Dynamic 1H and 15N nuclear magnetic resonance of free-base 15N-porphyrins

Abstract

¹⁵ N n.m.r. chemical shifts, the ¹J(NH) coupling constant, and the change of the band shapes of ¹H and ¹⁵N resonances with temperature have provided information on the location, degree of hydrogen bonding, and mechanism of tautomerism of the hydrogens in the core of free base ¹⁵N₄-protoporphyrin-IX dimethyl ester and ¹⁵N₄-coproporphyrin-III tetramethyl ester.