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991.
Amanda R. Buist Lynn Dennany Alan R. Kennedy Craig Manzie Katherine McPhie Brandon Walker 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(9):900-907
Proton transfer to the sulfa drug sulfadiazine [systematic name: 4‐amino‐N‐(pyrimidin‐2‐yl)benzenesulfonamide] gave eight salt forms. These are the monohydrate and methanol hemisolvate forms of the chloride (2‐{[(4‐azaniumylphenyl)sulfonyl]azanidyl}pyrimidin‐1‐ium chloride monohydrate, C10H11N4O2S+·Cl−·H2O, (I), and 2‐{[(4‐azaniumylphenyl)sulfonyl]azanidyl}pyrimidin‐1‐ium chloride methanol hemisolvate, C10H11N4O2S+·Cl−·0.5CH3OH, (II)); a bromide monohydrate (2‐{[(4‐azaniumylphenyl)sulfonyl]azanidyl}pyrimidin‐1‐ium bromide monohydrate, C10H11N4O2S+·Br−·H2O, (III)), which has a disordered water channel; a species containing the unusual tetraiodide dianion [bis(2‐{[(4‐azaniumylphenyl)sulfonyl]azanidyl}pyrimidin‐1‐ium) tetraiodide, 2C10H11N4O2S+·I42−, (IV)], where the [I4]2− ion is located at a crystallographic inversion centre; a tetrafluoroborate monohydrate (2‐{[(4‐azaniumylphenyl)sulfonyl]azanidyl}pyrimidin‐1‐ium tetrafluoroborate monohydrate, C10H11N4O2S+·BF4−·H2O, (V)); a nitrate (2‐{[(4‐azaniumylphenyl)sulfonyl]azanidyl}pyrimidin‐1‐ium nitrate, C10H11N4O2S+·NO3−, (VI)); an ethanesulfonate {4‐[(pyrimidin‐2‐yl)sulfamoyl]anilinium ethanesulfonate, C10H11N4O2S+·C2H5SO3−, (VII)}; and a dihydrate of the 4‐hydroxybenzenesulfonate {4‐[(pyrimidin‐2‐yl)sulfamoyl]anilinium 4‐hydroxybenzenesulfonate dihydrate, C10H11N4O2S+·HOC6H4SO3−·2H2O, (VIII)}. All these structures feature alternate layers of cations and of anions where any solvent is associated with the anion layers. The two sulfonate salts are protonated at the aniline N atom and the amide N atom of sulfadiazine, a tautomeric form of the sulfadiazine cation that has not been crystallographically described before. All the other salt forms are instead protonated at the aniline group and on one N atom of the pyrimidine ring. Whilst all eight species are based upon hydrogen‐bonded centrosymetric dimers with graph set R22(8), the two sulfonate structures also differ in that these dimers do not link into one‐dimensional chains of cations through NH3‐to‐SO2 hydrogen‐bonding interactions, whilst the other six species do. The chloride methanol hemisolvate and the tetraiodide are isostructural and a packing analysis of the cation positions shows that the chloride monohydrate structure is also closely related to these. 相似文献
992.
993.
Cécile Bousch Brandon Vreulz Kartikey Kansal Ali El-Husseini Dr. Samy Cecioni 《Angewandte Chemie (International ed. in English)》2023,62(49):e202314248
Glycan recognition by glycan-binding proteins is central to the biology of all living organisms. The efficient capture and characterization of relatively weak non-covalent interactions remains an important challenge in various fields of research. Photoaffinity labeling strategies can create covalent bonds between interacting partners, and photoactive scaffolds such as benzophenone, diazirines and aryl azides have proved widely useful. Since their first introduction, relatively few improvements have been advanced and products of photoaffinity labeling remain difficult to detect. We report a fluorinated azido-coumarin scaffold which enables photolabeling under fast and mild activation, and which can leave a fluorescent tag on crosslinked species. Coupling this scaffold to an α-fucoside, we demonstrate fluorogenic photolabeling of glycan-protein interactions over a wide range of affinities. We expect this strategy to be broadly applicable to other chromophores and we envision that such “fluoro-crosslinkers” could become important tools for the traceable capture of non-covalent binding events. 相似文献
994.
