Fluorescence and chemiluminescence behavior of distyrylbenzene bearing two arms of dipicolylaminomethyl groups: Interactions with zinc ion and ATP.

The absorption and fluorescence spectral study of the distyrylbenzene bearing two arms of the dipicolylaminomethyl groups, the effective ligands for Zn, was studied in the presence of Zn and ATP. Upon complexation of the distyrylbenzene with zinc ions in acetonitrile, enhancement of the fluorescence intensity was observed due to inhibition of intramolecular PET (photo-induced electron transfer) quenching, but no effect was found in aqueous media because the equilibrium laid to the free form of the ligands. In contrast, the addition of ATP disodium salt was effective to enhance the fluorescence intensity of the combination of the distyrylbenzne and Zn in aqueous media.

Peroxyoxalate chemiluminescence enhanced by oligophenylenevinylene fluorophores in the presence of various surfactants.

The effect of several surfactants on peroxyoxalate chemiluminescence (PO-CL) using oligophenylenevinylene fluorophores was investigated. Among several oligophenylenevinylenes consisting of stilbene units, linearly conjugated ones, such as distyrylbenzene and distyrylstilbene, effectively enhanced PO-CL efficiency. Various effects of anionic, cationic, amphoteric and non-ionic surfactants on the CL efficiency of PO-CL were determined using three oxalates and the distyrylbenzene fluorophore.

Toward a chemiluminescent molecular device: metal ion-enhanced chemiluminescence of benzylidenacridan with 15-monoazacrown-5.

The benzylidenacridans (1a-d) with one or more methoxy groups emit light from the excited N-methylacridone (NMA) when treated with a solution of sodium hypochlorite and alkaline hydrogen peroxide, in which a Hammett relationship with a negative rho value was applied between the chemiluminescence quantum yields and the sigma values. However, the dimethylamino group drastically inhibited the chemiluminescence in spite of its low sigma value. While the compound (2) with 15-monoazacrown-5 also showed a very weak chemiluminescence upon treatment with tetrabutylammonium hydroxide and hydrogen peroxide in acetonitrile, the chemiluminescence was enhanced up to 20 times in efficiency when divalent metal cations, such as magnesium and calcium ions, were added.

SmI2-promoted Reformatsky-type reaction and acylation of alkyl 1-chlorocyclopropanecarboxylates.

In the presence of HMPA in THF, highly stereoselective SmI(2)-promoted substitutions of alkyl 1-chlorocyclopropanecarboxylates 1 using various ketones, aldehydes (Reformatsky-type reaction), and acyl chlorides (acylation) proceeded to give trans-adducts (2 or 5) in good to high yield with excellent trans-stereoselectivity (trans-add/cis-add = > 99/1). The Reformatsky-type reaction of 1 with aldehydes and unsymmetrical ketones proceeded with moderate diastereoselectivity (re-face-adduct/si-face-adduct = 60/40-75/25).

Chemiluminescence of 4-styrylphthal-hydrazides with crown ether as ionophore.

Two 4-styrylphthalhydrazides bearing crown ether moieties as ionophores were prepared and their chemiluminescence (CL) behaviour was investigated. Their aerobic oxidation in the presence of excess tert-BuOK in DMSO provided the CL with much shorter emission wavelengths than those of the corresponding phthalate dianions, indicating that the emission arose from the excited phthalates incorporated with potassium ions at the ionophore sites. Such incorporation of potassium ions with the crown sites also reduced the fluorescence intensities of the phthalate dianions which caused an energy transfer CL, resulting in the additional emissions of the phthalhydrazide monoanions in much longer wavelength regions.

Fluorescence quenching of versatile fluorescent probes based on strongly electron-donating distyrylbenzenes responsive to aromatic chlorinated and nitro compounds, boronic acid and Ca(2+).

The fluorescence quenching behavior of two distyrylbenzenes (DSBs) newly prepared bearing strongly electron-donating groups was investigated. Several chlorinated and nitro compounds quench the fluorescence of both DSBs with various efficiencies depending on the electron-withdrawing properties; the strongly electron-withdrawing compound, such as 2,4,5-trichlorophenol and 2,4-dinitrofluorobenzene, effectively diminish the fluorescence intensities of the DSBs. The fluorescence quenching was also detected in the interaction between the azacrown DSB and phenylboronic acid, while the fluorescence recovers by adding triethylamine.

Highly stereoselective radical carbonylations of gem-dihalocyclopropane derivatives with CO.

A couple of radical carbonylations of gem-dihalocyclopropanes 1 using CO and Bu3SnH (formylation) or Bu3Sn(CH2CH=CH2) (allylacylation) successfully proceeded to give trans and cis adducts (2 and 3) with good to excellent stereoselectivity (trans/cis = >99/1-75/25 or 17/83-1/99). The formylation of 2,3-cis-disubstituted 1,1-dihalocyclopropanes enhanced trans selectivity (trans/cis = >99/1-95/5), whereas both 2,3-cis-disubstituted and 2-monosubstituted 1,1-dihalocyclopropanes underwent allylacylation with nearly complete trans selectivity (trans/cis = >99/1). Inherently less reactive gem-dichloro- and bromochlorocyclopropanes than gem-dibromocyclopropanes served as favorable substrates.

