Influence of aging time of the starting solution on the physical properties of fluorine doped zinc oxide films deposited by a simplified spray pyrolysis technique

Fluorine doped zinc oxide (FZO) films were fabricated from fresh and aged (4, 8, 12 and 16 days) starting solutions using a simplified and low cost spray pyrolysis technique. The X-ray diffraction study showed that the preferential orientation is along the (0 0 2) plane for all the films irrespective of the age of the solution. The crystallite size calculated using the Scherrer’s formula is comparatively smaller only for the film prepared from the starting solution having aging time 4 days which may be due to the efficient incorporation of fluorine atoms into the ZnO lattice. This phenomenon is confirmed by the minimum resistivity value (3.14 × 10⁻² Ω cm) obtained in this particular case. The visible transmittance and the optical band gap values are found to be in the range of 63–83% and 3.20–3.31 eV, respectively. The optical transmittance is found to decrease gradually as the aging time of the solution increases and the optical band gap is found to be slightly higher in the case of the film prepared from the fourth day solution. The scanning electron microscopy results depicted that the microstructure of ZnO:F films are largely influenced by the aging of the starting solution.     

Low-temperature deposition and crystallization of RuO2/TiO2 on cotton fabric for efficient solar photocatalytic degradation of o-toluidine

A green low-temperature deposition and crystallization method was developed to uniformly coat RuO₂/TiO₂ nanocomposite onto cotton fabrics for efficient solar photocatalysis. The sequential growth of anatase TiO₂ and rutile RuO₂ on the surface of the cotton was confirmed by XRD, Raman and XPS characterizations. After the deposition of RuO₂, the optical properties of RuO₂/TiO₂/Cotton revealed better visible light absorption and higher charge mobility, and XPS spectra showed that the peaks of Ti 2p_3/2 and O 1 s shifted towards the lower binding energies due to the interfacial charge transfer at the robust RuO₂/TiO₂ mediated with Ti–O–Ru bonding. The photocatalytic performances of the RuO₂/TiO₂/Cotton were evaluated towards the photodegradation of o-toluidine (o-TD), an aromatic amine widely used in the chemical industry. Compared with TiO₂/Cotton, RuO₂/TiO₂/Cotton exhibited a remarkable improvement in the photocatalytic activity. The presence of RuO₂ on the surface of TiO₂/Cotton narrowed the band gap and improved the absorption of visible light. Moreover, the successful formation of a robust heterogeneous interface between TiO₂ and RuO₂ suppressed the charge carrier (e^–/h⁺) recombination effectively. With the RuO₂/TiO₂ coating chemically bound to the cotton fibers, RuO₂/TiO₂/Cotton delivered long-term stability in photocatalytic activity and high mechanical durability even after 20 washing times. Our facile and scalable synthesis strategy paved a universal route to efficient immobilization of visible-light-responsible TiO₂-based photocatalysts on the low-heat-resistant substrates for various applications.

Graphical abstract

     

Anisotropic Mössbauer elastic scattering fraction of partially (47%) disordered polyvinylidene fluoride (PVF2)

The temperature dependent longitudinal and transverse Mossbauer elastic scattering fraction (MESF) of 47% disordered PVF₂ have been computed using anisotropic dynamical model valid for polymer of any degree of crystallinity. The calculated values show a marked anisotropy between the longitudinal and transverse fractions which can be easily observed.     

An unusual reductive cyclization

Li-NH₃ reduction of 1α-Ethynyl-1β-hydroxy-6-oxo-8a-methyl-1,2,3,4,6,7,8,8a octahydronaphthalene 5 furnishes, in addition to reported products, the tricyclic compound $\text{8}$.     

NaIO4/KI/NaCl: a new reagent system for iodination of activated aromatics through in situ generation of iodine monochloride

A new reagent system consisting of NaIO₄/KI/NaCl in aq AcOH has been found to be effective in iodinating a variety of activated aromatic substrates via in situ-generated iodine monochloride, to furnish iodoaromatics in excellent yields. This iodination procedure has been applied successfully for a cost-effective synthesis of 3,3′-diaminobenzidine, a key intermediate for preparing proton conducting membranes for fuel cell applications, with high yield and a purity of 99.7%.     

Synthesis of ethyl-α- propargyl acrylate - a useful five carbon synthon

The title compound has been synthesised via an alkylation, Wittig-Horner reaction sequence, Michael addition of several active methylene substrates with compound 1 has been carried out.     

Vertex 2-isomorphism

Whitney's theorem on 2-isomorphism characterizes the set of graphs having the same cycles as a given graph, where a cycle is regarded as a set of edges. In this paper, vertex 2-isomorphism is defined and used to prove a vertex analogue of Whitney's theorem. The main theorem states that two connected graphs have the same set of cycles, where a cycle is now regarded as a set of vertices, if and only if one can be obtained from the other by a sequence of simple operations. © 1992 John Wiley & Sons, Inc.     

Dual Fluorescence and Photoprototropic Characteristics of 2-Aminodiphenylsulphone-β-Cyclodextrin Inclusion Complex

The absorption and fluorescence spectral characteristics of 2-aminodiphenylsulphone (2ADPS) have been investigated in the presence of β-cyclodextrin (β-CDx) in water. Dual emission is observed upon the complexation of 2ADPS in β-CDx. The stoichiometry of the host:guest inclusion complex is found to be 2:1. Steady state and time-resolved fluorescence spectral analysis support the formation of 2:1 complex between β-CDx and 2ADPS. The large enhancement in fluorescence intensity of twisted intramolecular charge transfer (TICT) band in aqueous β-CDx solution is due to the decrease in non-radiative processes. The ground and the excited state pK_a values for the monocation-neutral equilibrium of 2ADPS in β-CDx are found to be different from the pK_a values in aqueous solution. In the presence of β-CDx, 2ADPS is found to be less basic in the ground and the excited states.     

The Mukaiyama-Michael addition of a β,β-dimethyl substituted silyl ketene acetal to α,β-unsaturated ketones using tetra-n-butylammonium bibenzoate as a nucleophilic catalyst

The Michael addition of a β,β-dimethyl substituted silyl ketene acetal [Me₂CC(OMe)OSiMe₃] to α,β-unsaturated ketones, namely, 2-cyclopentenone, 2-cyclohexenone, 3-methyl-2-cyclohexenone, isophorone, methyl vinyl ketone and mesityl oxide occurs smoothly in the presence of the nucleophilic catalyst, tetra-n-butyl ammonium bibenzoate (TBABB) in THF giving the corresponding 1,4-adducts in excellent yields.