Studies on Some Simple and Zeolite-Y Encapsulated 3d-Transition Metal Complexes of Schiff Bases Derived From 2-Aminobenzothiazole

In this regard Schiff base complexes have attracted wide attention. Furthermore, such complexes are found to play important role in analytical chemistry, organic synthesis, metallurgy, refining of metals, electroplating and photography. Many Schiff base complexes are reported in literature. Their properties depend on the nature of the metal ion as well as on the nature of the ligand. By altering the ligands it is possible to obtain desired electronic environment around the metal ion. Thus there is a continuing interest in the synthesis of simple and zeolite encapsulated Schiff base complexes of metal ions. Zeolites have a number of striking structural similarities to the protein portion of natural enzymes. Zeolite based catalysts are known for their remarkable ability of mimicking the chemistry of biological systems. In view of the importance of catalysts in all the areas of modern chemical industries, an effort has been made to synthesize some simple Schiff base complexes, heterogenize them by encapsulating within the supercages of zeoliteY cavities and to study their applications. The thesis deals with studies on the synthesis and characterization of some simple and zeoliteY encapsulated Mn(II), Fe(III), Co(II), Ni(II) and Cu(II) complexes and on the catalytic activity of these complexes on some oxidation reactions. Simple complexes were prepared from the Schiff base ligands SBT derived from 2-aminobenzothiazole and salicylaldehyde and the ligand VBT derived from 2-aminobenzothiazole and vanillin (4-hydroxy-3- methoxybenzaldehyde). ZeoliteY encapsulated Mn(II), Fe(III), Co(II), Ni(II) and Cu(II) complexes of Schiff base ligands SBT and VBT and also of 2-aminobenzothiazole were synthesized. All the prepared complexes were characterized using the physico-chemical techniques such as chemical analysis (employing AAS and CHN analyses), magnetic moment studies, conductance measurements and electronic and FTIR spectra. EPR spectra of the Cu(II) complexes were also carried out to know the probable structures and nature of Cu(II) complexes. Thermogravimetric analyses were carried out to obtain the information regarding the thermal stability of various complexes. The successful encapsulations of the complexes within the cavities of zeoliteY were ascertained by XRD, surface area and pore volume analysis. Assignments of geometries of simple and zeoliteY encapsulated complexes are given in all the cases. Both simple and zeoliteY encapsulated complexes were screened for catalytic activity towards oxidation reactions such as decomposition of hydrogen peroxide, oxidation of benzaldehyde, benzyl alcohol, 1-propanol, 2-propanol and cyclohexanol.

Dynamics of Land Use in Recently Settled Forest Areas: a Case Study of Attappady , Kerala

The present study on the dynamics of land use in recently settled forest areas. In the course of events, tribals lost their land; the demographic structure of Attappady changed; the cropping pattern got diversified; traditional techniques of production were ruined; new crops and new techniques of cultivation came to stay; and the entire cost and return structure of production underwent radical change. Migration to Attappady is essentially a continuation of the Malabar migration process from Travancore, through, some people from Tamil Nadu also had migrated to this region earlier. The demographic structure, along with land structure, has changed in favour of the settlers within a short span of time. Lack of security of ownership has acted as a strong reason for wanton exploitation of land resources. The major influencing factors on crop choices among settlers were labour endowment, date of settlement and education. Attappady is an unique ecosystem in Kerala characterized by many interdependables. The latest hand of environmental degradation is a grave danger especially on sloppy terrains,which are under cultivation of tapioca and dry annual crops like groundnuts, cotton, grams etc. Soil erosion as a result of the unplanned cultivation of these crops has resulted in dramatic decline in soil fertility and hence low crop productivity. This calls for a watershed management approach for the sustainable development of the region. A progressive agrarian transformation is warranted to maintain the homegarden as a sustainable production system in ecological and socio-economic terms.

Surface Properties and Catalytic Activity of Manganese Ferrospinels

In recent years considerable advances have been achieved in the study of the surface structure and mechanism of action of environmentally benign heterogeneous catalysts. The study entitled as surface properties and catalytic activity of manganese ferrospinels. In the present study we have prepared manganese ferrospinels of general formula Mn(1-x)BxFe2O4 via low temperature controlled co-precipation method. The study employed low temperature co-precipitation method for the preparation ofMn(1-x)BxFe2O4 specimens, where B is a metal cation such as Cr,Co, Ni,Cu and Zn. The catalytic activities of the systems were investigated for liquid-phase benzoylation of aromatic compounds and phenol hydroxylation and for vapour-phase reactions such as aniline alkylation, phenol methylation and ODH of ethylbenzene. The different series of manganese ferrites are proved to be excellent catalysts for various industrially important reactions such as Friedel-crafts benzoylation of aromatic compounds, methylation of aniline and phenol, hydroxylation of phenol and oxidative dehydrogenation of ethylbenzene. Due to the tightening of the environmental regulations, production of diphenols from phenol hydroxylation and reduction of phenolic pollutants in waste waters using these catalysts can be a promising approach because it demands only simple techniques and produce little environmental pollution.

