Studies of meneidic systems

The nmr spectra of 2,3-dihydro-1,4-diazepinium salts are discussed. From the magnitude of the coupling constants around the conjugated part of the molecules, a planar partial structure with complete electron delocalisation is indicated. The molecule as a whole adopts a half-chair configuration which rapidly inverts at room temperature. The effect of ring substitution on this exchange process is correlated with the size of the substituents. The mass spectra of a variety of 2,3-dihydro-1,4-diazepinium salts are reported. The molecular ion of the cation is only rarely observable due to thermal dissociation of the salt. The 1 2 major breakdown process involves the loss of the (N¹-C²) fragment but other pathways are also considered. The factors governing some anomalous fragmentation patterns are discussed. The rates of bromination in methanol of a number of 2,3-dihydro-1,4-diazepinium salts were measured under first-order conditions, normally by stopped flow methods. Differences in rate of factors of up to 10000 between dihydrodiazepines with only alkyl or aryl substituents, are correlated with steric effects in the region of the reaction site, 5,6,7-Unsubstituted 2,3-dihydro-1,4-diazepinium salts are tedious to make by standard methods, Their facile preparation from l,5-diaryl-1,5-diazapentadienium salts under high dilution conditions, is discussed, and the scope of the synthesis was explored. The mechanism of the reaction was investigated using mono-amine model compounds. Attempts to prepare 5,7-dimethyl-dihydrodiazepinium salts by this method generally resulted in the formation of 2-methylimidazolines. The parent 2,3-dihydro-1,4-diazepinium perchlorate was obtainable by this high dilution synthesis in sufficient quantities for a study of its properties to be made. it is active towards electrophiles, giving 6-substitution products, and reacts with-nucleophiles at the 5(7) position. In contrast to 5,7" substituted dihydrodiazepines, the 6-halogeno derivatives are inert towards nucleophiles at the 6-positiono A series of 1,2-dihydropyrimidines was prepared, and the chemical and spectroscopic properties of these heterocycles are compared with those of the isoelectronic 2,3-dihydro-1,4-diazepines. Dihydropyrimidines show meneidic reactions with electrophiles at the 5-position, taut only 6-unsubstituted derivatives react with nucleophiles at the 6-position. A convenient synthetic route from 4-methyldihydropyrimidines to 5-methyldihydrodiazepinium salts is described. The effect of electronic perturbation on the 1,5-diazapentadienium system was investigated using series of 1,3-dimethyl-1,2-dihydro-2-oxo- and 2-thiopyrimidinium salts. Substitution reactions of 4,6-unsutastituted derivatives with electrophiles have been shown to proceed by alternative mechanisms; those pyrimidines with 4(6)-methyl substituents also show substitution reactions in the methyl groups. Stable adducts are formed by reaction of the 4,6-unsubstituted compounds with bases. The structure and chemical properties of these pseudobases are discussed. The electronic structure of 2,3-dihydro-1,4-diazepinium perchlorates and the other 1,5-diazapentadienium salts considered in this thesis, was investigated by ¹³C nmr spectroscopy

The chemical characterisation by HPLC–PDA and HPLC–ESI–MS of unaged and aged fibre samples dyed with sawwort (Serratula tinctoria L.)

The acid-hydrolysed extracts of freshly dyed reference fibres of sawwort harvested from several different geographical locations were characterised by the use of high-performance liquid chromatography with photodiode array detection (HPLC–PDA) and coupled with electrospray ionisation mass spectrometric analysis (HPLC–ESI–MS). A related species, Serratula coronata L. was also characterised. The flavonols quercetin, 3-O-methylquercetin and kaempferol, and the flavones luteolin and apigenin were observed in all samples. Accelerated ageing studies confirmed the sensitivity of the flavonol components to photo-oxidative degradation. The poor lightfastness and small relative proportion of these flavonol components found in the extracts of freshly dyed sawwort limits their use as sawwort ‘markers’ in historical samples

A study of CP violation in B-+/- -> DK +/- and B-+/- -> D pi(+/-) decays with D -> (KSK +/-)-K-0 pi(-/+) final states

A first study of CP violation in the decay modes $B^\pm\to [K^0_{\rm S} K^\pm \pi^\mp]_D h^\pm$ and $B^\pm\to [K^0_{\rm S} K^\mp \pi^\pm]_D h^\pm$, where $h$ labels a $K$ or $\pi$ meson and $D$ labels a $D^0$ or $\overline{D}^0$ meson, is performed. The analysis uses the LHCb data set collected in $pp$ collisions, corresponding to an integrated luminosity of 3 fb$^{-1}$. The analysis is sensitive to the CP-violating CKM phase $\gamma$ through seven observables: one charge asymmetry in each of the four modes and three ratios of the charge-integrated yields. The results are consistent with measurements of $\gamma$ using other decay modes

Measurement of Upsilon production in collisions at root s=2.76 TeV

The production of $\Upsilon(1S)$, $\Upsilon(2S)$ and $\Upsilon(3S)$ mesons decaying into the dimuon final state is studied with the LHCb detector using a data sample corresponding to an integrated luminosity of 3.3 $pb^{-1}$ collected in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}=2.76$ TeV. The differential production cross-sections times dimuon branching fractions are measured as functions of the $\Upsilon$ transverse momentum and rapidity, over the ranges $p_{\rm T} Upsilon(1S) X) x B(Upsilon(1S) -> mu+mu-) = 1.111 +/- 0.043 +/- 0.044 nb, sigma(pp -> Upsilon(2S) X) x B(Upsilon(2S) -> mu+mu-) = 0.264 +/- 0.023 +/- 0.011 nb, sigma(pp -> Upsilon(3S) X) x B(Upsilon(3S) -> mu+mu-) = 0.159 +/- 0.020 +/- 0.007 nb, where the first uncertainty is statistical and the second systematic

Study of forward Z + jet production in pp collisions at √s=7 TeV

A measurement of the $Z(\rightarrow\mu^+\mu^-)$+jet production cross-section in $pp$ collisions at a centre-of-mass energy $\sqrt{s} = 7$ TeV is presented. The analysis is based on an integrated luminosity of $1.0\,\text{fb}^{-1}$ recorded by the LHCb experiment. Results are shown with two jet transverse momentum thresholds, 10 and 20 GeV, for both the overall cross-section within the fiducial volume, and for six differential cross-section measurements. The fiducial volume requires that both the jet and the muons from the Z boson decay are produced in the forward direction ($2.0<\eta<4.5$). The results show good agreement with theoretical predictions at the second-order expansion in the coupling of the strong interaction.A measurement of the $Z(\rightarrow\mu^+\mu^-)$+jet production cross-section in $pp$ collisions at a centre-of-mass energy $\sqrt{s} = 7$ TeV is presented. The analysis is based on an integrated luminosity of $1.0\,\text{fb}^{-1}$ recorded by the LHCb experiment. Results are shown with two jet transverse momentum thresholds, 10 and 20 GeV, for both the overall cross-section within the fiducial volume, and for six differential cross-section measurements. The fiducial volume requires that both the jet and the muons from the Z boson decay are produced in the forward direction ($2.0<\eta<4.5$). The results show good agreement with theoretical predictions at the second-order expansion in the coupling of the strong interaction