A new tavorite LiTiPO<Subscript>4</Subscript>F electrode material for aqueous rechargeable lithium ion battery

Herein, we demonstrate a safe, inexpensive, and stable cycle-life aqueous rechargeable Li-ion battery system using tavorite LiTiPO₄F as anode and Li[Li_0.2Co_0.3Mn_0.5]O₂ as cathode in aqueous electrolyte using 2 M Li₂SO₄. These materials have been synthesized via a simple and an efficient method called RAPET (reaction under autogenic pressure at elevated temperature) method, and for the first time, we have evaluated the electrochemical properties of LiTiPO₄F in aqueous electrolyte. Structural and morphological features have been characterized using X-ray diffraction and scanning electron microscopy techniques, and the electrochemical studies have been investigated by using cyclic voltammetry, galvanostatic charge/discharge studies, electrochemical impedance spectroscopic technique, potentiostatic intermittent titration techniques, and galvanostatic intermittent titration techniques. In galvanostatic charge/discharge studies, the capacity, cycle life, and columbic efficiency of LiTiPO₄F have been tested in combination with Li [Li_0.2Co_0.3Mn_0.5]O₂ cathode. In particular, LiTiPO₄F shows capacity of 82 mA h g^?1, the capacity retention was maintained 90 % even after the 45th cycle.     

Electronic structure of the TbMn<Subscript>0.33</Subscript>Ge<Subscript>2</Subscript> compound: Band calculation and optical experiment

The results of the investigation of the electronic structure and optical properties of the TbMn_0.33Ge₂ compound have been presented. The spin-polarized calculations of the band spectrum have been performed within the framework of the local spin density approximation (LSDA) with a correction for strong correlations in the 4f shell of the rare-earth ion (the LSDA + U method). The optical constants have been measured using the ellipsometric method and a number of spectral and electronic characteristics of the compound under investigation have been determined over a wide range of wavelengths. The interband part of the experimental dependence of the optical conductivity has been interpreted using the results of the calculation of the electron density of states.     

Synthesis, spectral characterization and crystal structure of N-2-hydroxy-4-methoxybenzaldehyde-N'-4-nitrobenzoyl hydrazone and its square planar Cu(II) complex

A new aroyl hydrazone, N-2-hydroxy-4-methoxybenzaldehyde-N'-4-nitrobenzoyl hydrazone (H2L) and its mixed ligand Cu(II) complex [CuLpy] [py, pyridine] have been prepared. The ligand is characterized by elemental analysis, electronic, infrared and NMR spectral studies and the complex by electronic, infrared, EPR spectral studies and the magnetic susceptibility data. The structures of the compounds were determined by single crystal X-ray diffraction studies. Both the ligand and the Cu complex crystallize into a triclinic lattice with a space group of PI. From the crystal studies, it is concluded that the ligand molecule exits in the keto form in the solid state, while at the time of complexation, it tautomerises into the enol form. The complex is formed by the double deprotonation of the ligand molecule--both the phenolic and the enolic protons.     

Efficient synthesis of sulfonyl azides from sulfonamides

Triflyl azide serves as an efficient diazo transfer reagent in this first direct synthesis of sulfonyl azides from readily available and stable sulfonamides. The process is experimentally simple, mild, and high-yielding. Sulfonyl azides participate in various catalytic transformations providing rapid access to diversely functionalized sulfonamide derivatives in good yields.     

A rhodamine-based chemosensor that works in the biological system

A new rhodamine-based reversible chemosensor (L1 ) is reported, which could bind Hg2+ and Cu2+ in aqueous methanol solution with detectable change in color. Cu2+ and Hg2+ ions responded differently toward the fluorescence output signals on binding to L1.L1 could also be used as a selective probe for monitoring Hg2+ adsorbed on bacteria using an optical microscope.     

Molecular biosensing system based on intrinsically disordered proteins

Intrinsically disordered proteins (IDPs) that undergo structural transition upon binding their target molecules are becoming increasingly known. IDPs, because of their binding specificity and induced folding properties, can serve as biological recognition elements for sensing applications. In this paper, BRCA1, an IDP, was utilized as the biological recognition element to detect tumor suppressor protein p53 through the BRCA1/p53 binding interaction to serve as a proof-of-concept for the use of IDPs as recognition elements. The binding resulted in a disordered-to-ordered BRCA1 conformational change, as seen in our circular dichroism (CD) measurements. This conformational change in BRCA1 (residues 219-498) was utilized in the detection of p53 (residues 311-393) via both intrinsic and extrinsic fluorescent probes. Intrinsic tryptophan residues within the BRCA1 sequence detected p53 (311-393) with a detection limit of 0.559 nM (0.112 pmol). Two environmentally sensitive fluorophores, tetramethylrhodamine-5-maleimide (TMR) and 6-((5-dimethylaminonaphthalene-1-sulfonyl)amino)hexanoic acid, succinimidyl ester (dansyl-X, SE) were conjugated to BRCA1 (219-498). Dansyl-X, SE-conjugated BRCA1 (219-498) detected p53 (311-393) with a detection limit of 1.50 nM (0.300 pmol). The sensitivities for TMR and dansyl-X, SE-conjugated BRCA1 for the detection of p53 were nearly threefold and twofold higher, respectively, than the sensitivity reported using intrinsic BRCA1 tryptophan fluorescence. CD measurements did not reveal a disruption of p53/dye-conjugated BRCA1 binding, thus validating the applicability of environmentally sensitive fluorophores as transduction moieties to detect molecules which bind to IDPs and induce a structural change.     

