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1.
Keiji Kabeta Shigeru Wakamatsu Takafumi Imai 《Journal of polymer science. Part A, Polymer chemistry》1996,34(14):2991-2998
Network methylethoxypolysilanes containing various substituents such as hexyl, phenyl, ethylene, hexamethylene, phenylene, and thiophene groups were prepared by a disproportionation reaction of 1,1,2,2-tetraethoxy-1,2-dimethyldisilane in the presence of the corresponding substituted alkoxysilanes. The reaction was considered to proceed via a silyl anion mechanism. The silyl anion produced from a disilane or a higher homologue attacked the alkoxysilane, and that caused the alkoxysilane moiety to be introduced into the polysilane. The amount of incorporated substituents varied from 3 to 29% of all organic substituents, depending on which alkoxysilane was reacted. The electrical conductivities of some polysilanes were measured, and the polymer with thiophene groups was found to show relatively higher conductivity of 10−5 Scm−1 after iodine doping. © 1996 John Wiley & Sons, Inc. 相似文献
2.
Shumaila Ashraf Yiming Zuo Shuai Li Caixia Liu Hang Wang Prof. Dr. Xiao Feng Prof. Dr. Pengfei Li Prof. Dr. Bo Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(59):13479-13483
The metalloid-centered covalent organic framework has attracted great interest from both its structure and application. Heavier elements have seldomly been incorporated in the covalent organic frameworks, even if they exhibit special structural features and properties. Herein, we reported the first crystalline germanate covalent organic framework with hexacoordinated germanate linked by an anthracene linker. The existence of counterion lithium ions in the framework provides a high CO2 uptake of 88.5 cm3 g−1 at 273 K and a high CO2/N2 selectivity of 101. A significantly improved lithium ion conductivity of 0.25 mS cm−1 at room temperature was observed due to the soft germanium center. 相似文献
3.
Zhuoliang Jiang Bo Wen Yaohui Huang Yihe Guo Yuzhe Wang Prof. Fujun Li 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2024,136(1):e202315314
Aprotic Li-O2 battery has attracted considerable interest for high theoretical energy density, however the disproportionation of the intermediate of superoxide (O2−) during discharge and charge leads to slow reaction kinetics and large voltage hysteresis. Herein, the chemically stable ruthenium tris(bipyridine) (RB) cations are employed as a soluble catalyst to alternate the pathway of O2− disproportionation and its kinetics in both the discharge and charge processes. RB captures O2− dimer and promotes their intramolecular charge transfer, and it decreases the energy barrier of the disproportionation reaction from 7.70 to 0.70 kcal mol−1. This facilitates the discharge and charge processes and simultaneously mitigates O2− and singlet oxygen related side reactions. These endow the Li-O2 battery with reduced discharge/charge voltage gap of 0.72 V and prolonged lifespan for over 230 cycles when coupled with RuO2 catalyst. This work highlights the vital role of superoxide disproportionation for Li-O2 battery. 相似文献
4.
Z. Sharaby J. Jagur-Grodzinski M. Martan D. Vofsi 《Journal of polymer science. Part A, Polymer chemistry》1982,20(4):901-915
The anionic polymerization of 1.3-cyclohexadiene (1.3-CHD) was investigated in temperatures that ranged from 25 to ?77°C. Initiation by lithium naphthalene (N?·,Li+) in tetrahydrofuran at ?20°C yields polymers with fairly narrow molecular weight distribution. The M?w of these polymers so prepared is ca. 20,000. Polymerization of 1.3-CHD conducted at room temperature is accompanied by the dehydrogenation and disproportionation of the monomer, especially when N?·,K+ acts as initiator. Oligomers are formed when hexamethylphosphoramide is used as a solvent. The mechanism of the initiation of the polymerization of 1.3-CHD by N?·,Li+ was elucidated and the rate constants at ?20°C in tetrahydrofuran of the elementary reactions were determined. It was established that the dianions formed by disproportionation of N?·,Li+ act as effective initiators for 1.3-CHD. The adducts formed constitute the cyclohexanyl and naphthyl carbanionic groups. The former carbanions (λmax ~ 275 nm) propagate the polymerization. The initially formed dimeric adducts are stabilized by the separation of the carbanionic end groups by the additional monomer units. Chain transfer to the monomer limits the growth of the polymers. The isomerization of the cyclohexadienyl anions, formed as result of chain transfer, may be followed by the elimination of lithium hydride. The latter reaction represents a termination step. Addition of 1.4-CHD to the reaction mixture enhances the chain transfer and the termination. 相似文献
5.
