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41.
Enantiomerically pure (R,R)-(+)-2,3-diphenylpiperazine with 98% ee was obtained by resolution of the corresponding racemic mixture using (1S)-(+)-10-camphorsulfonic acid. The partially resolved enriched sample of (S,S)-(-)-2,3-diphenylpiperazine with 73% ee was purified to obtain samples of 97% ee using different achiral acids via the preparation of either homochiral or heterochiral hydrogen bonded aggregates. 相似文献
42.
Time-resolved fluorescence of eight fluorescence probes were studied in EggPC bilayer membrane vesicles. Emission wavelength dependent fluorescence decays were analyzed in a model-independent way to obtain time resolved area normalized emission spectra (TRANES). The TRANES spectra of the probes studied were classified into four types: (1) spectra that are identical at all time (one emissive species), (2) spectra that show an isoemissive point (two emissive species), (3) spectra that shift continuously with time (slow solvation dynamics or multiple species), and (4) spectra that shift for a short time and thereafter one or two emissive species are indicated. The TRANES spectra of these eight probes, except RH421, belong to the type 1, 2, or 4. The continuous shift of the TRANES spectra that was observed for the probe RH421 is attributed to multiple ground state species and not due to slow solvation dynamics. 相似文献
43.
The effect of deuteration on the electrochemiluminescence (ECL) efficiencies of the mixed systems containing anthracene or
phenathrene has been examined using the single light pulse in the double potential programme. Deuteration of anthracene or
phenanthrene decreases the ECL efficiencies by factors of 1·2–16·0. This decrease appears to arise from the quenching of the
triplets by radical ions in solution. The quenching factors are estimated by using Marcus theory of electron transfer reactions. 相似文献
44.
The 1,2-shift observed during oxidation of organic substrates can arise by involvement of cation radicals. 相似文献
45.
N. Periasamy 《Journal of fluorescence》2001,11(3):161-166
Time-resolved fluorescence polarization (anisotropy) of a probe (guest molecule) in a micelle is used for testing different models of molecular dynamics. The experimental studies so far support the model that includes wobbling motion and translational diffusion for the guest molecule in the micelle. 相似文献
46.
Mariappan Periasamy Ramani Gurubrahamam Gopal P. Muthukumaragopal 《Tetrahedron: Asymmetry》2013,24(9-10):568-574
Enantiomerically pure (2S,6S)-2,6-diphenyltetrahydro-2H-thiopyran, (2S)-2-phenyltetrahydro thiophene, and (2S)-2-phenyltetrahydro-2H-thiopyran were prepared in 70–72% yields and with 86–99% ee via cyclization of the corresponding dimesylate in an SN2 cyclization reaction using sodium sulfide nonahydrate. The results on the application of various chiral sulfides in asymmetric Baylis–Hillman reactions are also described. 相似文献
47.
Several 5-alkoxymethyl- and 5-aminomethyl-substituted 8-hydroxyquinolines were synthesised. Their coordination complexes with Al(III) were also synthesised. These complexes are soluble and stable in common organic solvents and show green luminescence with high quantum yields. 相似文献
48.
Periasamy Manoravi Mathew Joseph Natrajan Sivakumar Rajagopalan Balasubramanian 《Analytical sciences》2005,21(12):1453-1455
A reflectron time-of-flight mass spectrometer (RTOFMS) with a laser ablation ion source was used to determine the isotopic ratio of 10B/11B present in boric acid solutions, using graphite as the matrix. The atom % 10B values obtained were within +/-1% of the actual ones. The determination of the boron isotopic ratio using this method is, in comparison to other methods, faster, less expensive and easier to perform. The results are compared with the values determined using thermal ionization mass spectrometry. 相似文献
49.
The application of Marcus theory of electron transfer reactions for the case of radical ion chemiluminescence of 9,10-diphenylanthracene (DPA) gives a high rate constant value (109–1010 M?1 s?1) for the formation of the second triplet state (T2). It is suggested that the near infrared emission observed during electrochemiluminescence of DPA is due to T2 → T1 fluorescence based on the high yield of T2 (≈0.7) in the electron transfer reaction. 相似文献
50.
Distributed feedback (DFB) laser action has been demonstrated in an optical fiber surrounded by a gain modulated dye solution of lower refractive index. The mechanism of feedback and gain is by evanescent wave interactions. 相似文献