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1.
《Chemical physics》1987,111(3):431-438
EPR measurements in single crystals of Cu(L-PHE)2, the copper derivative of the amino acid L-phenylalanine, were performed at 300 K and 9.7 GHz. The gyromagnetic factor, g, and the linewidth of the single EPR line were measured in three perpendicular planes of the sample. The gyromagnetic tensor was obtained, and its principal values are g1 = 2.211, g2 = 2.134, and g3 = 2.075. The single resonance is explained by the collapse of the resonances of the two magnetically non-equivalent copper sites due to the exchange interaction. The molecular g-factor of isolated copper ions is obtained from a model assuming axial symmetry. The results are g| = 2.266 and g⊥ = 2.075, indicating a d(x2 - y2) ground orbital. The orientations of the molecules in the crystal obtained by this model are in agreement with the crystallographic values. The linewidth data support a model which assumes exchange narrowing of the magnetic dipolar interaction in a two-dimensional magnetic structure, an incomplete collapse of the hyperfine structure, and contributions arising from non-isotropic exchange. A mean value ¦J¦=0.19 K is calculated for the isotropic exchange interactions between one copper and its six copper neighbors in Cu(L-PHE)2. Also, a lower limit ¦J′¦ > 0.02 K for the exchange coupling J′ between non-equivalent copper neighbors is obtained. 相似文献
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3.
《Tetrahedron letters》1986,27(36):4241-4244
Photooxidatlon of N-methoxy-2,4-disubstituted imidazoles, readily available by way of a three component cyclization followed by O-alkylation, leads to stable acyl Imines which react with various organometallics to afford α,α-disubstituted amino acid bis-amides in good yields. 相似文献
4.
《Tetrahedron: Asymmetry》1999,10(20):3887-3891
The preparation of a diamino substituted pyrrolidinone system in a diastereoselectively controlled manner is described. The procedure employed made use of electrophilic amination of a chiral bicyclic γ-lactam, which when subjected to sequential deprotection provided a simple route to a 3,4-diaminopyroglutaminol. The chemoselective deprotection of the amino functionality was also shown to be possible under mild hydrogenolytic conditions. 相似文献
5.
Zengwei Luo 《Tetrahedron letters》2007,48(10):1753-1756
Two benzo[de]isoquinoline 1,3-dione amino acids 1 and 2 were readily prepared, and their enantiodiscriminating ability were investigated by 1H NMR spectroscopy. It was found that 1 exhibited an excellent chiral recognition ability toward chiral α-phenylethylamine and some of its derivatives, leading to clear baseline separation of the multiplet of the probe groups in two enantiomers. The stoichiometric ratio and association constants of some host-guest complexes were determined. The interactions between the hosts and guest 3 were further studied by intermolecular NOE experiment and ESI-MS. 相似文献
6.
《Tetrahedron: Asymmetry》2014,25(24):1605-1611
The title compound was prepared as a racemate from (±)-mandelic acid-d5 in one step. The corresponding (−)-(R)-enantiomer (98% ee) was obtained by resolution with (−)-(R)-1-phenylethylamine and evaluated as a chiral solvating agent (CSA) for direct 1H NMR enantiomeric excess determination of mefloquine (Lariam®), chloroquine (Chloroquine Bayer®), and hydroxychloroquine (Plaquenil®) enantiomers. The displayed non-equivalence was high for signals in the aromatic region of all three antimalarials. Thus, the mandelic acid derivative described herein may be considered as the first efficient CSA ‘invisible’ in the aromatic region, useful for direct 1H NMR ee value determination of chiral quinoline-containing antimalarial drugs. 相似文献
7.
WANG Nai-Xing LI Ji-Sheng ZHU Dao-BenInstitute of Chemistry Chinese Academy of Sciences Beijing China 《中国化学》1996,14(2):167-170
Ammo acid derivatives react with C60 at 110-120℃to form adduct compounds.The products were isolated by column chromatography and were identified by FD-MS,UV-Vis,FT-IR and 13C NMR spectroscopies. 相似文献
8.
Ziya Kantarci Mehmet Karabacak M. Mahir Bülbül 《Journal of inclusion phenomena and macrocyclic chemistry》2001,40(4):317-321
Two new title compounds have been prepared in powder form. Their spectral data are found to be consistent with the structure foundin Hofmann-Td-type clathrates. 相似文献
9.
