Search results for "coupling [Higgs particle]"
showing 10 items of 443 documents
H2O, H2, HF, F2 and F2O nuclear magnetic shielding constants and indirect nuclear spin–spin coupling constants (SSCCs) in the BHandH/pcJ‐n and BHandH…
2009
Good performance of segmented contracted basis sets XZP, where X = D, T, Q and 5, for obtaining H2O, H2, HF, F2 and F2O nuclear isotropic shielding constants in the BHandH Kohn–Sham basis set limit was shown. The results of two‐ and three‐parameter complete basis set limit extrapolation schemes were compared with experimental results, earlier literature data and benchmark ab initio results. Similar convergence patterns of shieldings obtained from calculations using general purpose XZP basis sets and from polarization‐consistent basis sets pcS‐n and pcJ‐n, where n = 0, 1, 2, 3 and 4, designed to accurately predict magnetic properties were observed. On the contrary, the SSCCs were more sensit…
Selective Stepwise Suzuki Cross-Coupling Reaction for the Modelling of Photosynthetic Donor−Acceptor Systems
2009
A Suzuki reaction performed as a selective stepwise substitution of two boryl groups on a diarylporphyrin precursor is reported for straightforward construction of a porphyrin trimer, modeling photosynthetic donor-acceptor systems.
Systematic approach to β and 2vββ decays of mass A=100-136 nuclei
2015
In this work we perform a systematic study of pairs of single-β-decaying nuclei in the mass region A = 100–136 to extract information on the effective value of the axial-vector coupling constant gA. As the many-body framework we use the quasiparticle random-phase approximation (QRPA) and its proton-neutron variant (pnQRPA) in singleparticle valence bases with Woods-Saxon-calculated single-particle energies. It is found that, to a reasonable approximation, gA is a linear function of the mass number A, with a slightly different parametrization below and above the mass A = 121. Using the values of gA extracted from the linear fit, as well as an average constant value of gA, we calculate the tw…
ChemInform Abstract: Polycondensed Nitrogen Heterocycles. Part 22. Pyrrolo(3,4-d)-1,2,3-triazines: A New Ring System as Potential Antineoplastic Agen…
1990
Diazotization of the 3-aminopyrrole-4-carboxamides 6a,b under different conditions directly led to the new ring system pyrrolo[3,4-d]-1,2,3-triazine in excellent yields through an intramolecular coupling reaction. In all the cases it was impossible to isolate the intermediate 3-diazopyrroles.
ChemInform Abstract: Oxidative (Cross-)Coupling Reactions Mediated by C-H Activation of Thiophene Derivatives by Using Molybdenum(V) Reagents.
2015
The use of MoCl5 renders possible the preparation of various synthetically important polycyclic thienoacenes.
Bis(N-substituted oxamate)palladate(ii) complexes as effective catalysts for sustainable Heck carbon–carbon coupling reactions in n-Bu4NBr as the sol…
2015
Five bis(oxamato)palladate(II) complexes of the formulae (n-Bu4N)2[Pd(4-Fpma)2] (1), (n-Bu4N)2[Pd(4-Clpma)2] (2), (n-Bu4N)2[Pd(4-Brpma)2] (3), (n-Bu4N)2[Pd(4-Brpma)2]·H2O (3a), (n-Bu4N)2[Pd(4-MeOpma)2] (4) and (n-Bu4N)2[Pd(4-Isopma)2] (5) (n-Bu4N+ = tetra-n-butylammonium, 4-Fpma = N-4-fluorophenyloxamate, 4-Clpma = N-4-chlorophenyloxamate, 4-Brpma = N-4-bromophenyloxamate, 4-MeOpma = N-4-methoxyphenyloxamate and 4-isopma = N-4-isopropylphenyloxamate) have been easily prepared and characterized by spectroscopic methods and the crystal structures of two of them (3a and 4) have been determined by single crystal X-ray diffraction. Each palladium(II) ion in 3a and 4 is four-coordinate with two o…
Outstandingly robust anodic dehydrogenative aniline coupling reaction
2020
Abstract Oxidative treatment of anilines usually leads to the formation of black polymers, often referred to as “aniline black”. This over-oxidation is hardly controllable and also a challenging task in the anodic conversion of anilines. Here, a quick and efficient access to valuable building blocks by anodic cross- and homo-coupling of aniline and benzidine derivatives is reported. This electrosynthesis is easily performed in a simple undivided cell using constant current conditions. The key to the observed outstanding performance and robustness of this system is attributed to the used solvent 1,1,1,3,3,3-hexafluoroisopropanol. The extraordinary performance over a broad range of current de…
1H,13C and17O NMR study of chlorovanillins and some related compounds
1992
1H, 13C and 17O NMR chemical shifts and nJ(H,H), 1J(C,H) and 3J(C-6, H-formyl) spin—spin coupling constants of chlorinated vanillins (3-methoxy-4-hydroxybenzaldehydes) were determined. The variation in the long-range 4J(H,H) value between the formyl proton and an ortho-proton suggests that the ortho-substituent strongly forces the formyl group out of the aromatic plane. This can also be observed by considering the 3J(C-6,H-formyl) values and the 13C and 17O NMR chemical shifts. The 17O NMR chemical shifts show a linear correlation with the torsion angle of the formyl group calculated by molecular mechanics. The 13C and 17O NMR chemical shifts of the methoxyl group also possess strong predic…
Capping α-Cyclodextrin with Cyclotriveratrylene by Triple Disulfide-Bridge Formation
2013
Disulfide-bond formation is an expeditious coupling reaction to make macropolycyclic symmetrical receptors. It is used here for the preparation of unsymmetrical cavitands based on α-cyclodextrin (α-CDX) and cyclotriveratrylene (CTV) analogues. Accordingly, diastereomeric hemicryptophanes 2a and 2b were obtained in 11 % isolated yield by the iodine oxidation of a 1:1 mixture of racemic cyclotrithiophenolene (3) and the C3-symmetric trithiol derivative of permethylated α-cyclodextrin (PM α-CDX) 4. Remarkably, the target hemicryptophanes were obtained in a 5:3 diastereomeric ratio. The reaction produced mainly (34 %) a singly disulfide-bridged PM α-CDX dimer 7, however no traces of triply disu…
C-Glycosyl amino acids through hydroboration-cross-coupling of exo-glycals and their application in automated solid-phase synthesis.
2013
O-Glycosylation is one of the most important post-translational modifications of proteins. The attachment of carbohydrates to the peptide backbone influences the conformation as well as the solubility of the conjugates and can even be essential for binding to specific ligands in cell-cell interactions or for active transport over membranes. This makes glycopeptides an interesting class of compounds for medical applications. To enhance the long-term availability of these molecules in vivo, the stabilization of the glycosidic bond between the amino acid residue and the carbohydrate is of interest. The described modular approach affords β-linked C-glycosyl amino acids by a sequence of Petasis …