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71.
72.
We prove that a two-person, zero-sum stochastic game with arbitrary state and action spaces, a finitely additive law of motion
and a bounded Borel measurable payoff has a value.
Received December 1996/Final version November 1997 相似文献
73.
A newchola lariat ether (1, a 21-crown-6) was constructed fromreadily available precursors. The association constant of compound1 with alkali metal picrates was measured using Cram’s extraction protocol. Evidence is presented for the involvement of the
3-methoxy group for the complexation. Energy minimised structures show that the A-ring gets slightly distorted upon metal
ion binding.
Dedicated to Professor C N R Rao on his 70th birthday 相似文献
74.
17-Chlorosteroids from template-directed halogenation can be converted to 17(20) olefins with DBU or DBN. The dependence of this reaction on base-structure and reaction conditions suggests geometric control by liquid packing effects related to those operating in liquid crystals. 相似文献
75.
The aggregation properties of novel bile acid analogs-phosphonobile salts (PBS)-have been studied. The critical micellar concentration of 23 and 24-phosphonobile salts were measured using fluorescence and 31P NMR methods. All the ten synthesized phosphonobile salts formed gels at different pH ranges in water. The pH range at which individual PBSs could gelate water was narrow and influenced by the number and conformation of hydroxyl groups. A reversible thermochromic system has been developed (with 23-phosphonodeoxycholate at pH 3.3), which changes color upon gelation. The investigation of the first hydrogels derived from trihydroxy bile acid analogs 1 and 6 was made using fluorescence, 31P NMR, X-ray crystallography, circular dichroism and SEM. The present studies reveal that the gel network consists of a chiral, fibrous structure possessing hydrophobic interiors. 相似文献
76.
Maitra NT 《The Journal of chemical physics》2005,122(23):234104
Long-range charge-transfer excited states are notoriously badly underestimated in time-dependent density-functional theory (TDDFT). We discuss how exact TDDFT captures charge transfer between open-shell species: in particular, the role of the step in the ground-state potential, and the severe frequency dependence of the exchange-correlation kernel. An expression for the latter is derived, that becomes exact in the limit that the charge-transfer excitations are well separated from other excitations. The exchange-correlation kernel has the task of undoing the static correlation in the ground state introduced by the step, in order to accurately recover the physical charge-transfer states. 相似文献
77.
Ormosil (organically modified silane) such as n-octyl triethoxy silane has been found to aggregate in the form of normal micelles as well as reverse micelles in which the triethoxy silane moeities are hydrolyzed to form a hydrated silica network while the n-octyl groups are held together through hydrophobic interaction. These nanoparticles are spherical in shape and are nearly monodispersed with an average diameter of below 100 nm. The nanoparticles originating from the micellar aggregate have an hydrophobic core with a layer of the hydrated silica network at the surface. The hydrophobic core can host hydrophobic molecules such as tetraphenyl porphyrin, which is leached out of the particles extremely slowly compared to that in Triton X-100 micelles. The nanoparticles originating from the reverse micelles have a hydrated silica network in the core surrounded by the hydrophobic n-octyl chains on the particle surface. The hydrophilic silica cores of these nanoparticles have been used to encapsulate horseradish peroxidase (HRP) and the enzyme shows its activity and follows Michaelis-Menten kinetics. 相似文献
78.
Prithwiraj Byabartta 《Transition Metal Chemistry》2007,32(5):576-583
Silver triflate [AgOTf] assisted de-bromination gives [Ni(dppm/dppe/(PPh3)2)(OTf)2], which on reaction with aryldiethynyls and gold(I) phosphines in CH2Cl2 medium, by the self assembly technique, leads to [{Ni(dppm/dppe/(PPh3)2}{(1,4-AB)Au(PPh3)}2] [{Ni4(dppm/dppe/(PPh3)2)4(1,4AB)4}] [dppm/dppe = diphenyl phosphino-methane (1), -ethane (2), where OSO2CF3 is the triflate anion]. The maximum molecular peak of the corresponding molecule is observed in the ESI mass spectrum. I.r.
spectra of the complexes show –C=C– and –C=N–, as well as phosphine stretching. The 1H-n.m.r. spectra as well as 31P(1H)-n.m.r. suggest solution stereochemistry, proton movement, phosphorus proton interaction. Considering all the moities there
are a lot of carbon atoms in the molecule reflected by the 13C-n.m.r. spectrum. In the 1H–1H-COSY spectrum of the present complexes and contour peaks in the 1H–13C-HMQC spectrum, assign the solution structure and stereo-retentive transformation in each step. 相似文献
79.
Bile acids have been used for the first time as the building block for the construction of dendritic units. Orthogonally functionalized 7-deoxycholic and cholic acid derivatives were synthesized. The construction of a bile acid heptamer, a nonamer, and a decamer using the convergent strategy are described in detail. Chromatographic, spectral, and optical properties of these molecules have been investigated. Molecular modeling suggests that these molecules have globular shapes with nanometric dimensions. 相似文献
80.
Prithwiraj Byabartta 《Transition Metal Chemistry》2005,30(7):804-813
Ag+ assisted aquation of blue cis-trans-cis-RuCl2(RaaiR′)2 (4–6) leads to the synthesis of solvento species, blue-violet cis-trans-cis-[Ru(OH2)2(RaaiR′)2](ClO4)2 [Raai R′=p-R-C6H4
N=N–C3H2–NN–1–R′, (1–3), abbreviated as N,N′-chelator, where N(imidazole) and N(azo) represent N and N′, respectively; R = H (a), OMe (b), NO2 (c) and R′ = Me (1/4/7/10), CH2CH3 (2/5/8/11), CH2Ph (3/6/9/12)] that have been reacted with NO2−in warm EtOH resulting in violet dinitro complexes of the type, Ru(NO2)2(RaaiR′)2 (7–9). The nitrite complexes are useful synthons of electrophilic nitrosyls, and on triturating the compounds, (7b–9b) with conc. HClO4 nitro-nitrosyl derivatives, [Ru(NO2)(NO)(OMeaaiR′)2](ClO4)2 (10b–12b) are isolated. The solution structure and stereoretentive transformation in each step have been established from 1H n.m.r. results. All the complexes exhibit strong MLCT transitions in the visible region. They are redox active and display
one metal-centred oxidation and successive ligand-based reductions. The redox potentials of Ru(III)/Ru(II) (E1/2M) of (10b–12b) are anodically shifted by ∼
∼0.2 V as compared to those of dinitro precursors, (7b–9b). The ν(NO) >1900 cm−1 strongly suggests the presence of linear Ru–NO bonding. The electrophilic behaviour of metal bound nitrosyl has been proved
in one case (12b) by reacting with a bicyclic ketone, camphor, containing an active methylene group and an arylhydrazone with an active methine
group, and the heteroleptic tris chelates thus formed have been characterised. 相似文献