Fulleride-metal η5 sandwich and multi-decker sandwich complexes: A DFT prediction

The (C₆₀CN)⁻ formed by the reaction of CN⁻ with fullerene shows high electron rich character, very similar to C₆₀˙⁻, and it behaves as a large anion. Similar to Cp⁻, the bulky anion, (C₆₀CN)⁻, acts as a strong η⁵ ligand towards transition metal centers. Previous studies on η⁵ coordination of fullerene cage are reported for pseudo fullerenes whereas the present study deals with sandwich complexes of (C₆₀CN)⁻ with Fe(II), Ru(II), Cr(II), Mo(II), and Ni(II) and multi-decker sandwich complexes of CN–fullerides with Fe(II). The structural parameters of these complexes and the corresponding Cp⁻ complexes showed very close resemblance. Analysis of the metal-to-carbon bonding molecular orbitals showed that sandwich complex [Fe(η⁵-(C₆₀CN)⁻)₂] exhibit bonding features very similar to that of ferrocene. Also, a 6-fold decrease in the band gap energy is observed for [Fe(η⁵-(C₆₀CN)⁻)₂] compared to ferrocene. The energy of dissociation (ΔE) of the ligand (C₆₀CN)⁻ from [Fe(η⁵-(C₆₀CN)⁻)₂] is slightly lower than the ΔE of a Cp* ligand from a ferrocene derivative wherein each cyclopentadienyl unit is substituted with four tertiary butyl groups. The (C₆₀CN)⁻ ligand behaved as one of the bulkiest ligands in the chemistry of sandwich complexes. Further, the coordinating ability of the dianion, (C₆₀(CN)₂)²⁻ is evaluated which showed strong coordination ability simultaneously with two metal centers leading to the formation of multi-decker sandwich and pearl-necklace type polymeric structures.     

Polymer-templated self-assembly of a 2-dimensional gold nanoparticle network

We here report on the formation of well-ordered 2D gold nanostructures at the air/water interface. Spreading a mixture of alkanethiol-capped gold nanoparticles (AuNPs) and an amphiphilic poly(p-phenylene) on a water surface and compressing the mixture to a surface pressure of 40 mN/m lead to the formation of a network of well-ordered gold nanostructures. The structures are transferred horizontally (Langmuir-Sch?fer) onto a solid substrate and investigated with TEM, AFM, and X-ray reflectivity, showing a pattern that is repeating over several micrometers. AFM and X-ray reflectivity data at different surface pressures reveal that the polymer is lifting the AuNPs 1.5-2 nm in the vertical direction, away from the polymer layer, when the pressure is increased from 20 to 40 mN/m.     

A facial microwave-assisted synthesis, spectroscopic characterization and preliminary complexation studies of calix[4]pyrroles containing the hydroxamic-acid moiety

The synthesis, spectroscopic characterization and preliminary complexation properties of functionalized calix[4]pyrroles are described. To date, two generalized preparative approaches have been pursued (i) modifying the basic pyrrole-plus-ketone synthesis of calix[4]pyrrole by using microwave irradiation protocol, (ii) the basic meso-tetra(methyl) meso-tetra(p-nitrophenyl) calix[4]pyrrole skeleton was functionalized to give hydroxamic acids, especially in the meso-position of the macrocycles. The structures of novel calix[4]pyrrole hydroxamic acid derivatives were confirmed on the basis of various physico-chemical techniques such as elemental analysis, FT-IR, ¹H NMR and FAB-Mass. The results of preliminary studies on the extraction of vanadium (V) with the host calix[4]pyrrole hydroxamic acids were elucidated by significant examination of UV–Vis spectroscopy and ICP-AES. Single crystal structure of basic meso-tetra(methyl) meso-tetra (p-nitro phenyl) calix[4]pyrrole moiety has also been reported.     

Effect of UV irradiation on stabilized collagen: role of chromium(III)

Research on the effect of UV radiation on stabilized collagen is an area of potential interest owing to the fact that collagen is an important biomaterial finding immense use in various fields. In this present study, effect of UV irradiation on collagen stabilized using chromium(III) has been studied. The physical and optical properties affected by UV irradiation have been detailed. Viscosity measurements have shown that chromium(III) treated collagen has better stability against UV radiation than native collagen. Circular dichroic studies indicate that increase in concentration of chromium(III) does not affect the conformation of collagen however, the duration of irradiation has profound impact on the conformation of collagen. The fluorescence intensity of native collagen has been found to decrease more than that of chromium(III) treated collagen. The difference absorption spectra also shows that chromium(III) treatment brings about more stability to collagen against UV irradiation.