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Title: Molecular structure and spectroscopy of a bacteriopurpurin. A new class of bacteriochlorin photosensitizers

Abstract

Bacteriochlorins mediate energy and electron transfer in vivo and serve as biomimetic models of bacterial photosynthesis. Recently, the same physicochemical properties of the chromophores have made them attractive as photosensitizers for photodynamic therapy, a medical treatment that combines light, porphyrins, and oxygen to attack and destroy malignant tissue. Despite the intense biophysical, chemical, and medicinal interest in bacteriochlorins, very few high precision structures of the chromophores exist to provide the basis for theoretical calculations that seek to predict their extensively studied physicochemical properties. The authors report here the synthesis, spectral characterization, and structural determination of a metal-free bacteriopurpurin 1, a paradigm for a new class of photosensitizers comprised of porphyrins at the saturation level of bacteriochlorins flanked by two annelated, exocyclic cyclopentenyl rings. The molecule exhibits a very red-shifted Qy transition at 843 nm and is readily oxidized (at 0.39V vs SCE) to a {pi} cation radical with a distinctive EPR signal. The crystallographic results for 1 unambiguously identify the bacteriopurpurin, provide the first stereochemical parameters for this new class of expanded bacteriochlorins, extend the high resolution structural database for bacteriochlorins, and form the basis for theoretical calculations which correctly describe the optical features and electron density profile of 1more » and its cation radical.« less

Authors:
 [1]; ; ;  [2]
  1. Miravant Medical Technologies, Santa Barbara, CA (United States)
  2. Brookhaven National Lab., Upton, NY (United States). Dept. of Applied Science
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL), Upton, NY
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
696653
DOE Contract Number:  
AC02-98CH10886
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical
Additional Journal Information:
Journal Volume: 103; Journal Issue: 34; Other Information: PBD: 26 Aug 1999
Country of Publication:
United States
Language:
English
Subject:
40 CHEMISTRY; 14 SOLAR ENERGY; BACTERIA; PHOTOSYNTHESIS; PHOTOCHEMICAL ENERGY STORAGE; ENERGY TRANSFER; PORPHYRINS

Citation Formats

Robinson, B.C., Barkigia, K.M., Renner, M.W., and Fajer, J. Molecular structure and spectroscopy of a bacteriopurpurin. A new class of bacteriochlorin photosensitizers. United States: N. p., 1999. Web. doi:10.1021/jp991138a.
Robinson, B.C., Barkigia, K.M., Renner, M.W., & Fajer, J. Molecular structure and spectroscopy of a bacteriopurpurin. A new class of bacteriochlorin photosensitizers. United States. doi:10.1021/jp991138a.
Robinson, B.C., Barkigia, K.M., Renner, M.W., and Fajer, J. Thu . "Molecular structure and spectroscopy of a bacteriopurpurin. A new class of bacteriochlorin photosensitizers". United States. doi:10.1021/jp991138a.
@article{osti_696653,
title = {Molecular structure and spectroscopy of a bacteriopurpurin. A new class of bacteriochlorin photosensitizers},
author = {Robinson, B.C. and Barkigia, K.M. and Renner, M.W. and Fajer, J.},
abstractNote = {Bacteriochlorins mediate energy and electron transfer in vivo and serve as biomimetic models of bacterial photosynthesis. Recently, the same physicochemical properties of the chromophores have made them attractive as photosensitizers for photodynamic therapy, a medical treatment that combines light, porphyrins, and oxygen to attack and destroy malignant tissue. Despite the intense biophysical, chemical, and medicinal interest in bacteriochlorins, very few high precision structures of the chromophores exist to provide the basis for theoretical calculations that seek to predict their extensively studied physicochemical properties. The authors report here the synthesis, spectral characterization, and structural determination of a metal-free bacteriopurpurin 1, a paradigm for a new class of photosensitizers comprised of porphyrins at the saturation level of bacteriochlorins flanked by two annelated, exocyclic cyclopentenyl rings. The molecule exhibits a very red-shifted Qy transition at 843 nm and is readily oxidized (at 0.39V vs SCE) to a {pi} cation radical with a distinctive EPR signal. The crystallographic results for 1 unambiguously identify the bacteriopurpurin, provide the first stereochemical parameters for this new class of expanded bacteriochlorins, extend the high resolution structural database for bacteriochlorins, and form the basis for theoretical calculations which correctly describe the optical features and electron density profile of 1 and its cation radical.},
doi = {10.1021/jp991138a},
journal = {Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical},
number = 34,
volume = 103,
place = {United States},
year = {1999},
month = {8}
}