Chromic and Binding Properties of OxP Derivatives

As discussed in Sect.  4.5 , chromic changes in dye molecules can be caused by protonation (halochromism) or by change of solvent properties (solvatochromism). In this chapter we show our results about halochromism and solvatochromism of the oxoporphyrinogen derivatives OxP, Bz2OxP and Bz4OxP. Aside from the complete description of color variation, particular protonated species are identified and the binding constants were determined, where possible.