Photo-physical Investigation of Bistable Molecular Magnetic Materials: Design, Synthesis and Applications

Abstract

The work reported in this thesis is structured around four interconnected studies that explore distinct, yet interrelated facets of molecular magnetism. An overview of the chapters presented in this thesis is outlined below: Chapter 1 provides an opening remark to the field of Molecular Magnetism, covering a general introduction to the field, providing a summary of the synthesis strategy utilized during this thesis, emphasizing the significance of cyanide-bridged building blocks and metal complexes. The chapter also covers the fundamental physical properties exhibited by molecule-based magnets, including photo/thermo-induced metal-to-metal electron transfer (MMET), spin crossover (SCO), and single-molecule magnets (SMM). The chapter concludes by providing the motivation and addressing the scientific problem behind the work presented in this thesis. Chapter 2 delves into the magnetic bistability exhibited by molecular Prussian blue (PB) and Prussian blue analogues (PBAs). This chapter is divided into two sections, where the first part covers the molecular replicas of PB and PBAs as molecular cubic units. In the second part, the impact of alkali-metal cation insertion into the cavity of the cubic core of the molecular replicas of PB is discussed. By examining the effects of temperature and light on these systems, this study highlights their potential for application due to their reversible switching properties. Chapter 3 focuses on the structural and magnetic versatility of [CoFe] complexes. This chapter is again divided into two sections; the first examines how reactant stoichiometries influence the overall system, while the second focuses on the effects of minor modifications in the ligand environment. This chapter elucidates how stoichiometric control, cyanide bridging angles, solvent molecules, and ligand environment can significantly influence the overall magneto-structural responses, offering new perspectives on designing tunable magnetic materials. Chapter 4 systematically investigates the multi-stimulus responsive spin state switching in iron (II) based complexes. The aspects of structural symmetry breaking, spin state switching, and pressure-tuned T1/2 transition are discussed and explored in this chapter. This chapter expands our current understanding of spin crossover dynamics and their practical implications. Chapter 5 explores the integration of porosity and magnetic response within a cyanido-bridged heterometallic framework. The study explores how guest molecules influence magnetic properties, presenting a novel strategy for creating responsive magnetic materials. Through these chapters, the work reported in this thesis seeks to deepen the understanding of stimuli-responsive magnetic materials and to provide insights into their potential applications in advanced functional devices. The work is systematically organised and discussed to give the reader a better understanding of the field, the novelty of the work, and its future applications. I hope the findings presented here will attract further research into the fascinating and interdisciplinary field