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221.
Muhammad Kaleem Khosa Paul T. Wood Simon M. Humphrey William T. A. Harrison 《Acta Crystallographica. Section C, Structural Chemistry》2016,72(1):63-67
Compounds containing copper(I) are of interest for their role in biological processes. The nature of short (< ∼3.2 Å) Cu...Cu contacts within these compounds has been debated, being either described as weakly attractive (bonding) `cuprophilic' interactions, or simply as short metal–metal distances constrained by ligand geometry or largely ionic in nature. The title three‐dimensional Cu+‐containing coordination polymer, [Cu3(C7H7N2O2)Cl2]n, was formed from the in situ reduction of CuCl2 in the presence of 3,5‐diaminobenzoic acid and KOH under hydrothermal conditions. Its complex crystal structure contains ten distinct CuI atoms, two of which lie on crystallographic inversion centres. The copper coordination geometries include near‐linear CuOCl and CuN2, T‐shaped CuOCl2 and distorted tetrahedral CuOCl3 groups. Each CuI atom is also associated with two adjacent metal atoms, with Cu...Cu distances varying from 2.7350 (14) to 3.2142 (13) Å; if all these are regarded as `cuprophilic' interactions, then infinite [01] zigzag chains of CuI atoms occur in the crystal. The structure is consolidated by N—H...Cl hydrogen bonds. 相似文献
222.
Adel M. Al-Ghazzawi Musa H. Abu Zarga Shtaywy S. Abdalla 《Natural product research》2020,34(8):1180-1185
AbstractTwenty-two alkaloids, were isolated from Fumaria densiflora. Two of these alkaloids, N-methyl-5-hydroxystylopine chloride and fumaricine N-oxide, were isolated for the first time from natural sources. Parfumine and fumaritine, in concentrations ranging from 3?×?10?7 to 9?×?10?4?M, caused concentration–dependent relaxation of ileum longitudinal segment. Also, parfumine and fumaritine in concentrations ranging from 3?×?10?4 to 9?×?10?2?M, caused concentration – dependent decrease in heart rate of the isolated perfused heart. A concentration of parfumine of 3?×?10?2?M increased but a higher concentration (9?×?10?2?M) decreased the amplitude of contraction of the isolated perfused heart. On the other hand, fumaritine, in concentrations ranging from 3?×?10?4 to 3?×?10?2?M, caused concentration – dependent increase, but a higher concentration (9?×?10?2?M) caused a decrease in the amplitude of contraction of the isolated perfused heart. 相似文献
223.
Ahmed Kamal Mahendra Sandbhor Kaleem Ahmed S. F. Adil Ahmad Ali Shaik 《Tetrahedron: Asymmetry》2003,14(24):3861-3866
A new practical method for the enzymatic synthesis of 1,2-diols has been developed by employing a lipase catalyzed one-pot transesterification protocol. A series of substituted -acetoxyphenylethanones 3a–g have been reduced to the corresponding alcohols under mild conditions employing sodium borohydride and moist neutral alumina, and further subjected for lipase catalyzed irreversible transesterification in the same pot to give mono- and diacetate diols (R)-4 and (S)-5, which on hydrolysis afforded terminal 1,2-diols, (R)- and (S)-6 in high enantiomeric excess. 相似文献
224.
Amy V. Hall Dmitry S. Yufit David C. Apperley Larry Senak Osama M. Musa David K. Hood Jonathan W. Steed 《Chemical science》2020,11(30):8025
In this work we develop photoreactive cocrystals/salts of a commercially-important diacetylene, 10,12-pentacosadiynoic acid (PCDA, 1) and report the first X-ray crystal structures of PCDA based systems. The topochemical reactivity of the system is modified depending on the coformer used and correlates with the structural parameters. Crystallisation of 1 with 4,4′-azopyridine (2), 4,4′-bipyridyl (3), and trans-1,2-bis(4-pyridyl)ethylene (4) results in unreactive 2 : 1 cocrystals or a salt in the case of 4,4′-bipiperidine (5). However, salt formation with morpholine (6), diethylamine (7), and n-butylamine (8), results in highly photoreactive salts 12·7 and 1·8 whose reactivity can be explained using topochemical criteria. The salt 1·6 is also highly photoreactive and is compared to a model morpholinium butanoate salt. Resonance Raman spectroscopy reveals structural details of the photopolymer including its conformational disorder in comparison to less photoactive alkali metal salts and the extent of solid state conversion can be monitored by CP-MAS NMR spectroscopy. We also report an unusual catalysis in which amine evaporation from photopolymerised PCDA ammonium salts effectively acts as a catalyst for polymerisation of PCDA itself. The new photoreactive salts exhibit more reactivity but decreased conjugation compared to the commercial lithium salt and are of considerable practical potential in terms of tunable colours and greater range in UV, X-ray, and γ-ray dosimetry applications.In this work we develop photoreactive cocrystals/salts of a commercially-important diacetylene, 10,12-pentacosadiynoic acid (PCDA, 1) and report the first X-ray crystal structures of PCDA based systems. 相似文献
225.
