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61.
采用共沉淀法制备了手性胺(L-脯氨酸、D-脯氨酸、(1R,2R)-1,2-二苯基乙二胺二磺酸钠((1R,2R)-DPENDS)、(1S,2S)-1,2-二苯基乙二胺二磺酸钠((1S,2S)-DPENDS))修饰的羟基磷灰石(HAP).并采用傅里叶变换红外(FT-IR)光谱,扫描电子显微镜(SEM),X射线衍射(XRD)和比表面积测定(BET)等仪器分析手段对其进行表征.以手性胺修饰的羟基磷灰石做载体负载RuCl2(TPP)3催化苯乙酮不对称加氢反应,详细考察温度、压力、碱的浓度、手性胺负载量等条件对催化反应的影响.在氢气压力为5.0 MPa、30℃条件下反应4 h,苯乙酮的不对称加氢反应,可获得99.9%转化率和77.8%对映选择性,其结果优于对应的均相催化反应.实验结果证明,催化反应在载体表面完成,催化剂通过简单离心分离可循环使用. 相似文献
62.
报导了对位取代的四苯基卟啉衍生单酸的合成及表征,阐述了一些有关共轭叶琳平面环体系的结构理论。 相似文献
63.
5,10,15,20-Tetraphenylporphyrin (TPP) was synthesized and self-assembled on iron surface to form adlayers. Some surface analysis techniques such as XPS, FT-IR and SEM were performed to characterize the adlayers. The corrosion inhibition ability was investigated by using the technique of electrochemical impedance spectroscopy (EIS) and polarization curves in 0.5 M H2SO4. Results showed that the presence of the porphyrin adlayers was able to protect iron from corrosion effectively and longer immersion time would lead to better inhibition performance. In addition, molecular simulation studies were applied to optimize the adsorption structures of TPP molecules on iron surface. Calculated results indicated that the middle macrocycle of the TPP molecules assumed a nearly flat orientation with respect to the iron surface and the four centrosymmetric benzene rings were tilted by 44.8° and 58.8° because of the steric hindrance effect. 相似文献
64.
65.
El-Nahass MM Zeyada HM Aziz MS Makhlouf MM 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(13-14):3026-3031
The optical absorption of thermally-evaporated tetraphenylporphyrin (TPP), in the UV-vis-NIR region has been studied. The absorption spectra recorded in the UV-vis region for the as-deposited and annealed films showed different absorption bands, namely the Soret, B, at region 360-490 nm, Q-band region consist of four bands in the region 500-720 nm and two other bands labeled N and M in UV region. The Soret band always shows splitting in all the TPP thin films and the effect of annealing on the intensities of these components have been observed. The spectra of the infrared absorption allow characterization of vibrational modes for the powder, as deposited and annealed thin films. Some of the optical absorption parameters, namely molar extinction coefficient (epsilon), half band width (Deltalambda), electronic dipole strength (q2), and oscillator strength (f), of the principal optical transitions have also been evaluated. 相似文献
66.
《Surface and interface analysis : SIA》2005,37(1):1-14
We report calculations of electron inelastic mean free paths (IMFPs) for 50–2000 eV electrons in 14 elemental solids (Li, Be, diamond, graphite, Na, K, Sc, Ge, In, Sn, Cs, Gd, Tb, and Dy) and for one solid (Al) using better optical data than in our previous work. The new IMFPs have also been used to test our TPP‐2M equation for estimating IMFPs in these materials. We found surprisingly large root‐mean‐square (RMS) deviations (39.3–71.8%) between IMFPs calculated from TPP‐2M and those calculated here from optical data for diamond, graphite and cesium; previously we had found an average RMS deviation of 10.2% for a group of 27 elemental solids. An analysis showed that the large deviations occurred for relatively small computed values of the parameter β in the TPP‐2M equation (β ~ 0.01 for diamond and graphite) and also for relatively large values of β (β ~ 0.25 for Cs). Although such extreme values of β are unlikely to be encountered for many other materials, the present results indicate an additional limitation in the reliability of the TPP‐2M equation. We also show that the parameter Nv in the TPP‐2M equation should be computed for the rare‐earth elements from the number of valence electrons and the six 5p electrons. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
67.
DU Pei-ge AN Li-ping QIU Fang-ping LU Gang 《高等学校化学研究》2006,22(1):65-67
IntroductionTripeptidyl peptidaseⅠ(EC3.4.14.9)is identi-cal to pepstatin-insenstive carboxyl proteinase that ismutated when CLN2occurs,and the fibroblasts frompatients with CLN2are deficient in lysosomal TPPⅠ[1].It is the exopeptidase activity of TPPⅠt… 相似文献
68.
Keisuke Maruyoshi 《Tetrahedron》2004,60(24):5163-5170
Polyamines such as spermidine and spermine are known to interact with polyanionic biomolecules under physiological conditions. Conformation analysis of these highly flexible acycles is virtually unprecedented due to the lack of appropriate methodologies. Spin-spin coupling constants, which are often utilized for acyclic systems, are rather uninformative for polyamines due to unresolved 1H NMR signals of their tri- and tetra-methylene moieties. We attempted to solve this problem by synthesizing diastereospecifically deuterated spermidine, (1S∗,2S∗)-1,8-diamino-4-azaoctane-1,2,3,3,5,5,6,6,7,7,8,8-d12. To evaluate its utility, 1H-1H spin coupling constants were measured as trihydrochloride or tripolyphosphate salt. The relevant coupling constant markedly decreased upon complexation to tripolyphosphate. Under neutral pH, where the net charge of tripolyphosphate became tetravalent, the coupling constant was small; as pH was lowered to 1.4, where the charge was divalent, the constant increased significantly. These data clearly indicate that, when interacting with polyanions, spermidine undergoes conformational changes to increase bent conformation, which could be effectively monitored by the deuterated spermidine. 相似文献
69.
Srinivasa Rao Karumuri Joydeep Choudhury Nirmal Kumar Sarkar Ramendu Bhattacharjee 《Pramana》2009,72(3):517-525
One of the most interesting areas of current research in molecular physics is the study of the vibrationally excitated states
of medium and large molecules. In view of the considerable amount of experimental activity in this area, one needs theoretical
models within which to interpret experimental data. Using Lie algebraic method, the vibrational energy levels of nickel metalloporphyrins
like Ni(OEP), Ni porphyrin and Ni(TPP) are calculated for 16 vibrational modes. The algebraic Hamiltonian
, where A
i
, A
ij
and λ
ij
are the algebraic parameters which vary from molecule to molecule and C
i
, C
ij
and M
ij
are algebraic operators. The vibrational energy levels are calculated using algebraic model Hamiltonian and the results are
compared with the experimental values. The results obtained by this model are very accurate.
相似文献
70.
A New Organic Up-conversion Laser Dye HEASPS 总被引:3,自引:0,他引:3
Yan REN Guang Yong ZHOU Chun WANG Xiao Mei WANG Zhi LIU Xian ZHAO Wen Tao YU Min Hua JIANG 《中国化学快报》2000,11(8):685-688
TWo-photon absorption (TPA) is such a process in which a molecule simultaneouslyabsorbs tWo photons to access an excited state. The charm of the materials with largeTPA cross section is due to the virtUe of using near-IR tWo-photon as pump source forUV-visible excitation, which leads to a deeper penetration in the media. In addition, thequadratic intensity dependence of the tWo-photon process allows for excitation ofchromophores with a high degree of spatial selectivity. In laser device … 相似文献