The talk will discuss recent advances in photobase/photoacid research. We will consider the photophyiscs of polymer-embedded photobases and photoacids to control the hydrophilicity/hydrophobicity balance and, hence, the swelling behaviour of polymers and polymer nanoparticles. We will show that polymer integration of well-known photoactive molecular building blocks not only changes the rate but also the yield oft he intermolecular proton transfer reaction. The second part of the presentation will report on advances in synthesizing and spectroscopically characterizing transition metal compounds, which act as photobases upon visible-light excitation. The discussion will start with Ru(II) complexes with photobasic ligands and continue to show how the concept can be transferred to Fe(II) complexes.