2 and 1:3) and concentrations (1.5 to 200 mg·ml – 1) of ZnO modified cellulose. The antifungal activity of ZnO modified cellulose (1:1) was evaluated against Aspergillus niger, Phanerochaete chrysosporium, and Geotrichum candidum. ZnO modified cellulose ratio of 1:1 at the tested concentration remarkably inhibited the mycelial growth of the fungus. The antifungal efficacy of ZnO modified cellulose depended on the concentration of the sample concerned, therefore maximal inhibition of mycelia growth occurred at the highest concentration (5 mg).

Synthesis of mono-crystalline Ga 2 O 3 Nanorods was done by sol-gel transformation of gallium(III) isopropoxide (Ga(OPr i ) 3 ). XRD studies were done to determine the planes and crystal structure of synthesized nanorods that showed the synthesis of β-Ga 2 O 3 (a) . TEM studies of synthesized Ga 2 O 3 confirmed the synthesis of monocrystalline β-Ga 2 O 3 nanorods. To study the effect of precursor chemistry and to determine role of precursor structures on the crystal structure, phase and morphology of the Ga 2 O 3 , a new modified precursor complex was synthesized. The reaction of Ga(OPr i ) 3 with N-phenylsalicylaldimine, [C 6 H 4 (OH)CH=N(C 6 H 5 )] in 1:1 M ratio yielded [{(H 5 C 6 )N = CH-C 6 H 4 O}Ga(OPr i ) 2 ]. The newly synthesized complex was characterized by elemental analyses, molecular weight measurement, FT-IR and NMR ( 1 H and 13 C) spectral studies. Spectral studies of the modified complex suggest the presence of bi-dentate mode of attachment of Schiff's base in the solution state. Sol-gel transformations of [{(H 5 C 6 )N = CH-C 6 H 4 O}Ga(OPr i ) 2 ] in organic medium, yielded γ-Ga 2 O 3 ( b ), as found by XRD studies. TEM image of the sample ( a ) revealed the formation of nano-rods of oxide with average diameter of ~100 nm whereas the TEM image of sample ( b ) showed presence of nano-sized particles of oxide with average particle size of 10 nm. Morphological and compositional studies of synthesized samples (a) and (b) were carried out using SEM and EDX. The method provides a possibility of large scale synthesis of dissimilar shaped and pure Ga 2 O 3 nanoparticles.

Oxime-modified aluminium(III) isopropoxide, [Al(OiPr){ONC(CH3)2}2] was used as a sol-gel precursor to deposit alumina film on steel substrate by dip coating method. The thermogravimetric analysis (TGA) of the above compound indicates its clean one step decomposition to alumina at low temperature, making it a suitable spray pyrolysis deposition (SPD) precursor for deposition of alumina film over steel at 400 °C. The formed alumina films (dip and spray coated) were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy-dispersive X-ray spectroscopic (EDX) techniques. The XRD patterns of the films suggest deposition of amorphous alumina films while the FTIR and EDX analyses indicate the presence of alumina film on steel substrate. SEM images of coated samples indicate deposition of crack-free alumina films. The thickness of alumina films (dip and spray coated) were found to be in the range of ~ 1.4 ± 0.2 μm as indicated by their cross sectional views. The corrosion protection of the deposited alumina films has been checked by the electrochemical studies; open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The electrochemical studies suggest corrosion resistive nature of the alumina film in 3.5% (w/v) NaCl solution.

Semiconductor-based photocatalyst has been used for the degradation of the organic pollutant from wastewater. Metal oxides (ZnO, TiO2) and graphitic carbon nitride (g-C3N4) has been widely used as a catalyst among various semiconductors. However, pure g-C3N4 suffers from significant disadvantages, including poor disparity, low surface area, and high electron-hole pairs recombination, and metal oxides (ZnO and TiO2) are only UV light-responsive, which reduces photocatalytic activity. We have explained various methods for fabrication of ZnO-g-C3N4 and TiO2-g-C3N4 nanocomposite to develop visible light responsive photocatalyst with high surface area, low bandgap, reduce electron-hole pairs recombination, and porous structure. The photocatalytic activity of graphitic carbon-based (ZnO-g-C3N4 and TiO2-g-C3N4) nanocomposites towards organic pollutants are systematically mentioned in this review. The synergetic effect of g-C3N4 and metal oxide in nanocomposite also mention by the photocatalytic mechanism.

