Synthesis, separation, and characterization of spiro-fused cycloalkyl-embedded 5,15-porphodimethenes

Abstract

The synthesis of cycloalkyl-fused porphodimethenes from a mixture of products was investigated. Each product was separated via silica gel column chromatography and characterized using nuclear magnetic resonance (NMR) and UV-visible absorption spectroscopies, and mass spectrometry. X-ray crystal structure analysis revealed their gable-like bent conformations bearing perpendicular cycloalkyl rings in which the dipyrrin pairs contacted closely so that the neighboring pyrrole rings formed circular hydrogen bonding networks, such as those in porphyrins. Such configurations also caused extreme downfield shifts of the methylene protons of the cycloalkyl rings in the 1H NMR spectra.