Oxazolochlorins. 11. Tuning The Dynamic High Ph Sensing Range Of [Meso-Tetraarylporpholactonato]M(Ii) Complexes By Variation Of The Central Metal Ion, The Aryl Substituents, And Introduction Of A Beta-Nitro Group

Based on the high pH-sensing ability of [meso-tetrakis(pentafluorophenyl) porpholactonato]-platinum(II), we investigated the influence of the metal (M = Zn(II), Ni(II), Cu(II), Pd(II), Ag(II), Pt(II)), the aryl group (Ar = C6H5, C6F5), and the presence of a beta-NO2 group on the pH sensing range. The syntheses of the novel beta-nitroporpholactone derivatives are described, and their regiochemistry deduced by spectroscopic and single crystal X-ray diffraction methods. The UV-vis base titration midpoints for all derivatives were determined in an aqueous solution containing a surfactant, showing that the metal has the least influence, thus identifying a cheaper and easier method to prepare porpholactone M complex-based high pH-sensors. The influence of the pentafluorophenyl groups and the beta-nitration were comparable with respect to their ability to increase the nucleophilicity of the porpholactone toward hydroxide, but the optical response for the pentafluorophenyl-substituted derivative were stronger. beta-Nitration and pentafluorophenyl-substitution had additive effects.