Environmental control of reactions: enhancement of .mu.-oxo dimer formation from iron(III) porphyrins in organized monolayer assemblies as a model for membrane catalysis

Hopf, Frederick R.; Moebius, D.; Whitten, David G.

doi:10.1021/ja00422a054

Cited by 34 publications

(13 citation statements)

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“…The surface pressure was an unprecedented 70 mN/m for a porphyrin monolayer and the molecular area was 2.75 nm 2 . This area corresponds to the value usually found for tetraphenylporphyrin with four hydrophobic side chains, , and we assume that the porphyrin plane lies about 2.5 nm above the water surface, corresponding to the length of the bixin chains. This assumption is qualitatively supported by the finding that the porphyrin chromophores are not protonated on an aqueous substrate of pH 3.…”

Section: Resultsmentioning

confidence: 94%

Solid Vesicle Membrane Made of meso-Tetrakis[(bixinylamino)-o-phenyl]porphyrins

et al. 1997

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Tetrakis(aminophenyl)porphyrin with four bixin side chains in statistical orientation with respect to the porphyrin plane and its zinc(II) complex produced stable colloidal solutions in water at pH 9. Cryoelectron microscopy showed spherical unilamellar vesicles with diameters ranging from 30 to 120 nm and a membrane thickness of 4.7 ( 0.5 nm, corresponding to a monomolecular layer with the bixin side chains tilted by 30°. The stiff vesicle membranes were not sensitive to the addition of sodium chloride and survived adsorption to dry solid surfaces. Furthermore, the vesicles were totally polymerized by visible light. These polymer vesicles remained intact in 95% ethanol, and scanning force microscopy (SFM) images showed perfectly spherical shapes on graphite. A slow collapse is only observed on hydrated mica. The tetrabixinporphyrin also produced stable monolayers on water surface which polymerized upon irradiation. Combination of the polyene vesicle with an electron-accepting porphyrin, namely a synthetic guanidinium porphyrin or 2-anthraquinone sulfonate, led to light-induced long-lived charge separations.

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Section: Resultsmentioning

confidence: 94%

Solid Vesicle Membrane Made of meso-Tetrakis[(bixinylamino)-o-phenyl]porphyrins

et al. 1997

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“…The ion-coordination films were prepared by contacting builtup multilayers of 2,4-dihydroxy-N -octadecylbenzylideneamine with aqueous solutions containing Cu(OAC) 2 . Spectral changes owing to coordination of Cu(II) ions to ligands have been probed by FTIR spectra and UV-Vis absorption spectra.…”

Section: Resultsmentioning

confidence: 99%

“…Metal complexes are compounds with fascinating chemical, optical, electrical, thermal, and electrooptical properties (1)(2)(3)(4)(5). Metal complexes incorporated into LB films can be employed as semiconductors, molecular metals, biosensors, and environmental sensors (6)(7)(8).…”

Section: Introductionmentioning

confidence: 99%

Structure Studies on Ion Coordination in 2,4-Dihydroxy-N-Octadecybenzylideneamine LB Films by UV–Vis Absorption and FTIR Spectroscopy

Pang

Liang²

2000

Journal of Colloid and Interface Science

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“…is p-chlorobenzene sulfonate or p-bromobenzene sulfonate; the crystals having fluoroborate or bromide as the counterion for the stilbazole salt show only monomer fluorescence and no photodimerization (ref. [13][14][15][16][17][18][19][20][21][22][23][24]. In contrast to the similarities between the photochemistr;-of 4 in monolayer assernblies and crystals.…”

Section: Unfmolecular Processesmentioning

confidence: 99%

“…Studies of the rate and pH dependence of 11-oxo dimer formation in solution and in f1lms ind1cate that the generation of dimeric sites favorably affects both the rate and equilibrium for dimer formation (ref. 23). …”

Section: ~02-cl8h37mentioning

confidence: 99%

Photochemistry of organic chromophores incorporated into fatty acid monolayers

Whitten

Hopf

Quina

et al. 1977

Pure and Applied Chemistry

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-The photochernical behavior of several different chromophores incorporated as surfactant molecules in organized monolayer assernblies is reported. For several systerns rather pronounced differences are observed between reacttvity in solution and in the assernblies. Many of the dtfferences can be ascrtbed to packing phenomena and to restrictions on diffusion and rnolecular motion in the condensed assemblies. Among the reactions studied which are subject to strong environmental influences in the assernblies are cis-trans photoisomerization, ligand photoejection, excimer and photodimer formation and electron transfer reactions. Photoreactions occurring at an assernblysolution interface have also been observed including the cleavage of water mediated by a layer-bound excited state of a surfactant rutheniurn complex. INTRODUtTIONIt has long been known that arnphipathic rnolecules such as fatty acids, which contain both water soluble (hydrophilic) and water insoluble (hydrophobic) groups, form rnonolayers when spread on water or other polar surfaces. Techniques for the study of such monolayer filrns were developed by Pockels (l) and Langrnuir and Blodgett (2) and in rnany cases the filrns were used to investigate rnolecular properties such as shape and size. It was found by Langrnuir as early as 1917 that rnonol ayer filrns spread on water could be transferred to solid supports (ref. 3). Although the techniques for handling these filrns have been widely used, it has been only recently that the techniques have been re:fined and applied to the construction of highly organfzed rnolecular systerns. Sirnplification and elaboration of the techniques for preparation and study of monolayer assernblies has been due largely to the investigations of Kuhn and coworkers (4-6). These investigators have also used organfzed monolayer assernblies to study a variety of phenomena rangtng from electronic energy transfer and photographic sensitization to interference and electrooptical effects (ref. 4). To a large extent the rapid progress in the use and study of monolayer assernblies has been rnade possible by the application of modern spectroscopic techniques. The facility with which absorption and luminescenca spectra can be obtained for monolayer assernblies on optically transparent supports suggested that these techniques rnight also be applied to investigate reactions and photoprocesses.One of our chief reasons for investigatfng reactions in organized rnonolayer assernblies is that the controlled regular structure of the assernbly provides a bridge between the extremes of crystalline solid and fluid solution. The intermediacy of a monolayer assernbly between liquid and solid is suggested by several observations. It is generally found that Chromophores of cornponent surfactant molecules rnafntain specffic orientatfon with respect to the layer plane (ref. 4). Studfes of the distance dependence of singlet-singlet energy transfer also fndfcate a regular structure wfth the spacing anticipated on the basis of closelypacked exten...

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Environmental control of reactions: enhancement of .mu.-oxo dimer formation from iron(III) porphyrins in organized monolayer assemblies as a model for membrane catalysis

Cited by 34 publications

References 0 publications

Solid Vesicle Membrane Made of meso-Tetrakis[(bixinylamino)-o-phenyl]porphyrins

Solid Vesicle Membrane Made of meso-Tetrakis[(bixinylamino)-o-phenyl]porphyrins

Structure Studies on Ion Coordination in 2,4-Dihydroxy-N-Octadecybenzylideneamine LB Films by UV–Vis Absorption and FTIR Spectroscopy

Photochemistry of organic chromophores incorporated into fatty acid monolayers

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