DFT Study of PH3 Physisorption and Chemisorptions on Boron Nitride Nanotubes

The adsorption of PH₃ molecules on the NiB,N-doped(4,4) and (5,5) BNNT_S surfaces has been investigated using density functional theory (DFT). The adsorption energies, geometric and electronic structures of the adsorbed systems were studied to judge the possible application of NiB,N-doped BNNT_S in PH₃ monitoring systems. Our calculated results showed that NiB,N-doped BNNT_S had much higher adsorption energy and shorter binding distances than pure BNNT_S owning to chemisorptions of the PH₃ molecule. The obtained density of states (DOS) and frontier orbitals demonstrated that the orbital hybridization was obvious between the PH₃ molecule and Ni_B,N-doped BNNT_S. However, due to weak physisorption according to the total electron density maps, there was no evidence for hybridization between PH₃ molecule and pure BNNTS. It was shown that after doping of Ni atom, the primary symmetry of BNNT_S decreased which enhanced the chemical activity of BNNT_S towards PH₃ molecules. According to the obtained results, we highlight the high potential application of Ni_B,N-doped BNNT_S in the design and fabrication of PH₃ sensing devices.

     

Highly stable copper/carbon dot nanofluid

Copper/carbon dot nanohybrids (Cu/CD NHs) were prepared via a facile precipitation method through a disproportionation reaction. The surface characterization was performed by various techniques such as XRD, FTIR and TEM. Then, water-based nanofluids composed of Cu/CD NHs at 0.1 and 0.5 mass% were prepared, and their thermo-physical properties including thermal conductivity, viscosity, density and specific heat were evaluated at various temperatures. The water-based Cu/CD nanofluid demonstrated to be a potential heat transfer fluid with a high stability. It was found that the thermal conductivity can be enhanced by increasing the nanoparticle concentration and temperature. Almost 1.25-fold increase in thermal conductivity has been achieved by raising the temperature up to 50 °C and at the concentration of 0.5 mass%. The heat capacity was found to increase with increasing concentration. Moreover, by increasing temperature the density and viscosity of the as-prepared nanofluid decreased, whereas the heat capacity showed an increasing trend.     

Comprehensive studies on polymer electrolyte and dye-sensitized solar cell developed using castor oil-based polyurethane

Comprehensive characterization of new polymer electrolyte system prepared using polyurethane derived from castor oil polyol was undertaken. The castor oil polyol was synthesized via transesterification and reacted with 4,4′-diphenylmethane diisocyanate to form polyurethane. Polyurethane electrolyte films were prepared by addition of sodium iodide in different weight percentage with respect to the weight of the polymer. The electrolyte films were analyzed using Fourier transform infrared spectroscopy, dynamic mechanical analysis, electrochemical impedance spectroscopy, transference number measurement, and linear sweep voltammetry. Fourier transform infrared spectroscopy results confirmed the complexation between polymer and salt. Tan delta peak observed in the tan δ–temperature curve plotted using data obtained from dynamic mechanical analysis indicated that the glass transition temperature of polyurethane decreased with the addition of sodium iodide. The highest conductivity of 4.28 × 10^?7 S cm^?1 was achieved for the film with 30 wt% of sodium iodide. The performances of dye-sensitized solar cell using the electrolyte systems were analyzed in terms of short-circuit current density, open-circuit voltage, fill factor, and energy conversion efficiency. The polymer electrolyte with 30 wt% sodium iodide showed the best performance with energy conversion efficiency of 0.80%.     

Crystal structure of diheterolevulosan II: α-d-Fructofuranose-β-d-fructopyranose 1,2′:2,1′ dianhydride and molecular mechanics calculations on diheterolevulosan II and IV with chair and boat conformations of the central 1,4-dioxane ring

C₁₂H₂₀O₁₀,M _r=324.28, orthorhombic,P2₁2₁2₁,a=9.4476(8),b=10.2247(8),c=13.5827(11) Å,V=1312.07(18) ų,Z=4,D _x=1.642 g cm^?3, MoKα radiation (λ=0.71073 Å)μ=1.4 cm^?1,F(000)=688,T=295 K, finalR=0.041 for 1089 reflections withI≥2.5σa(I). The molecule consists of aβ-d-fructopyranose and a α-d-fructofuranose ring which are linked by a 1,4-dioxane ring. The pyranose ring and the dioxane ring both have a chair conformation, and the furanose ring has an envelope conformation. All six hydroxyl groups act as donors in intermolecular hydrogen bonding. Each molecule is hydrogen-bonded to eight neighbor molecules by fourteen hydrogen bonds, forming a three-dimensional framework. The hydrogen bonds of varying geometry give rise to five sharp hydroxyl stretch vibrations in the infrared spectrum. In diheterolevulosan IV the central dioxane ring is a boat. Molecular mechanics calculations on diheterolevulosan II and IV having different boat and chair conformations of the dioxane ring show that the lowest energy conformations correspond to the conformations observed in the crystal structure. For comparison the calculations also have been applied to 1,4-dioxane having boat and chair conformations.     

