Novel Conformational Isomerism in a Six-Coordinate Silver(I) Complex of a Sexadentate Macrocycle With an N3S3 Donor Set

1989 ◽  
Vol 42 (8) ◽  
pp. 1387 ◽  
Author(s):  
SB Silong ◽  
JD Kildea ◽  
AH White
Keyword(s):  
Structural Characterization ◽  
Condensation Product ◽  
Complex Cation ◽  
Conformational Isomerism ◽  
Novel Environment ◽  
Conformational Isomer ◽  
Template Reaction

The synthesis and structural characterization of the condensation product formed by a template reaction of 2,6-diacetylpyridine and 3,6,9-trithiaundecane-1,11-diamine about silver(I) (as perchlorate ) are described. Crystals are monoclinic, C2/c, a 27.114(10), b 7.546(5), c 22.137(10) �, β 105.35(3)°, Z= 8×[AgL]+(ClO4)-(L = C17H25N3S3). R was 0.057 for 2372 'observed' reflections. The six-coordinate silver(I) atom lies in a novel environment comprised of a mer-triaza moiety derived from 2,6-diacetylpyridine [Ag-N, 2.422(8) (central), 2. 538(8), 2.546(9)� (distal)] and a fac-trithia moiety straddling its plane [Ag-S, 2.603(6) (central), 2.815(4), 2.881(3) � (distal)]. The complex cation is a different conformational isomer to that found in the previously studied tetraphenylborate salt. In the latter, Ag-N are 2.422(9) (central), 2.613(9), 2.399(7) � (distal), with Ag-S 2.670(3) (central), 2.655(3), 2.949(4) � (alstal).

Structural Systematics of Rare Earth Complexes. II. Structural Characterization of Lanthanoid(III) Picrate Hydrates: the Triclinic P1, 11.5 Hydrates of the Later Rare Earths and Yttrium

1994 ◽  
Vol 47 (2) ◽  
pp. 339 ◽  
Author(s):  
JM Harrowfield ◽  
WM Lu ◽  
BW Skelton ◽  
AH White
Keyword(s):  
Aqueous Solution ◽  
Rare Earth ◽  
Structural Characterization ◽  
Complex Cation ◽  
Water Molecules ◽  
Complex Ions ◽  
X Ray ◽  
Lattice Water ◽  
Structure Determinations

Picrates of dysprosium(III), holmium(III), erbium(III), thulium(III), ytterbium(III), lutetium(III) and yttrium(III) have been found to crystallize as needles from aqueous solution, seemingly best described as 11.5 hydrates. Single-crystal X-ray structure determinations have been performed at c. 295 K on the Dy , Er , Lu and Y species, and show them to be isomorphous , triclinic, Pī , a 20.043(7) → 20.019(5), b 11.533(2) → 11.471(2), c 8.1567(7) → 8.1538(8) Ǻ, α 88.60(1) → 88.40(1), β 87.12(2) → 87.06(1), γ 75.07(2) → 75.05(2)°, V 1819 → 1807 Ǻ3 ( Dy → Lu; the Y and Er values are intermediate). Complex ions [ Ln ( pic )(OH2)7]2+ are observed, with a pair of uncoordinated picrate anions and 4.5 lattice water molecules; this result is in contrast to that of the monoclinic, P 21/c, series found for La → Pr and Nd → Tb, in which the complex cation contains two picrate anions.

Characterization of Chemical Impurities in Glutaraldehyde

1975 ◽  
Vol 33 ◽  
pp. 620-621
Author(s):  
B. J. Grenon ◽  
A. J. Tousimis
Keyword(s):  
Glutaric Acid ◽  
Spectroscopic Analysis ◽  
Aldol Condensation ◽  
Condensation Product ◽  
Amorphous Solid ◽  
Water Soluble ◽  
Impurity Component ◽  
Chemical Impurities ◽  
Soluble Liquid

Ever since the introduction of glutaraldehyde as a fixative in electron microscopy of biological specimens, the identification of impurities and consequently their effects on biologic ultrastructure have been under investigation. Several reports postulate that the impurities of glutaraldehyde, used as a fixative, are glutaric acid, glutaraldehyde polymer, acrolein and glutaraldoxime.Analysis of commercially available biological or technical grade glutaraldehyde revealed two major impurity components, none of which has been reported. The first compound is a colorless, water-soluble liquid with a boiling point of 42°C at 16 mm. Utilizing Nuclear Magnetic Resonance (NMR) spectroscopic analysis, this compound has been identified to be — dihydro-2-ethoxy 2H-pyran. This impurity component of the glutaraldehyde biological or technical grades has an UV absorption peak at 235nm. The second compound is a white amorphous solid which is insoluble in water and has a melting point of 80-82°C. Initial chemical analysis indicates that this compound is an aldol condensation product(s) of glutaraldehyde.

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.

Structural characterization of the PPIase domain of FKBP51, a cochaperone of human Hsp90

2011 ◽  
Vol 44 (06) ◽  
Author(s):  
A Bracher ◽  
C Kozany ◽  
AK Thost ◽  
F Hausch
Keyword(s):  
Structural Characterization ◽  
Ppiase Domain

Structural characterization of dendrobine-type sesquiterpene alkaloids from the stems of Dendrobium nobile using LC-MS/MS

Planta Medica ◽  
2014 ◽  
Vol 80 (10) ◽  
Author(s):  
YH Wang ◽  
B Avula ◽  
N Abe ◽  
F Wei ◽  
M Wang ◽  
...  
Keyword(s):  
Structural Characterization ◽  
Dendrobium Nobile

Structural characterization of monacolin compounds from red yeast rice by liquid chromatography and tandem mass

Planta Medica ◽  
2015 ◽  
Vol 81 (11) ◽  
Author(s):  
YH Wang ◽  
B Avula ◽  
Z Zhang ◽  
M Wang ◽  
S Sagi ◽  
...  
Keyword(s):  
Liquid Chromatography ◽  
Structural Characterization ◽  
Red Yeast Rice ◽  
Tandem Mass ◽  
Red Yeast
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