Conformationally rigid trifluoromethyl-substituted alpha-amino acid designed for peptide structure analysis by solid-state 19F NMR spectroscopy.
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Biomedical subjects
Publications and source records attributed to Alexander N Chernega.
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Salts of N-trifluoromethylsulfonyl derivatives of trifluoromethyl- and phenylsulfonimidoyl imides have been synthesized by two different routes. Both methods are one-pot reactions, that run in mild conditions with good yields. Two novel organic super acids: bis[N-(trifluoromethylsulfonyl)trifluoromethanesulfonimidoyl]imide and N,N'-bis(trifluoromethyl-sulfonyl)diimino trifluoromethanesulfonic acid were prepared and the structure of their potassium salts was obtained by single-crystal X-ray diffraction.
The molecular structure of aluminium and iron(III) complexes with 3-phenyl and 3-(4-pyridyl) (HL) substituted acetylacetonate ligands is appreciably distorted. For AlL3 and FeL3 this shows that the orientation of the side pyridyl-N donor atoms lone pairs is about 90 and 135 degrees which favours the assembly of heterobimetallic square patterns in Al(Fe)L3 complexes with metal ions. This was employed for the modular construction of semi-regular heterobimetallic networks, in which the pyridyldiketonate ligands bridge pairs of Fe(Al)/Cd(Co) metal ions and support the structure of 1D and 2D coordination polymers. The unprecedented 2D structure of [Cd[AlL3](CH3OH)[NO3]2].2CHCl3 and Cd[AlL3](CH3OH)Br2].2CHCl3 . 2CH3OH is based upon plane tiling by a set of heterobimetallic squares and octagons, while [Cd[FeL3]2(NO3)2].2H2O and [Co[AlL3]2Cl2].4CHCl3 . 2CH3OH are 1D polymers and exist as chains of heterobimetallic squares sharing opposite vertices.
The dense packing of shape complementary N-donor molecules dominates the self-assembly of coordination polymers possessing sodalite-like topology and supports nanosize molecular cages.
The ethyl ester of beta-bromoperfluorodithiocrotonic acid reacts with dimethyl acetylenedicarboxylate to give 1,4-difluoro-2,3-bis(trifluoromethyl)-but-2-ene-1,4-diylidene-2,2'-bis(4',5'-dicarbomethoxy-1',3'-dithiole) (4), a new type of vinylogue of tetrathiafulvalene. The thermal transformations of this compound lead, depending on the temperature, to the formation of the cyclization products: 11,14-difluoro-2,3,8,9-tetra(carbomethoxy)-12,13-bis(trifluoromethyl)-1,4,7,10-tetrathiadispiro[4.0.4.4]tetradeca-2,8,11,13-tetraene (8) or 5,8-difluoro-6,7-bis(trifluoromethyl)-2,3-bis(carboxymethyl)-1,4-benzodithiine (11).
Cross-linking of corrugated square grid coordination layers by anionic bridging groups generates five-connected coordination networks; the 3D topologies of mixed-anion cobalt(II) and nickel(II) complexes with a tetramethyl-substituted 4,4'-bipyrazolyl ligand are supported by mu-SO4(2-) functions and exist as neutral or cationic five-connected arrays involving additional terminal (NCS-) or non-coordinated (NO3-, ClO4-) groups.