Study and characterization of crystalline hydrate/polymorph forms of 5,11-dihydro-11-ethyl-5-methyl-8-(2-(1-oxido-4-quinolinyl)ethyl-6H-dipyrido(3,2-B:2',3'-E)(1,4)diazepin-6-one by solid-state NMR and solution NMR. | LitMetric
Boehringer Ingelheim Pharmaceuticals Inc., 900 Ridgebury Rd., Ridgefield, CT 06877, United States.
Published: April 2010
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Article Abstract
A novel inhibitor of reverse transcriptase was studied by solid-state NMR. Three phases of the compound were examined which included the dihydrate and two anhydrous polymorphs (Form I and Form III). By correlating (1)H and (13)C solution NMR with the solid-state (13)C NMR CP/MAS and CPPI spectral editing experiments, comparative (13)C assignments were made for each phase. Polymorphs of Form I and Form III and the dihydrate were easily distinguished based upon chemical shift patterns of the carbon resonances. The (1)H spin-lattice relaxation times were also measured for each phase which provided information on the mobility and relative crystallinity. The (13)C ssNMR spectrum of Form I showed the presence of a minor component identified as the dihydrate. Weight/percent quantitation of major and minor components in Form I was obtained from integrated intensities of a 50:50 mixture containing weighed amounts of Form I and the pure dihydrate. Comparison of the ssNMR and X-ray powder diffraction techniques is discussed.
The two-dimensional (2D) refocused INADEQUATE NMR experiment, which correlates double-quantum (DQ) and single-quantum (SQ) coherences, is widely used to probe the chemical connectivities in solids. Nevertheless, the multiplets along the F dimension reduce the resolution and sensitivity of this experiment. The Composite-Refocusing (CR) technique with two excitation pulses has been proposed to suppress these multiplets in 2D INADEQUATE spectra of liquids.
The present work reports on the preparation, characterization, and evaluation of a set of novel triphenyl-modified silica-based stationary phases without and with embedded ion-exchange sites for mixed-mode liquid chromatography. The three synthesized triphenyl phases differed in additionally incorporated ion-exchange sites. In one embodiment, allyltriphenylsilane was bonded to thiol-modified silica by thiol-ene click reaction, leading to particles with no ion-exchange sites.
We report hitherto elusive side-on η2-bonded palladium(0) carbonyl (anthraquinone, benzaldehyde) and arene (benzene, hexa-fluorobenzene) palladium(0) complexes and present the catalytic hydrodefluorination of hexafluorobenzene by cyclohexene. The comparison with respective cyclohexene, pyridine and tetrahydrofuran complexes reveals that the experimental ligand binding strengths follow the order THF < C6H6 < C6F6 < cyclohexene < pyridine < benzaldehyde < anthraquinone. To understand this surprising order, the complexes' electronic structures were elucidated by nuclear magnetic resonance (NMR), single crystal X-Ray diffraction (sc-XRD), ultraviolet/visible (UV/Vis) electronic absorption, infrared (IR) vibrational, Pd L3-edge X-ray absorption (XAS), and X-ray photoelectron (XP) spectroscopic techniques, complemented by Density Functional Theory (DFT) calculations including energy decomposition (EDA-NOCV) and effective oxidation state (EOS) analyses.
The rapid advancement of industrial production has led to an increase in water pollutants, posing a significant threat to public health. With the deepening of research on pollutant adsorbents. The application of silsesquioxane-based cross-linked polymer networks in water pollution treatment has gradually attracted people's attention.
