250 research outputs found
Synthesis of Functional Chlorophyll Derivatives and Construction of Light-Harvesting Supramolecules
No full text近畿大学Kindai University博士（理学）主査：佐賀, 佳央 教授
学内授与番号：理第82号Naoya Takahashi, Sunao Shoji, Hitoshi Tamiaki, Yoshitaka Saga "Self-Assembly of Zinc Bacteriochlorophyll d Derivative Possessing a Triethoxysilyl Group at the 17-Propionate Residue" Bulletin of the Chemical Society of Japan, September 2012, Volume 85, Issue 9, Pages 989–994
https://doi.org/10.1246/bcsj.20120043 掲載
Naoya Takahashi, Hitoshi Tamiaki, Yoshitaka Saga "Synthesis and self-assembly of amphiphilic zinc chlorophyll derivatives possessing a crown ether at the 17-propionate residue" Tetrahedron 6 May 2013, Volume 69, Issue 18, Pages 3638-3645
https://doi.org/10.1016/j.tet.2013.03.015 掲載
Naoya Takahashi, Keiya Hirota, and Yoshitaka Saga "Facile transformation of the five-membered exocyclic E-ring in 132-demethoxycarbonyl chlorophyll derivatives by molecular oxygen with titanium oxide in the dark" Journal of Porphyrins and Phthalocyanines 2015, Volume 19, Issue 04, Pages 631-637
https://doi.org/10.1142/S1088424615500054 掲載doctoral thesi
ChemInform Abstract: Synthesis of Zinc 3‐Hydroxymethyl‐porphyrins Possessing Carbonyl Groups at the 13‐ and/or 15‐Positions for Models of Self‐Aggregative Chlorophylls in Green Photosynthetic Bacteria.
No full textC132-Methylation of methyl pheophorbide a and stereoselective preparation of methyl (132R)-methylpyropheophorbide a
No full textThe (132R)-methoxycarbonyl group of methyl pheophorbide a, one of the chlorophyll-a derivatives, was converted to a methyl group through methylation at the C132 position followed by removal of the methoxycarbonyl group. The methylation of the C132 carboanion gave a 4:1 mixture of methyl 132-methyl-pheophorbide a and its 13 2-epimer. The successive pyrolysis of the major methylated product afforded methyl (132R)-methyl-pyropheophorbide a with a small amount of its (132S)-epimer. The substitution effects at the C132 position including stereochemistry were discussed on the basis of 1D/2D NMR, UV-vis absorption, and circular dichroism spectroscopic analyses as well as molecular modeling simulation. © 2014 Elsevier Ltd. All rights reserved.journal articl
Phototriggered Dynamic and Biomimetic Growth of Chlorosomal Self-Aggregates
No full textSupramolecular
polymerizations mimicking native systems, which
are step-by-step constructions to form self-aggregates, were recently
developed. However, a general system to successively and spontaneously
form self-aggregates from monomeric species remains challenging. Here,
we report a photoinduced supramolecular polymerization system as a
biomimetic formation of chlorophyll aggregates which are the main
light-harvesting antennas in photosynthetic green bacteria, called
“chlorosomes”. In this system, inert chlorophyll
derivatives were UV-irradiated to gradually produce active species
through deprotection. Such active monomers spontaneously assembled
to form fiberlike chlorosomal self-aggregates in a similar manner
as a dynamic growth of natural chlorosomal self-aggregates. The study
would be useful for elucidation of the formation process of the chlorosomal
aggregates and construction of other supramolecular structures in
nature
Derivatives with Ethynylene and Phenylene Groups Inserted Between the Hydroxymethyl Group and the Chlorin π‐Skeleton (ChemPhotoChem 5/2020)
No full textPhotoactivated Supramolecular Assembly Using “Caged Chlorophylls” for the Generation of Nanotubular Self-Aggregates Having Controllable Lengths
No full textLiving
supramolecular polymerization is a breakthrough system to
control the size of supramolecular aggregates. Multidimensional (2D
or 3D) self-aggregates of chiral and unsymmetric molecules are observed
in nature. For instance, a chlorosome, which is the main light-harvesting
antenna in green photosynthetic bacteria, possesses tubular structures
of chlorophyll pigments with J-type slipped cofacial and circular
arrangements. Here, we report size-controllable construction of chlorosome-like
aggregates by photoactivated supramolecular assembly of “caged
chlorophyll”. The caged chlorophylls, which were nonassembling
(inert) species, were illuminated with UV-light to give the active
species one by one, and then the resulting active monomers spontaneously
assembled to construct tubular self-aggregates. The length of such
chlorosome-like aggregate tubes was dependent on the UV-irradiation
duration and intensity of UV-light. The photoactivated supramolecular
assembly system would be useful for application of (opto)electronic
devices such as solar cells and artificial photosynthesis
Derivatives with Ethynylene and Phenylene Groups Inserted Between the Hydroxymethyl Group and the Chlorin π‐Skeleton
No full textSynthesis and self-aggregation of chlorophyll derivatives possessing a pyrazole ring at the C3 position
No full textChlorophyll compounds possessing an N-(un)substituted pyrazole ring at the C3 position were synthesized by the reaction of chlorophyll-a derivative having a trifluoromethyl-β-diketonate group with (substituted) hydrazines in 2,2,2-trifluoroethanol through the pyrazoline ring. The substituents on the C3-heterocyclic 5-membered ring affected the electronic absorption and emission of the monomeric chlorin molecules. Vis, CD and 1H NMR spectra of the zinc chlorin bearing an N-unsubstituted pyrazole showed its dimerization in a nonpolar organic solvent. © 2015 Elsevier B.V. All rights reserved.journal articl
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