Environmental and other chemical factors lead to decimated corrosive behaviour of metallic materials that is a severe hazard and an emerging challenge for times. Different protection strategies have been proposed to suppress this problem and among them graphene based coatings are considered to be great technique against corrosive behaviour because of its hydrophobic properties and ability to provide corrosion resistance of composite material. The incorporation of functional nanoparticles can provide the corrosion resistance to mild steel. It regarded a promising nonmaterial in corrosion protection. Present written text focuses on the preventive applications of graphene based nanomaterials, nanocomposites, polymeric coating techniques and their methods to fight the corrosive act of steel.

Reactions of aluminium(III) iso-propoxide with acetoxime in anhydrous benzene yielded complexes of the type [Al(OiPr)3-n{ONC(CH3)2}n], where n = 1, 2 or 3. These complexes were characterized by elemental analysis, FTIR and NMR (1H, 13C, 27Al) spectral studies. Spectral studies of these complexes suggest the presence of bi-dentate mode of the oximato moieties in the solution state. Soft transformations of aluminium(III) iso-propoxide and their oxime derivatives to pure alumina were carried out by the sol-gel technique. The powder XRD patterns of all the formed alumina suggest formation of cubic phase (γ-alumina) with average crystallites size of 7–30 nm. Optically transparent crack free alumina film was deposited on glass substrate using alumina sol, prepared by complex [Al(OiPr){ONC(CH3)2}], through dip coating method. The film sintered at 500 °C is amorphous in nature as indicated by XRD study. The alumina film is found to be ∼95% optically transparent in the visible region. The observed particle size distribution of alumina thin film in AFM images is found to be 13 ± 2 nm.

Heteroleptic complexes of the type [V(NPh)(O i Pr)3-n {(ONC)(CH3)(C4H3O-2)} n ] {where n = 1 (1), 2 (2) and 3 (3)} were synthesized by the reactions of [V(NPh)(O i Pr)3] (A) with 2-acetylfuryl oxime in different molar ratios in anhydrous benzene. All these new derivatives have been characterized by elemental analyses, Fourier transform infrared spectroscopy, nuclear magnetic resonance (1H, 13C {1H}), 51V) and fast atom bombardment mass spectral studies. Spectral studies appear to be indicating mono-dentate and bi-dentate mode of attachment of the oximato moieties in the solution and solid state, respectively. Fast atom bombardment mass study of one of the representative derivative, [V(NPh){(ONC)(CH3)(C4H3O-2)}3] (3) suggests the monomeric nature of all these complexes. Thermogravimetric curve of [V(NPh){(ONC)(CH3)(C4H3O-2)}3] (3) shows large thermal events. Hydrolysis of [V(NPh)(O i Pr)3] (A) and [V(NPh){(ONC)(CH3)(C4H3O-2)}3] (3) in moist propan-2-ol medium yielded vanadia, (a) and (b), respectively. However, hydrolysis of [V(NPh)(O i Pr)3] (A) in n-hexane medium using calculated amount of water yielded hybrid material, (vn).The presence of (V = NPh) group in (vn) is confirmed by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectral studies as well as by the thermogravimetric study. The X-ray diffraction patterns of vanadia, (a) and (b) indicate formation of orthorhombic phase and the scanning electron microscope images of (a) and (b) show rod like morphology of the crystallites. Absorption spectra of vanadia, (a) and (b) indicate energy band gaps of 2.62 and 2.43 eV, respectively. Heteroleptic complexes of the type [V(NPh)(O i Pr)3-n {(ONC)(CH3)(C4H3O-2)} n ] {where n = 1, 2 and 3} were synthesized by the reactions of [V(NPh)(O i Pr)3] with 2-acetylfuryl oxime. Hydrolysis of [V(NPh)(O i Pr)3] and [V(NPh){(ONC)(CH3)(C4H3O-2)}3] in moist propan-2-ol medium yielded vanadia in orthorhombic phase, whereas, hydrolysis of [V(NPh)(O i Pr)3] in n-hexane medium yielded hybrid material containing (V = NPh) linkages.

