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Title of Thesis

Sumera Mahboob
Institute/University/Department Details
Department of Chemistry/ Quaid-i-Azam University Islamabad
Inorganic Chemistry
Number of Pages
Keywords (Extracted from title, table of contents and abstract of thesis)
organogermanium compounds, dicarboxylic acids, hydrogermylation reactions, unsaturated propenoic acids, germa-γ-lactones, amino-terminated organogermanium polyamides

The work described in this thesis consists of the synthesis of organogermanium compounds based upon hydrogermylation reactions of HGeC13 with various substituted unsaturated propenoic acids such as 3-phenylpropenoic acid, 3-methyl propenoic acid, 2-methyl propenoic acid, 3-(m-methylphenyl) propenoic acid, 3-(p-methylpheny1)propenoic acid, 3-(m-methoxyphenyl)propenoic acid, 3-(o-methoxyphenyl)propenoic acid, 3-(p-methyl phenyl)propenoic acid, 3-(o-fluorophenyl)propenoic acid, 3-(p-fluorophenyl)propenoic acid, 3-(o-bromophenyl)propenoic acid and 3-(p-hydroxyphenyl)propenoic acid producing trichorogermyl-substituted-propanoic acids 1-12 of the general formula Cl3Ge-CH(R1)CH(R2) COOH where R1 = CH3, C6H5, H, m-CH3C6H4, p-CH3C6 H4, O-OCH3C6 H4, m-OCH3C6 H4, p-OCH3C6 H4, O-FC6 H4, P-FC6 H4, o-BrC6H4, p-OHC6 H4, R2 = H, CH3 and dicarboxylic acids such as trans-glutaconic acid, itaconic acid, fumaric acid, mesaconic acid and citraconic acid producing the trichorogermyl of dicarboxylic acids 25-32 of the general formula HOOC-R-COOH where R = -CH2CH(GeCl3)CH2-, -CH(CH2GeCl3) CH2-, -CH(GeCl3)CH2-, -CH (GeCl3)CH(CH3)- and -CH(CH3)CH(GeCl3)-. The synthesized compounds were characterized by elemental analysis, FTIR, 1H and 13C NMR. Single crystal X-ray diffraction was also carried out in some cases. Powder XRD also confirmed the crystalline nature of all these compounds.

The trichorogermyl-substituted-propanoic acids undergo complexation with 8-quinolinol to give a new series of germa-γ-lactones 13-24 by an intra and inter-molecular condensation. These germa- γ -lactones are five membered ring compounds containing germanium and oxygen atoms with the general formula [(Ox)2GeCH(R1)CH(R2)COO]. All the germa-y-lactones thus synthesized were characterized by elemental analysis, FTIR, 1H, 13C NMR, mass spectroscopy and single crystal X-ray diffraction analysis of some selected compounds and tested for their biological activity. The cytotoxicity test of compounds 13-24 against brine shrimp larvae indicate that compounds 13, 14, 16, 18,20,22 and 23 are 100 % cytotoxic in their higher doses with LD50 255.30, 135.20, 129.62,282.31, 301.31,329.51 and 271.48 µg/mL respectively. The results of antifungal studies of these compounds indicate that compound 13 was active against fungus Candida albicans (the only known fungus associated with AIDS) with 92.3 % inhibition. The investigated compounds were found to be more active against fungi than bacteria. In Vitro leishmanicidal bioassay was also carried out and all compounds exhibited an excellent activity against leishmanial parasites with IC50 ranging from 1.56-0.78, < 0.78 µg/mL and IC100 = 1.5-50 µg/mL relative to the reference drug Amphotericin B with IC50 = 0.18 µg/mL. Inhibitory activities of the present series of germa-γ-lactones were determined against three types of enzymes: α-glucosidase type (IV),β-g1ucuronidase and urease in 0.67 mM, 0.50 mM and 0.57 µM concentrations of the corresponding samples. The results of urease kinetics reveal that they inhibit bacterial as well as plant urease activities in a concentration dependent and non-competitive fashion. The structure activity relationship of different substituents at the y position to germanium appeared to be complex involving multiple microbial, parasitic and enzyme inhibition mechanisms.

The substituted trichlorogermyldicarboxylic acids were then converted into their acid chloride and condensed with various para-substituted aromatic diamines in the presence of an organic base, Et3N, to give 32 new oligomeric polyamides 33-64 of the general formula [-NH-Ar-NH-CO-R-CO-]n where Ar = phenyl, 1,4-biphenyl, 2,5-dimethyl phenyl, 1,4-diphenylether, 2,2€™-dimethyl-l,4-biphenyl, 2,2€™-dimethoxy-l,4-biphenyl. The compounds were characterized by spectral methods such as FTIR, multinuclear NMR 1H, l3C, and solid state l3C), MALDI and SEM/EDX. These oligomeric products were found to be insoluble in common organic solvents such as THF, DMSO, DMF and NMP but soluble conc. H2SO4 and TF AA. Powder XRD studies indicate an amorphous nature of the polyamides. The surface morphology studied by SEM shows a sponge like appearance with larger cavities (0.47-1.14 µm) connected with internal irregular network.

These polyamides were found to exhibit high Tg in the range of 198-350 °C and are stable up to 200-400 oC. TG-FTIR studies indicate that initial decomposition of the polyamides start with the evolution of CO. Thermodynamic and kinetic parameters such as Ea, n, A, ”H and ”S were calculated from TG curves by using the Horowitz/Metzger and Coats/Redfern methods. The values of activation energies obtained by the Horowitz method are much higher than Coats method and fall in the range of 83.63±0.02 to 403 ±0.06 KJ/mol and 12.58±0.09 to 51.72±0.02 KJ/mol respectively.

Download Full Thesis
4720.42 KB
S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents
396.34 KB
2 1 Literature Review And Introduction 1
727.99 KB
  1.1 Organogermanium Compounds 1
  1.2 References 21
3 2 Results And Discussion 26
1010.21 KB
  2.1 Germa- γ -Lactones Derived From Unsaturated Monocarboxylic Acids 26
  2.2 Amino-Terminated Organogermanium Polyamides Derived From Unsaturated Dicarboxylic Acids 35
  2.3 Conclusions 59
  2.4 References 60
4 3 Biological Studies 62
522.77 KB
  3.1 Biological Studies 62
  3.2 Conclusions 77
  3.3 References 78
  4 Thermal Studies And Morphology Of Amino-Terminated Organogermanium Polyamides 80
  4.1 Thermal Studies Of Amino-Terminated Organogermanium Polyamides 80
  4.2 Scanning Electron Microscopy 87
  4.3 Conclusions 91
  4.4 References 92
5 5 Experimental Procedures 94
1813.36 KB
  5.1 General Procedures For The Syntheses Of Organogermanium Compounds 95
  5.2 Synthesis Of Compounds 13-24 101
  5.4 Organogermanium Compounds Derived From Unsaturated Discarboxylic Acids 109
  5.5 Synthesis Of Compounds 30-32 111
  5.6 Synthesis Of Compounds 25a-33a 113
  5.7 Synthesis Of Compounds 33-64 114
  5.8 References 136
  5.9 Appendices