Efficient synthesis of chromeno[2,3-c]pyrazolyl-pyrazolol(s) in hydrotropic solution and their anti-infective potential

Research on Chemical Intermediates - We report synthesis of chromeno[2,3-c]pyrazolyl-pyrazolol(s) with anti-infective potential in aq. sodium p-toluenesulfonate (NaPTS) hydrotropic solution under...     

Uncertainty Quantification for Systems with Random Initial Conditions Using Wiener–Hermite Expansions

A number of engineering problems, including laminar-turbulent transition in convectively unstable flows, require predicting the evolution of a nonlinear dynamical system under uncertain initial conditions. The method of Wiener–Hermite expansion is an attractive alternative to modeling methods, which solve for the joint probability density function of the stochastic amplitudes. These problems include the "curse of dimensionality" and closure problems. In this paper, we apply truncated Wiener–Hermite expansions with both fixed and time-varying bases to a model stochastic system with three degrees of freedom. The model problem represents the combined effects of quadratic nonlinearity and stochastic initial conditions in a generic setting and occurs in related forms in both classical dynamics, turbulence theory, and the nonlinear theory of hydrodynamic stability. In this problem, the truncated Wiener–Hermite expansions give a good account of short-time behavior, but not of the long-time relaxation characteristic of this system. It is concluded that successful application of truncated Wiener–Hermite expansions may require special adaptations for each physical problem.     

Highly active and reusable catalyst from Fe-Mg-hydrotalcite anionic clay for Friedel-Crafts type benzylation reactions

Fe-Mg-hydrotalcite (Mg/Fe = 3) anionic clay with or without calcination (at 200–800‡C) has been used for the benzylation of toluene and other aromatic compounds by benzyl chloride. Hydrotalcite before and after its calcination was characterized for surface area, crystalline phases and basicity. Both the hydrotalcite, particularly after its use in the benzylation reaction, and the catalyst derived from it by its calcination at 200–800‡C show high catalytic activity for the benzylation of toluene and other aromatic compounds. The catalytically active species present in the catalyst in its most active form are the chlorides and oxides of iron on the catalyst surface.     

Synthesis of analcime-type zeolite from natural stilbite by hydrothermal method

Using calcined stilbite, aluminium hydroxide and sodium hydroxide as ingradients, the procedure to synthesize a zeolite by hydrothermal method is described. Studies on characterisation (of crystals grown) by X-rays and by infrared spectroscopy, and their morphology by a scanning electron microscope are reported. That the crystals grown have cubic symmetry with a = 13.66 Å and that they are analcime type is established. From infrared spectral studies it is confirmed that the crystals are zeolites. Needle, prismatic, and layer crystals obtained are illustrated and described.     

Polyoxometalates as chemically and structurally versatile components in self-assembled materials

Polyoxometalates (POMs) are anionic molecular metal oxides with expansive diversity in terms of their composition, structure, nuclearity and charge. Within this vast collection of compounds are dominant structural motifs (POM platforms), that are amenable to significant chemical tuning with minimal perturbation of the inorganic oxide molecular structure. Consequently, this enables the systematic investigation of these compounds as inorganic additives within materials whereby structure and charge can be tuned independently i.e. [PW₁₂O₄₀]³⁻vs. [SiW₁₂O₄₀]⁴⁻ while also investigating the impact of varying the charge balancing cations on self-assembly. The rich surface chemistry of POMs also supports their functionalisation by organic components to yield so-called inorganic–organic hybrids which will be the key focus of this perspective. We will introduce the modifications possible for each POM platform, as well as discussing the range of nanoparticles, microparticles and surfaces that have been developed using both surfactant and polymer building blocks. We will also illustrate important examples of POM-hybrids alongside their potential utility in applications such as imaging, therapeutic delivery and energy storage.

Polyoxometalates are anionic molecular metal oxides with diversity in composition, structure, nuclearity and charge. Their adaptable chemistry leads to potential for self-assembly with other building blocks into a variety of hybrid structures.     

Hydrothermal Synthesis of Zeolite Crystals Using Natural Scolecite

Natural scolecite is converted into analcime type zeolite by hydrothemal method at 180 °C at autogeneous pressure for 24 to 160 hours growth runs. Mordenite is detected in the final product. Cube and spheroid crystals of the products are illustrated and described. Crystals synthesized are characterized by X-ray diffraction, infrared spectroscopy EDAX and scanning electron microscopy. Particle size is estimated as 20–60 microns, induction period for nucleation as 12 hrs, and lattice parameter of cube crystals as 13.70 Å. Mechanism of growth, influence of anions and duration of growth etc. are discussed. It is established that the crystals grow in the system Na₂O Al₂O₃ SiO₂ H₂O.     

Thermal behaviour of natural stilbite crystals

Observations of the behaviour of natural stilbite crystals on dehydration are reported. Results of TG, DTA, static weight loss measurements, X-ray diffractometric analysis and IR studies are described and interpreted. It is established that the stilbite structure collapses at about 400°C. It is shown that around 300°C, stilbite changes into a mixture of epistilbite and heulandite, and that around 350°C, the resulting prominent phase is a mixture of heulandite and chabazite.     

Thermal Behaviour and Adsorption Properties of Natural Stilbite

Crystals collected from the Ellora valley(Aurangabad, MS, India) of the Deccan traps of India have beencharacterized as a stilbite (St) by X-ray diffraction, IRspectroscopy and chemical analyses. The thermal behaviour was studiedusing TG and DTA techniques. The sample was exchanged at refluxtemperature with NH4Cl and NH4St was prepared. This was furthertransformed to the H-form of stilbite (HSt) by heating at 573 K for 12 h.The samples so prepared were used for adsorption studies. The comparativestudy of sorption of these samples shows an increase in the sorptioncapacity of HSt. The isosteric heat was also computed for these samples.     

Mixed micelle formation with hydrophobic and hydrophilic Pluronic block copolymers: implications for controlled and targeted drug delivery

Pluronic block copolymers offer affluent phase behavioral characteristics and are extensively investigated for drug delivery applications. Hydrophobic Pluronics produce larger aggregates whereas hydrophilic Pluronics often generate small-sized micelles in aqueous milieu. To overcome the limitations and combine the advantages of different kinds of Pluronics the mixing of such two types of Pluronics is studied here, especially for hydrophobic Pluronic L81 and relatively hydrophilic Pluronic P123. Critical micelle concentration (CMC) of the developed binary mixtures was 0.032 mg/ml as evidenced from pyrene fluorescence spectroscopy and is located in between that of the individual Pluronics. Dynamic light scattering (DLS) showed very small particle sizes (～20 nm) and low polydispersity indices for most of the mixed micelles. Transmission electron microscopy (TEM) demonstrated spherical shape of micelles. Based upon the ratio of hydrophobic and hydrophilic Pluronics, dispersions of varied stability were obtained. With 0.1/1.0 wt.% and 0.5/3.0 wt.% of Pluronic L81/P123, stable dispersions were obtained. Stability was assessed from turbidity measurement, size analysis and clarity of dispersion on standing. Micelles were also found to be stable in bovine serum albumin (BSA) solution. Mixed micelles showed fairly high entrapment efficiency, loading capacity and sustained release profile for aceclofenac (Acl), a model hydrophobe. Presence of salt lowered Acl solubilization in micelles. Thermodynamic parameters for Acl solubilization in mixed micelles revealed high partition coefficient values and spontaneity of drug solubilization. Thus, the developed novel mixed micelles hold promise in controlled and targeted drug delivery owing to their very small size, high entrapment efficiency and stability.