Reactions of [Al(OPri)3] with [VO(OPri)3] in presence of halo-acetic acid, CX3COOH in anhydrous benzene yielded complexes of the type, [AlVO(OOCCX3)2(OPri)4], where X = F (1) or Cl (2). The compounds were characterised by elemental analyses, FT-IR and NMR (1H, 27Al & 51V) spectral studies. The desired single-phase aluminium vanadate, AlVO4, (a & b) have been obtained easily from the precursors, (1) and (2), respectively, by the sol-gel process. Formation of triclinic phase in both of the AlVO4 (a & b) samples was confirmed by powder XRD patterns. SEM image of (b) exhibits formation of nano-grains with agglomers like surface morphologies. Composition of AlVO4 sample (b) was investigated by EDX analysis, which shows presence of aluminium and vanadium in 1:1 atomic ratio. Absorption spectra of (a) and (b) samples indicate an energy band gap of 3.60 and 3.75 eV, respectively.

A series of organotin(IV) semicarbazone adducts of the type R2SnCl2·nLH (1–6) were synthesized by the reactions of R2SnCl2 with newly synthesized carvone semicarbazone (LH) in anhydrous ethanol [where R = CH3, n = 1 (1), 2 (2); R = C4H9, n = 1 (3), 2 (4); and R = C6H5, n = 1 (5), 2 (6)]. All the compounds have been characterized by elemental analyses, FT-IR, NMR (1H, 13C, 119Sn) and FAB mass spectral studies. 119Sn NMR studies suggest monodentate mode of attachment of the ligand with central tin atom in the solution state. Thermogravimetric study of (6) shows large thermal events. Transformations of (4) and (6) to pure tin oxides (i and ii, respectively) have been carried out using sol–gel technique. Powder XRD patterns of the formed tin oxides indicate the formation of tetragonal cassiterite structure. SEM images of (i) and (ii) show wire- and grain-like morphologies of the crystallites, respectively. A series of organotin(IV) semicarbazone adducts were synthesized by the reactions of diorganotin dichloride with newly synthesized carvone semicarbazone. Transformations of some of the newly synthesized adducts to pure tin oxides have been carried out using sol–gel technique. Powder XRD patterns of the formed tin oxides indicate the formation of tetragonal cassiterite structure, while SEM images show wire- and grain-like morphologies.

A glycol ether modified precursor, [Nb{O(CH2CH2O)2}(OPri)3] (A) was prepared by the reaction of Nb(OPri)5 with O(CH2CH2OH)2 in 1:1 molar ratio in anhydrous benzene. Further reactions of A with a variety of internally functionalized oximes in different molar ratios, yielded heteroleptic complexes of the type, [Nb{O(CH2CH2O)2}(OPri)3−n{ON = C(CH3)(Ar)}n] (1–9) {where Ar = C4H3O-2, n = 1 [1], n = 2 [2], n = 3 [3]; C4H3S-2, n = 1 [4], n = 2 [5], n = 3 [6]; C5H4N-2, n = 1 [7], n = 2 [8], n = 3 [9]}. All the above derivatives have been characterized by elemental analyses, FT-IR, NMR (1H, 13C {1H}) and FAB mass studies. Spectral studies of 1–9 suggest the presence of mono- and bi-dentate mode of oxime moieties, in the solution and in the solid states, respectively. FAB mass studies indicate monomeric nature for 3 and dimeric nature for A. TG curves of A and 6 show their low thermal stability. Soft transformation of A and 3 to pure niobia, a and b, respectively have been carried out by sol–gel technique. The XRD patterns of niobia a and b suggest the formation of nano-size crystallites of average size of 10.8 and 19.5 nm, respectively. The XRD patterns also indicate the formation of monoclinic phase of the niobia in both the cases. Absorption spectra of a and b suggest energy band gaps of 4.95 and 4.39 eV, respectively.