The aim of this investigation was to develop a basic understanding of the emulsification process by considering simple systems such as n-hexane, n-heptane, n-decane, and kerosene oil in water. The technique employed for the purpose was ultrasonification. The effect of ultrasonification time, chain length, viscosity, surface tension, oil content, and ionic strength of the media on the quality of emulsion has been studied. The emulsions were viewed through microscope to measure the number, size, and size distribution of droplets. Quantification of turbidity and viscosity was also used to characterize the emulsions. It has been found that the number and size of the droplets vary with the time of ultrasonification, contents of oils, molecular mass of the oils, and ionic strength of the media, and hence the quality of the emulsion is influenced by these parameters. The droplet size decreases, whereas the number of drops increases with the time of emulsification, approaching an optimum distribution at about 15 min of ultrasonification. Further, the increase in the molecular mass of the oil increases the size of the droplets and hence decreases the stability of the emulsion. The addition of electrolytes encourages coalescence and enhances the instability in the system. The results are in accord with the equations proposed by us. 相似文献
226.
M. M. Musa W. M. Markus A. A. Elghondi R. H. Etwir A. H. Hannan E. A. Arafa 《Journal of Radioanalytical and Nuclear Chemistry》1995,198(1):17-22
We have determined the concentration of 25 trace elements in crude petroleum from seven Libyan oil fields by instrumental neutron activation analysis. Crude oil samples were irradiated with a thermal neutron dose rate of 1012 and 1013 n·cm–2·s–1 in the Tajoura research reactor. The concentration of U, Br, Mg, Cu, Na, V, Cl, Al, Mn and Ca is in a range of 0.015 to 84 ppm and that of sulphur of 0.12 to 1.8%. The elements Sc, Cr, Ni, Fe, Co, Zn, Ag, Se, Sb, Ba, Cs, Yb, Hf and Hg have a concentration range of 0.009 to 8747 ppb. The coefficients of variation are within 10%. The elements V and Ni occur as both porphyrin and non-porphyrin and the ratio of these two forms varies over a wide range. The V/Ni ratios are located between 0.17 and 6.67, which are comparable to the reported values for the crude oils from other countries. 相似文献
227.
The synthesis of the first diorganotellurium dithiocyanates is reported. It is argued that the tellurium interacts more strongly with the nitrogen than with the sulphur atom of the NCS group. Two structural classes are noted: (a) R2Te(NCS)2 (R Ph, p-CH3O · C6H4) in which interaction of tellurium with the two NCS groups is equal and in which intermolecular association via long TeS bonds probably occurs; (b) [R2Te(NCS)](NCS) (R p-C2H5O · C6H4) in which the tellurium interacts unequally with the two NCS groups to give a structure with some “telluronium salt” character.The chemistry of MePh2Te(NCS) is studied. In solvents of reasonable polarity (e.g. DMSO), and probably in the solid state, it behaves as an essentially ionic telluronium salt [MePh2Te](NCS). However, in CDCl3 solution it exists in a covalent form, MePh2Te(NCS), from which reductive elimination of, exclusively, methyl thiocyanate occurs. The mechanism of the decomposition is not simple: initially it is probable that a free radical pathway dominates, but after approximately 100 min the rate of decomposition increases. There is evidence that the second rate process is catalysed by diphenyltelluride. Other salts, [MePh2Te]X (X BF4, PF6) are reported for comparison. 相似文献
228.
Evidence is presented which supports the intermediacy of dipolar Baylis-Hillman-type adducts in the synthesis of coumarin and chromene derivatives from the reaction of 2-hydroxybenzaldehydes with methyl acrylate in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO). 相似文献
229.
G. Z. Stasevich O. N. Bubel' I. G. Tishchenko Yasser Musa 《Chemistry of Heterocyclic Compounds》1988,24(12):1321-1324
The reaction of oxiranyl--dimethylaminovinyl ketones with secondary amines, hydrochloric, and hydrobromic acids leads to the formation of the corresponding 2-aminomethyl- and 2-halomethyl-3-(2H)-furanones.For Communication 1, see [1].Translated from Khimiii Geterotsiklicheskikh Soedinenii, No. 12, pp. 1600–1603, December, 1988.Original article submitted May 20, 1987. 相似文献
230.
The synthesis and characterization of some novel compounds of organotin(IV) chlorides with monomethyl glutarate is reported; the ligand molecule appears to be bound to the tin atom through the carbonyl oxygen. The results obtained through 1H‐13C‐119Sn NMR, FT‐IR and 119Sn Mössbauer spectra show that the diorganotin(IV) complexes have hexacoordination with octahedral geometry. Biological screening of the complexes reveals that the diorganotin(IV) complexes show significant activity against all microorganisms. 相似文献