http://localhost:8081/jspui/handle/123456789/4 Thu, 10 Jul 2025 22:34:28 GMT 2025-07-10T22:34:28Z http://localhost:8081/jspui/handle/123456789/17379 Title: ORGANOTIN(IV) CARBOXYLATES: POTENTIAL ANTI-TUMOR AND ANTI-INFLAMMATORY AGENTS Authors: Vats, Monika Abstract: Organornetallic chemistry is the study of chemical compounds containing carbon - metal bonds. Today organometallic chemistry has reached a noticeable position due to its tremendous contribution in pharmaceutical, semiconductors, catalysis, agricultural, and other technological applications. Among them one of the fastest growing lelds is bioorganometallic chemistry. Research in bioorganornetallic medicinal chemistry focuses on designing new types of drug molecules by utilizing various techniques such as combinatorial chemistry, computer-aided molecular design and new types of highly sophisticated receptor-based and cell biological assays for drug activity. lhc large amount of novel functions, new structures and various properties lead to the phenomenal success of transition—metal organometallic chemistry (TMOC). Along with organotransition complexes, the spectacular progress has also been made in organometallic compounds of main group elements such as aluminum, boron, lead, lithium, silicon and tin. Organotin complexes exhibit structural diversity which contributes to various applications. Organotin(IV) compounds have been found useful in several industrial and commercial applications such as agricultural biocides, disinfectants. anti-fouling agents, wood preservatives, stabilizers for poly(vinyl chloride), flame retardants, smoke suppressants, anti-wear agents, hornogenous catalysts, recycling agents and curing agents for room temperature "vulcanization" of' silicones. Organotin(IV) complexes have also been used as versatile synthetic reagents for various organic transformations and as catalyst for the production of polyoretlianes. A number of organotin(lV) compounds have found to be toxic, and there is increasing concern regarding their widespread use in environmental and Ar biological systems. During the last few decades, organotins have emerged as potential biologically active compounds exhibiting antimicrobial, antiviral, antiherpes, antituberclosis, anti-inflammatory, anti-tumor and antihypertensive activities. Their signilicance from chemotherapeutic point of view has been enhanced further, because of their interactions with some clinically recommended drugs. Furthermore, it has been revealed that the biological activity of organotin compounds may be due to the transportation of R1Sn (n = 2 or 3) moieties formed by dissociation of easily hydrolysable groups attached to tin atom or organotin(W) compounds as one entity across the cell, and hence formulate the structure-activity correlation. It has been found that organotin compounds exhibit potential anti-tumor activity. Among organotin compounds, organotin carboxylates are very important. Organotin(IV) carboxylates contain 11 Sn -o bond formed through 000 group and therefore, exhibit a number of interesting structural features which enable them to exhibit anti-tumor activity. Anti-tumour activity and mode of action of -- organotin carboxylates have been studied and reported in the literature, however literature does not reveals the exact mechanism for their activity. Though several organotin(IV) carboxylates have been reported but there is lack of information about coordination behaviour of simple carboxylic acids of plant/animal origin which are biologically important, and the structural features of corresponding organotin carboxylates have not been studied in detail. Several organotin(IV) carboxylates with antiviral. antibacterial and antifungal activity have been studied, but little work on in vitro anti-cancer activity of the organotin(IV) carboxylates has been reported. Moreover, the mode of action of simple organotin halides has been studied extensively. 1-lowever, few studies explaining the mechanism for anti-tumor activity of organotin(IV) carboxylates has been reported. The motive of the present work is to view insight the pathway of anti-tumor activity of the organotin(IV) carboxylates via various assays: enzyme assays. DNA fragmentation, acridine orange and cornet assay. Anti-tumor activity and anti-inflammatory activity are related to each other. Every deadly disease is associated with pain or inflammation, therefore, an anti-tumor drug with anti-inflammatory properties is desirable, in light of this anti-inflammatory and acute toxicity studies have also been performed. Microwave-assisted method for the synthesis of organotin complexes has emerged as quick. environment friendl, Cost effective and energy efficient. Very few examples are known in literature for the synthesis of organotin(IV) carboxylates via microwave-assisted