Some bis(cyclopentadienyl)titanium(IV) complexes of the type [Cp2TiCl2−n{L}n] {where, n = 1 or 2; L = ONC(R)Ar; R = H or CH3 and Ar = C5H4N-2, C4H3O-2 or C4H3S-2} have been synthesized by the metathetical reactions of Cp2TiCl2 with the sodium salt of internally functionalized oximes in 1:1 and 1:2 stoichiometry in anhydrous THF. All these red to brown colored solid derivatives have been characterized by elemental analyses, FT-IR and NMR (1H and 13C{1H}) spectral studies. The FAB mass spectra of some representative derivatives indicate their monomeric nature. Oximato ligands in all the complexes appear to bind the titanium via N and O in a dihapto (-N, O) manner in the solid state. Thermogravimetric curves of [Cp2TiCl{ONC(CH3)C5H4N-2}] and [Cp2Ti{ONC(CH3)C5H4N-2}2] suggest the formation of hybrid materials CpTiO(Cl) and Cp2TiO, respectively, as the final products at 900 °C under nitrogen atmosphere. Sol–gel transformations of Cp2TiCl2, [Cp2TiCl{ONC(CH3)C5H4N-2}] and [Cp2Ti{ONC(CH3)C5H4N-2}2] yielded titania a–c, respectively, at low sintering temperature (600 °C). The powder XRD patterns, IR as well as Raman spectra of all these oxides indicate the formation of nano-sized anatase phase. The SEM images of titania a–c indicate agglomers like surface morphologies. The absorption spectra of a–c exhibit an energy band gap in the range of 3.47–3.71 eV. Copyright © 2011 John Wiley & Sons, Ltd.

Germanium tetra(tertiary butoxide), [Ge(O t Bu) 4 ], has been prepared by the reaction of GeCl 4 with KOBu t in benzene. It is a monomeric crystalline solid having a distorted tetrahedral configuration, defined by the coordination of four OBu t groups around germanium atom. The TG analysis showed that the compound is thermally stable and volatilizes at around 130 °C. Europium doped and un-doped germanium oxide nanoparticles were prepared based on the urea hydrolysis of Ge(O t Bu) 4 /Eu(OOCCH 3 ) 3 in ethylene glycol medium at 150 °C followed by heating the resulting product at 750 °C. The nanoparticles were characterized by XRD, TEM and PL measurements. The europium doped nanoparticles, which were nearly monodispersed (∼30 nm), showed luminescence and the Eu 3+ ions were occupying the surface of the GeO 2 nanoparticles.

Reaction of [VO(OPr i )3] (1) with [O(CH2CH2OH)2] in 1:1 molar ratio in anhydrous benzene yield glycol-modified precursor, [VO{OCH2CH2OCH2CH2O}{OPr i }] (2). Further reactions of (2) with internally functionalized oximes in anhydrous benzene yield heteroleptic complexes of the type [VO{OCH2CH2OCH2CH2O}{ON=C(R)(Ar)}] (3–8) {where R=CH3, Ar=C4H3O-2 (3), C4H3S-2 (4), C5H4N-2 (5); and when R=H, Ar=C4H3O-2 (6), C4H3S-2 (7), C5H4N-2 (8)}. All these derivatives have been characterized by elemental analyses, molecular weight measurements and spectroscopic techniques. The crysoscopic molecular weight measurement as well as FAB mass study suggests dimeric nature of (2). However, FAB mass spectrum of (4), and the crysoscopic molecular weight measurements of (3), (4), (5) and (6) indicate the monomeric behavior of the oximato derivatives (3–8). Hexa-coordination around vanadium(V) has been proposed for both monomeric and dimeric derivatives. Sol–gel transformations of (1), (2) or (4) to vanadia [(a), (b) or (c), respectively] have been carried out at low sintering temperature (600 °C). The XRD patterns of (a), (b) or (c) indicate formation of a single orthorhombic phase in all the three cases. The SEM images suggest grain like [for (a) and (b)] and rod like [for (c)] morphology of the crystallites. IR, Raman spectra as well as EDX analyses indicate formation of pure vanadia. Absorption spectra of the vanadia (b) and (c) suggest energy band gaps of 2.53 and 2.65 eV, respectively.

