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Various 2-substituted indoles were prepared by heteroannulation of o-iodoanilines and terminal alkynes in a one-pot reaction with a Pd(II)-NaY zeolite catalyst. The product formation largely depended on the solvent, base, and reaction temperature. The recycled catalyst showed good reusability in the heteroannulation reaction. 相似文献
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Russell J. DeOrazio Jun-Ho Maeng Brian A. Sherer Ian L. Scott Sham S. Nikam 《合成通讯》2013,43(23):3551-3555
The double metallation of 6-bromo-3H-benzothiazol-2-one and 6-bromo-3H-benzoxazol-2-one with methyl magnesium bromide and alkyllithium bases is described. Alkylation with a variety of electrophiles occurs at the 6-position of the heterocycles in good yields. 相似文献
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Trisubstituted thiazoles were synthesized with excellent yields using ligand-free, palladium-catalyzed, direct 5-arylation of 2,4-disubstituted thiazole and conventional or microwave-assisted heating. The palladium-catalyzed reaction yields were significantly influenced by LiCl additive, solvent, and heating method. The reaction times were reduced dramatically by employing microwave radiation instead of conventional heating. The synthetic methods can be applied to diverse 2,4,5-trisubstituted thiazoles by varying the aryl bromide and disubstituted thiazole reactants. 相似文献
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Peripherally and Axially Carboxylic Acid Substituted Subphthalocyanines for Dye‐Sensitized Solar Cells
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Dr. Mine Ince Dr. Anaïs Medina Dr. Jun‐Ho Yum Dr. Aswani Yella Dr. Christian G. Claessens Dr. M. Victoria Martínez‐Díaz Prof. Michael Grätzel Dr. Mohammad K. Nazeeruddin Prof. Tomás Torres 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(7):2016-2021
A series of subphthalocyanines (SubPcs) bearing a carboxylic acid group either at the peripheral or axial position have been designed and synthesized to investigate the influence of the COOH group positions on the dye‐sensitized solar cell (DSSC) performance. The DSSC devices based on SubPcs with axially substituted carboxylic acid groups showed low photovoltaic performance, whereas peripherally substituted one exhibited higher power conversion efficiency owing to improved injection from LUMO of SubPcs to the TiO2 conduction band. 相似文献
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We propose and demonstrate a simple technique for determining the M/# parameter of a holographic recording material. In this method, divergent object and reference beams are used to produce a spatially varying index modulation. One can analyze the resultant diffraction pattern to find M/# by using only a single grating; existing techniques require many gratings. 相似文献
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We investigate the instability of one-dimensional dangling-bond (DB) wires fabricated on the H-terminated C(001), Si(001), and Ge(001) surfaces by using density-functional theory calculations. The three DB wires are found to show drastically different couplings between charge, spin, and lattice degrees of freedom, resulting in an insulating ground state. The C DB wire has an antiferromagnetic spin coupling between unpaired DB electrons, caused by strong electron–electron interactions, whereas the Ge DB wire has a strong charge-lattice coupling, yielding a Peierls-like lattice distortion. For the Si DB wire, the antiferromagnetic spin ordering and the Peierls instability are highly competing with each other. The physical origin of such disparate features in the three DB wires can be traced to the different degree of localization of 2p, 3p, and 4p DB orbitals. 相似文献
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Solvatochromic vibrational frequency shifts of a few different infrared (IR) probe molecules have been studied by carrying out quantum chemistry calculations for a number of their water clusters. We are particularly focused on the vibrational solvatochromic and electrochromic effects on the CO, CN, and CF stretch modes in carbon monoxide, acetone, 4-cyanopyridine, p-tolunitrile, fluorobenzene, and 3-fluoropyridine. Using multiple interaction site antenna model, we show that their solvatochromic vibrational frequency shifts can be successfully described by considering spatially nonuniform electrostatic potential generated by the surrounding water molecules. It turns out that the CO and CF stretch mode frequencies are approximately proportional to the solvent electric field projected onto the bond axes, whereas the vibrational frequencies of the nitrile stretch mode in 4-cyanopyridine and p-tolunitrile are not. Consequently, it is confirmed that the vibrational Stark tuning rates of the CO and CF stretching modes can be directly used to describe their solvatochromic frequency shifts in condensed phases. However, the nitrile stretch mode frequency shift induced by solvent electrostatic potential appears to be more complicated than its electrochromic phenomenon. To examine the validity of the distributed interaction site model for solvatochromic frequency shifts of these vibrational chromophores, we thus calculated the vibrational Stark tuning rates of the CO, CN, and CF stretch modes and found that they are in good agreement with the experimental results found in literatures. This confirms that a collection of properly chosen distributed interaction sites can be an excellent electric antenna sensing local electrostatics that affects on vibrational frequencies of IR probe modes. 相似文献