method. Hence the drive \\as to synthesize the organotin(IV) carboxylates via new microwave-aided methodology and as well as via conventional thermal method, and compare the two methods completely through physical data, analytical measurements and spectroscopic studies. Keeping in view the wide range of applications of the organotin(IV) compounds and the biological importance of simple carboxylic acids of planllanimal origin, it was considered to synthesize oragnotin(IV) derivatives of carboxylic acids viz. lauric acid, myristic acid, stearic acid, orotic acid, hippuric acid, glucuronic acid, mandelic acid and gallic acid, and investigate their structural and biological aspects. An attempt has been made to compile the work to obtain a better insight into the coordination behaviour of organotin(IV) moieties with carboxylic acids along with their anti-tumor activity, their mode of action for cytotoxicty and anti-inflammatory activity. In order to maintain the clarity of the presentation. the work embodied in the thesis is systematically divided into the following chapters. - First chapter presents the general introduction and an overvicv of some important applications of organotin(IV) compounds. A critical and comprehensive review of the available literature on the organotin(IV) carboxylates with special reference to their synthetic procedures. structural characterization, their anti-tumor activity and mode of action has also been presented. Second chapter incorporates the details of make, purity and other specifications of the materials used in the present study. The specifications of the instruments used for spectroscopic studies (FTJR, NMR and ESI-MS) and the details of the procedures used therein have been included. The methodology used for the biological studies (anti-tumor activity, enzyme assays. DNA-fragmentation, acridinc orange, comet assay, anti-inflammatory and toxicity studies of the synthesized complexes) has also been presented. The results obtained from these studies have been compiled and discussed in Chapters 3, 4, 5 and 6. Third chapter includes the synthesis and characterization of tn- and diorganotin complexes of the general formula RSn(L), [n = 3, in = I. R Me, n-Pr, n-Bu and Ph n = 2, m 2, R = Me, ii- Bu and n-Oct: L anion of laurie acid (lILA). stearic acid (HSA) and myristic acid (lIMA)I have been synthesized. The synthesized complexes have been characterized by elemental analysis, 1k. 'H. '3C. ''9Sn NMR and ESI-MS spectral studies. Triorganotin(IV) carboxylates and diorganotin(IV) carboxylates adopt trigonal bipyramidal and octahedral geometry around tin atom, respectively. The complexes have been screened in vitro for anti-tumor activity against five human cell lines i'i:. MCF-7 (mammary), 14EK-293 (kidney). PC-3 (prostate). lICT-15 (colon) and I lepG-2 (liver). Enzyme assays viz, lipid peroxidase, glutathione peroxidase, glutathione reductase and total glutathione assay have also been carried out to explore the cause of cytotoxiciy. The results of the enzymes assay indicate that ROS generation may be responsible for cytotoxicity but elevation in (lactate dehydrogenase) LDH suggests that necrosis cannot be excluded. Further, DNA ftagmentation, acridine orange and comet assay support the apoptosis as main cause of cytotoxicity of organotin(IV) carboxylates whereas the necrosis plays a minor role. The anti-inflammatory activity evaluation shows that the complexes possess moderate activity. Acute toxicity of the complexes has also been discussed in the chapter. Fourth chapter of' the thesis deals with the synthesis of triorganotin(lV) orotates [R3Sn(H,0r). R = Me, n-Bu and Ph], diorganotin(IV) orotates [R2Sn(H20r)2. R = Me, n-13u, n-Oct and Ph] and n-Bu2Sn(l-l0r) [FLOr = monoanion. l-10r2 = dianion of orotic acid (1 1Or) j. On the basis of various spectroscopic studies it is revealed that R3Sn(1 120r) and R7Sn(l 120r)2 exhibit distorted trigonal bi pyramidal and distorted octahedral geometry. respectively, and n-BwSn(HOr) iv shows both live-and six-coordination geometry around tin, in vitro anti-tumor screening against MCF-7. HEK-293, PC-3, HCT-15 and HepG-2 cell lines suggest that the n-Oct2Sn(1-I20r)2 is the most active complex among all of the studied complexes. DNA fragmentation and anti-oxidant enzyme assays on MCF-7 and PC-3 cell lines suggest that cytotoxic effect of the complexes is selectively mediated through the induction of apoptosis. The results obtained for the anti-inflammatory and toxicity of the synthesized triorganotin(IV) derivatives are also discussed. Fifth chapter enumerates the synthesis and characterization of triorganotin(lV) derivatives ci' hydroxy acids of general formula, R3Sn(L) [R = Me, n-13u and Ph; 1. = anion of glucuronic (I IC ILL). gallic (HGal) and mandelic (I-lMal) acid]. The complexes R-Sn(L) exhibit