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Rajib Choudhury Hope E. Parker Kassandra M. Cendejas Kalie L. Mendenhall 《Tetrahedron letters》2018,59(31):3020-3025
The rational design of environmentally sensitive small molecule fluorophores with superior photophysical properties is critical for fluorimetry based biosensing. Herein, we have developed a new donor-acceptor fluorophore for quantitative detection of Human Serum Albumin (HSA) in aqueous samples. The fluorophore was easily prepared by Knoevenagel condensation, and showed excellent photophysical properties and positive solvatochromism. The design of the fluorophore was based on a nitrogen donor—π-conjugation—nitrile acceptors (D—π—A) to preserve efficient intramolecular charge transfer and long-wavelength emission. The fluorophore showed remarkable “turn-on” fluorescence in presence of HSA, which led to quantitative determination of the protein in aqueous buffer samples. Structure and electronic properties of the fluorophore played important roles on the superior HSA sensing ability. The findings indicate that minor changes in design strategy can be advantageous while developing long-wavelength (far red or near infrared) emitting fluorophores for biosensing and bioimaging. 相似文献
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G. D. Mendenhall 《Angewandte Chemie (International ed. in English)》1977,16(4):225-232
Most organic compounds react very slowly with atmospheric oxygen at room temperature. The weak chemiluminescence accompanying this autoxidation can be amplified and measured by sensitive instruments. Emission of light from many materials can also be induced mechanically and photochemically. The intensity-time curves are so characteristic that they can be used to establish whether the composition and history of two samples are identical. Moreover, numerous physical properties can be correlated with emission and thus measured. 相似文献
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The pyrolysis of n-propyl nitrate and tert-butyl nitrite at very low pressures (VLPP technique) is reported. For the reaction the high-pressure rate expression at 300°K, log k1 (sec?1) = 16.5 ? 40.0 kcal/mole/2.3 RT, is derived. The reaction was studied and the high-pressure parameters at 300°K are log k2(sec?1) = 15.8 ? 39.3 kcal/mole/2.3 RT. From ΔS1,?10 and ΔS2,?20 and the assumption E?1 and E?2 ? 0, we derive log k?1(M?1·sec?1) (300°K) = 9.5 and log k?2 (M?1·sec?1) (300°K) = 9.8. In contrast, the pyrolysis of methyl nitrite and methyl d3 nitrite afford NO and HNO and DNO, respectively, in what appears to be a heterogeneous process. The values of k?1 and k?2 in conjunction with independent measurements imply a value at 300°K for of 3.5 × 105 M?1·sec?1, which is two orders of magnitude greater than currently accepted values. In the high-pressure static pyrolysis of dimethyl peroxide in the presence of NO2, the yield of methyl nitrate indicates that the combination of methoxy radicals with NO2 is in the high-pressure limit at atmospheric pressure. 相似文献
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Study of the reaction by very-low-pressure pyrolysis (VLPP) in the temperature range of 550–850°K yields for the high-pressure Arrhenius parameters where θ = 2.303RT in kcal/mole. These in turn yield for the high-pressure second-order recombination of tBu + NO, k?1 = (3.5 ± 1.7) × 109 1./mole·sec at 600°K. For the competing reaction l./mole·sec and E4 ≥ 4.2 kcal/mole. The bond dissociation energy DHo (tBu-NO) was determined to be (39.5 ± 1.5) kcal/mole, both from the equilibrium constant and from the activation energy of reaction (1), obtained from RRKM calculations. A ‘free-volume’ model for the transition state for dissociation is consistent with the data. A limited study of the system at 8–200 torr showed an extremely rapid inhibition by products and a very complex set of products. 相似文献
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