Seong-Keuck Cha 《Journal of Polymer Science.Polymer Physics》1997,35(1):165-172
Pyrrole, thiophene, and a mixture of the two monomers were electrochemically polymerized to investigate polymerization rates and the morphology change of the polymer matrix, and to improve the aging and cyclic voltammetric behaviors of the polymers. Thiophene was polymerized on a smooth surface of Pt electrode by two steps. The first step was controlled by electron transfer at the electrical double layer and the other by diffusion of the monomer reacting on the immobilized layer consisting of the precoated thiophene polymer. The electropolymerization rate of the second step was 1.85 × 10−4 cm3 mol−1 s−1, which is faster by 8.63 × 102 times than the first step. Some supporting electrolytes such as KPF6, LiClO4, TBAP, and TBABF4 were employed in the polymerization reaction to see the effects of dopant anions on the polymerization rate, and KPF6 was the fastest one at 2.41 × 10−6 cm s−1. However, owing to its sensitivity to oxygen, LiClO4 was used for the polymerization that is fairly stable in air and the same rate as KPF6. For the competitive polymerization reaction of the two monomers the rate of thiophene was found to be about 11 times slower than that of thiophene alone. When the starting concentration of the thiophene monomer was higher than pyrrole by five times, its portion in the composite polymer was found to be only 8–10%. However, this level gave desirable results in terms of redox properties and aging. The resistance against aging was explained by the morphology change, which came from great shrinking of its porosity. © 1997 John Wiley & Sons, Inc. 相似文献
6.
Dr. Kristína Plevová Dr. Péter Kisszékelyi Dr. Denisa Vargová Samuel Andrejčák Viktor Tóth Lukáš Fertáľ Dr. Erik Rakovský Dr. Juraj Filo Prof. Dr. Radovan Šebesta 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(62):15501-15507
Diastereoselective double C−H heteroarylation of chiral ferrocenes provides valuable compounds with multiple functionalities using mild reaction conditions and simple reagents. Pd-Complexes with chiral mono-protected amino acids afforded corresponding heteroarylated ferrocenyl amines in good yields and high diastereomeric purities. In this way, a variety of indole, thiophene, pyrrole, or furan substituents were introduced to the ferrocene moiety. Furthermore, a range of relevant functional groups, for example ketone, ester, chloro, nitro, or silyl, are tolerated by this method. An alternative combination of amino acid and ferrocenyl amine configurations was leveraged to provide the complementary diastereomeric products. The products of C−H heteroarylation can be transformed into corresponding phosphines. Absolute configurations of CH-activation products were confirmed by the combination of X-ray crystallographic analysis and CD spectroscopy. 19F NMR kinetic study and DFT calculations provided insights into the reaction mechanism and reasons governing stereoinduction. 相似文献
7.
