INTRAMOLECULAR EXCIMER FORMATION and MOLECULAR RECOGNITION OF MODIFIED CYCLODEXTRINS APPENDED BY TWO NAPHTHALENE RINGS*

The intramolecular excimer formation of 6A,6B-, 6A,6C-, 6A,6D-, and 6A,6E-bis(2-naphthyl-sulfonyl)-γ-cyclodextrins (1, 2, 3, and 4, respectively) and 6A.6B-, 6A,6C-, and 6A,6D-bis(2-naphthyl-sulfonyl)-β-cyclodextrins (5, 6, and 7, respectively) has been studied in 10% ethylene glycol aqueous solution. The two naphthyl rings are co-included in the γ-cyclodextrin cavities of1–4, and marked excimer emission was observed for 2, 3, and 4. On the other hand, almost pure monomer emission was observed for 5, 6, and 7 due to inclusion of one of two naphthyl rings in the β-cyclodextrin cavities. Compounds 2, 3, 6, and 7 showed remarkable guest-induced enhancement in the excimer emission, and this property was used for detecting several organic compounds with remarkable molecular recognition.     

Furopyridines. VI. Preparation and reactions of 2- and 3-substituted furo[2,3-b]pyridines

This paper describes the synthesis and chemical properties of some 2- and 3-substituted furo[2,3-b]pyridines. Reaction of ethyl 2-chloronicotinate 1 with sodium ethoxycarbonylmethoxide or 1-ethoxycarbonyl-1-ethoxide gave β-keto ester 2 or ketone 5 , respectively. Ketonic hydrolysis of 2 afforded ketone 3, from which furo[2,3-b]pyridine 4 was obtained by the method of Sliwa. While, 2-methyl derivative 7 was prepared from 5 by reduction, O-acetylation and the subsequent pyrolysis. Reaction of ketone 3 with methyllithium gave tertiary alcohol 8 which was O-acetylated and pyrolyzed to give 3-methyl derivative 9 . Formylation of 4 , via lithio intermediate, with DMF yielded 2-formyl derivative 10 , from which 7 , was obtained by Wolff-Kishner reduction. Dehydration of the oxime 11 of 10 gave 2-cyano derivative 12 , which was hydrolyzed to give 2-carboxylic acid 13 . Reaction of 3-bromo compound 14 with copper(I) cyanide gave 3-cyano derivative 15 . Alkaline hydrolysis of 15 afforded compound 16 and 17 , while acidic hydrolysis gave carboxamide 18 . Reduction of 15 with DIBAL-H afforded 3-formyl derivative 19 . Wolff-Kishner reduction of 19 gave no reduction product 9 but hydrazone 20 . Reduction of tosylhydrazone 21 with sodium borohydride in methanol afforded 3-methoxymethylfuro[2,3-b]pyridine 22 .     

A conductive metal–organic framework photoanode

We report the development of photosensitizing arrays based on conductive metal–organic frameworks (MOFs) that enable light harvesting and efficient charge separation. Zn₂TTFTB (TTFTB = tetrathiafulvalene tetrabenzoate) MOFs are deposited directly onto TiO₂ photoanodes and structurally characterized by pXRD and EXAFS measurements. Photoinduced interfacial charge transfer dynamics are investigated by combining time-resolved THz spectroscopy and quantum dynamics simulations. Sub-600 fs electron injection into TiO₂ is observed for Zn₂TTFTB–TiO₂ and is compared to the corresponding dynamics for TTFTB–TiO₂ analogues that lack the extended MOF architecture. Rapid electron injection from the MOF into TiO₂ is enhanced by facile migration of the hole away from the interfacial region. Holes migrate through strongly coupled HOMO orbitals localized on the tetrathiafulvalene cores of the columnar stacks of the MOF, whereas electrons are less easily transferred through the spiral staircase arrangement of phenyl substituents of the MOF. The reported findings suggest that conductive MOFs could be exploited as novel photosensitizing arrays in applications to slow, and thereby make difficult, photocatalytic reactions such as those required for water-splitting in artificial photosynthesis.

