title: High-resolution structure and conformational dynamics of rigid, cofacially aligned porphyrin-bridge-quinone systems as determined by NMR spectroscopy and ab initio simulated annealing calculations.
abstract: The high-resolution solution structure and dynamics of a cofacially aligned porphyrin--phenylene--quinone compound have been determined using (1)H NMR spectroscopy and simulated annealing calculations. Members of this class of pi-stacked assemblies feature a 1,8-naphthyl pillaring motif that enforces sub van der Waals interplanar separations between juxtaposed porphyryl, aromatic bridge, and quinonyl components of the donor--spacer--acceptor compound; this structural motif gives rise to a comprehensive set of structurally significant NOE signatures that can be used as constraints in quantitative structural calculations. Examination of such data using ab initio simulated annealing analytical methods shows that 5-[8'-(4' '-[8' "-(2' " ',5' "-benzoquinonyl)-1' "-naphthyl]-1' '-phenyl)-1'-naphthyl]-10,20-diphenylporphyrin displays an unusual degree of conformational homogeneity in the condensed phase, and represents a rare example where such an analysis determines unequivocally a single unique structure in solution.
authors.affiliation: Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA.
authors.forename: P M
authors.initials: PM
authors.lastname: Iovine
authors.forename: G
authors.initials: G
authors.lastname: Veglia
authors.forename: G
authors.initials: G
authors.lastname: Furst
authors.forename: M J
authors.initials: MJ
authors.lastname: Therien