Yinam Li Tae‐Hoon Kim Qinghua Zhao Euh‐Kyung Kim Seung‐Hon Han Yun‐Hi Kim Jin Jang Soon‐Ki Kwon 《Journal of polymer science. Part A, Polymer chemistry》2008,46(15):5115-5122
We have designed and synthesized a new polymer, which could be used in the organic thin film transistor (OTFT). Poly[2,6‐bis(3′‐dodecythiophene‐2′‐yl)anthracene] (PDTAn), which is composed with anthracene moiety and dodecyl alkyl thiophene, was synthesized by oxidative polymerization using iron (III) chloride. The mole ratio of FeCl3 and monomer (4.2:1), keeping low temperature during the initiation reaction, amount of solvent, and dropping order were very important for oxidative polymerization without crosslinking. The molecular weight of the polymer (Mw) was measured to be 40,000 with 2.85 of polydispersity index by GPC. The physical and optical properties of the polymer were characterized by differential scanning calorimetry (DSC), cyclic voltammetry (CV), and optical absorption and photoluminescence (PL) spectroscopy. A field‐effect mobility of 1.1 × 10?4 cm2 V?1 S?1, a current on/off ratio of 105, and the Vth at ?15.2 V had been obtained for OTFTs using this polymer semiconductor by solution coating. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5115–5122, 2008 相似文献
8.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(49):15883-15888
Herein we report that a small amount of graphite can unexpectedly act as the catalyst to greatly promote the microwave exfoliation and reduction of graphite oxide in ambient air. The reaction can be finished in a few seconds in contrast to more than ten minutes without catalyst. The catalytic microwave exfoliated graphite oxide (CMEGO) is of higher quality than the traditional microwave exfoliated graphite oxide, including a much higher exfoliation degree with thinner graphene sheets and higher specific surface area (886 m2 g−1 vs. 466 m2 g−1), a much larger C/O ratio (19.4 vs. 6.3) and a higher lattice crystallinity, as well as significantly improved electrical conductivity (53180 S m−1 vs. 5140 S m−1). The CMEGO is used as anode for lithium‐ion battery (LIB) and sodium‐ion battery (SIB), and delivers ultrahigh reversible capacities, remarkable rate capabilities, and superior cycling stabilities in both LIB and SIB. 相似文献
9.
A new network polymer electrolyte matrix with polyether in the side chains and main chains was synthesized by the azo-macroinitiator method and urethane reaction. The macroinitiator, polymer and network polymer were confirmed by Fourier-transform infrared (FT-IR) spectroscopy and 1H NMR. FT-IR was also used to study the environment of lithium ions doped in these network polymer electrolytes. Three important groups are considered: N-H, carbonyl, and ether groups. The thermal properties of the polymer electrolytes were measured by differential scanning calorimetry and thermogravimetric analysis. The Tg value of this polymer is less than that of a general comb-like polymer. Added lithium ions interact with the oxygen atoms on ether groups, causing the Tg of the polymer electrolyte to increase. Moreover, the interaction between lithium ions and ether groups decreases the decomposition temperature of the polymer. The conductivity measured by AC impedance reached a maximum of 10−4 S cm−1. A plot of conductivity vs. temperature fit the Vogel-Tamman-Fulcher equation, indicating that ionic mobility in this network polymer electrolyte is coupled to segmental chain movements. 相似文献
10.
Sun Young Kim Minjung Kang Dr. Dong Won Kang Hyojin Kim Jong Hyeak Choe Hongryeol Yun Prof. Chang Seop Hong 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(2):e202214301
We proposed a new strategy to maximize the density of acidic groups by modulating the electronic effects of the substituents for high-performance proton conductors. The conductivity of the sulfonated 1-MeL40-S with methyl group corresponds to 2.29×10−1 S cm−1 at 80 °C and 90 % relative humidity, remarkably an 22100-fold enhancement over the nonsulfonated 1-MeL40 . 1-MeL40-S maintains long-term conductivity for one month. We confirm that this synthetic method is generalized to the extended version POPs, 2-MeL40-S and 3-MeL40-S . In particular, the conductivities of the POPs compete with those of top-level porous organic conductors. Moreover, the activation energy of the POPs is lower than that of the top-performing materials. This study demonstrates that systematic alteration of the electronic effects of substituents is a useful route to improve the conductivity and long-term durability of proton-conducting materials. 相似文献
11.