The Effect of Dopants on the Microwave Dielectric Properties of Ba (Mg 0.33 Ta 0.67) O3 Ceramics

The effect of dopants with different valencies and ionic radii on the densification, structural ordering, and microwave dielectric properties of Ba(Mg1/3Ta2/3)O3 (BMT) is investigated. It is found that dopants such as Sb2O5, MnO, ZrO2, WO3, and ZnO improve the microwave dielectric properties of BMT. Addition of trivalent dopants is detrimental to the cation ordering and dielectric properties of BMT. A correlation between the microwave dielectric properties of BMT and ionic radii of the dopant has been established. The variation of the dielectric properties of pure and doped BMT at cryogenic temperatures is also discussed.

Theory of Breaking of a Potyrner Molecule under Tension

The thesis presents the dynamics of a polymer chain under tension. It includes existing theories of polymer fracture, important theories of reaction rates, the rate using multidimensional transition state theory and apply it to the case of polyethylene etc. The main findings of the study are; the life time of the bond is somewhat sensitive to the potential lead to rather different answers, for a given potential a rough estimate of the rate can be obtained by a simples approximation that considers the dynamics of only the bond that breaks and neglects the coupling to neighboring bonds. Dynamics of neighboring bonds would decrease the rate, but usually not more than by one order of magnitude, for the breaking of polyethylene, quantum effects are important only for temperatures below 150K, the lifetime strongly depends on the strain and as the strain varies over a narrow range, the life varies rapidly from 105 seconds to 10_5 seconds, if we change one unit of the polymer by a foreign atom, say by one sulphure atom, in the main chain itself, by a weaker bond, the rate is found to increase by orders of magnitude etc.

Salient Features of the North Indian Ocean Associated with the Indian summer Monsoon

This study deals with the salient features of the north Indian ocean associated with the summer monsoon. The focus is given on the Arabian sea mini warm pool, which is a part of the Indian ocean. It primarily study the certain aspects of the atmosphere and ocean variability in the north Indian ocean. The attempt were made to understand various aspects of time –scale variability of major features occurring in the Indian summer monsoon. The result from the thesis can be utilized as an input for model studies for prediction of monsoon, understanding ocean dynamics, radar tracking and ranging etc.

Studies on the Synthesis and Transformations of a Few Dibenzoylalkene-type Systems

The aim of the study is to synthesise several dibenzoylakene-type systems such as acenaphthenone-2-ylidene ketones 47 and phenanthrenone-9-ylidene ketones 48 by the condensation reaction of acenaphthenequinone and phenanthrenequinone with methyl ketones. Here studies the thermal and photochemical transformations of acenaphthaenone-2-ylidene ketones 3a-c.These acenaphthenone –2-ylidene ketones underwent extensive decomposition on heating. The objectives of present study is to synthesise acenaphthenone-2-ylidene ketones by the Claisen-Schmidt condensation of acenaphthenequinone and methyl ketones, it is to synthesise phenanthrenone –9-ylidene ketones by the Claisen-Schmidt condensation of phenanthrequinone and methyl ketones, thermal studies on acenaphthenone-2-ylidene ketones and phenanthrenone-9-ylidene ketones, photochemical studies on acenaphthenone-2-ylidene ketones and phenanthrenone –9-ylidene ketones to establish the generality of dibenzoyalkene rearrangement. Cyclic voltammetric studies on these dibezoyalkenes to compare their redox behaviour with that of the cis and trans isomers of dibenzoyl-ethylene, dibenzoylstilbene. These results should provide some information about their reactivity, and to assess and exploit the potential of these systems as quinonemethides. This study conclude that a number of new dibenzolalkene-type systems have been synthesized by the Claisen-Schmidt condensation of 1,2-diketones such as phenanthequinone and acenaphthenequinone with methyl ketones. Some of these compounds have been shown to undergo interesting photochemical transformations. Based on the results it is conclude that phenanthjrenone-9-ylidene ketones are excellent Michael acceptors. Methanol adds to these to yield the corresponding furanols. These furanols are unstable and are slowly converted to phenanthro-2 (3H)-furanones

Synthesis, Characterization and Properties of Ca5A2TiO12 (A=Nb, Ta) Ceramic Dielectric Materials for Applications in Microwave Telecommunication Systems

Microwave ceramic dielectric materials Ca5Nb2TiO12 and Ca5Ta2TiO12 have been prepared by a conventional solid-state ceramic process. The structure was studied by X-ray diffraction and the dielectric properties were characterized at microwave frequencies. The ceramics posses a relatively high dielectric constant, very low dielectric loss (Q5 x f > 30000GHz) and small temperature variation of resonant frequency. These materials are potential candidates for dielectric resonator applications in microwave integrated circuits. [DOI: 10. 1 143/JJAP.41.3834]