Spectres de masse de phospholipides et polypeptides non proteges. Une technique simple d'obtention du spectre complet.

Direct introduction of diacyl-lecithins in the ionization chamber on a gold support gives the molecular ion and structurally significant fragments; the same is true with unprotected small polypeptides.     

Chetracin A,a new epipolythiodioxopiperazine having a tetrasulfide bridge from chaetomium abuense and C. retardatum

A new epipolythiodioxopiperazine, designated chetracin A, exhibiting remarkable cytotoxicity, was isolated from Chaetomium spp. The compound was proved to have the 11α 11′α-dihydroxychaetocin nucleus by NMR and correlation reactions and found to have the tetrasulfide bridge by X-ray analysis.     

Isolation of a new neolignan,magnosalicin, from magnolia salicifolia

A new neolignan named magnosalicin (4) was isolated as a biologically active compound from the buds of $\text{Magnolia salicifolia}$, which have been used as a Chinese medicinal drug, especially for nasal allergy. A unique arrangement of substitution groups on a tetrahydrofuran ring indicates magnosalicin (4) being a neolignan. Its biogenetical formation mechanism is also discussed.     

Intramolecular charge-transfer process of jet-cooled (p-cyanophenyl)pentamethyldisilane: roles of the torsional motion and the Si-Si bond change

To investigate the intramolecular charge-transfer (ICT) process of (p-cyanophenyl)pentamethyldisilane (CPDS), laser-induced fluorescence, dispersed fluorescence, and two-color resonance enhanced two-photon ionization spectra were measured in a jet-cooled isolated condition. Dual fluorescence of CPDS was observed from a ground vibrational level in the locally excited pipi state. Similar to an emission from the charge-transfer (CT) state in solution, one of the dual emissions of the isolated molecule in the jet was assigned as the CT emission. A significant vibrational dependence on the ICT process was found as exciting vibronic levels of the molecule. It was identified that the promoting mode of the ICT process is a torsional motion of the disilanyl group with respect to the phenyl ring. It was also revealed that an effective appearance energy of the CPDS cation via the CT state is much lower than that via the locally excited pipi state suggesting that the electronic configuration of the CT state is similar to that of the cation. On the basis of an electronic configuration of the cationic state, that of the CT state was suggested to be of the (sigma(Si)(-)(Si), 2ppi) type.     

A package compound of a metal atom with a hydrocarbon [4][4][4][4][3](1,2,3,4,5)ferrocenophane

Perbridged ferrocenes ($\text{9}$ and $\text{11}$: the title compound) have been synthesized and characterized by spectroscopies and X-ray diffraction, and an interesting rotational disorder has been found by the X-ray crystal analyses of both $\text{9}$ and $\text{11}$.     

Reaction volume of protonic ionization for buffering agents. Prediction of pressure dependence of pH and pOH

Reaction volumes V^o at infinite dilution and 25°C are obtained by use of a Hashitani dilatometer for protonic ionizations of buffering agents. Combined with recent finding by Hamann that the pressure dependence of the activity coefficient can be estimated by the limiting Debye-Hueckel law even at high ionic strength, one can predict the pH and pOH for these buffer solutions at high pressure.     

Facile synthesis of 6a-carbaprostaglandin i2

The optically active 6a-carbaprostaglandin I₂ (2), a stable mimic of natural prostacylin (1), was synthesized from the lactone 4 or the hydroxy acid 5, which were general synthetic intermediates for natural prostaglandins.