Supramolecular chemistry, part 93 - Electrostatic interactions between positively charged porphyrins and nucleotides or amides: buffer-dependent dramatic changes of binding affinities and modes

The association strength of positively charged porphyrins with anionic spec ies can be orders of magnitude higher than reported in the literature, depe nding on the chosen buffer; the buffer also determines the dominating inter action mechanism, leading to stronger stacking contributions at higher salt concentrations; even electroneutral amides show a hitherto not recognized interaction between the negatively charged carbonyl oxygen and the positive ly charged pi-surface of the porphyrin system.