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111.
Banerjee A Grewer C Ramakrishnan L Jäger J Gameiro A Breitinger HG Gee KR Carpenter BK Hess GP 《The Journal of organic chemistry》2003,68(22):8361-8367
The synthesis and characterization of a new photolabile protecting group (caging group) for carboxylic acids, the 2-(dimethylamino)-5-nitrophenyl (DANP) group, is described. This compound has a major absorption band in the visible wavelength region with a maximum near 400 nm (epsilon400 = 9077 M(-1) cm(-1) at pH 7.4 and 21 degrees C). The caging group is attached through an ester linkage to the carboxyl functionality of beta-alanine, which activates the inhibitory glycine receptor in the mammalian central nervous system. Such caged compounds play an important role in transient kinetic investigations of fast cellular processes. Upon photolysis of DANP-caged beta-alanine, the caging group is released within 5 micros. Quantum yields of 0.03 and 0.002 were obtained in the UV region (308 and 360 nm) and the visible region (450 nm), respectively. Laser-pulse photolysis experiments, using 337 or 360 nm light, were performed with the caged compound equilibrated with HEK 293 cells transiently transfected with cDNA encoding the alpha1 homomeric, wild-type glycine receptor. The experiments demonstrated that neither DANP-caged beta-alanine nor its byproducts inhibit or activate the glycine receptors on the cell surface. Under physiological conditions, the DANP-caged beta-alanine is water-soluble and stable and can be used for transient kinetic measurements. 相似文献
112.
Santosh K. Mondal Parimal Paul Rita Roy Kamalaksha Nag 《Transition Metal Chemistry》1984,9(7):247-250
Summary Complexes of nickel(II), palladium(II), copper(II), cobalt(II), and cobalt(III) with methyl-2-(-salicylaldiminoethyl)-cyclopent-1-en-dithiocarboxylate (H2L1) and methyl-2-(-salicylaldiminoisopropyl)cyclopent-1-en-dithiocarboxylate (H2L2) have been prepared. They contain the donor sites ONNS. The metal(II) ions from neutral, monomeric square planar chelate complexes. The cobalt(III) complexes [CoL1-(H2O)2]X (X=Cl or ClO4) appear to betrans-diaqua-species. All compounds have been characterized by a number of physico-chemical methods. 相似文献
113.
Abstract —Chloride anions, when added to DCMU [3-(3,4-dichlorophenyl)-1,1-dimethylurea]-treated spinach chloroplasts, change the rate of decay of the delayed light emission in the seconds region but do not change the shape or the temperature dependence of the decay. Benzoate anions, on the other hand, change both the rate and the shape of the decay of the delayed light emission. These results are consistent with a model in which the membrane potential and the structure of the reaction center affect the decay kinetics of the delayed light emission in the seconds region. 相似文献
114.
115.
Rabindra N. Roy James J. Gibbons Guilio LaCross Jr. Charles W. Krueger 《Journal of solution chemistry》1976,5(5):333-343
The two thermodynamic dissociation constants of glycine at 11 temperatures from 5 to 55°C in 50 mass % methanol-water mixed solvent have been determined from precise emf measurements with hydrogen-silver bromide electrodes in cells without liquid junction. The first acidic dissociation constant (K
1)for the process HG+H++G± is expressed as a function ofT(oK) by the equation pK
1 = 2043.5/T – 9.6504 + 0.019308T. At 25°C, pK
1is 2.961 in the mixed solvent, as compared with 2.350 in water, with H°=1497 cal-mole–1, G°=4038 cal-mole–1, S°=–8.52 cal-°K–1-mole–1, and C
p
o
=–53 cal-°K–1-mole–1. The second acidic dissociation constant (K
2)for the process G±H++G– over the temperature range studied is given by the equation pK
2 = 3627.1/T – 7.2371 + 0.015587T. At 25°C, pK
2is 9.578 in MeOH–H2O as compared with 9.780 in water, whereas H° is 10,257 cal-mole–1, G° is 13,063 cal-mole–1, S° is –9.41 cal-°K–1-mole–1, and C
p
o
is –43 cal-°K–1-mole–1. The protonated glycine becomes weaker in 50 mass % methanol-water, whereas the second dissociation process becomes stronger despite the lower dielectric constant of the mixed solvent (=56.3 at 25°C). 相似文献
116.