We report the development of photosensitizing arrays based on conductive metal–organic frameworks (MOFs) that enable light harvesting and efficient charge separation.     

Simultaneous determination of free and bound adriamycin, adriamycinol, adriamycinone and duanorubicin in plasma using column-switching technique and protein-coated pre-columns

Adriamycin, adriamycinol, adriamycinone and duanorubicin were simultaneously determined by the development of an on-line plasma clean-up system. A short protein-coated Lichrosorb, RP-8, RP-2, CN and muBondapak phenyl as well as ODS silica have been examined for their performance as pre-columns. The drugs and metabolites were separated from weakly retained plasma components through two steps; phosphate buffer saline, pH 7.4 and 15% acetonitrile in 0.1 M sodium dihydrogen phosphate, pH 3. The chromatographic conditions were: ODS/TM column, flow rate 1 ml/min, 35% acctonitrile in 0.1 M sodium dihydrogen phosphate (pH 3) containing 0.3% heptafluorobutyric acid as mobile phase. The detection was carried out using fluorescence monitor operated at an emission 555 nm and excitation 460 nm. Good resolution was obtained within 13 min. This method is reproducible for analysis of drugs and metabolites (99.3-100.1%, CV < 2%) in plasma.     

A novel method for preparation of imidazolium tetrafluoroborate ionic liquids

A new method for the preparation of substituted imidazolium tetrafluoroborate salt, some of which are known as versatile room temperature ionic liquids, is proposed. The new method based on N-methylation of imidazole provided tetrafluoroborate derivatives containing no counterions, with shorter time and lower cost than conventional ion-exchange method.     

Efficient photocurrent generation by self-assembled monolayers composed of 3 10-helical peptides carrying linearly spaced naphthyl groups at the side chains

Self-assembled monolayers (SAMs) were prepared on a gold substrate from a 310-helical peptide carrying three naphthyl groups at the side chain (SSN3B) or from the reference peptides carrying no or one naphthyl group. The 310-helical conformation of SSN3B in solution was confirmed by 1H NMR spectroscopy and geometry optimization. Cyclic voltammetry and infrared absorption-reflection spectroscopy showed vertical molecular orientation and a well-packed structure in the SSN3B SAM. Anodic photocurrent was successfully generated by the SSN3B SAM in the presence of triethanolamine, and the current intensity was found to be much larger than those by the other SAMs from peptides carrying one naphthyl group. It was therefore concluded that the linearly spaced naphthyl groups along the helical axis act as photosensitizer and electron-hopping site to promote photocurrent generation remarkably.     

Environmental Radiation Monitoring after the Accidental Release from Bituminization Demonstration Facility

The fire and explosion of the Bituminization Demonstration Facility at PNC Tokai Works were occurred on March 11th, 1997. As soon as the fire occurred, environmental monitoring was started. The influence of accidental release was recognized from some samples of airborne dust and surface soil on site. No influence was recognized from the samples off site except the airborne dust collected at O-arai (20 km south). The official statement by the Nuclear Safety Commission of Japan was: "It was less than the value which has an influence on the environment and health."     

Simple and rapid extraction method of total egg lipids for determining organochlorine pesticides in the egg

A simple and rapid extraction method of total egg lipids for determination of organochlorine pesticides (OCPs) in the egg was developed. After being mixed with anhydrous sodium sulphate, the extraction of lipids in egg yolk was performed using n-hexane–acetonitrile (2:1, v/v). Troublesome emulsions did not occur. Using the present method, an average of 3.03 g of egg lipids was collected from 10 g of egg yolk. Compared with classical methods, the present method is handy; needs much shorter analysis time and less requirement of solvents and has higher efficiency of egg lipid extraction and higher recoveries of OCPs.