J-Aggregation of a Water-Soluble Tetracationic Porphyrin in Mixed LB Films with a Calix[8]arene Carboxylic Acid Derivative (original) (raw)
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The Journal of Physical Chemistry B, 2000
In this paper, the formation of the different aggregates of a water-soluble tetracationic porphyrin, TMPyP, anchored to an anionic phospholipid matrix, DMPA, and assembled in LB films has been investigated. The use of different solid substrates such as hydrophilic glass and supports modified by the transfer of monolayers of several lipids has been employed to assemble the TMPyP molecules in the mixed monolayer with DMPA (in a molar ratio of 1:4) as monomer (TMPyP 4+), dimer, diprotonated monomer (TMPyPH 2 6+), and tetramer aggregates. The porphyrin is organized as a monomer (TMPyP 4+) when the mixed monolayer is directly transferred onto a hydrophilic glass plate. Also, if the glass and the porphyrin are separated by spacer layers such as a monolayer sequence EAv/AAV/EAv/AAV, the porphyrin monomer is identified. Porphyrin dimers are formed at the air-water interface in monolayers of 1:4 TMPyP/DMPA 20 and may be transferred to solid substrates by the transfer of this system on top of the DMPA monolayer, i.e., (DMPAV/TDv) n. In these multilayers, a small fraction of porphyrin molecules is transferred as diprotonated monomer. Finally, the transfer on hydrophilic glass plates of 1:4 TMPyP/DMPA monolayers of the Y type assembled a packed tetramer of TMPyP. By applying the extended dipole approximation to the spectra measured, we proposed a model where the central planes of the two consecutive porphyrins are twisted by 22.5°, forming a helix.
Bulletin of the Institute For Chemical Research Kyoto University, 1993
This paper is dedicated to Professor Tohru Takenaka on the occasion of his retirement. Aggregation behaviors of amphiphilic porphyrins with one (THPPH1) , two (cis-THPPH2 and trans-THPPH2) , three (THPPH3) and four (THPPH4) hexadecyloxyphenyl chains have been investigated in Langmuir-Blodgett (LB) films by means of UV-vis absorption spectroscopy and Cu (II) metallation. For the LB films of THPPH1, cis-and trans-THPPH2, the Soret absorptions are red-shifted (434nm) relative to the solution value (420nm) ,where as the Q-state absorptions are essentially unaltered. For the films of THPPH3 and THPPH4, the Soret bands are split into two components; one is red-shifted (440nm) and the other blue-shifted (398nm) with respect to the dilute solution value. The spectral data are interpreted in terms of exciton interactions between the porphyrin Soret excited states and are used to deduce the molecular arrangement of the porphyrin macrocycles in the films. When transferred from the monolayers on aqueous Cu (II) subphase, the LB films of THPPH1, cis-THPPH2, trans-THPPH2 and THPPH3 give the Q-state bands at 552 and 518 nm, being characteristic of copper-porphyrin complex, and the film of THPPH4 gives the Q-state absorption bands identical with those of its free base form. Time dependence of Cu (II) metallation of the LB films of these amphiphilic porphyrins demonstrate the metallation rate on the order of THPPH1) cis-THPPH2) trans-THPPH2) THPPH3) THPPH4.
2020
This paper is dedicated to Professor Tohru Takenaka on the occasion of his retirement. Aggregation behaviors of amphiphilic porphyrins with one (THPPH1) , two (cis-THPPH2 and trans-THPPH2) , three (THPPH3) and four (THPPH4) hexadecyloxyphenyl chains have been investigated in Langmuir-Blodgett (LB) films by means of UV-vis absorption spectroscopy and Cu (II) metallation. For the LB films of THPPH1, cis-and trans-THPPH2, the Soret absorptions are red-shifted (434nm) relative to the solution value (420nm) ,where as the Q-state absorptions are essentially unaltered. For the films of THPPH3 and THPPH4, the Soret bands are split into two components; one is red-shifted (440nm) and the other blue-shifted (398nm) with respect to the dilute solution value. The spectral data are interpreted in terms of exciton interactions between the porphyrin Soret excited states and are used to deduce the molecular arrangement of the porphyrin macrocycles in the films. When transferred from the monolayers on aqueous Cu (II) subphase, the LB films of THPPH1, cis-THPPH2, trans-THPPH2 and THPPH3 give the Q-state bands at 552 and 518 nm, being characteristic of copper-porphyrin complex, and the film of THPPH4 gives the Q-state absorption bands identical with those of its free base form. Time dependence of Cu (II) metallation of the LB films of these amphiphilic porphyrins demonstrate the metallation rate on the order of THPPH1) cis-THPPH2) trans-THPPH2) THPPH3) THPPH4.