Photochemical behavior of some p-styrylstilbenes and related compounds: spectral properties and photoisomerization in solution and in solid state.

The spectral properties and Z,E-photoisomerizations of three 4-styrylstilbenes, a 4,4'-bis(P-methylstyryl)benzene and a 4,4'-distyrylstilbene were investigated in solution and in the solid state. Some notable features of the absorption and fluorescence spectra due to the structures and the phases (solution or solid) were observed, especially the Stokes shifts. Interesting photochemical behaviors in solution and in the solid state were also found.

Unprecedented chemiluminescence behaviour during peroxyoxalate chemiluminescence of oxalates with fluorescent or electron-donating aryloxy groups.

A series of diaryl and bis(4-styrylphenyl) oxalates with electron-donating substituents or fluorescent moieties were subjected to the peroxyoxalate chemiluminescence (PO-CL) reaction, some of which were found to behave in a unprecedented manner. The reaction of bis(p-methyoxyphenyl) oxalate, as a representative example, emits light due not only to the emission from the externally added excited fluorophore, but also from the presumable excimer of p-methoxyphenol. Also, during the reaction of the bis(4-styrylphenyl) oxalates, the emission based on the fluorescence as well as the excimer of the eliminating group were observed.

Regiocontrolled benzannulation of diaryl(gem-dichlorocyclopropyl)methanols for the synthesis of unsymmetrically substituted alpha-arylnaphthalenes: application to total synthesis of natural lignan lactones.

[reaction: see text] An efficient synthesis of highly substituted alpha-arylnaphthalene analogues has been developed utilizing Lewis acid-promoted regiocontrolled benzannulation of aryl(aryl')-2,2-dichlorocyclopropylmethanols (aryl not equal aryl'; abbreviated as AACMs). Both AACM diastereomers were easily prepared via highly stereoselective addition (>95/5) of ArLi to gem-dichlorocyclopropropyl aryl' ketones. The choice of Lewis acids determined the cyclization regioselectivity of the present benzannulation.

Chemiluminescence in autoxidation of phosphonate carbanions. Phospha-1,2-dioxetanes as the most likely high-energy intermediates.

Autoxidation of the phosphonate carbanions derived from 9-phosphono-10-hydroacridanes provided chemiluminescence ascribed to the excited acridone anion. The intramolecular CIEEL (chemically initiated electron exchange luminescence) mechanism can be applied to this chemiluminescence because of the much higher emission efficiency compared to that of 9-phosphono-10-methylacridanes. The effect of the phosphonate substituents on the emission efficiency and especially on the rates of the chemiluminescence decay can be interpreted to originate from the valence deviation of the phosphorus atoms, which is connected with the substituent effect on the geometrical selectivity in the olefination reaction of the phosphonate carbanions.

Self-assembly and regioselective photodimerization of anthracene having a dendritic substituent.

[reaction: see text] Thermotropic liquid crystallinity can be induced for an anthracene having a dendritic substituent. The photodimerization reaction of an anthracene moiety in the smectic phase proceeded quantitatively and regioselectively.

The key intermediates that interact with the fluorophores in the peroxyoxalate chemiluminescence reaction of 2,4,6-trichlorophenyl N-aryl-N-tosyloxamates.

A kinetic study of peroxyoxalate chemiluminescence reactions employing 2,4,6-trichlorophenyl N-aryl-N-tosyloxamates supports the 1,2-dioxetanones still bearing the eliminating group as the key intermediates that interact with the fluorophores rather than 1,2-dioxetanedione.

Peroxyoxalate chemiluminescence of N,N'-bistosyl-1H,4H-quinoxaline-2,3-dione and related compounds. Dependence on electronic nature of fluorophores.

The title compound N,N'-bistosyl-1H,4H-quinoxaline-2,3-dione (TsQD) provides peroxyoxalate chemiluminescence (PO-CL) when reacted with hydrogen peroxide in the presence of fluorophores. The chemiluminescence (CL) efficiency of TsQD was superior to that of other related compounds such as bis(2,4,6-trichlorophenyl) oxalate (TCPO), a typical oxalate for the peroxyoxalate PO-CL, under an aqueous condition. Factors affecting the PO-CL efficiency are discussed from the viewpoint of the structures of the substrates and the electronic nature of the fluorophores.

Halogenovinyl Sulfones. 6.(1) Synthesis of Condensed Heterocycles by Diastereoselective Intramolecular Diels-Alder Reactions of Sulfonyl-Substituted Trienes.

Sulfonyl trienes having a chiral center on the allyl carbon of the diene moiety were prepared from L-amino acid as chiral building blocks. Intramolecular Diels-Alder reaction of the sulfonyl trienes having E-geometry on the diene moiety proceeded on the si-face and exo-selectively to give cis-isoindoles as a sole product in good yields. But using the sulfonyl trienes having Z-geometry on the diene part, the ratio of the diastereomers of the products decreased to about 80:20.