jo300963m_si_001.pdf (14.38 MB)
meso-Arylporpholactones and their Reduction Products
journal contribution
posted on 2012-08-03, 00:00 authored by Christian Brückner, Junichi Ogikubo, Jason
R. McCarthy, Joshua Akhigbe, Michael
A. Hyland, Pedro Daddario, Jill L. Worlinsky, Matthias Zeller, James T. Engle, Christopher J. Ziegler, Matthew J. Ranaghan, Megan
N. Sandberg, Robert R. BirgeThe rational syntheses of meso-tetraaryl-3-oxo-2-oxaporphyrins 5, known as porpholactones, via MnO4–-mediated oxidations of the corresponding meso-tetraaryl-2,3-dihydroxychlorins
(7) is detailed. Since chlorin 7 is prepared
from the parent porphyrin 1, this amounts to a 2-step
replacement of a pyrrole moiety in 1 by an oxazolone
moiety. The stepwise reduction of the porpholactone 5 results in the formation of chlorin analogues, meso-tetraaryl-3-hydroxy-2-oxachlorin (11) and meso-tetraaryl-2-oxachlorins (12). The reactivity of 11 with respect to nucleophilic substitution by O-, N-, and
S-nucleophiles is described. The profound photophysical consequences
of the formal replacement of a pyrrole with an oxazolone (porphyrin-like
chromophore) or (substituted) oxazole moiety (chlorin-like chromophore
with, for the parent oxazolochlorin 12, red-shifted Qx band with enhanced oscillator strengths)
are detailed and rationalized on the basis of SAC–CI and MNDO-PSDCI
molecular orbital theory calculations. The single crystal X-ray structures
of the porpholactones point at a minor steric interaction between
the carbonyl oxygen and the flanking phenyl group. The essentially
planar structures of all chromophores in all oxidation states prove
that the observed optical properties originate from the intrinsic
electronic properties of the chromophores and are not subject to conformational
modulation.
History
Usage metrics
Categories
Keywords
carbonyl oxygenReduction ProductsTheSACchromophoreoxazolone moietyporpholactones pointnucleophilic substitutionreplacementporpholactone 5 resultstheory calculationsoscillator strengthsoxazole moietychlorin analoguesoxidation statespyrrole moietysteric interactionchlorin 7photophysical consequencesphenyl group
Licence
Exports
RefWorks
BibTeX
Ref. manager
Endnote
DataCite
NLM
DC