trigonal bipyramidal geometry which is well supported by elemental analysis, IR, 'II, 3C, ''9Sn NMR and ESI-MS spectral data. l'hesc organotin(IV) carboxylates have been screened in vitro against five cancer cell lines of - human origin viz. MCF-7, HEK-293, PC-3, I ICT- l 5 and HepG-2. These complexes are found to be cytotoxic to mildly cytotoxic in nature, and exhibited activity in the range 4-30 .tg/rnl.. Enzyme assays like, glutathione reductase, glutathione peroxidase, total glutathione content and lipid peroxidase assay on MCF-7 cells have also been performed. The results indicate that the reactive oxygen species generated in the cancer cells by the organotin(IV) carboxylates is responsible for cell death. Marginal increase of lactate dehydrogenase suggests that necrosis is also occurring to a small extent. DNA fragmentation assay, acridine orange assay and comet assay clearly support that the cell death is mainly due to apoptosis. The results obtained for the in vivo anti-inflammatory activity (% inhibition) and toxicity (LD50 in mg/kg) of the synthesized derivatives have been compiled and discussed in this chapter. Sixth chapter of the thesis incorporates microwave assisted reaction between triorganolin chlorides or diorganotin chlorides/oxides and hippuric acid (liHA), in 1:1 or 1:2 molar ratio which resulted in the formation of R3Sn(HA) (R = Ph, n-E3u. and Me) and RSn(l-IA)2 (R = n-Oct, n-Bu and Me) [HA = anion ot'hippuric acid], respectively. llowcvcr, complexes were also synthesized through conventional thermal conditions for comparison. The chapter contains complete comparison between the conventional thermal method (time taking, energy and solvent consuming) and microwave assisted method (cost effective, swift, environmental friendly and simple) on the basis of yield, time taken for synthesis and solvent consumed, physical characteristics, elemental analysis, IR. NMR and ESI-MS spectroscopic studies. In vitro anti-tumor screening, anti-inflammatory activity and acute toxicity of the complexes have also been discussed in this chapter. Fri, 01 Feb 2013 00:00:00 GMT http://localhost:8081/jspui/handle/123456789/17379 2013-02-01T00:00:00Z http://localhost:8081/jspui/handle/123456789/17378 Title: ENANTIOMERIC RESOLUTION OF SOME PHARMACEUTICALS BY LIQUID CHROMATOGRAPHY Authors: Lal, Manohar Abstract: The importance of chirality of the molecules has been recognized and is required to be addressed for biologically active compounds, in the areas dealing with pharmaceuticals, agrochemicals, food analysis, fragrances, chiral pollutants, asymmetric synthesis, clinical and forensic evaluation. This interest can be attributed largely to the fact that the enantiomers may have different pharmacological activities, as well as different pharmacokinetic and pharmacodynamic effects in chiral systems. Therefore, development of efficient analytical methods for enantioseparation has become an essential part of the drug development process. Among the various available methods for obtaining enantiomerically pure compounds, liquid chromatographic (LC) techniques particularly high performance liquid chromatography (HPLC) is extensively used for resolution of a variety of chiral biochemicals. Present thesis deals with studies on direct and indirect enantioseparation of certain chiral carbonyl compounds, J3-amino alcohols, proteinogenic-a-amino acids, se lenomethionine, 3-blockers, (RS)-ketorolac and (RS)-amlodipine. These chiral compounds/ drugs have wide applications in the field of chemistry, biochemistry, medicine, etc. The enantiomcric separation has been carried out using different chiral derivatizing reagents (CDRs), chiral stationary phases (CSPs) and chiral selectors. First chapter deals with preamble to present studies including importance of chirality in pharmaceuticals, and brief introduction to the applicable important scientific terminology. Various scientific terms such as chirality, enantiomers and their biological significance, chiral compounds, chiral chromatographic separation approaches, chiral selector (for TLC), CSPs, CDRs and their applications have been discussed in brief. The CDRs have been classified in different categories depending upon the nature of functional group present in anatytes. Secoiid chapter presents the literature survey of chosen CDRs, CSPs and analytes. Third chapter deals with the description of the common experimental procedures used for present studies. It includes materials, instrumentation, preparation of stock solutions, extraction of active pharmaceutical ingredient from formulations. The details with respect to methods for synthesis of CDRs along with their characterization data, synthesis of diastereomers followed by separation using reversed phase-HPLC are described in subsequent chapters. In all, 17 CDRs were synthesized