10213-78-2Relevant articles and documents
Novel preorganized hemispherands to encapsulate rare earth ions: Shielding and ligand deuteration for prolonged lifetimes of excited Eu3+ ions
Oude Wolbers, Manon P.,Van Veggel, Frank C. J. M.,Snellink-Ru?l, Bianca H. M.,Hofstraat, Johannes W.,Geurts, Frank A. J.,Reinhoudt, David N.
, p. 138 - 144 (1997)
Quenching of the luminescent excited state of Eu3+ ions by C-H high-vibrational modes was studied by deuteration of the encapsulating ligand and the solvent. Novel polydentate hemispherands providing nine donor atoms, which form overall neutral complexes with rare earth ions, were synthesized in nine steps, allowing the easy incorporation of deuterium atoms (IIa-d·Eu3+). The introduction of tert-butyl groups at the aromatic rings of the ligand further increased the solubility of the complexes in organic solvents (29·Eu3+ and 34·Eu3+). Photophysical studies, viz., luminescence spectra and lifetime measurements, revealed that significant quenching of the Eu3+ excited state is induced by nearby C-H vibrational modes. Substitution of these quenching C-H modes for C-D bonds in the azacrown bridge leads to an enhancement of the luminescent lifetime by a factor of 1.5. C-H high-vibrational modes of the pendant arms which are at a larger distance to the Eu3+ ion than the azacrown bridge hydrogen atoms (determined from the MD calculations) are less efficient quenchers. The number of coordinating methanol molecules to 11a·Eu3+, 29·Eu3+, and 34·Eu3+ estimated by the 'Horrocks equation' is 0.9, 1.2, and 1.9, respectively, as was predicted by MD calculations. Moreover, the experimental data show that quenching of the excited state of well-shielded Eu3+ ions by the C-H modes of the ligand is of the e order of magnitude as quenching by one O-H mode.
Design of new potent and selective secretory phospholipase A2 inhibitors. Part 5: Synthesis and biological activity of 1-alkyl-4-[4,5-dihydro-1,2,4-[4H]-oxadiazol-5-one-3-ylmethylbenz-4′-yl(oyl)] piperazines
Boukli, Latifa,Touaibia, Mohamed,Meddad-Belhabich, Nadia,Djimde, Atime,Park, Chang-Ha,Kim, Jung-Joo,Yoon, Joo-Hyoung,Lamouri, Aazdine,Heymans, Francoise
, p. 1242 - 1253 (2008/09/17)
Among the different PLA2s identified to date, the group IIA secretory PLA2 (sPLA2 GIIA) is implied in diverse pathological conditions. In this work we describe the synthesis, inhibitory activities, and structure-activity relationships (SAR) of a new class of substituted piperazine derivatives. The in vitro fluorimetric assay using two groups of enzymes, GIB and GIIA, revealed several compounds as highly potent inhibitors (IC50 = 0.1 μM). The in vivo activity assessed by ip or per os administration in a carrageenan-induced edema test in rats showed that two compounds proved to be as potent as indomethacin (10 mg/kg).
Low pressure derived mixed phosphorous- and sulfur-containing reaction products useful in power transmitting compositions and process for preparing the same
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, (2008/06/13)
A phosphorous- and sulfur-containing additive and its use to impart anti-wear and/or antioxidant properties to oleaginous compositions such as fuels and lubricating oils, particularly power transmission compositions, such as automatic transmission fluids, is disclosed. The additive comprises a mixture of products formed by simultaneously reacting (1) a beta-hydroxy thioether, such as thiobisethanol, and (2) a phosphorous-containing reactant, such as tributyl phosphite. The reaction is carried out under reduced pressure conditions (e.g., -40 KPa to -100 KPa) to limit the amount of thioether species in said additive to less than about 45 mole %.