Mononuclear, five-coordinate lanthanide amido and aryloxide complexes bearing tetradentate (N2O2) Schiff bases 总被引:2,自引:0,他引:2
Schuetz SA Silvernail CM Incarvito CD Rheingold AL Clark JL Day VW Belot JA 《Inorganic chemistry》2004,43(20):6203-6214
Two monomeric, five-coordinate lanthanide complexes, [bis-5,5'-(1,3-propanediyldiimino)-2,2-dimethyl-4-hexene-3-onato]samarium[2,6-bis(tert-butyl)-4-methylphenoxide] and [bis-5,5'-(1,3-propanediyldiimino)-2,2-dimethyl-4-hexene-3-onato]erbium[2,6-bis(tert-butyl)-4-methylphenoxide], were isolated from the reactions of 2,6-bis(tert-butyl)-4-methylphenol with [bis-5,5'-(1,3-propanediyldiimino)-2,2-dimethyl-4-hexene-3-onato]lanthanide[bis(trimethylsilyl)amido] (lanthanide = Er(3+) and Sm(3+)). The purified phenoxides were recovered in excellent yields and analytical purity, and the reactions proceeded cleanly without Schiff-base degradation or cluster formation. Analogously, [bis-3,3'-(1,3-propanediyldiimino)-1-phenyl-2-butene-1-onato]erbium[bis(trimethylsilyl)amido] was also directly converted to [bis-3,3'-(1,3-propanediyldiimino)-1-phenyl-2-butene-1-onato]erbium[2,6-bis(tert-butyl)-4-methylphenoxide]; however, a less sterically demanding alcohol (i.e., ethanol) yielded a neutral trinuclear oxo alkoxide species with each dianionic Schiff base asymmetrically bridging through micro-oxo interactions. In this polynuclear cluster, each symmetry-related, seven-coordinate erbium(III) ion exhibits monocapped trigonal prismatic geometry, which assembles by sharing triangular capped faces. Single-crystal X-ray diffraction revealed square-pyramidal metal coordination in each five-coordinate lanthanide ion with varied S(4) ruffling of the "square base" donor atoms and the six-membered propylene diamine chelate ring adopting the boat conformation. To contrast the effect of subtle ligand changes, we also report the synthesis and characterization of [bis-5,5'-(2,2-dimethyl-1,3-propanediyldiimino)-2,2-dimethyl-4-hexene-3-onato]samarium[bis(trimethylsilyl)amido], having gem-dimethyl substituents appended to the propylene bridge central carbon. The six-membered diamine chelate ring in this compound adopts the chair conformation without metal-hydrocarbon interaction. Also presented are qualitative activity observations and polymerization data for the polymerization of rac-lactide and epsilon-caprolactone using the five-coordinate lanthanide amidos and phenoxides. 相似文献
995.
Combined delta2H, delta13C and delta15N isotopic analysis of MDA and MDMA extracted from seized "ecstasy" tablets provides an isotopic "fingerprint" of the active ingredient allowing individual tablets to be linked to a common batch. Correlating these data with 2H NMR analysis of the extracts has the potential to study both the natural precursor materials and synthetic pathways used in the preparation of MDA and N-substituted homologues. 相似文献
996.
Dr. Peng Shi Xuelin Wang Brandon Davis James Coyne Prof. Cheng Dong Joshua Reynolds Prof. Yong Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(29):11990-11995
An ability to promote therapeutic immune cells to recognize cancer cells is important for the success of cell-based cancer immunotherapy. We present a synthetic method for functionalizing the surface of natural killer (NK) cells with a supramolecular aptamer-based polyvalent antibody mimic (PAM). The PAM is synthesized on the cell surface through nucleic acid assembly and hybridization. The data show that PAM has superiority over its monovalent counterpart in powering NKs to bind to cancer cells, and that PAM-engineered NK cells exhibit the capability of killing cancer cells more effectively. Notably, aptamers can, in principle, be discovered against any cell receptors; moreover, the aptamers can be replaced by any other ligands when developing a PAM. Thus, this work has successfully demonstrated a technology platform for promoting interactions between immune and cancer cells. 相似文献
997.
Nina M. Bsch Mariana Borsa Ute Greczmiel Brandon I. Morinaka Muriel Gugger Annette Oxenius Anna L. Vagstad Jrn Piel 《Angewandte Chemie (International ed. in English)》2020,59(29):11763-11768
Proteusins are a family of bacterial ribosomal peptides that largely remain hypothetical genome‐predicted metabolites. The only known members are the polytheonamide‐type cytotoxins, which have complex structures due to numerous unusual posttranslational modifications (PTMs). Cyanobacteria contain large numbers of putative proteusin loci. To investigate their chemical and pharmacological potential beyond polytheonamide‐type compounds, we characterized landornamide A, the product of the silent osp gene cluster from Kamptonema sp. PCC 6506. Pathway reconstruction in E. coli revealed a peptide combining lanthionines, d ‐residues, and, unusually, two ornithines introduced by the arginase‐like enzyme OspR. Landornamide A inhibited lymphocytic choriomeningitis virus infection in mouse cells, thus making it one of the few known anti‐arenaviral compounds. These data support proteusins as a rich resource of chemical scaffolds, new maturation enzymes, and bioactivities. 相似文献
998.
Brandon C. Presley Barry K. Logan Susan A. Jansen-Varnum 《Biomedical chromatography : BMC》2020,34(3):e4786
Studies of the metabolic and pharmacological profiles of indole carboxamide synthetic cannabinoids (a prevalent class of new psychoactive substances) are critical in ensuring that their use can be detected through bioanalytical testing. We have determined the in vitro Phase I metabolism of one such compound, PX-1 (5F-APP-PICA), and appropriate markers to demonstrate human consumption. PX-1 was incubated with human liver microsomes, followed by analysis of the extracts via high-resolution mass spectrometry. A total of 10 metabolites were identified, with simultaneous defluorination and monohydroxylation of the pentyl side chain as the primary biotransformation product (M1). Additional metabolites formed were hydroxylation products of the indole and benzyl moieties, distal amide hydrolysis, N-desfluoropentyl, and carboxypentyl metabolites. Three monohydroxylated metabolites specific to PX-1 were identified and are reported for the first time in this study. The primary metabolite, M1, was further oxidized to M5, a carboxypentyl metabolite. M8 is PX-1 specific, possessing an intact fluoropentyl side chain. These three metabolites are the most suitable for implementation into bioanalytical assays for demonstrating PX-1 consumption. The findings of this study can be used by analytical scientists and medical professionals to determine PX-1 ingestion and predict the metabolites of synthetic cannabinoids sharing structural elements. 相似文献
999.