Charles E. Keller

27Al NMR relaxation studies of molten salts containing ethylaluminum dichloride

Abstract The microdynamics of room temperature molten salts containing EtAlCl2 are examined by 27Al NMR relaxation methods as a function of melt composition and temperature. The melts examined include neat EtAlCl2 and mixtures of EtAlCl2, 1-ethyl-3-methylimidazolium chloride (MEICl) and AlCl3. Information obtained from this study indicates interactions between EtAlCl2 containing species (EtAlCl3− and EtAlCl2 dimers) and MEICl or AlCl3. Quadrupole coupling constants obtained for 27Al using the extreme narrowing condition compare favorably with those obtained previously by the dual spin probe (DSP) method.

13C NMR RELAXATION STUDIES OF 1:2 LICL-ETHYLALUMINUM DICHLORIDE SOLUTIONS

A new room-temperature molten salt, 1:2 LiCl-ethylaluminum dichloride (LiCl-EtAlCl2, f.p. about 178 K), is examined using 13C relaxation methods at 7.05 T (−25 to + 80 °C). The methylene carbon undergoes scalar relaxation of the ‘second kind’ as it is coupled to a faster relaxing (quadrupolar) nucleus. LiCl-EtAlCl2 undergoes a significant liquid-state phase change between 5 and 15 °C as evidenced by observed changes in the relaxation properties of the methylene and methyl carbons and J(13C−27Al). The J(13C−27Al) coupling constants are 75 (− 10 to + 5 °C) and 11 Hz (15–65 °C), indicating a change in structure between 5 and 15 °C. Chemical shift anisotropies of 56 and 48 ppm are obtained for the methylene and methyl carbons in the EtAlCl2 dimer part of the 1:2 LiCl-EtAlCl2 solution.

Inhibition of human leukocyte elastase and cathepsin G by isoxazoline derivatives

Abstract The interaction of a series of derivatives of cis-N-hydroxy-3-phenyl-2-isoxazoline-4,5-dicarboximide toward human leukocyte elastase and cathepsin G was investigated. Both enzymes were rapidly acylated and the corresponding acyl enzymes exhibited variable stability.

A general approach toward the design of inhibitors of serine proteinases: inhibition of human leukocyte elastase by substituted dihydrouracils

Abstract A general approach toward the rational design of potential inhibitors of serine proteinases is described. The approach is exemplified and validated through the use of appropriate heterocyclic systems in inhibiting human leukocytes elastase (HLE).

Characterization of species in ethylaluminum dichloride molten salts by 27Al NMR

Abstract A new room temperature melt containing 1-ethyl-3-methyl- imidazolium chloride (MEICI) and ethylaluminum dichloride (EtAlCl 2 ) contains EtAlCl 2 dimers and EtAlCl 3 − as determined by 27 Al NMR of neat EtAlCl 2 and a saturated LiClEtAlCl 2 solution at 60 °C. The 27 Al NMR peaks in the MEIClEtAlCl 2 melt at 129 and 102 ppm are assigned to the dimers ( cis and trans ) of EtAlCl 2 (129 ppm) and EtAlCl 3 − (102 ppm), respectively. Semi-empirical calculations support the formation of EtAlCl 3 − over EtAlCl 2 dimer formation from Cl − and EtAlCl 2 .

Conformational Studies of Haloperidol

The high field1H,19F, and13C NMR spectra of haloperidol (HP) in CDCl3 solution were recorded and analyzed with the aid of both homonuclear (H, H-COSY, H, H-COSYLR) and heteronuclear (H,C-COSY) chemical shift correlation experiments. Through space interactions between (1) the piperidine ring and the chlorinated phenyl ring and (2) the fluorinated phenyl ring and a methylene group were identified using phase sensitive Nuclear Overhauser and Exchange Spectroscopy (NOESY). The NOESY results are consistent with a planar structure rather than a folded version of haloperidol.