Ti(OPri)4 reacts with HOSi(OtBu)3 in anhydrous benzene in 1:1 and 1:2 molar ratios to afford alkoxy titanosiloxane precursors, [Ti(OPri)3{OSi(OtBu)3}] (A) and [Ti(OPri)2{OSi(OtBu)3}2] (B), respectively. Further reactions of (A) or (B) with glycols in 1:1 molar ratio afforded six complexes of the types [Ti(OPri)(O–G–O){OSi(OtBu)3}] (1A–3A) and [Ti(O–G–O){OSi(OtBu)3}2] (1B–3B), respectively [where G = (CH2)2 (1A, 1B); (CH2)3 (2A, 2B) and {CH2CH2CH(CH3)} (3A, 3B)]. Both (A) and (B) are liquids while all the other products are viscous liquids which get solidified on ageing. Cryoscopic molecular weight measurements of the fresh products indicate their monomeric nature. FAB mass studies of (A) and (B) also indicate monomeric nature. However, FAB mass spectra of the two representative solids (1A) and (2B) suggest dimeric behavior of the glycolato derivatives. (A) distills at 85 °C/5 mm while other products get decomposed even under reduced pressure. TG analyses of (A), (B), (1A), and (1B) suggest formation of titania–silica materials at 200 °C for (A) and (B) and 350 °C for (1A) and (1B). The products have been characterized by elemental analyses, FTIR and 1H, 13C & 29Si-NMR techniques. All these products are soluble in common organic solvents indicating a homogenous distribution of the components on the molecular scale. The Si/Ti ratio of the oxide may be controlled easily by the composition of the starting precursors. Hydrolysis of the glycol modified derivative, (1A) by the Sol–Gel technique affords the desired homogenous titania–silica material, TiO2·SiO2 in nano-size while, the precursor (A) yields a non-stiochiometric silica doped titania material. However, pyrolysis of (A) yields nano-sized crystallites of TiO2·SiO2. All these materials were characterized by FTIR, powder XRD patterns, SEM images, and EDX analyses.

Reactions of Me 2 SiCl 2 in a 1:2 molar ratio with internally functionalized oximes in the presence of Et 3 N in anhydrous benzene afford compounds of the type [Me 2 Si{ON C(R)Ar} 2 ] {where R = Me, Ar = 2-C 5 H 4 N ( 1 ), 2-C 4 H 3 O ( 2 ), 2-C 4 H 3 S ( 3 ); R = H, Ar = 2-C 5 H 4 N ( 4 ), 2-C 4 H 3 O ( 5 ), 2-C 4 H 3 S ( 6 )}. Molecular weight measurements of all these derivatives in freezing benzene and the FAB mass spectral studies of 1 and 6 indicate that these complexes are monomeric. The 1 H and 13 C{ 1 H} NMR spectra suggest that the oximate moieties are monofunctional monodentate in solution. 29 Si{ 1 H} NMR signals appear in the region expected for tetra-coordinated dimethyl silicon atoms. Single crystal X-ray diffraction analysis of [Me 2 Si{ON C(H)C 4 H 3 O-2} 2 ] ( 5 ) confirms the presence of a distorted tetrahedron as the immediate environment around silicon. Secondary weak β-donor bonding is also observed in the solid state, indicating that silicon is in the (4+2) coordination state. The TGA curve of [Me 2 Si{ON C(H)C 4 H 3 O-2} 2 ] shows the high thermal stability and volatile nature of the complex. A comparison of hydrolytic studies of a mixture of [Me 2 Si{ON C(CH 3 )C 4 H 3 O-2} 2 ] and Al(OPr i ) 3 in a 1:2 molar ratio with those of pure Al(OPr i ) 3 under similar conditions by the sol–gel technique suggests the formation of a silicon embedded amorphous powder 7 and γ-alumina 8 , respectively. The variation in specific surface area, total pore volume and pore size indicate formation of mesoporous materials.

