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61.
Lorenzo Grande Vishnu Teja Chundi Di Wei Chris Bower Piers Andrew Tapani Ryhänen 《Particuology》2012,10(1):1-8
Graphene-based materials are intriguing from the perspective of fundamental science and technology because they are non-toxic, chemically and thermally tolerant, and mechanically robust. Graphene exhibits superior electrical conductivity, high surface area and a broad electrochemical window that may be particularly advantageous for their applications in energy storage devices. In addition, graphene can be prepared in the form of a colloidal suspension with adjustable solubility and thus is suitable for printing applications and offers both transparency and good conductivity at the same time. In this review, applications of graphene in solar cells, batteries, supercapacitors and fuel cells are summarized with the latest developments. Furthermore, graphene as a conductive ink for printed electronics is also discussed. 相似文献
62.
63.
We show that if M is a stable unsuperstable homogeneous structure, then for most κ ? |M|, the number of elementary submodels of M of power κ is 2κ. 相似文献
64.
Tapani Hyttinen 《Mathematical Logic Quarterly》1996,42(1):421-432
Let Δ be a set of formulas. In this paper we study the following question: under what assumptions on Δ, the concept “a complete Δ-type p over B does not fork over A ? B” behaves well. We apply the results to the structure theory of ω1-saturated models. Mathematics Subject Classification: 03C45. 相似文献
65.
Helena Riihimki Teija Kangas Pekka Suomalainen Heidi K. Reinius Sirpa Jskelinen Matti Haukka A. O. I. Krause Tapani A. Pakkanen Jouni T. Pursiainen 《Journal of molecular catalysis. A, Chemical》2003,200(1-2):81-94
A set of new phosphane ligands designed to increase the branched-to-normal ratio of the hydroformylation reaction were prepared in the same way as the previously reported ortho-alkyl substituted arylphosphanes, which have shown increased i/n ratios in the hydroformylation of propene and 1-hexene. In order to determine the relationship between the catalytic behavior and stereoelectronic properties of the ligands, various functional alkyl groups (methyl, isopropyl, cyclohexyl) were placed on the phosphorus atom directly and in the ortho position of the phenyl ring connected to phosphorus. In the hydroformylation reaction of propene and 1-hexene a higher i/n ratio resulted with nearly all the ligands compared with that of triphenylphosphane. Additionally as the ortho-alkyl-substituent became larger, it had a favorable effect on the i-selectivity. Characterization of the ligands was carried out by NMR spectroscopy (mainly 1H, 31P{1H}, 13C{1H}, HSQC/HETCOR and COSY-90). Properties of the ligands were also studied by quantum mechanical calculations and by synthesizing three Rh(acac)(CO)(PR3) derivatives. The o-alkyl-substituent was orientated outside the ligands’ cone angle in the X-ray crystal structures of (2-cyclohexylphenyl)dicyclohexylphosphane and (2,5-dimethylphenyl)bis(4-pyridyl)phosphane, and Rh(acac)(CO)(PR3) complex of (2-methylphenyl)dicyclohexylphosphane. 相似文献
66.
The gas-phase proton affinities of 4,4'-di(R)-2,2'-bipyridines (R: H, Br, Cl, NO(2), Me) were determined by mass spectrometric measurements and by ab initio calculations at the HF/6-31G and MP2/6-31G levels of theory. The energy barriers for rotation about the central C-C bond were also studied computationally. Two minima were found for both unprotonated and protonated species, the global minima being at the trans planar and cis planar conformations, respectively. Local minima for the unprotonated compounds were at the cis nonplanar conformation and for the protonated compounds at the trans nonplanar. Two different proton affinity values were calculated for each compound by employing different conformations for the protonated species. The computational values were in good agreement with the experimental proton affinities. Substituents affect the proton affinity according to their ability to withdraw or to donate electrons, halogen and nitro-substituted bipyridines having a lower proton affinity and methyl-substituted bipyridine having a higher proton affinity than 2,2'-bipyridine itself. 相似文献
67.
Aapo U. Hrknen Markku Ahlgrn Tapani A. Pakkanen Jouni Pursiainen 《Journal of organometallic chemistry》1997,530(1-2):191-197
Three tetranuclear clusters [Ru4H4(CO)11(PPh3)] (1), [Ru4H2(CO)12(PPh3)] (2) and [Ru3IrH(CO)12(PPh3)] (3) were formed in the reaction of [Ir(CO)Cl(PPh3)2] and Na[Ru3H(CO)11] in tetrahydrofuran. Complexes 1–3 were characterized by IR and 1H and 31P NMR, and the structure of the clusters was confirmed by single crystal X-ray analysis. In 2 and 3 one of the carbonyls bridges between two ruthenium atoms; otherwise the compounds contain only terminal carbonyls. 相似文献
68.