Marty C. Wilkes 《Journal of heterocyclic chemistry》1991,28(4):1163-1164
A new type of “azaphilic addition” reaction of methyl lithium to 3,6-bisalkylthio-1,2,4,5-tetrazines has been discovered. Methyl lithium adds at the tetrazine nitrogen of 1 affording 4 while nitrogen nucleophiles displace tetrazine alkylthio groups at carbon affording 3 . The structures of the N-alkyl products were determined by 1H- and 13C-nmr and uv experiments. Reversing the order of methyl lithium addition caused the formation of a bicyclic tetrazine 6 . Grignard reagents add in the same fashion as methyl lithium. 相似文献
12.
Zhengcheng Zhang Leslie J. Lyons Ryan West Khalil Amine Robert West 《Silicon Chemistry》2007,3(5):259-266
New comb polysiloxanes with mixed substituents were synthesized by hydrosilylation of PMHS with 4-allyloxymethyl-[1,3]dioxolan-2-one
and tri(ethylene glycol) allyl methyl ether (AMPEO3). The effect of the incorporation of carbonate groups on ionic transport, viscosity and thermal properties has been investigated.
When doped with lithium bis(trifluorosulfonyl) imide, LiTFSI, the mixed substituted polysiloxane polymers with varying carbonate
content all exhibited conductivity higher than those for the polysiloxanes with pure carbonate or pure oligoethyleneoxy substituents.
The maximum ambient conductivity in this series was 1.62× 10−4 S/cm, occurring for the polymer containing 8.5% polar carbonate groups at a doping level of EO/LiTFSI = 15. The impedance
measurement results showed that polymers containing larger amounts of carbonate groups exhibited lower conductivity, probably
because of their increased viscosity and higher glass transition temperature. The conduction mechanism for these new comb
polymers obeys free volume theory, as indicated by conductivity data fit to the VTF equation.
We dedicate this paper to Professor Dick Jones, polysilane pioneer and valued friend. 相似文献
13.
《Tetrahedron letters》1988,29(11):1219-1222
Electrophilic phosphorus reagents such as [(Cl)(i-Pr2N)P]+ [AlCl4]− and PhPCl2/AlCl3 are found to insert into monocyclic cyclopropanes to yield phosphetanes. The utility of this new method is demonstrated by synthesizing the first phosphetanes bearing phenyl substituents at carbon. 相似文献
14.
N. F. Zalisnaya B. E. Davydov G. V. Mavrenkova T. S. Zhuravleva 《Macromolecular Symposia》1990,37(1):269-272
WCL-catalyzed bulk copolymerization of phenyl-acetylene (PhA) with 3-bromo-1-propyne was carried out. Soluble, colored products with different comonomer content were obtained. The copolymer structure was estimated by IR spectroscopy and elemental analysis; their molecular weight being 2000–3000. These copolymers were used to study the ability of doping with such acceptors as FeCL3, Sn(Ph)4, tetracyanobenzoquinone (TCNQ). The conductivity of the copolymers was found to increase from 10−13 to 10−3/cm with doping. Substitution of the lithium derivative of the polymer with SnCL3 for Li leads to an increase of conductivity as well. 相似文献
15.
《Journal of solid state chemistry》1991,94(2):260-273
Dense ceramics (Li4+xSi1−xAlxO4 with 0 ≤ x ≤ 0.3) are obtained by sintering at 700–900°C, without prior calcination, of sol-gel powders prepared by an alkoxide-hydroxide route. In comparison with the pure lithium orthosilicate (3 × 10−4 S · cm−1 at 350°C), only a slight enhancement of the ionic conductivity is noted for monophase ceramics with Li4SiO4-type structure (5 × 10−4 S · cm−1 at 350°C for x = 0.3). Higher conductivity (2 × 10−2 S · cm−1 at 350°C) is observed for an heterogeneous material formed of a lithium silicoaluminate phase (x = 0.2) with the Li4SiO4-type structure coexisting with lithium hydroxide. In this two-phase material, ac conductivity and 7Li spin-lattice relaxation data are consistent with the formation of a new kinetic path, via a thin layer along the interface, which enhances the lithium mobility. 相似文献
16.
