Hybrid αγ Polypeptides: Structural Characterization of a C12/C10Helix with Alternating Hydrogen-Bond Polarity

2008 ◽  
Vol 120 (34) ◽  
pp. 6530-6532 ◽  
Author(s):  
Prema G. Vasudev ◽  
Sunanda Chatterjee ◽  
Kuppanna Ananda ◽  
Narayanaswamy Shamala ◽  
Padmanabhan Balaram
Keyword(s):  
Hydrogen Bond ◽  
Structural Characterization ◽  
Bond Polarity

Hybrid αγ Polypeptides: Structural Characterization of a C12/C10Helix with Alternating Hydrogen-Bond Polarity

2008 ◽  
Vol 47 (34) ◽  
pp. 6430-6432 ◽  
Author(s):  
Prema G. Vasudev ◽  
Sunanda Chatterjee ◽  
Kuppanna Ananda ◽  
Narayanaswamy Shamala ◽  
Padmanabhan Balaram
Keyword(s):  
Hydrogen Bond ◽  
Structural Characterization ◽  
Bond Polarity

scholarly journals Co(NCS)2(abpt)2 and Ni(NCS)2(abpt)2 [abpt is 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole]: structural characterization of polymorphs A and B

2021 ◽  
Vol 77 (12) ◽  
Author(s):  
Helen E. Mason ◽  
Judith A. K. Howard ◽  
Hazel A. Sparkes
Keyword(s):  
Hydrogen Bond ◽  
Structural Characterization ◽  
Spin Crossover ◽  
Stacking Interactions ◽  
Π Stacking

The synthesis and structures of bis[4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole-κ2 N 2,N 3]bis(thiocyanato-κN)cobalt(II), [Co(NCS)2(C12H10N6)2] or Co(NCS)2(abpt)2, and bis[4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole-κ2 N 2,N 3]bis(thiocyanato-κN)nickel(II), [Ni(NCS)2(C12H10N6)2] or Ni(NCS)2(abpt)2, are reported. In both cases, two polymorphs, A and B, were identified and structurally characterized. For both polymorphs, the structures obtained with the different metals, i.e. CoII or NiII, were found to be isostructural. All of the structures contained an intramolecular N—H...N hydrogen bond, C—H...N interactions and π–π stacking interactions. No structural evidence was observed for a thermal spin crossover for either of the Co(NCS)2(abpt)2 polymorphs between 300 (2) and 120 (2) K.

Structural characterization of protonated benzeneseleninic acid, the dihydroxyselenonium ion

2000 ◽  
Vol 56 (6) ◽  
pp. 1029-1034 ◽  
Author(s):  
Henning Osholm Sørensen ◽  
Nicolai Stuhr-Hansen ◽  
Lars Henriksen ◽  
Sine Larsen
Keyword(s):  
Hydrogen Bond ◽  
Chemical Shift ◽  
Structural Characterization ◽  
Strong Acid ◽  
Crystallization Behaviour ◽  
Methyl Group ◽  
Bond Lengths ◽  
Pyramidal Configuration

The structure of the dihydroxyphenylselenonium ion (C_{6}H_{7}O_{2}Se^{+}) has been determined in its benzenesulfonate (C_{6}H_{5}O_{3}Se^{-}) and p-toluenesulfonate (C_{7}H_{7}O_{3}S ^{-}) salts. Whereas the former salt is disordered, the latter less dense salt is well defined. This difference in crystallization behaviour is attributed to a C—H...O hydrogen bond involving the methyl group of the p-toluenesulfonate ion. The two salts display very similar hydrogen-bond arrangements and differ only with respect to the stacking of the phenyl groups. The dihydroxyselenonium ion is a strong acid with a pK value of −0.9 determined from the variation of the 77Se chemical shift. A comparison with the two deprotonated species reveals a systematic increase in the Se—O bond lengths and the pyramidal configuration around Se with the number of protons attached.

scholarly journals New insights in the discovery of novelh-MAO-B inhibitors: structural characterization of a series ofN-phenyl-4-oxo-4H-chromene-3-carboxamide derivatives

2015 ◽  
Vol 71 (5) ◽  
pp. 547-554 ◽  
Author(s):  
Ligia R. Gomes ◽  
John Nicolson Low ◽  
Fernando Cagide ◽  
Daniel Chavarria ◽  
Fernanda Borges
Keyword(s):  
Hydrogen Bond ◽  
Carbonyl Group ◽  
Intramolecular Hydrogen Bond ◽  
Structural Characterization ◽  
Phenyl Ring ◽  
Carbonyl Groups ◽  
Pyrone Ring ◽  
Mao B ◽  
Intramolecular Hydrogen

SixN-substituted-phenyl 4-oxo-4H-chromene-3-carboxamides, namelyN-(2-nitrophenyl)-4-oxo-4H-chromene-3-carboxamide, C16H10N2O5(2b),N-(3-methoxyphenyl)-4-oxo-4H-chromene-3-carboxamide, C17H13NO4, (3a),N-(3-bromophenyl)-4-oxo-4H-chromene-3-carboxamide, C16H10BrNO3, (3b),N-(4-methoxyphenyl)-4-oxo-4H-chromene-3-carboxamide, C17H13NO4, (4a),N-(4-methylphenyl)-4-oxo-4H-chromene-3-carboxamide, C17H13NO3, (4d), andN-(4-hydroxyphenyl)-4-oxo-4H-chromene-3-carboxamide, C16H11NO4, (4e), have been structurally characterized. All compounds exhibit ananticonformation with respect to the C—N rotamer of the amide and atrans-related conformation with the carbonyl groups of the chromone ring of the amide. These structures present an intramolecular hydrogen-bonded network comprising an N—H...O hydrogen bond between the amide N atom and the O atom of the carbonyl group of the pyrone ring, forming anS(6) ring, and a weak Car—H...O hydrogen bond in which the carbonyl group of the amide acts as acceptor for the H atom of anortho-C atom of the exocyclic phenyl ring, which results in anotherS(6) ring. The N—H...O intramolecular hydrogen bond constrains the carboxamide moiety such that it is virtually coplanar with the chromone ring.

New ultrastructural findings about Borrelia burgdorferi by cryofixation, negative staining, thin sectioning and scanning techniques

1990 ◽  
Vol 48 (3) ◽  
pp. 582-583
Author(s):  
S. F. Hayes ◽  
M. D. Corwin ◽  
T. G. Schwan ◽  
D. W. Dorward ◽  
W. Burgdorfer
Keyword(s):  
Lyme Disease ◽  
Borrelia Burgdorferi ◽  
Structural Characterization ◽  
Negative Staining ◽  
Low Speed ◽  
Thin Sectioning ◽  
Ultrastructural Findings

Characterization of Borrelia burgdorferi strains by means of negative staining EM has become an integral part of many studies related to the biology of the Lyme disease organism. However, relying solely upon negative staining to compare new isolates with prototype B31 or other borreliae is often unsatisfactory. To obtain more satisfactory results, we have relied upon a correlative approach encompassing a variety EM techniques, i.e., scanning for topographical features and cryotomy, negative staining and thin sectioning to provide a more complete structural characterization of B. burgdorferi.For characterization, isolates of B. burgdorferi were cultured in BSK II media from which they were removed by low speed centrifugation. The sedimented borrelia were carefully resuspended in stabilizing buffer so as to preserve their features for scanning and negative staining. Alternatively, others were prepared for conventional thin sectioning and for cryotomy using modified procedures. For thin sectioning, the fixative described by Ito, et al.

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