Chapter 1 serves as an introduction to the concepts and methods used throughout this thesis. This chapter highlights how main group and transition metal carbonyl complexes have potential therapeutic applications. The latter part of this chapter focuses on photodynamic therapy specifically using porphyrins. This is followed by an overview on the time resolved infrared (TRIR) spectroscopy. Also discussed are the excited states, energy transfer and applications of time-resolved infrared spectroscopy. Chapter 2 contains with a short literature review on the dipyrrins and metal coordinated dipyrrin compounds. It describes the luminescence and photophysical properties of various transition metal based dipyrrin complexes reported in literature. This chapter describes the synthesis and characterisation of novel dipyromethenes and their corresponding coordination to form tetra and tri carbonyl complexes of Re metal. Further in this chapter these complexes were accessed for their ability to act as CO releasing molecules (CORMs) using the myoglobin assay procedure both photochemically and thermally. Also presented are the results of time resolved infrared spectroscopy experiments, which show the existence of excited states based on intra-ligand charge transfer within the dipyrrin moiety.