The AM1 semiempirical method was used for theoretical searching of activation of thiophene as a diene for the Diels-Alder reaction. The reactivity of thiophene, electron-withdrawing and electron-donating substituted thiophenes, as well as the S-methylthiophenium ion were studied as the diene for Diels-Alder reactions by evaluating their frontier orbital energies and by calculating reaction barriers with activated and deactivated dienophiles. It was demonstrated that slight activation of the thiophene ring can be obtained with both electron-donating and electron-withdrawing groups attached to the thiophene ring. It was predicted that the actual transformation of thiophenes into the corresponding S-methylthiophenium anions is the best means of activating the thiophenes. The calculated activation energies for normal (non-activated) dienophiles are moderate so mild reaction conditions are predicted. If dienophiles are activated with electron-donating substituents, AM1 calculations predict a two step cycloaddition reaction with a very small activation barrier. 相似文献
17.
David G. Hewitt Lin Jing 《Journal of polymer science. Part A, Polymer chemistry》1998,36(7):1093-1106
Trifunctional carbosilanes containing hydroxy and cyano groups have been synthesized in good yields and incorporated into polyether-based electrolytes. The new linear and cross-linked modified PEOs have been characterized by DSC and conductivity measurements. The effect of silane content, the length of the PEO block, glycerol concentration, and temperature on glass transition temperature and conductivity of lithium salts complexes of these materials has been evaluated. The new materials showed improved conductivity (∼ 10−5 S cm−1) at ambient temperatures compared with unmodified polyethers. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1093–1106, 1998 相似文献
18.
In this work, samples of Y0.07Sr0.93Ti1-xFexO3-δ with 20, 40, 60 and 80 mol% of iron amount were prepared by a low-temperature polymer precursor method. The SEM-EDS analysis proved that analyzed Y0.07Sr0.93Ti1-xFexO3-δ samples were composites of two Ti- and Fe-rich perovskite samples. This kind of composite consists of two phases in which one has a good ionic and the other electronic conductivity, which makes such a composite a potential mixed ionic and electronic conductors (MIECs) material. The total electrical conductivities of analyzed samples were measured in air atmosphere (cathode conditions in Solid Oxide Fuel Cell). The values changed from ∼10−3 to 10−1 S cm−1 and depended on the ratio between two observed perovskite phases. The 0.12 S cm−1 conductivity value at 800 °C for sample with the highest amount of Fe-rich perovskite in the structure makes this composite material a candidate for air electrode in electrochemical devices. 相似文献
19.
《Electrochemistry communications》2007,9(8):1980-1984
Lithium lanthanoid silicates find importance as a solid electrolyte in high temperature lithium batteries in view of its high ionic conductivity at high temperatures. An first ever attempt is made to synthesis a new high temperature solid electrolyte viz., lithium samarium holmium silicate by sol–gel process and it has been characterized by thermal analysis (TGA–DTA), X-ray diffraction (XRD), infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Lithium ion conductivity of 0.8087 × 10−7 Ω−1 cm−1 at 25 °C was obtained and it increases with increasing temperature. For the first time a highest conductivity of 0.1095 × 10−2 Ω−1 cm−1 was obtained at 850 °C which is high compared to other high temperature lithium battery solid electrolytes. 相似文献
20.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2018,130(5):1375-1379
The growth of lithium dendrites and low coulombic efficiency restrict the development of Li metal anodes. Polymer electrolytes are expected to be promising candidates to solve the issue, but ways to obtain a polymer electrolyte that integrates high ionic conductivity and high mechanical toughness is still challenging. By introducing a double polymer network into the electrolyte design to reshape it, a tough polymer electrolyte was developed with high conductivity, and stable operation of lithium metal anodes was further realized. The double network (DNW) gel electrolyte has high modulus of 44.3 MPa and high fracture energy of 69.5 kJ m−2. The conductivity of DNW gel is 0.81 mS cm−1 at 30 °C. By using this gel electrolyte design, the lithium metal electrode could be cycled more than 400 times with a coulombic efficiency (CE) as high as 96.3 % with carbonate‐based electrolytes. 相似文献