using CC (cyanuric chloride; trichloro-s-triazine) and (S)-Naproxen as starting materials. In ten of these reagents, (the DCT, dichloro-s-triazine) enantiomerically pure amines (viz., (R)-(+)-naphthy lethyl amine and (S)-(+)- I -benzyl-3-aminopyrrolidine, amino acids (viz., L-Leu, L-Val, D-Phg, L-Ala), and amino acid amides (viz., L-Leu-NH2, L-Val-NH2, D-Phg-NH2, L-Ala-NH2) were incorporated in cyanuric chloride as chiral auxiliaries. Six MCT (monochloro-s-triazine) reagents were synthesized by incorporating L-Ala-NH2, D-Phg-NH2, L-Leu-NH2, and L-Val-NH, and (R)-(+)-NEA and (S)-(+)-BAP) as chiral auxiliaries in 6- butoxy / methoxy derivative of s-triazine. Besides, (5')-Nap based CDR, (S)-2-(6-methoxynaphthalen-2-yl)propanehydrazide (NAP-H), was synthesized by its reaction with hydrazine hydrate in presence ofdicyclohexylcarbodiimide (DCC) as coupling agent. Fourth chapter presents indirect enantioseparation of amino acids, selenomethionine and amino alcohols. It has been divided into three sections. Section A: It deals with the development of a sensitive method for separation of 19 diastereomers from a mixture of thirty and determination of D-amino acids in scalemic mixtures in the absence of pure D-enantiomers. Diastereomers of 15 DL-proteinogenic amino acids were synthesized under microwave irradiation using four new CDRs. Two enantiomerically pure amines, namely, (R)-(+)-NEA, and (S)-(+)-BAP were selected as chiral auxiliaries and introduced in CC and its 6-butoxy derivative to synthesize these CDRs. The CDRs so obtained 14 were characterized and their optical purity was ascertained. The mixture of 30 diastereomers was separated on C18 column in a single run using a linear gradient of mobile phase from 100% A (Water-MeCN, 90:10) to 100% B (Water-MeCN, 10:90), containing TFA, in 50 mm (flow rate 1.0 rnL min1 detection at 230 nm). Chromatographic conditions were optimized. UV spectra of each pair of diastereomers were captured with PDA detector. Comparison of chromatogram of the multicomponent mixture with the chromatograms of the diastereomeric pairs of individual amino acids revealed that a few of the diastereomers co-eluted. Yields and stability of diastereomers were established. The separation behaviour in terms of retention times and resolutions were compared on the basis of effect of chiral auxiliaries (i.e. aniines) and achiral substituents (i.e. chlorine or butoxy group) in the CDRs and the hydrophobic side chains of amino acids. The focus of investigation of this section was (a) to develop new CDRs with enhanced UV absorption characteristics, (b) to examine/evaluate the effect of hydrophobicity of achiral substituent in CC (on enantioseparation) and (c) to obtain lower LOD in comparison to existing literature. The developed separation method was validated in terms of accuracy, precision, linearity, recovery, LOD and LOQ. Section B: This section explores the HPLC indirect resolution of DL-selenomethionine (SeMet) using four newly synthesized CC based CDRs (two DCT and two MCT). To develop CDRs, It enantionierically pure, (R)-(+)-NEA, and (S-(+)-BAP were introduced as chiral auxiliary in CC and its 6-butoxy derivative by nucleophilic substitution of one chlorine atom in each of them. The CDRs so obtained were characterized and their optical purity was ascertained. Diastereomcrs of DL-SeMet were synthesized under MWl for 60 or 90s (at 80% power of 800 W). Diastereomers were separated on a C18 column using RP-HPLC and mixtures of MeCN with aq TFA as mobile phase. The detection was made at 230 nm using PDA detector. The separation behaviour in terms of retention times and resolutions were compared. The separation method was validated for linearity, accuracy, precision, recovery and LOD. Section C. In this section an indirect HPLC enantioresolution of eight selected 13-amino alcohols has been achieved on certain CC based CDRs. In 6-methoxy triazine and CC a Cl atom was substituted with chiral auxiliaries like L-Ala, D-Phg, L-Leu, and L-Val and their amides to obtain twelve CDRs (three sets; 2 DCT and I MCT). Using MWI and each of the twelve CDRs, diastereomers of eight amino alcohols were synthesized. The resulting diastereomers were separated by RP-HPLC using C18 column and eluting mixtures of MeCN with aq.TFA in a linear gradient (45 mm) with UV detection at 230 nm. The flow rate of the mobile phase and the concentration of TFA and organic modifier in it were varied to optimize the method, so developed, for chromatographic separation of d iastereomers. The results (in terms of resolution Rs, and retention factor k) obtained for the three sets of diastereomers were compared among themselves and among the three groups. The effects of le chiral auxiliaries (in terms of acid and amides variants), constituting CDRs, on separation were also evaluated. The