《Tetrahedron: Asymmetry》1998,9(23):4249-4252
(S)-N-Benzylproline (BP) was obtained by the reaction of (S)-proline and benzylchloride in high chemical yield (89%). (S)-2-[N-(N′-Benzylprolyl)amino]benzophenone (BPB) was synthesized in amounts greater than 100 g by the SOCl2 promoted condensation of BP with 2-aminobenzophenone (yield 82%). Ni(II) complexes of Schiff's bases derived from BPB and amino acids were prepared by an improved procedure involving the use of KOH as a base and MeOH as solvent (yield 90–91%). 相似文献
10.
The hydrolyzed Ru(η 6 -C6H5(CH2)2OH)Cl2(DAPTA) (DAPTA = 3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane) binding to guanine(G), adenine (A), cytosine(C), cysteine (Cys), and histidine (His) residues were explored using the B3LYP hybrid functional and IEF-PCM solvation models. The computed activation barriers for the reactions of diaqua complex were lower than those of chloroaqua complex except for binding to cytosine. For the chloroaqua complex, the activation free energy was lowest when binding to cytosine (10.5 kcal/mol). Whereas, the substitution reaction of diaqua complex binding to cysteine showed the lowest activation free energy with 10.1 kcal/mol, closely followed by histidine (15.8 kcal/mol), adenine (20.1 kcal/mol), cytosine (20.7 kcal/mol), and guanine (24.4 kcal/mol) by turns. It could be deduced that the completely hydrolyzed Ru(η 6 -C6H5(CH2)2OH)Cl2(DAPTA) compounds might preferentially bind to amino acids residues in vivo. In addition, to simulate the protein and DNA environment in vivo, a detailed investigation of the activation free energies for the substitution reactions in dependence of the dielectric constant ε (4, 24, and 78.39) was systematically performed as well. The calculated results demonstrated that the environmental effect had a little impact on these substitution reactions. 相似文献
11.
《Tetrahedron: Asymmetry》1999,10(10):1861-1865
Hydroxylamines derived from 2-pyrrolidinyl nitrones can be easily and unambiguously distinguished by 1H NMR spectroscopy. A strong hydrogen bond which can be observed both in the solid state and solution is responsible for the preferred conformation of the title compounds. 相似文献
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Gaber M. Abu El-Reash 《Transition Metal Chemistry》1993,18(5):493-496
Summary The synthesis and characterization of CrIII, MnII, FeIII, CoII, NiII, CuII, ZnII, CdII and UO
inf2
sup2+
complexes of N-isonicotinamido-N-benzoylthiocarbamide (H2IBTC) are reported. I.r. spectral data show that the ligand behaves in a bidentate, tridentate and/or tetradentate manner. Different stereochemistries are proposed for CrIII, MnII, FeIII, CoII, NiII and CuII complexes on the basis of spectral and magnetic studies. The i.r. data indicate that the carbonyl oxygen of the benzoyl moiety is the backbone of chelation in most complexes. 相似文献
14.
The thermal decomposition behaviour of the complexes of rare earth metals with histidine: RE(His)(NO3)3H2O (RE=La—Nd, Sm—Lu and Y; His=histidine) was investigated by means of TG-DTG techniques. The results indicated that the thermal decomposition processes of the complexes can be divided into three steps. The first step is the loss of crystal water molecules or part of the histidine molecules from the complexes. The second step is the formation of alkaline salts or mixtures of nitrates with alkaline salts after the histidine has been completely lost from the complexes. The third step is the formation of oxides or mixtures of oxides with alkaline salts. The results relating to the three steps indicate that the stabilities of the complexes increase from La to Lu.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
15.
