Pd(OAc)2/dppf as an efficient and highly active catalyst for the allylation of amines, alcohols and carboxylic acids with 1-phenyl-1-propyne

Pd(OAc)₂/1,1′-bis(diphenylphosphino)ferrocene as an efficient, highly active catalyst for the allylation of amines, alcohols and carboxylic acids with 1-phenyl-1-propyne has been developed. The effect of various reaction parameters, such as ligand, time, solvent, temperature, metal: ligand ratio and catalyst concentration on yields of the product were investigated. The optimized procedure works well under mild operating conditions and permits rapid generation of a library for various allylated products.     

Giant Enhancement of Second Harmonic Generation Accompanied by the Structural Transformation of 7‐Fold to 8‐Fold Interpenetrated Metal–Organic Frameworks (MOFs)

Interpenetration in metal–organic frameworks (MOFs) is an intriguing phenomenon with significant impacts on their properties, and functional applications. Herein, we show that a 7‐fold interpenetrated MOF ( 1 ) is transformed into an 8‐fold interpenetrated MOF by the loss of DMF in a single‐crystal‐to‐single‐crystal manner. This is accompanied by a giant enhancement of the second harmonic generation (SHG ca. 125 times) and two‐photon photoluminescence (ca. 14 times). The strengthened π–π interaction between the individual diamondoid networks and intensified oscillator strength of the molecules aid the augment of dipole moments and boost the nonlinear optical conversion efficiency. Large positive and negative thermal expansions of 1 occur at 30–150 °C before the loss of DMF. These results offer an avenue to manipulate the NLO properties of MOFs using interpenetration and provide access to tunable single‐crystal NLO devices.     

CH Oxygenation and N‐Trifluoroacylation of Arylamines Under Metal‐Free Conditions: A Convenient Approach to 2‐Aminophenols and N‐Trifluoroacyl‐ortho‐aminophenols

Direct ortho‐hydroxylation through C?H oxygenation and N‐trifluoroacylation of anilines was achieved in a single step under metal‐free conditions by using a combination of TFA and oxone. The method allowed the formation of functionalised amino phenolic compounds such as ortho‐hydroxy‐N‐trifluoroacetanilides in good yields with broad substrate scope.     

Wall permeability studies on Ti4+ doped Ni-Zn ferrite

Compositions of Ni_0.6Zn_0.4Fe₂O₄ with variable weight percent addition of TiO₂ exhibit wall permeability dominance. With increase of TiO₂ concentration the permeability decreases which is related to the impedance to the domain wall motion. The permeability obeys the Globus model with evident wall bulging effect.     

Thermophysical properties of binary mixtures of odichlorobenzene and o-chlorophenol with diethyl ether, tetrahydrofuran, cyclohexane and anisole

Measurement of density and viscosity has been used for evaluating derived parameters for binary system of o-dichlorobenzene and o-chlorophenol with diethyl ether, tetrahydrofuran, cyclohexane and anisole at the different temperatures and at atmospheric pressure. From these, excess parameters have been calculated over entire range of composition. The variation of derived parameters as well as the sign and magnitude of corresponding excess functions has been used to investigate the type and extent of interaction between the component molecules of the binary mixture.     

Polymer-surfactant layered heterostructures by electropolymerization of phenosafranine in Langmuir-Blodgett films

Langmuir-Blodgett (LB) films of the water-soluble dye phenosafranine (PS) have been prepared by its adsorption from aqueous dye solution to an arachidic acid (AA) monolayer at the air-water interface. Atomic force microscopy (AFM) images of the LB films revealed the effect of change in pH of deposition on the degree of complexation of AA with the PS dye. Well-defined circular islands and holes were observed which disappeared with the increase in pH. Polarized absorption studies indicated that the dye molecules are oriented uniaxially with their long axis titled at a constant angle to the surface normal of the LB film. Within the restricted geometry of the LB film, the PS dye was electropolymerized to form a two-dimensional film of poly(phenosafranine) sandwiched between arachidic acid layers. The film was characterized by IR spectroscopy, cyclic voltammetry, and AFM. X-ray diffraction studies reveal the presence of a layer structure in the AA-PS LB film before and after polymerization. The polymer film showed highly anisotropic electrical conductivity of ca. 10 orders of magnitude. This indicates the formation of two-dimensional polyPS layers between arachidic acid layers resulting in a layered heterostructure film having alternate conducting and insulating regions. Also, the conductivity of the polyPS prepared from LB film was found to be approximately 2.5 times higher than the conductivity of polyPS prepared by solution polymerization method.     

Organocatalytic enantioselective formal synthesis of HRV 3C-protease inhibitor (1R,3S)-thysanone

A short and efficient organocatalytic enantioselective formal synthesis of HRV 3C-protease inhibitor (1R,3S)-thysanone is achieved in a nine-step with 98.7% enantiomeric excess, by employing l-proline-catalyzed asymmetric α-aminooxylation of aldehyde and Oxa-Pictet-Spengler cyclization as the key steps.     

Thermal hysteresis and domain states in Ni-Zn ferrites synthesized by oxalate precursor method

Nickel zinc ferrites with generic formula, Ni_XZn_1−XFe2O4 (with X=0.28-0.40) were synthesized by an oxalate precursor route starting with acetates to study their magnetic properties. The saturation magnetization versus temperature curves resemble those of R type ferrites. The system shows the presence of Yafet-Kittel type of spin. It is observed that magnetic moment (n_B) values increase with the addition of Ni²⁺. The remanance ratio R tends to increase with the addition of Ni²⁺, which has been attributed to the increase of magnetocrystalline anisotropy constant (K1). The values of R compare well with the theoretical value (0.87). The coercive force (H_c) tends to increase with the addition of Ni²⁺, which has been related to the reverse domain formation. Studies on temperature variation of R and H_c reveal that these parameters are thermally insensitive, which confirms the presence of multi domain grains in the material. These observations have been supported by a.c. susceptibility studies.     

Sequential determination of urea and HMTA in the process solution of sol-gel route of advanced nuclear fuel fabrication

Determinations of hexamethylene tetramine (HMTA) and urea in the process solutions are required to optimize their concentrations for obtaining high quality ceramic oxide microspheres, for monitoring the washing procedure and for their subsequent recovery, recycling or waste disposal. Determination of urea in the feed solution by conventional procedures is difficult as it contains HMTA. It is more so in the effluent as it contains hydrolytic products like formaldehyde, methylol derivatives of urea, ammonium nitrate and ammonium hydroxide used for washing the gel microspheres. This work describes a derivative potentiometric method using a microprocessor-based autotitrator. Peaks on the first derivative of the titration plot corresponded to constituents of different basicities. Urea was selectively hydrolyzed at room temperature by the catalytic action of urease enzyme leaving HMTA unaffected. Ammonium hydroxide and ammonium bicarbonate produced from urea and HMTA were sequentially titrated for the analysis of the feed solution to obtain the three corresponding peaks respectively. Two separate titrations were required for the analysis of the effluent solution, which contained free ammonia also. One aliquot was first titrated directly without adding urease (for free ammonia and HMTA) and another aliquot was titrated after treatment with urease. The end points due to the ammonia used for washing and that from urea hydrolysis merged resulting in the appearance of three peaks again. Using this sequential method the relative standard deviations were found to be 0.81% and 1.38% for urea and HMTA, respectively, in eight determinations when the aliquots contained 50 to 75 mg of urea and 75 to 125 mg of HMTA. Feed and effluent solutions of the process stream were analyzed.