elution order for the diastereomers was determined. The separation method was validated for linearity, accuracy, precision, recovery and LOD. Literature survey reveals that the CC based CDRs have been applied for the first time for enantioseparation of racemic 3- amino alcohols. Fqfth chapter deals with the synthesis of naproxen hydrazide reagent (S)-2-(6-methoxynaphthalen-2-yl)propanehydrazide (NAP-I-I) followed by its application as CDR for the enantioseparation of certain carbonyl compounds. The reagent was characterized and its chiral purity was established. It was used as a CDR for the synthesis of hydrazone diastereomers, under MWI, of four aldehydes and two ketones. The respective diastereomers were resolved by RP-HPLC using C18 column and gradient eluting mixture of MeCN with aq. TFA. The separated diastereomers were detected at 231 nm using PDA detector. The method was validated for linearity, accuracy, precision, recovery and LOD. For a series of hydrazones LOD was found to be in the range 1.62 to 1.65 prnol mU'. The synthesis of naproxen hydrazide reagent using DCC as coupling reagent and its use as chiral derivatizing reagent for RP-HPLC enantioseparation of carbonyl analytes have not been reported yet. Sixth chapter is devoted to direct resolution of enantiomers of (RS)-Ketorolac (Ket) and (RS)-Amlodipine (Ami) on two polysaccharide-based chiral columns, viz. Lux Cellulose-2 and Lux Amylose-2 containing cellulose tris-(3-chloro-4-methylphenyl) carbamate and amylose tris-(5-chloro-2-rnethylphenyl) carbamate, as the chiral materials, respectively. Enantioseparation were carried out under normal and reversed phase (NP and RP) elution mode with suitable mobile phase compositions. The results obtained from two columns were compared among themselves in regards to their ability to provide baseline resolution. The effects of the nature and concentration of alcoholic modifier and pH of mobile phase on the retention and resolution were studied. The detection was made photochemically using PDA detector for identification of enantiomers. The effect of alcoholic/ organic modifier on enantioselectivity and resolution of enantiomers was evaluated. The sequence of the eluted enantiomers was ascertained by (iv) performing optical rotation studies on polarimeter. The method was validated in terms of accuracy, precision and linearity in the range of 30-70 tg mr1 and the r2 was >0.99. Seventh chapter deals with direct TLC enantioseparations of four n-blockers, namely, (RS)-atenolol, propranolol, metoprolol and bisoprolol using azithromycin (AZM) as a chiral impregnating agent as well as chiral mobile phase additive. Impregnated thin-layer plates were prepared by spreading slurry of silica gel prepared in the solution of AZM. The enantioseparation was attempted using different binary, ternary and quaternary combinations of solvents systems containing MeCN, MeOl-1, 17120 and CHC13; triethylamine was added to adjust pH. The spots were located using iodine vapor. The developed TLC method was validated for linearity, accuracy, precision, recovery and LOD. The influences of pH, temperature and amount of chiral selector were examined on enantioseparation. Sat, 01 Jun 2013 00:00:00 GMT http://localhost:8081/jspui/handle/123456789/17378 2013-06-01T00:00:00Z http://localhost:8081/jspui/handle/123456789/17352 Title: THEORETICAL STUDIES OF HYDROBORATIONAND ALLIED REACTIONS Authors: Singh, Satya Prakash Abstract: Hydroboration of olefins is one of the most important reactions in synthetic organic chemistry, because the organoboranes formed are very useful intermediates and are subject to a large number of organic transformations under mild conditions. In the present work we investigate the computationally hydroboration of strained cyclopropane ring, which is known to exhibit in several instances olefin like behavior. Hydroboration of substituted cyclopropanes are also studied. The analogous hydroalumination of cyclopropane using A1H3 is also studied. Addition of MgH2 and LiH to cyclopropane are also investigated. All calculations have been performed using the Gaussian 98W suite of programs. The thesis is divided into six chapters, whose contents are outlined below. V The First chapter presents a general introduction and an overview of hydroboration and allied reactions. Emphasis is placed on the transition structures along the reaction path. The related hydroalurnination reaction and addition of hydrides of magnesium and lithium are also reviewed. A critical review of the available literature on computational studies on hydroboration and related reactions are presented, comparisons with relevant experiments are also made wherever possible. The Second chapter outlines the computational methods used. A brief introduction to the techniques of geometry prediction, using ab initio