Organocations in zeolite synthesis: fused bicyclo [l.m.0] cations and the discovery of zeolite SSZ-48

A set of zeolite synthesis experiments is described where lattice substitution is varied in the context of the structure of particular structure-directing organocations (at times referred to as templates). In this particular series, the organocations are constructed as members of a fused bicyclo organonitrogen class of compounds, described as having ring construction [l.m.n], where n = 0. We show that these compounds can best be achieved from starting cyclic ketones that are converted to imines via a Beckman rearrangement reaction. A particular approach to the Beckmann reaction works best in our hands. In some instances isomeric organocations are made and separated. Often their use in zeolite synthesis led to different products. There is a high correlation for the space-filling details of the guest organocations and the type of crystalline host lattice developed in the synthesis. In one instance involving isomers of a decahydroquinoline derivative, a new zeolite, SSZ-48, is discovered and contains only one of the isomers. Characterization of the isomers and their use in the zeolites is followed by (13)C MAS NMR analyses. Some details of the new zeolite are given and it is shown that a reasonable symmetry operation predicting a 14-ring zeolite could be generated under similar conditions to SSZ-48 (a 12-ring zeolite).     

Cinchona alkaloid/sulfinyl chloride combinations: enantioselective sulfinylating agents of alcohols

We report a novel approach to asymmetric sulfinylation reactions based on a cinchona alkaloid/sulfinyl chloride combination that acts as the first asymmetric sulfinylating agents of achiral alcohols. Both enantiomers of arenesulfinates are obtained with up to 99% ee. The significantly high enantioselectivity observed in this case could be explained by dynamic kinetic resolution.     

Relative inhibitory activity of berberine-type alkaloids against 12-O-tetradecanoylphorbol-13-acetate-induced inflammation in mice

Forty eight derivatives of berberine-type alkaloids were examined for their inhibition activity against the induction of edema on mouse ear by application of 12-O-tetradecanoylphorbol-13-acetate (TPA). Berberine had an inhibitory effect against TPA-induced ear edema at a grade corresponding to those of quercetin, caffeine and cepharanthine. Berberine derivatives had stronger inhibitory activity than palmatine derivatives. 9-N,N-Diphenylcarbamoyl derivatives of both 9-demethylberberine and 9-demethylpalmatine had rather strong activity. These inhibitory activities are about ten times the activity of the respective mother compounds. Furthermore, 9-N-monophenylcarbamoyl derivatives and N,N-diphenylcarbamoyl chloride are found to have no effect.     

Gas chromatographic determination and gas chromatographic-mass sepectrometric analysis of chloramphenicol, thiamphenicol and their metabolites.

A rapid and accurate gas chromatographic (GC) method is described for the determination of chloramphenicol, thiamphenicol and their metabolites excreted in human urine. These excretions were pre-treated with diazomethane and N,O-bis(trimethylsilyl)acetamide, so that they could be easily subjected to GC with satisfactory separation from each other and also from other urinary excretions, and could be determined simultaneously. The structures of the metabolites were confirmed by GC combined with mass spectrometric measurements of the GC peaks. The application of the method to urine specimens enabled more precise results for the amounts of metabolites present to be obtained; the excretion of thiamphenicol glucuronide was not observed.     

Molecular orbital study of the effects of ionic amino acid residues on proton transfer energetics in the active site of carboxypeptidase a

As part of a study of the catalytic mechanism of carboxypeptidase A, two proton transfers in the system Glu 270 H₂OZnHis 69-Asp 142 are treated with an ab initio MO method. Results show that the proton transfers are strongly affected by the environment. It is predicted that the proton between His 69 and Asp 142 is covalently bonded to His 69.     

Synthesis of bidentate pyridylazo and thiazolylazo reagents and the spectrophotometric determination of copper in a flow-injection system

Some pyridylazo and thiazolylazo compounds were synthesized as spectrophotometric reagents for copper(II). The water-soluble bidentate ligand, 4-(3,5-dibromo-2-pyridylazo)-N-ethyl-N-(3-sulfopropyl)aniline (3,5-diBr-PAESA), provides the greates sensitivity, forming a 1:2 Cu:L in the presence of sodium dodecylsulfate. The molar absorptivity of the complex is 1.24 × 10⁵ l modl^?1 cm^?1 at 638 nm. Copper(II) (10–200 μg l^?1) is easily and quickly (60 h^?1) determined in a flow-injection system. Application to the determination of copper(II) in serum is described.     

Promotion of stable triplex formation by partial incorporation of 2',5'-phosphodiester linkages into triplex-forming oligonucleotides

Pentadecamer homopyrimidine oligonucleotides containing three or more 2',5'-phosphodiester linkages in different modes were prepared and used to evaluate the ability as a triplex-forming oligonucleotide (TFO), and it was found that discontinuous replacement of the 3',5'-phosphodiester linkages in TFO by 2',5'-linkages significantly stabilizes parallel-motif triplexes.     

