This Thesis describes the synthesis, structural, photochemical and photophysical studies of modified retinal protonated Schiff bases in solution. Ultrafast laser spectroscopy, NMR and circular dichroism studies were employed to investigate speed, yield and selectivity of photoisomerisation in these chromophores. Chapter 1 introduces relevant biological, photophysical and photochemical aspects of retinal protonated Schiff base photoisomerisation. It includes an overview of synthetic approaches to modified retinal synthesis pertinent to this this work. Chapter 2 discuses the investigation of the hypothesis that twisting of the chromophore’s isomerising double bond is responsible for ultrafast photoisomerisation in the protein environment. In these studies it was discovered that addition of a methyl group to the retinal backbone in solution results in protein-like photophysics. Chapter 3 presents photopysical and photochemical studies of modified all-trans retinal protonated Schiff bases that culminate in a qualitative model for the influence of electronic factors on photochemical and photophysical behaviour of these chromophores in solution. Chapter 4 describes structural and photophysical investigations of 11-cis retinal protonated Schiff bases. NMR studies indicate conformational flexibility of the chromophores. The first synthetic solution-based chromophore to reach rhodopsins’s speed of photoisomerisation is described. Chapter 5 presents an attempt to gain conformational information on retinal protonated Schiff bases using circular dichroism spectroscopy. Transfer of stereochemical information from the covalently attached stereogenic centre to the retinal backbone is demonstrated.