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

Journal Article · Thu May 16 00:00:00 EDT 1991 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100163a035· OSTI ID:5975990

Barber, D C; Freitag-Beeston, R A; Whitten, D G ^[1]

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1. Univ. of Rochester, NY (United States)

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.

• DOE Contract Number: FG05-86ER75299
• OSTI ID: 5975990
• Journal Information: Journal of Physical Chemistry; (United States), Vol. 95:10; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

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