Development of 3d-4f and Cu based catalytic methodologies

This thesis deals with the use of Schiff base, amyloid peptide and benzotriazole scaffolds to synthesise 3d-4f and copper complexes and hybrid materials, investigate their catalytic properties and develop novel cost-, time- and step-efficient methodologies for the domino ring-opening/electrocyclization reaction of furfural and amines for the synthesis of trans-4,5-diaminocyclopentenones and the corresponding Stenhouse salts, as well as the coupling of aldehyde, amine and alkyne for the synthesis of propargylamines, to replace existing catalytic protocols. Chapter 1 serves as a general introduction to the chemistry discussed in the thesis. The first part emphasises on the synthetic aspects of coordination complexes. A rationale regarding the selection of the employed ligands is presented. The second part presents an overview of methodologies in catalysis, related to the methodologies developed in the present thesis, towards the synthesis of the organic derivatives. Chapter 2 focuses on the synthesis and characterisation of a new bimetallic tetranuclear complex Ni2Dy2 and its use as a catalyst towards the domino ring-opening/electrocyclization reaction of furfural and amines. The present catalytic system surpasses the efficiency of other reported systems, and the scope and limitations are described. Chapter 3 describes the first amyloid fibril core decorated by a heterometallic entity. The tetranuclear 3d-4f entity is of the type Zn2Dy2. The functionalized assembly behaves as a Lewis acid and catalyses the ring-opening/electrocyclization reaction of furfural and amines at a nanoscale level. Chapters 4 describes the synthesis and characterisation of a CuII complex with the use of a Schiff Base ligand, and its use as a catalyst towards the A3 coupling reaction. Control experiments, cyclic voltammetry and theoretical studies shed light on the mechanism of the reaction, suggesting the formation of an in situ radical specie. Chapter 5 reports the synthesis and characterisation of a relatively unexplored, in coordination chemistry and catalysis, hybrid pyridine-benzotriazole based CuII complex and its use towards the A3 coupling reaction. Control experiments, cyclic voltammetry and theoretical calculations account for a detailed mechanistic pathway and the development of an efficient methodology. Chapter 6 provides an overall conclusion of this thesis while highlighting the contributions of this work to the reported literature and discusses some potential future directions. Finally, experimental and synthetic details, as well as crystallographic data, are presented in Chapter 7 and Chapter 8, respectively. The bibliography is presented in Chapter 9.