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Title: Atropisomer-specific formation of premicellar porphyrin J-aggregates in aqueous surfactant solutions

Abstract

The 4,0-atropisomer of intermediate (C{sub 6} or C{sub 7}) to long (C{sub 16}) chain length picket fence porphyrins (PFPs) exhibit red-shifted absorption and reduced singlet and triplet lifetimes in dilute aqueous surfactant solutions (i.e. below the critical micelle concentration). The spectral and photophysical behavior of these species is consistent with formation of premicellar aggregates containing two or more porphyrin chromophores lying in an offset, face-to-face arrangement ({lambda}{sub max} {approximately}426 nm, broad) or monomeric porphyrin in homogeneous or micellar solution ({lambda}{sub max} = 418-420 nm, sharp). The most characteristic behavior is noted at intermediate chain lengths for the free base or Pd(II) complex of 4,0-meso-tetrakis(2-hexanamidophenyl)porphyrin (4,0-THex) and for the free base of 4,0-THept, suggesting an optimal molecular hydrophobicity, side-chain length, and molecular topology for complex formation. The premicellar surfactant-porphyrin complexes are formed selectively from the 4,0-atropisomer and exhibit an SDS/porphyrin ratio of 3.2 for 4,0-THex. Acid-base titration behavior of the 4,0-THex J-aggregates suggests a structure in which the porphyrin core is isolated from the anionic surfactant head groups in a relatively hydrophobic microenvironment. Addition of alcohols or surfactant to disorganized aqueous aggregates of short- and long-chain 4,0-PFPs, respectively, apparently results in a modest reorganization of porphyrin chromophores ({lambda}{sub max} {approximately}436-438 nm)more » indicative of an inherent tendency toward J-aggregation for the 4,0-isomer. 102 refs., 6 figs., 10 tabs.« less

Authors:
; ;  [1]
  1. Univ. of Rochester, NY (United States)
Publication Date:
OSTI Identifier:
5975990
DOE Contract Number:  
FG05-86ER75299
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry; (United States)
Additional Journal Information:
Journal Volume: 95:10; Journal ID: ISSN 0022-3654
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; MICELLAR SYSTEMS; CHEMICAL PREPARATION; ABSORPTION SPECTROSCOPY; AGGLOMERATION; ANIONS; AQUEOUS SOLUTIONS; CUSPED GEOMETRIES; EXPERIMENTAL DATA; FLUORESCENCE SPECTROSCOPY; MOLECULAR STRUCTURE; PALLADIUM COMPLEXES; PORPHYRINS; SURFACTANTS; VISIBLE SPECTRA; CARBOXYLIC ACIDS; CHARGED PARTICLES; COMPLEXES; DATA; DISPERSIONS; EMISSION SPECTROSCOPY; HETEROCYCLIC ACIDS; HETEROCYCLIC COMPOUNDS; INFORMATION; IONS; MAGNETIC FIELD CONFIGURATIONS; MIXTURES; NUMERICAL DATA; OPEN CONFIGURATIONS; ORGANIC ACIDS; ORGANIC COMPOUNDS; ORGANIC NITROGEN COMPOUNDS; SOLUTIONS; SPECTRA; SPECTROSCOPY; SYNTHESIS; TRANSITION ELEMENT COMPLEXES; 400201* - Chemical & Physicochemical Properties

Citation Formats

Barber, D C, Freitag-Beeston, R A, and Whitten, D G. Atropisomer-specific formation of premicellar porphyrin J-aggregates in aqueous surfactant solutions. United States: N. p., 1991. Web. doi:10.1021/j100163a035.
Barber, D C, Freitag-Beeston, R A, & Whitten, D G. Atropisomer-specific formation of premicellar porphyrin J-aggregates in aqueous surfactant solutions. United States. https://doi.org/10.1021/j100163a035
Barber, D C, Freitag-Beeston, R A, and Whitten, D G. 1991. "Atropisomer-specific formation of premicellar porphyrin J-aggregates in aqueous surfactant solutions". United States. https://doi.org/10.1021/j100163a035.
@article{osti_5975990,
title = {Atropisomer-specific formation of premicellar porphyrin J-aggregates in aqueous surfactant solutions},
author = {Barber, D C and Freitag-Beeston, R A and Whitten, D G},
abstractNote = {The 4,0-atropisomer of intermediate (C{sub 6} or C{sub 7}) to long (C{sub 16}) chain length picket fence porphyrins (PFPs) exhibit red-shifted absorption and reduced singlet and triplet lifetimes in dilute aqueous surfactant solutions (i.e. below the critical micelle concentration). The spectral and photophysical behavior of these species is consistent with formation of premicellar aggregates containing two or more porphyrin chromophores lying in an offset, face-to-face arrangement ({lambda}{sub max} {approximately}426 nm, broad) or monomeric porphyrin in homogeneous or micellar solution ({lambda}{sub max} = 418-420 nm, sharp). The most characteristic behavior is noted at intermediate chain lengths for the free base or Pd(II) complex of 4,0-meso-tetrakis(2-hexanamidophenyl)porphyrin (4,0-THex) and for the free base of 4,0-THept, suggesting an optimal molecular hydrophobicity, side-chain length, and molecular topology for complex formation. The premicellar surfactant-porphyrin complexes are formed selectively from the 4,0-atropisomer and exhibit an SDS/porphyrin ratio of 3.2 for 4,0-THex. Acid-base titration behavior of the 4,0-THex J-aggregates suggests a structure in which the porphyrin core is isolated from the anionic surfactant head groups in a relatively hydrophobic microenvironment. Addition of alcohols or surfactant to disorganized aqueous aggregates of short- and long-chain 4,0-PFPs, respectively, apparently results in a modest reorganization of porphyrin chromophores ({lambda}{sub max} {approximately}436-438 nm) indicative of an inherent tendency toward J-aggregation for the 4,0-isomer. 102 refs., 6 figs., 10 tabs.},
doi = {10.1021/j100163a035},
url = {https://www.osti.gov/biblio/5975990}, journal = {Journal of Physical Chemistry; (United States)},
issn = {0022-3654},
number = ,
volume = 95:10,
place = {United States},
year = {1991},
month = {5}
}