Electrical and optical properties of Cd1−xZnxS (0x0.18) grown by chemical bath deposition

Cd_1−xZn_xS films with 0x0.18 were grown by chemical bath deposition technique on glass substrates from an aqueous solution containing cadmium and zinc sulfate, ammonia and thiourea. Microstructural features, obtained from X-ray diffraction and scanning electron microscopy (SEM) measurements, reveal a predominance of Wurtzite structure and an homogenous microstructure formed by densely microcrystallines for all the samples studied. Cd_1−xZn_xS semiconductor was found to be resistive and of n-type. Also, the electron density decreases with increased x and the mobility reaches a maximum around x=0.12. Which means that the Cd_1−xZn_xS films at this composition are of high crystalline quality, i.e. having reduced intrinsic defect concentrations.     

Effect of dual fullerenes on lifetimes of charge-separated States of subphthalocyanine-triphenylamine-fullerene molecular systems

Photoinduced intramolecular electron-transfer events of the newly synthesized subphthalocyanine-triphenylamine-fullerene triad (SubPc-TPA-C60) and subphthalocyanine-triphenylamine-bisfullerene tetrad (SubPc-TPA-(C(60))(2)) were studied. The geometric and electronic structures of the triad were probed by ab initio B3LYP/3-21G method, which predicts SubPc-TPA(*+)-C(60)(*-) as a stable charge-separated state. The photoinduced events via the excited singlet state of SubPc were monitored by time-resolved emission measurements as well as transient absorption techniques. Efficient charge-separations via the excited states of SubPc were observed with the rates of approximately 10(10) s(-)1. Compared with the SubPc-TPA dyad, a long-lived charge-separated state was observed for the SubPc-TPA-C(60) triad with the lifetime of the radical ion pairs (tau(RIP)) of 670 ns in benzonitrile. Interestingly, further charge stabilization was achieved in the charge-separated state of SubPc-TPA-(C(60))(2), in which the tau(RIP) was found to be 1050 ns in benzonitrile.     

A three‐dimensional net of Δ‐tris(1,10‐phenanthroline)ruthenium(II) in the dual‐metal self‐assembly of bis[tris(1,10‐phenanthroline)ruthenium(II)] tetraisothiocyanatoiron(II) bis(perchlorate)

The title compound, [Ru(C₁₂H₈N₂)₃]₂[Fe(NCS)₄](ClO₄)₂, crystallizes in a tetragonal chiral space group (P4₁2₁2) and the assigned absolute configuration of the optically active molecules was unequivocally confirmed. The Δ‐[Ru^II(phen)₃]²⁺ complex cations (phen is 1,10‐phenanthroline) interact along the 4₁ screw axis parallel to the c axis, with an Ru...Ru distance of 10.4170 (6) Å, and in the ab plane, with Ru...Ru distances of 10.0920 (6) and 10.0938 (6) Å, defining a primitive cubic lattice. The Fe atom is situated on the twofold axis diagonal in the ab plane. The supramolecular architecture is supported by C—H...O interactions between the [Ru^II(phen)₃]²⁺ cation and the disordered perchlorate anion. This study adds to the relatively scarce knowledge about intermolecular interactions between [Ru(phen)₃]²⁺ ions in the solid state, knowledge that eventually may also lead to a better understanding of the solution state interactions of this species; these are of immense interest because of the photochemical properties of these ions and their interactions with DNA.     

Structural and Electronic Properties of New Materials Based on Thiophene and Phenylene

Theoretical study on the geometries and electronic properties of new conjugated compounds based on thiophene and phenylene was carried out. The theoretical ground-state geometries and electronic structures of the studied molecules were obtained using the density functional theory (DFT) method at B3LYP level with 6-31G(d) basis set. The electronic properties were determined by ZINDO/s, CIS/3-21G(d), and TD//B3LYP/3-21G(d) calculations performed on the B3LYP/6-31(d) optimized geometries. The effects of the ring structure and the substituents on the geometries and electronic properties of these materials were discussed. The results of this study indicate how the electronic properties can be tuned by the backbone ring or side group and suggest these compounds as good candidates for opto-electronic applications.     

Asymmetric autocatalytic Mannich reaction in the presence of water and its implication in prebiotic chemistry

An enantioselective process in which the chiral Mannich product acts as a catalyst for its own replication was observed to occur under various conditions in the presence of water.     

Coordination properties of hydralazine Schiff base Synthesis and equilibrium studies of some metal ion complexes

In the present study, a new ligand is prepared by condensation of hydralazine (1-Hydralazinophthalazine) with 2-butanon-3-oxime. The acid-base equilibria of the schiff-base and the complex formation equilibria with the metal ions as Cu(II), Ni(II), Co(II), Cd(II), Mn(II) and Zn(II) are investigated potentiometrically. The stability constants of the complexes are determined and the concentration distribution diagrams of the complexes are evaluated. The effect of metal ion properties as atomic number, ionic radius, electronegativity and ionization potential are investigated. The isolated solid complexes are characterized by conventional chemical and physical methods. The potential coordination sites are assigned using the i.r. and (1)H NMR spectra. The structures of the isolated solid complexes are proposed on the basis of the spectral and magnetic studies.