S. Roy S. Sengupta D. Mukherjee P. K. Mukherjee 《International journal of quantum chemistry》1986,29(2):205-210
We report in this paper the results of outer and inner valence IP calculations for the HF molecule using two different many-body methods for the direct evaluation of energy differences. The first is the nonperturbative coupled-cluster based linear response theory (LRT) and the second is the hermitian open-shell many-body perturbation theory (MBPT). A Huzinaga-Dunning (9s5p→ 5s3p/3s) basis has been used. LRT uses an “ionization operator” S as in the equation of motion method (EOM) to generate the ionized states from a coupled-cluster type of ground state. S is chosen to consist of single ionization and ionization-cum-shake-up operators, thus treating the Koopmans as well as the shake-up states on equal footing. LRT would thus be capable of computing both the outer and the inner valence regions with equal facility. This is borne out by the results. For the open-shell MBPT, the model space is chosen to be spanned by the singly ionized determinants. The convergence of the results for the inner valence region is slow, and the results obtained from the [2, 1] Pade' approximants are presented. Unlike the LRT, the inner valence region is not reproduced with full complexity in MBPT, indicating that it is essential to modify the theory by way of expanding the model space to contain the shake-up determinants also. 相似文献
117.
Roy G. Miller Darryl R. Fahey Harry J. Golden Larry C. Satek 《Journal of organometallic chemistry》1974,82(1):127-137
Thermolysis of trans-chloro(2-allylphenyl)bis(triethylphosphine)nickel(II), I, in tetrachloroethylene has afforded indene as the major hydrocarbon product along with lesser amounts of allylbenzene and trans-β-methylstyrene. Organonickel products were trans-chloro(trichlorovinyl)bis(triethylphosphine)nickel(II), II, chloro[2-(trans-propenyl)phenyl]bis(triethylphosphine)nickel(II), III, and trans-dichlorobis(triethylphosphine)nickel(II). Compound III was the major product from thermolysis of I in benzene. Chloro[2-(cis-propenyl)phenyl]bis(triethylphosphine)nickel(II), IV, and III could be synthesized independently by treatment of chloro-2-(cis-propenyl)benzene and chloro-2-(trans-propenyl)benzene, respectively, with nickel acetylacetonate and triethylaluminium in the presence of triethylphosphine. Thermolysis of I in benzene containing allylbenzene led to the formation of trans-β-methylstyrene. The thermolysis of I in benzene in the presence of cis-1,4-hexadiene caused the skeletal rearrangement of the diene to trans-2-methyl-1,3-pentadiene. A catalyst derived from ethylenebis(triphenylphosphine)nickel(0) and hydrogen chloride isomerized allylbenzene to trans-β-methylstyrene. 相似文献
118.
Densities of aqueous solutions of a series of polymethonium chloride and bromide salts (CH3)3–N–(CH2)n–N–(CH3)3X2 have been measured at 25°C. Apparent molal volumes have been calculated, and methylene-group contributions to the limiting apparent molal volumes °v have been estimated. Constant values of the methylene-group contribution of 16.5 and 17.0 cm3-mole–1 were obtained for the bromide and chloride salts, respectively. These values are consistent with methylene-group contributions reported for other series of organic electrolytes. 相似文献
119.
Novel anionic dinuclear mixed-ligand peroxo complexes of the type [(UO2)2(O2)3L(H2O)2]3− (L = Histidinate, aspartate, salicylate, Imidazolate and glutamate) have been synthesized from the interaction of uranyl ion (UO22+) with peroxide (O22−) in the presence of the respective coligand (L) at pH 9–10. The sparingly soluble complexes were characterized by elemental analyses, FT-IR, laser Raman (LR) and UV-vis spectroscopy and solution electrical conductance measurements. Based on these studies, a double bridged dinuclear structure involving one peroxo and the mixed ligand L (via-COO−) has been tentatively proposed. Infra-red coupled with LR spectra evidenced structurally different metal bound peroxides (ν2 and σ:σ). An aqueous solution of the salicylate and aspartate complexes have been shown to convert triphenylphosphine (PPh3), cyclohexene, styrene and SO2 to the corresponding OPPh3, 1,2 cyclohexanediol, phenylethyleneglycol and SO42−, respectively. 相似文献
120.
The viscosity deviation (Δη), the excess molar volume (V
E) and the ultrasonic speed (u) have been investigated from viscosity (η) and density (ρ ) measurements of binary liquid mixtures of 1,2-dimethyoxyethane with methanol, ethanol, propan-1-ol, butan-1-ol,
pentan-1-ol, hexan-1-ol or octan-1-ol over the entire range of composition at 298.15 K. The excess volumes are negative over
the entire range of composition for all of the mixtures with the exception of hexan-1-ol and octan-1-ol. The excess isentropic
compressibilities (K
S
E) and viscosity deviations are negative for all of the mixtures. The magnitudes of the negative values of V
E decrease with the number of carbon atoms of the alkan-1-ol. The trend of increasing K
S
E values with the chain length of the alkanol is similar to that observed in the case of V
E. Graphs of V
E, Δ η, K
S
E, Δ u, L
f
E and Z
E against composition are presented as a basis for a qualitative discussion of the results. 相似文献