Stevens CJ Dallanegra R Chaplin AB Weller AS Macgregor SA Ward B McKay D Alcaraz G Sabo-Etienne S 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(10):3011-3020
The IrIII fragment {Ir(PCy3)2(H)2}+ has been used to probe the role of the metal centre in the catalytic dehydrocoupling of H3B?NMe2H ( A ) to ultimately give dimeric aminoborane [H2BNMe2]2 ( D ). Addition of A to [Ir(PCy3)2(H)2(H2)2][BArF4] ( 1 ; ArF=(C6H3(CF3)2), gives the amine‐borane complex [Ir(PCy3)2(H)2(H3B?NMe2H)][BArF4] ( 2 a ), which slowly dehydrogenates to afford the aminoborane complex [Ir(PCy3)2(H)2(H2B? NMe2)][BArF4] ( 3 ). DFT calculations have been used to probe the mechanism of dehydrogenation and show a pathway featuring sequential BH activation/H2 loss/NH activation. Addition of D to 1 results in retrodimerisation of D to afford 3 . DFT calculations indicate that this involves metal trapping of the monomer–dimer equilibrium, 2 H2BNMe2 ? [H2BNMe2]2. Ruthenium and rhodium analogues also promote this reaction. Addition of MeCN to 3 affords [Ir(PCy3)2(H)2(NCMe)2][BArF4] ( 6 ) liberating H2B? NMe2 ( B ), which then dimerises to give D . This is shown to be a second‐order process. It also allows on‐ and off‐metal coupling processes to be probed. Addition of MeCN to 3 followed by A gives D with no amine‐borane intermediates observed. Addition of A to 3 results in the formation of significant amounts of oligomeric H3B?NMe2BH2?NMe2H ( C ), which ultimately was converted to D . These results indicate that the metal is involved in both the dehydrogenation of A , to give B , and the oligomerisation reaction to afford C . A mechanism is suggested for this latter process. The reactivity of oligomer C with the Ir complexes is also reported. Addition of excess C to 1 promotes its transformation into D , with 3 observed as the final organometallic product, suggesting a B? N bond cleavage mechanism. Complex 6 does not react with C , but in combination with B oligomer C is consumed to eventually give D , suggesting an additional role for free aminoborane in the formation of D from C . 相似文献
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17.
The title metal-organic framework, [Tb2(MFDA)3(DMF)2(H2O)3] · (H2O)3(DMF)6} n (I) (H2MFDA = 9,9-dimethylfluorene-2,7-dicarboxylic acid, DMF = N,N-dimethylformamide), has been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction (CIF file CCDC no. 995892). Complex I crystallizes in triclinic space group \(P\bar 1\) with a = 13.0022(3), b = 13.3793(3), c = 25.8929(4) Å, α = 84.060(2)°, β = 88.104(2)°, γ = 66.361(2)°, V = 4104.05(15) Å3, C75H104N8O26Tb2, M = 1851.50, ρ c = 1.498 g/cm3, μ(MoK α) = 1.790 mm?1, F(000) = 1896, GOF = 1.055, Z = 2, the final R 1 = 0.0522 and wR 2 = 0.1380 for I > 2σ(I). In MOF I, the Tb2 dinuclear units double-bridged by two carboxylate groups are connected together by MFDA ligands to give rise to a 3D architecture that consists in two types of 1D open channels along the y axis with about 6 × 8 and 9 × 12 Å2 dimensions. The solvent accessible space for the desolvated I is 53.4% of the total volume. The 3D structure can also be rationalized as a six-connected (3.411.52.6) topological network by considering the Tb2 dinuclear units as six-connected nodes and MFDA ligands as linkers, respectively. 相似文献
18.
Danijel Kikelj Aleš Krbavčič Slavko Pečar Alenka Tomažič 《Monatshefte für Chemie / Chemical Monthly》1991,122(4):275-281
Summary Synthesis of the hydrochloride oftrans-2-(2-aminocyclohexyloxy)acetic acid (4) fromtrans-2-(2-azidocyclohexyloxy)acetic acid (1) is described.4 was acylated at the amino group to give compounds5–8.1 was converted into acid chloride (9) and amides10–13.
Synthese und Funktionalisierung dertrans-2-(2-Aminocyclohexyloxy)- undtrans-2-(2-Azidocyclohexyloxy)essigsäure
Zusammenfassung Die Synthese destrans-2-(2-Aminocyclohexyloxy)essigsäurehydrochlorids (4), ausgehend vontrans-2-(2-Azidocyclohexyloxy)essigsäure (1), wird beschrieben.4 wurde durch Acylierung der Aminogruppe in die Verbindungen5–8 übergeführt.1 wurde in das Säurechlorid9 und die Carbonsäureamide10–13 umgewandelt.相似文献
19.
R. H. JONES J. CHEN J. M. THOMAS A. GEORGE M. B. HURSTHOUSE R. XU S. LI Y. LU G. YANG 《ChemInform》1992,23(44):no-no
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option. 相似文献