Synthesis of some new 4-imino-3,5,7-trisubstituted-pyrido[2,3-d]pyrimidine-2(1H)-thiones

The synthesis of 4-imino-3,5,7-trisubstituted-pyrido[2,3-d]pyrimidine-2(1H)-thiones is described. The elemental analysis, ir and nmr spectral data confirm the structure of the products.     

Synthesis and photophysics of leadsulphide nanocrystallites

Nanoparticles of lead sulphide have been stabilized in the presence of excess Pb²⁺ in aqueous basic medium by a simple chemical route of synthesis. These PbS nanoparticles were synthesized very conveniently at room temperature using hexametaphosphate as stabilizer. These nanoparticles have an absorption extending into the NIR region. A significant quantum confinement effect made the bandgap of lead sulphide nanoparticles produce a blue shift from 0.41 eV to about 1.5 eV. The size and morphology of the particles were studied by TEM. Particles were relatively small sized (about 6 nm) having narrow size distribution. XRD data analysis indicate that the product is a mixture of PbS, PbO and Pb(OH)₂. Both XRD pattern and HRTEM images confirm the crystalline structure of lead sulphide crystals. IR spectroscopy indicates the formation of PbS. PbS nanoparticles were fairly stable and could be stored for about three weeks at room temperature and for about two months at 5°C without agglomeration. These particles were photoactive and sensitized the reaction of aniline by light leading to the formation of azobenzene.     

Synthesis of some new mesoionic heterocycles

The synthesis of various substituted 1-hydroxy-2-chloroacetyl-6-thia-10b-aza-2a-azoniaaceanthrylene hydroxide inner salt, 1-hydroxy-6-thia-10b-aza-2a-azoniaaceanthrylene hydroxide inner salt, 1-hydroxy-2-piperidinoacetyl-6-thia-10b-aza-2a-azoniaaceanthrylene hydroxide inner salt is described. The ir is also included.     

An overview of commonly used semiconductor nanoparticles in photocatalysis

The depletion of non-renewable resources and rise in global warming has caused great concern to humankind. With a view to use renewable source of energy and to eliminate hazardous chemical compounds from air, soil, and water, photocatalysis utilizing solar energy is becoming a rapidly expanding technology. Semiconductor nanoparticles have the ability to undergo photoinduced electron transfer to an adsorbed particle governed by the band energy positions of the semiconductor and the redox potential of the adsorbate. A brief overview of metal oxides and sulphides that can act as sensitizers for light-induced redox processes due to their electronic structure is presented here.     

A Comprehensive Stability Study of Vardenafil Using Quality by Design Approach

Chromatographia - A novel, dual gradient LC method for quantification of vardenafil (VR) and its degradant products was developed with a multivariate approach. In the QbD approach, primary...     

Photophysics and photocatalytic behavior of composite CdS-purine nanoparticles in the presence of certain indoles

The photophysics of purine-capped Q-CdS has been examined in the presence of certain indoles. The addition of indole does not modify electronic spectrum of purine-capped Q-CdS but it forms a fluorescing charge-transfer intermediate with illuminated CdS, which has an emissive peak at 495 nm. The intensity and the lifetime of this intermediate are enhanced initially with an increase in concentration of indole. In the presence of other indoles, the fluorescence is simply quenched in a dynamic process without forming any fluorescing intermediate. In contrast, emissive CT intermediate is not formed in the presence of indole or any of its derivatives with adenine-capped Q-CdS. In all the cases the quenching of fluorescence, monitored by steady state and time-resolved methods, follows the Stern-Volmer relationship and takes place with a bimolecular rate constant of approximately 10(10) dm(3)mol(-1)s(-1). Purine-capped Q-CdS sensitizes the reactions of the investigated indole(s)-O2 couple much more efficiently than adenine-capped Q-CdS. The differences in quenching of fluorescence and reactivity of holes between purine-capped Q-CdS and adenine-capped Q-CdS are explained by the difference in the binding of indole to the particle. In the case of purine-capped Q-CdS, specific channels for the binding of the solutes are created through the H-bond with the surface-capped purine.     

Untersuchung der IR-und NMR-Spektren einiger substituierter Cumarine

Ohne Zusammenfassung

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IR and NMR spectral studies on a few substituted coumarins (short communication)

     

Syntheses of some hydroxylated metabolites of psychotropic trifluoromethyl analogs of chlorpromazine

The syntheses of 7-hydroxy derivatives of trifluoperazine, nor,-trifluoperazine, fluphenazine, triflupromazine and nor,-triflupromazine are described. These were prepared as analytical standards for the identification of these metabolites in biological materials.     

A review on the synthesis of TiO<Subscript>2</Subscript> nanoparticles by solution route

TiO₂ can be prepared in the form of powder, crystals, or thin films. Liquid-phase processing is one of the most convenient and utilized methods of synthesis. It has the advantage of allowing control over the stoichiometry, production of homogeneous materials, formation of complex shapes, and preparation of composite materials. However, there may be some disadvantages such as expensive precursors, long processing times, and the presence of carbon as an impurity. In comparison, the physical production techniques, although environment friendly, are limited by the size of the produced samples which is not sufficient for a large-scale production. The most commonly used solution routes in the synthesis of TiO₂ are reviewed.