Porphyrin/calixarene self-assemblies in aqueous solution
Journal of Photochemistry and Photobiology A-chemistry, 2008
The variations of calix[4]arene linkages between phenolic units and of the cationic substituents on the porphyrin periphery affect modes of interaction and photophysical parameters of porphyrin/calixarene complexes. 5,10,15,20-Tetrakis(N-methylpyridinium-2-yl)porphyrin (TMPyP2) forms stable complexes with tetrasulfonated calix[4]arene, thiacalix[4]arene and sulfonylcalix[4]arene of the 1:1 stoichiometry with the binding constants above 106, (9.3±0.9)×105 and (8.3±0.8)×104M−1, respectively. We suggest that quenching of the singlet and
Thin Solid Films, 2011
The orientation and aggregation of various porphyrin derivatives at the air-water interface and in Langmuir-Blodgett films were investigated. Monolayer properties of these molecules, where long alkyl chain(s) were covalently bound through different functionality of varying hydrophilicity were studied by measuring surface pressure area isotherms. Such derivatives, where ether functionality (functionalities) was (were) used for linking long alkyl chain(s), did not form uniform monolayer; instead they were found to form multilayer clusters or aggregates on the water surface. On the other hand, porphyrin derivative functionalized at the four peripheral phenyl rings with eight hexadecyl ether chains formed stable spherical vesicles when deposited on mica. Tetra N-alkyl pyridinium porphyrins with long alkyl chain were found to form various phases on the water surface. Evidence of transition from horizontal orientation to vertical orientation of porphyrin rings of porphyrin molecules having C 14 chains was observed. This type of transition was lost with the porphyrin molecule with a relatively smaller chain (C 8 ).
Journal of Physical Organic Chemistry, 2001
A series of multi-porphyrin arrays were synthesized and the self-assembly behaviour of these compounds at the air-water interface was investigated by the Langmuir-Blodgett technique. It was found that as the overall area of the porphyrin molecules was increased, upon going from a mono-to bis-to a tetra-and then to hexaporphyrin species, the intermolecular stacking between the molecules also increases, resulting in more stable monolayers. In the case of the hexaporphyrin species the intermolecular interactions are so strong that monolayer formation is irreversible. All porphyrin monolayers can be transferred to a glass surface with good transfer ratios, leading to highly ordered porphyrin films in which the chromophores are arranged orthogonal to the glass surface.
Journal of Colloid and Interface Science, 2005
Langmuir monolayers and Langmuir-Blodgett (LB) films of 5,10,15,20-tetra-(p-chlorophenyl) terbium/gadolinium porphyrin hydroxyl compound (TbOH and GdOH) and their mixtures with stearic acid (SA) in a molar ratio of 1:1 were investigated by Brewster angle microscopy (BAM), ultraviolet-visible (UV-vis), and infrared (IR) spectroscopy and atomic force microscopy (AFM). π-A isotherms showed that well-defined Langmuir monolayers were formed at an air/water interface for the porphyrins and their mixture with SA. The BAM observations suggest that the π-π interaction between the GdOH molecules is stronger than that between the TbOH molecules. This result can be further confirmed by the AFM measurements. After the introduction of SA, the π-π interaction between the TbOH molecules is broken and thus two phases formed in the mixed LB film. However, it cannot break the stronger π-π interaction between the GdOH molecules. Therefore, no phase separation is observed in the GdOH/SA LB film. IR reflection-absorption (RA) spectra showed that the COOH groups of SA are partly converted to COO − groups, suggesting that there is an interaction between MOH and SA in the films. This interaction leads the benzene rings of TbOH to rotate toward parallel to the substrate and those of GdOH to rotate toward perpendicular to the substrate. All these results have demonstrated that the central metal ions have great effects on the organization and formation of the films.
Mixed Thin Films of a Cationic Amphiphilic Porphyrin andn-Alkanes
Langmuir, 2004
Langmuir and Langmuir-Blodgett (LB) films of a cationic amphiphilic porphyrin mixed with n-alkanes octadecane and hexatriacontane were prepared and characterized, to examine the influence of the alkanes on film structure and stability. While the structure present in these films was controlled primarily by the porphyrin, the addition of the alkanes resulted in significant changes to both the phase behavior of the Langmuir films and the molecular arrangement of the LB films. These changes, as well as the observed chain length effects, are explained in terms of the intermolecular interactions present in the films.
Self-Organization of Amphiphilic Porphyrins at the Air-Water Interface
Langmuir, 1995
The Langmuir-Blodgett film forming properties of a series of pyridyl((hexadecyloxy)phenyl)porphyrins have been examined. Good monolayers of these compounds have been prepared in most cases without the use of matrix molecules and the monolayers are readily transferable to glassy slideB. The small mean molecular areas, as obtained from the aurface-pressure-area isotherms, indicate a tilted orientation of the porphyrin rings with respect to the water surface. It was found by means of UV-vis absorption spectroscopy at the air-w ater interface and by Brewster angle microscopy that intermolecular interaction between porphyrin rings mutually directs the organization at submonolayer coverage. Upon compression, the self-assembled domains come into close contact without reorganization of the layer structure. It was also demonstrated that porphyrins with three and four aliphatic side chains self-assembled into a highlyordered arrangement in contrast to the porphyrins with one and two alkyl chains.