Chapter one serves as an introduction to the principles and methods used throughout this thesis. The principles of photophysics are discussed generally and also in relation to porphyrins and dipyrromethenes. Potential applications for the novel thienyl dyes and related metal carbonyl complexes synthesised are then presented. This is followed by an outline of the techniques of laser flash photolysis, time-resolved infrared (TRIR) spectroscopy and time correlated single photon counting. Chapter two involves the study of thienyl porphyrins. This chapter begins with a literature survey on the synthesis, photophysics and electrochemistry of thienyl porphyrin systems. The synthesis of the porphyrins studied is given, followed by their photophysical and electrochemical properties. The effect of the thienyl moiety on the ground state and excited state properties of the porphyrin macrocycle is examined Chapter three commences with a general introduction to Sonogashira-Hagihara type cross coupling reactions and is followed by a literature survey on the synthesis and photochemistry of thienyl based organometallic systems. The synthesis of the novel systems produced for this study is then described and the photophysical properties are examined. Electrochemical data are also presented. The photochemistry of the Co2(CO)6 complexes are examined by steady state photolysis in the presence of a trapping ligand. Three of the complexes were studied by TRIR on a picosecond timescale and the quantum yields of CO loss were determined at a range of excitation wavelengths. Chapter four commences with a literature survey focusing on the photophysics of pyridyl porphyrins and related organometallic systems. The synthesis of the monopyridyltriphenyl porphyrin and metal carbonyl derivatives produced for this study is described. The photochemistry of the complexes was examined by pump and probe TRIR spectroscopy on a picosecond timescale. Chapter five contains with a short literature review on the synthesis and photophysics of dipyrromethanes and dipyrrin compounds. The synthesis of a series of substituted thienyl dipyrromethanes, related dipyrrin complexes and corresponding dicobalt complexes is presented. Preliminary photophysical measurements are discussed. Finally chapter six discusses future work for chapters 3, 4 and 5.