A supramolecular photosynthetic triad of slipped cofacial porphyrin dimer, ferrocene, and fullerene

A supramolecular triad consisting of self-assembled imidazolyl-zinc-porphyrin dimer, ferrocene, and fullerene was successfully constructed, resulting in long-lived charge separated species after efficient photoinduced electron transfer and charge shift reactions.     

Ratiometric fluorescence detection of pyrimidine/purine transversion by using a 2-amino-1,8-naphthyridine derivative.

A new class of abasic site-binding fluorescence ligands, Naph-NBD in which 7-nitrobenzo-2-oxa-1,3-diazole (NBD) is connected to 2-amino-7-methyl-1,8-naphthyridine (Naph) by a propylene linker, is presented for the ratiometric assay for SNPs typing. In solutions buffered to pH 7.0 (I = 0.11 M, at 5 degrees C), Naph-NBD is found to selectively recognize pyrimidine bases over purine bases opposite the abasic site in DNA duplexes (K11/M(-1): T, 8.1 x 10(6); C, 2.5 x 10(6): G, 0.33 x 10(6); A, 0.27 x 10(6)). The binding of Naph-NBD is accompanied by significant quenching of the fluorescence from the naphthyridine moiety (lambda max, 409 nm), while the emission from the NBD (lamda max, 544 nm) is relatively unaffected. Such a fluorescence response of Naph-NBD allows the emission ratio detection of pyrimidine/purine transversion.     

Synthesis of copper monolayer and particles at aqueous–organic interface

Using aqueous–organic interface (water–oleic acid) reduction of Cu²⁺ by ascorbic acid, hydrophobic copper monolayer and copper particles have been prepared and characterized. The resultant monolayer could be transferred from the interface onto solid substrate or be dissolved to yield an organosol and copper nanoparticles.     

Synthesis of 5‐ and 8‐Deoxytetrodotoxin

Tetrodotoxin, a toxic principle of puffer fish intoxication, is one of the most famous marine natural products owing to its complex structure and potent biological activity, which leads to fatal poisoning. Continuous synthetic studies on tetrodotoxin and its analogues to elucidate biologically interesting issues associated with tetrodotoxin have led to the development of versatile routes for a variety of tetrodotoxin derivatives. With the aim of investigating the structure–activity relationship of tetrodotoxin with voltage‐gated sodium channels, this study describes the first total syntheses of 5‐deoxytetrodotoxin, a natural analogue of tetrodotoxin, and 8‐deoxytetrodotoxin, an unnatural analogue, from a newly designed, versatile intermediate in an efficient manner. An estimation of the biological activities of these compounds reveals the importance of the hydroxy groups at the C‐5 and C‐8 positions on the inhibition of voltage‐gated sodium channels.     

Introduction of 2-methoxycarbonylallyl end group by copolymerization of methyl α-(phenoxymethyl)acrylate accompanying with addition-fragmentation reaction

Copolymerizations of methyl α-(phenoxymethyl)acrylate (MPMA) with methyl acrylate, methyl methacrylate, styrene, and methyl α-ethylacrylate were carried out. Addition of a polymer radical to MPMA followed by the subsequent fragmentation of poly(MPMA) radical resulted in the 2-methoxycarbonylallyl end group and phenoxy radical in the course of the copolymerization. The extent of the fragmentation determined by ¹H-NMR spectroscopy depends on reactivity of the MPMA radical toward the reference monomers. An increase in the addition rate of the MPMA radical to the reference monomer brought about suppression of the fragmentation. The addition of the MPMA radical to styrene seems to be sufficiently fast to prevent the fragmentation. Since the rate of the fragmentation relative to the propagation was considerably accelerated by raising the temperature to 110°C, MPMA can be used as a novel chain transfer agent to control molecular weight and end group at a temperature above 100°C. © 1993 John Wiley & Sons, Inc.     

Difference in photochemical behavior in 3,6‐ and 2,5‐di‐tert‐butyl‐3H‐azepine: The first photochemical bond formation between 2‐ and 6‐position of 3H‐azepine ring

Different photochemical behavior between 3,6‐ and 2,5‐di‐t‐butyl‐3H‐azepine was observed. The former gave wavelength dependent products 3,5‐di‐t‐butylpyridine on irradiation through Pyrex filter via photolysis and 4,7‐di‐t‐butyl‐2‐azabicyclo[3.2.0]hepta‐2,6‐diene on irradiation through quartz filter via photo‐isomerization. Meanwhile, 2,5‐di‐t‐butyl derivative gave exclusively a labile 2,5‐di‐t‐butyl‐6‐azabicyclo‐[3.2.0]hepta‐2,6‐diene on irradiation through Pyrex filter via hitherto unknown photoisomerization mode of the bond formation between 2‐ and 6‐position of the ring.     

Prorocentrol, a polyoxy linear carbon chain compound isolated from the toxic dinoflagellate Prorocentrum hoffmannianum

A polyoxy linear carbon chain compound, prorocentrol (1), was isolated from cultured cells of the dinoflagellate Prorocentrum hoffmannianum, which produces a polyether carboxylic acid, okadaic acid. The structure of 1 was elucidated by detailed analyses of 2D NMR spectra. Compound 1 possesses 30 hydroxy groups, 1 ketone, and 8 double bonds on the C65-linear carbon chain. Its partial relative configuration was deduced by the proton-proton and long-range carbon-proton coupling constants, and compound 1 showed moderate cytotoxicity and antidiatom activity.     

Energy Transfer Followed by Electron Transfer in a Porphyrin Macrocycle and Central Acceptor Ligand: A Model for a Photosynthetic Composite of the Light‐Harvesting Complex and Reaction Center

A mimic for nature's solar cells : Simple mixing of nonaporphyrin macrocycle N‐( 1 –Zn)₃ and acceptor ligand C₆₀–ZnP–Tripod affords a supramolecular architecture (see scheme), in which the excitation energy collected by the macrocycle is transferred efficiently to the central ZnP acceptor, inducing charge separation between the ZnP and C₆₀ sites.