Collision energy dependence of the O(1D) + HCl --> OH + Cl(2P) reaction studied by crossed beam scattering and quasiclassical trajectory calculations on ab initio potential energy surfaces

The dynamics of the O(1D) + HCl --> OH + Cl(2P) reaction are investigated by a crossed molecular beam ion-imaging method and quasiclassical trajectory calculations on the three ab initio potential energy surfaces, the ground 1(1)A' and two excited (1(1)A' and 2(1)A') states. The scattering experiment was carried out at collision energies of 4.2, 4.5, and 6.4 kcal/mol. The observed doubly differential cross sections (DCSs) for the Cl(2P) product exhibit almost no collision energy dependence over this inspected energy range. The nearly forward-backward symmetric DCS indicates that the reaction proceeds predominantly on the ground-state potential energy surface at these energies. Variation of the forward-backward asymmetry with collision energy is interpreted using an osculating complex model. Although the potential energy surfaces obtained by CASSCF-MRCI ab initio calculations exhibit relatively low potential barriers of 1.6 and 6.5 kcal/mol for 1(1)A' and 2(1)A', respectively, the dynamics calculations indicate that contributions of these excited states are small at the collision energies lower than 15.0 kcal/mol. Theoretical DCSs calculated for the ground-state reaction pathway agree well with the observed ones. These experimental and theoretical results suggest that the titled reaction at collision energies less than 6.5 kcal/mol is predominantly via the ground electronic state.     

Probing the effect of the binding site on the electrostatic behavior of a series of carotenoids reconstituted into the light-harvesting 1 complex from purple photosynthetic bacterium Rhodospirillum rubrum detected by stark spectroscopy

Reconstitutions of the LH1 complexes from the purple photosynthetic bacterium Rhodospirillum rubrum S1 were performed with a range of carotenoid molecules having different numbers of C=C conjugated double bonds. Since, as we showed previously, some of the added carotenoids tended to aggregate and then to remain with the reconstituted LH1 complexes (Nakagawa, K.; Suzuki, S.; Fujii, R.; Gardiner, A.T.; Cogdell, R.J.; Nango, M.; Hashimoto, H. Photosynth. Res. 2008, 95, 339-344), a further purification step using a sucrose density gradient centrifugation was introduced to improve purity of the final reconstituted sample. The measured absorption, fluorescence-excitation, and Stark spectra of the LH1 complex reconstituted with spirilloxanthin were identical with those obtained with the native, spirilloxanthin-containing, LH1 complex of Rs. rubrum S1. This shows that the electrostatic environments surrounding the carotenoid and bacteriochlorophyll a (BChl a) molecules in both of these LH1 complexes were essentially the same. In the LH1 complexes reconstituted with either rhodopin or spheroidene, however, the wavelength maximum at the BChl a Qy absorption band was slightly different to that of the native LH1 complexes. These differences in the transition energy of the BChl a Qy absorption band can be explained using the values of the nonlinear optical parameters of this absorption band, i.e., the polarizability change Tr(Deltaalpha) and the static dipole-moment change |Deltamu| upon photoexcitation, as determined using Stark spectroscopy. The local electric field around the BChl a in the native LH1 complex (ES) was determined to be approximately 3.0x10(6) V/cm. Furthermore, on the basis of the values of the nonlinear optical parameters of the carotenoids in the reconstituted LH1 complexes, it is possible to suggest that the conformations of carotenoids, anhydrorhodovibrin and spheroidene, in the LH1 complex were similar to that of rhodopin glucoside in crystal structure of the LH2 complex from Rhodopseudomonas acidophila 10050.     

Profiling of N- and O-glycopeptides of erythropoietin by capillary zwitterionic type of hydrophilic interaction chromatography/electrospray ionization mass spectrometry

Capillary zwitterionic-type hydrophilic interaction chromatography (ZIC-HILIC)/ESI-MS has been applied to the Glu-C digest of recombinant human erythropoietin (rhEPO) expressed in Chinese hamster ovary (CHO) cells. N-Glycopeptides (105) and O-glycopeptides (8) were detected in a single run of the capillary ZIC-HILIC/ESI-MS analysis. Among them, N-acetyl-neuraminic acids (Neu5Ac) of N- and O-glycans were partially acetylated and some were replaced with N-glycoyl-neuraminic acid (Neu5Gc). Their retentions in the ZIC-HILIC separation can be explained to some extent with the degree of acetylation and N-glycoylation, both of which influence the hydrophilicity/hydrophobicity of the N- and O-glycan moieties of glycopeptides.