SCF and Density Functional methods, and of characterization of stationary points on the potential energy surface are given. The Third chapter deals with the computational studies of the hydroboration of cyclopropane with borane. Optimization of the key species, complex, transition structure and the addition product formed is the reaction done at Hartree-Fock, MP2 and DFT/133LYP level, using 631G**, 6-31 l++G**, AUG-cc-pVTZ and Dunnings basis, cc-pVDZ. Two types of transition structures have been reported: a three-centered transition structure in which borane approaches along the plane of the cyclopropane ring and the second in which borane approaches perpendicular to the plane of the ring. The critical geometrical parameters are also reported. The bond making and bond breaking phenomena are shown using HOMO's of the complex and transition structure. Relative energies of the stationary species are presented. (i) Frequency analyses were also performed to confirm that the structures obtained were true minima on the PES or saddle points as the case may be. IRC calculations are done from each transition state, showing clearly the transition state moving towards the reactant and product sides. Single point energies computed at B3LYP optimized geometries at different ab initio level have also been reported. The Fourth chapter of the thesis incorporates computational studies on the hydroboration of substituted cyclopropane, the substituents used are —F, -Cl, -CN, - NC, -CH3 and —(CH3)2. The geometries of the stationary structures are performed at the DFT/B3LYP level using 631G** basis set in each cases and the nature of each stationary point was probed by frequency calculations. Single point calculation at different ab initio level have also been performed. These studies point to different possible path'ays for the addition of BH3 to cyclopropanes. The Fifth chapter of the thesis reports investigation of the hydroalumination of cyclopropanes. Ab initio and DFT/B3LYP calculations have been performed with 631G**, 6311++G** and Dunning's cc-pVDZ and AUG-cc-pVTZ basis sets. These calculations revealed four-centered transition states with B located in the plane of along and perpendicular to the cyclopropane ring. The viability of reaction has been confirmed by using energy barriers calculated for the reaction path. The Sixth chapter reports the theoretical study of the addition of hydrides of lithium and magnesium i.e. and MgH2 and LiH to cyclopropane. First the addition of MgH2 to cycloproapne have been discussed. All calculation are performed using RHF, MP2 and DFT/B3LYP level of theory using 631G** and 6311++G** basis set. Both the possible approaches along the plane of the ring and perpendicular to the ring are investigated. A study of LiH addition follows. Same levels of calculations as used for addition of MgH2 to cyclopropane are used. Single point calculations at the higher level of theory are also reported. Fri, 01 Feb 2013 00:00:00 GMT http://localhost:8081/jspui/handle/123456789/17352 2013-02-01T00:00:00Z http://localhost:8081/jspui/handle/123456789/17067 Title: STRUCTURAL PATTERN AND THE STABILITY OF WATER CLUSTEkS IN GAS HYDRATES Authors: Shilpi, V. Abstract: The scarcity and the high demand for natural gas lead to the search for alternative energy sources. Gas Hydrate is one of such energy sources which is not yet explored. The main reason for this is their existence at extreme conditions like very low temperatures and high pressures at which experimental studies are difficult. Modeling can give insight to the structure and stability of Gas Hydrates at favorable conditions for their effective use. Structural pattern and the stability of various types of water cages that occur in gas hydrates viz. Dodecahedral (512), Tetrakaidecahedral (51262) and Hexakaidecahedral (51264) cages are studied using the SWB and SWEB models and density functional Becke97-D in conjunction with cc-pVTZ basis set. In addition to the dodecahedral cages, the validity of these models is also tested for comparing the relative stability of isomers of other families of (1420)20 clusters viz. Edge-sharing pentagonal prisms (ESPP), Face-sharing pentagonal prisms (FSPP), Fused cubes (FC), and Irregular-dodecahedron (IDD). The fused cages formed by the combinations of two dodecahedral cages, two irregular-dodecahedral cages and a dodecahedral cage with an irregular-dodecahedral cage are also studied. A strategy is explained for obtaining the fused cages having maximum number of strong hydrogen bonds. The influence of various structural features such as homodromic rings, heterodromic rings and AADD type of water molecules on the stability of all the above geometries has also been explained. Sun, 01 Jun 2014 00:00:00 GMT http://localhost:8081/jspui/handle/123456789/17067 2014-06-01T00:00:00Z