Syntheses and Structural Investigations of Iron(III) Ternary Complexes And Cu(II) Binary Complexes of Nucleotide and its Constituents

Includes bibliograhical references

PhD;2023;Inorganic and Physical Chemistry

Nucleotide is the monomeric unit of DNA and RNA, being the building block of nucleic acid, it plays important roles in many biological processes. For example, Adenosine tri phosphate (ATP) acts as a storage and transporter of chemical energy in the living cell. But it is impossible to predict the activity of nucleotides without considering the role of metal ions in it. All nucleotides involved enzyme-catalyzed reactions including DNA and RNA polymerases, usually need Mg2+ divalent cation. This thesis offers the syntheses and structural insights of metal ternary and binary complexes with nucleotides and with their constituents. In the first chapter, a series of ternary complexes of Fe(III)-TPA-5'-Nucleotide Monophosphate [5'-FTNMP] have been synthesized and characterized with single crystal XRD and different spectroscopic techniques. Structural investigations reveal the formation of homo base pairs (A-motif, i-motif) in the case of 5'-FTAMP and 5'-FTCMP complexes. In the second chapter, the specificity of homo base pair formation has been verified by using 5'-dAMP, 5'-dCMP, 2'-AMP, 2'-CMP, 3'-AMP, 3'-GMP. Structures of 5'-FTdAMP and 5'-FTdCMP reveal the intactness of homo base pair formations although environment of water molecules are completely different from the relative structures discussed in the previous phase. The structural details of 2'-FTAMP and 2'-FTCMP signifies the effect of change in position of phosphate group where formation of homo base pair is unobserved, instead of that intramolecular hydrogen bond between 3'-OH and phosphate’s oxygen atoms have been established. Formations of weak π-π stacking interaction between adenine moieties and direct hydrogen bond interaction between guanine moieties are also observed in case of 3'-FTAMP and 3'-FTGMP. A comparative structural discussion has been made in the subsequent chapter to get an idea about the sugar ring conformation, nucleobase conformation and interaction of guest of water molecules in the structural stability of these complexes. Conformation of most of the nucleobase conformations about the glycosyl bond are anti, although in a few cases, preferred conformations are syn. The sugar moieties are found to exhibit C2'/C3', endo/exo conformation. To evaluate the effect of guest water molecules on the nucleotide conformation, a variable temperature experiment is carried out on the crystal of 2'-FTCMP and this experiment leads to the single crystal to single crystal (SCSC) transformation. The last chapter presents the binary coordination complex of Cu(II) with adenine nucleobase and with its N9-derivatives. Here several copper-adenine/N9-Adenine derivative complexes are synthesized in different reaction conditions (e.g, pH, counter anions) and peculiar coordination chemistry are discussed in detail. In Cu(II)-N9-adenine derivative complexes, Watson-Crick and Hoogsteen types of hydrogen bond base pairs have been observed between the discreate molecules and formed different kinds of supramolecular architectures. Encouraged from the previous results, a novel copper(II) coordination polymer is synthesized, and structural aspects are discussed thoroughly with potential applications.