Investigations towards new multidentate ligands as potential multimodal imaging agents

Abstract

A Coordination chemistry based historical perspective of contrast agents which are utilised in various imaging modalities, forms the basis of Chapter 1. Chapter 1 also highlights the various latest advancements and the challenges confronted therein. Chapter 1 culminates in highlighting the need for dual purpose contrast agents. Chapter 2 and Chapter 3 deals with rx)lyarnino poly carboxylate derivatives based on EDTA and DTPA respectively. Chapter 2 sheds light upon Teslascan and other related manganese based potential contrast agents. It also highlights the emergence of Mn (II) as the direct competitor for Gd (HI) in the face of Nephrogenic Systemic Fibrosis (NSF) reported for Gd based contrast agents. The chapter culminates in describing the synthesis of a library of EDTA bisamides, including four new EDTA bisamides. Chapter 3 in turn takes a detailed look at a series of DTPA analogues and DTPA bisamides synthesized by scientists all over the world. It also highlights the various synthetic methodologies undertaken by the able scientists. The chapter culminates in describing four new multidentate ligands synthesized in this project, namely two new DTPA analogues and two new DTPA Bisamides. It has been shown that the synthetic methodology utilised to synthesize symmetric naphtha derivative L5 is fairly unique. Chapter 4 and Chapter 5 report the investigations carried out on these new multidentate ligands in terms of relaxometry, potentiometry and luminescence. Interesting results were obtained from relaxometric and luminescence measurements. For instance, symmetric naphtha derivative, reported a relaxivity of 8.8 mM'V1, relaxivity obtained for Mn (II) complex of EDTA bisamide of 4-aniinomethylpyridine is also highly commendable. Investigations on the optical properties of the multidentate ligands require a separate chapter. Thus it is has been allotted Chapter 5. DTPA bisamide of N, N-Bis (tert- butoxycarrx)nyl)memyl-2-bromcmylamine was found to quench the fluorescence upon binding with Cu (II), indicating its application as luminescent sensor for Cu (II)