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根据微孔磷酸铝合成数据的特点,针对合成数据库中合成参数过多和交叉描述等问题,利用改进的遗传编程算法对具有(6,8)元环的微孔磷酸铝合成参数进行特征提取,优化出新的复合特征来更好地描述磷酸铝合成中溶剂和模板剂的特征,并通过参数进化过程的研究,考察了模板剂和溶剂对产物生成的具体影响,从而指导具有特定结构磷酸铝的定向合成. 相似文献
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《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1986,42(8):869-879
The vibrational spectra of 4-(dimethylamino)benzaldehyde (DABA) and its zinc complex are presented and vibrational assignments are proposed. Significant differences between the spectra of the parent molecule and the complex are observed. Examination of the form of the normal modes facilitates explanation of proposed frequency shifts of ring modes upon complexation. The spectra of the complex are interpreted by employing a quinonoid-type structure for the DABA ligand. 相似文献
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《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1982,38(7):759-765
Molecular structures of mercaptoacetaldehyde and mercaptoacetone in the crystalline state and in solutions have been studied by 1H-NMR, Raman and infrared spectroscopy. Both compounds exist as centrosymmetric dimers having six-membered 1,4-dithian ring skeletons in the crystalline state and in freshly-prepared dimethylsulfoxide and pyridine solutions. In equilibrium solutions, non-centrosymmetric dimers having 1,4-dithian ring skeletons and the monomer also exist. No evidence that suggests the existence of five-membered ring dimer in solutions has been obtained for both compounds. The most stable species in solution is the non-centrosymmetric dimer in the case of mercaptoacetaldehyde and the monomer in the case of mercaptoacetone. 相似文献
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《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1988,44(4):379-384
The near u.v. spectra of 2,4-diamino-6-piperidinopyrimidine (desoxyminoxidil) and 2,4-diamino-6-piperidinopyrimidine-3-oxide (minoxidil) can be viewed as perturbed pyrimidine spectra. The u.v. properties of pyrimidine and a series of aminopyrimidines, specifically 2,4,6-triaminopyrimidine, are examined to obtain u.v. spectral assignments for desoxyminoxidil and minoxidil. Minoxidil and its desoxy counterpart have Cs symmetry, and all π → π* absorptions are allowed 1A′ ← 1A′ transitions. The two lowest energy π →- π* absorptions observed in minoxidil (262 nm, 292 nm) are tentatively assigned as very mild oxygen → pyrimidine ring charge-transfer transitions. Intensity decreases in protic solvents, and the results of simple Hückel molecular orbital calculations indicate that the 292 nm transition has more charge-transfer character than the 262 nm absorption. The protonated species of desoxyminoxidil and minoxidil have very similar u.v. spectra. This is due to the lack of oxygen-related charge transfer in protonated minoxidil, and the high probability that the positive charge resides in similar environments in the minoxidil and desoxyminoxidil molecular frameworks. 相似文献
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《Journal of organometallic chemistry》1987,320(1):53-62
The structure of the new compound [Mo(η5-C5H5)2(2-NHNC5H4)][PF6] (1) has been determined. The crystals are orthorhombic, space group Pca21 with a 20.807(1), b 8.0030(8), c 10.056(3) Å, V 1674.5 Å3, Z = 4. The structure of [Mo(η5-C5H5)2(2-ONC5H4)][PF6] (2) has also been determined. The crystals are orthorhombic, space group Pnma with a 12.727(3), b 10.174(2), c 12.918(1) Å, V 1672.8 Å3, Z = 4. The structures were solved by Patterson and difference electron density syntheses and refined by least-squares to R of 0.028 for 1287 reflections for 1 and 0.059 for 1178 reflections for 2.Although not isostructural the two cationic complexes have equivalent geometries with the normal bent bismetallocene structure. For 1 the MoN bond lengths are 2.160(8) and 2.142(9) Å, with a NMoN bond angle of 59.8(3)°, whereas for 2 MoO is 2.142(10), MoN is 2.138(11) Å, the NMoO angle is 61.2(4)°. These parameters are discussed and compared with the corresponding data for similar biscyclopentadienyl complexes of molybdenum(IV). Extended Hückel molecular orbital calculations have been carried out to throw light on the nature of the bonding between the metal and the bidentate ligand. 相似文献
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Prof. Dr. Guobing Yan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(29):e202200231
Hydrodefluorination (HDF) is a very important fundamental transformation for conversion of the C−F bond into the C−H bond in organic synthesis. In the past decade, much progress has been achieved with HDF through the utility of low-valent metals, transition-metal complexes and main-group Lewis acids. Recently, novel methods have been introduced for this purpose through photo- and electrochemical pathways, which are of great significance, due to their considerable environmental and economical advantages. This Review highlights the HDF of fluorinated organic compounds (FOCs) through photo- and electrochemical strategies, along with mechanistic insights. 相似文献
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??We study the linear quadratic optimal stochastic control problem which is jointly driven by Brownian motion and L'{e}vy processes. We prove that the new affine stochastic differential adjoint equation exists an inverse process by applying the profound section theorem. Applying for the Bellman's principle of quasilinearization and a monotone iterative convergence method, we prove the existence and uniqueness of the solution of the backward Riccati differential equation. Finally, we prove that the optimal feedback control exists, and the value function is composed of the initial value of the solution of the related backward Riccati differential equation and the related adjoint equation. 相似文献
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TiO_2因具有多种优异的特性被广泛应用在半导体光催化领域,但是纳米结构的TiO_2颗粒细微,在进行光催化反应之后,难以回收再利用。本文以廉价钛铁矿为原料制备光催化剂TiO_2,同时利用副产物铁合成Fe_3O_4,并采用简单温和的浸渍法制备Fe_3O_4/TiO_2磁性复合材料。通过XRD、FT-IR、SEM、EDS等手段对材料形态结构进行表征分析,并以光降解有机污染物若丹明B为探针反应,考察其光催化性能。结果表明,质量比为1∶10的Fe_3O_4/TiO_2复合材料结构稳定、分散均匀,具有最优的光催化活性(波长356nm下反应3h,若丹明B降解率达到64.0%),并表现出良好的重复性。同时,动力学结果显示降解符合一级反应动力学。 相似文献
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