[Zr(OPr(i))(4)·Pr(i)OH] reacts with [HOSi(O(t)Bu)(3)] in anhydrous benzene in 1:1 and 1:2 molar ratios to afford alkoxy zirconosiloxane precursors of the types [Zr(OPr(i))(3){OSi(O(t)Bu)(3)}] (A) and [Zr(OPr(i))(2){OSi(O(t)Bu)(3)}(2)] (B), respectively. Further reactions of A or B with glycols in 1:1 molar ratio afforded six chemically modified precursors of the types [Zr(OPr(i))(OGO){OSi(O(t)Bu)(3)}] (1A-3A) and [Zr(OGO){OSi(O(t)Bu)(3)}(2)] (1B-3B), respectively [where G = (-CH(2)-)(2) (1A, 1B); (-CH(2)-)(3) (2A, 2B) and (-CH(2)CH(2)CH(CH(3)-)} (3A, 3B)]. The precursors A and B are viscous liquids, which solidify on ageing whereas the other products are all solids, soluble in common organic solvents. These were characterized by elemental analyses, molecular weight measurements, FAB mass, FTIR, (1)H, (13)C and (29)Si-NMR studies. Cryoscopic molecular weight measurements of all the products, as well as the FAB mass studies of 3A and 3B, indicate their monomeric nature. However, FAB mass spectrum of the solidified B suggests that it exists in dimeric form. Single crystal structure analysis of [Zr{OSi(O(t)Bu)(3)}(4)(H(2)O)(2)]·2H(2)O (3b) (R(fac) = 11.9%) as well as that of corresponding better quality crystals of [Ti(O(t)Bu){OSi(O(t)Bu)(3)}(3)] (4) (R(fac) = 5.97%) indicate the presence of a M-O-Si bond. TG analyses of 3A, B, and 3B indicate the formation of zirconia-silica materials of the type ZrO(2)·SiO(2) from 3A and ZrO(2)·2SiO(2) from B or 3B at low decomposition temperatures (≤200 °C). The desired homogenous nano-sized zirconia-silica materials [ZrO(2)·nSiO(2)] have been obtained easily from the precursors A and B as well as from the glycol modified precursors 3A and 3B by hydrolytic sol-gel process in organic media without using any acid or base catalyst, and these were characterized by powder XRD patterns, SEM images, EDX analyses and IR spectroscopy.

Reactions of [Ti(OPr(i))(4)] with various oximes, in anhydrous refluxing benzene yielded complexes of the type [Ti{OPr(i)}(4-n)(L)(n)], where, n = 1-4 and LH = (CH(3))(2)C=NOH (1-4), C(9)H(16)C=NOH (5-8) and C(9)H(18)C-=NOH (9-12). The compounds were characterized by elemental analyses, molecular weight measurements, FAB-mass, FT-IR and NMR ((1)H, (13)C{(1)H}) spectral studies. The FAB-mass spectra of mono- (1), and di- (2), (6), (10) substituted products indicate their dimeric nature and that of tri- (3) and tetra- (4), (8) substituted derivatives suggest their monomeric nature. Crystal and molecular structure of [Ti{ONC(10)H(16)}(4)center dot 2CH(2)Cl(2)] (8A) suggests that the oximato ligands bind the metal in a dihapto eta(2)-(N, O) manner, leading to the formation of an eight coordinated species. Thermogravimetric curves of (3), (6) and (10) exhibit multi-step decomposition with the formation of TiO(2) as the final product in each case, at 900 degrees C. Low temperature (similar to 600 degrees C) sol-gel transformations of ( 2), (3), (4), (6), (7) and (8) yielded nano-sized titania (a), (b), (c), (d), (e) and (f), respectively. Formation of anatase phase in all the titania samples was confirmed by powder XRD patterns, FT-IR and Raman spectroscopy. SEM images of (a), (b), (c), (d), (e) and (f) exhibit formation of nano-grains with agglomer like surface morphologies. Compositions of all the titania samples were investigated by EDX analyses. The absorption spectra of the two representative samples, (a) and (f) indicate an energy band gap of 3.17 eV and 3.75 eV, respectively. (C) 2010 Elsevier Ltd. All rights reserved.