Porphyrin tweezer 1 forms 1:1 complexes with a series of acyclic aliphatic
alpha,omega-diamines. Chain elongation of the diamines is accompanied by a
red-shift in W-vis maxims and increase in half band-widths of the Soret ban
ds. These changes are accounted for, respectively, by a decrease in exciton
coupling and an increase in structural flexibility.