Krupenya DV Selivanov SI Tunik SP Haukka M Pakkanen TA 《Dalton transactions (Cambridge, England : 2003)》2004,(16):2541-2549
A series of [Rh(6)(CO)(16)] substituted derivatives containing Ph(2)P(alkenyl) ligands has been synthesized starting from the [Rh(6)(CO)(16-x)(NCMe)(x)](x= 1, 2) clusters and Ph(2)P((CH(2))(n)CH=CH(2))(n= 2, 3) phosphines. It was shown that the terminal alkenyl substituents in these phosphines easily undergo isomerization in the coordination sphere of the hexarhodium complexes to give the allyl -CH(2)CH=C(H)R (R = Me and Et) fragments coordinated through the double bond of the rearranged organic moieties. The solid-state structure of two clusters, [Rh(6)(CO)(14)(mu2,kappa3-Ph(2)PCH(2)CH=C(H)CH(3))](4) and [Rh(6)(CO)(14)(mu2,kappa3-Ph(2)PCH(2)CH=C(H)CH(2)CH(3))](8), was established by X-ray crystallography. Solution structures of the products obtained were also characterized by IR and NMR ((1)H, (31)P, (1)H-(1)H COSY and (1)H-(1)H NOE) spectroscopy. It was shown that 4 and 8 exist in solution as mixtures of three isomers (A, B and C), which differ in the conformation of the coordinated allyl fragment. A similar (two species, A and B) equilibrium was found to occur in the solution of the [Rh(6)(CO)(14)(mu2,kappa3-Ph(2)PCH(2)CH=CH(2))](2) cluster. The dynamic behaviour of 2, 4 and 8[Rh(6)(CO)(14)(mu2,kappa3-Ph(2)PCH=CH(2))] has been studied using VT (31)P and (1)H-(1)H NOESY NMR spectroscopy, rate constants and activation parameters of the (A<-->B) isomerization processes were determined. It was shown that the most probable mechanism of this isomerization involves a dissociative [Rh6(CO)(14)(kappa1-Ph(2)P(alkenyl))] intermediate and re-coordination of the double bond to the same metal atom where the process started from. The conversion of the A and B species in and into the third isomer very likely occurs through the transfer of an allyl hydrogen atom onto the rhodium skeleton to give eventually cis conformation of the coordinated allyl fragment. 相似文献
69.
Jouni Pursiainen Tapani A. Pakkanen Juhani Jääskeläinen 《Journal of organometallic chemistry》1985,290(1):85-98
A new ruthenium-rhodium mixed-metal cluster HRuRh3(CO)12 and its derivatives HRuRh3(CO)10(PPh3)2 and HRuCo3(CO)10(PPh3)2 have been synthesized and characterized. The following crystal and molecular structures are reported: HRuRh3(CO)12: monoclinic, space group P21/c, a 9.230(4), b 11.790(5), c 17.124(9) Å, β 91.29(4)°, Z = 4; HRuRh3(CO)10(PPh3)2·C6H14: triclinic, space group P, a 11.777(2), b 14.079(2), c 17.010(2) Å, α 86.99(1), β 76.91(1), γ 72.49(1)°, Z = 2; HRuCo3(CO)10(PPh3)2·CH2Cl2: triclinic, space group P, a 11.577(7), b 13.729(7), c 16.777(10) Å, α 81.39(4), β 77.84(5), γ 65.56°, Z = 2. The reaction between Rh(CO)4? and (Ru(CO)3Cl2)2 tetrahydrofuran followed by acid treatment yields HRuRh3(CO)12 in high yield. Its structural analysis was complicated by a 80–20% packing disorder. More detailed structural data were obtained from the fully ordered structure of HRuRh3(CO)10(PPh3)2, which is closely related to HRuCo3(CO)10(PPh3)2 and HFeCo3(CO)10(PPh3)2. The phosphines are axially coordinated. 相似文献
70.
Comparison of Models Used for UV Index Calculations 总被引:1,自引:1,他引:1
Peter Koepke Alkiviadis Bais Dimitrios Balis Michael Buchwitz Hugo De Backer Xavier de Cabo Pierre Eckert Paul Eriksen Didier Gillotay Anu Heikkilä Tapani Koskela Bozena Lapeta Zenobia Litynska Jeronimo Lorente Bernhard Mayer Anne Renaud Ansgar Ruggaber Günther Schauberger Gunther Seckmeyer Peter Seifert Alois Schmalwieser Harry Schwander Karel Vanicek Mark Weber 《Photochemistry and photobiology》1998,67(6):657-662