Electrochemistry of 1,2,5-thiadiazole 1,1-dioxide derivatives with 3,4 substituents presenting separated, connected, and fused Pi-systems

1999 ◽  
Vol 77 (4) ◽  
pp. 511-517 ◽  
Author(s):  
Esther Lea Svartman ◽  
José Alberto Caram ◽  
María Virginia Mirífico ◽  
Enrique Julio Vasini
Keyword(s):  
Theoretical Chemistry ◽  
Structural Studies ◽  
Spectroscopy Data ◽  
X Ray ◽  
X Ray Crystallography ◽  
Organic Electrochemistry ◽  
Pi Systems ◽  
Voltammetric Behavior ◽  
Bulk Electrolysis ◽  
Acetonitrile Solutions

The voltammetric electroreduction properties of 1,2,5-thiadiazole 1,1-dioxide derivatives with different 3,4 substituents have been investigated in aprotic (mainly acetonitrile) solvent solution. The 3,4 substituents, selected according to the characteristics of their π-system, were phenanthro-9,10 (connected π-system) and acenaphtho-1,2 (fused π-system). New measurements are also presented for 3,4-diphenyl (separated π-systems). The basic properties of the substrates were investigated through voltammetry in acidic acetonitrile solutions. The substrates were more easily electroreduced (between -0.6 and -1.0 V vs. Ag/Ag+, acetonitrile solvent) than the parent (non-1,1-dioxide) heterocycles (which are electroreduced at ca. -2.5 V). They were also more easily electroreduced (by ca. 0.4 V) than the corresponding diketones (benzil, 9,10-phenanthrenequinone, and acenaphthenequinone). The influence on voltammetric behavior of the electron-withdrawing properties of the 1,2,5-thiadiazole 1,1-dioxide ring and that of the structure of the molecules was analyzed in light of previous structural studies by X-ray crystallography and theoretical chemistry calculations. Bulk electrolysis experiments in acidic acetonitrile solutions of the phenanthro[9,10-c] derivative produced its previously unreported dihydrogenated derivative (thiadiazoline), which oxidizes easily. Infrared spectroscopy data suggested that the structure of this compound differs from that of 3,4-diphenyl-1,2,5-thiadiazoline 1,1-dioxide.Key words: organic electrochemistry, 1,2,5- thiadiazoles, structure-reactivity relations.

Synthesis, Characterisation and Structural Studies of [Zn(phen)3][Fe(CN)5(NO)]·2H2O·0.25MeOH and [(bipy)2(H2O)Zn(μ-NC)Fe(CN)4(NO)]·0.5H2O

2003 ◽  
Vol 58 (9) ◽  
pp. 916-921 ◽  
Author(s):  
Amitabha Datta ◽  
Samiran Mitra ◽  
Georgina Rosair
Keyword(s):  
Infrared Spectroscopy ◽  
Thermogravimetric Analysis ◽  
Octahedral Geometry ◽  
Distorted Octahedral Geometry ◽  
Structural Studies ◽  
Crystal Lattices ◽  
X Ray ◽  
X Ray Crystallography ◽  
Distorted Octahedral ◽  
Solvent Molecules

Two new bimetallic complexes [Zn(phen)3][Fe(CN)5(NO)] · 2 H2O · 0.25 MeOH, (1) and [(bipy)2(H2O)Zn(μ-NC)Fe(CN)4(NO)] · 0.5 H2O, (2), have been isolated (where phen = 1,10-phenanthroline and bipy = bipyridyl) and characterised by X-ray crystallography [as the 2 H2O · 0.25 CH3OH solvate for (1) and hemihydrate for (2)] infrared spectroscopy and thermogravimetric analysis. Substitution of phenanthroline for bipyridyl resulted in a cyano-bridged bimetallic species rather than two discrete mononuclear metal complexes. The bond angles of Fe-N-O were shown to be practically linear for both 1 [179.2(7)°] and 2 [178.3(3)°], and the Zn atoms have distorted octahedral geometry. The solvent molecules in both crystal lattices take part in forming hydrogen-bonded networks.

scholarly journals The fluoride permeation pathway and anion recognition in Fluc family fluoride channels

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Benjamin C McIlwain ◽  
Roja Gundepudi ◽  
B Ben Koff ◽  
Randy B Stockbridge
Keyword(s):  
Binding Sites ◽  
Anion Recognition ◽  
Anion Binding ◽  
Structural Studies ◽  
Planar Bilayer ◽  
X Ray ◽  
X Ray Crystallography ◽  
Molecular Determinants ◽  
Cytoplasmic Accumulation ◽  
Oriented System

Fluc family fluoride channels protect microbes against ambient environmental fluoride by undermining the cytoplasmic accumulation of this toxic halide. These proteins are structurally idiosyncratic, and thus the permeation pathway and mechanism have no analogy in other known ion channels. Although fluoride binding sites were identified in previous structural studies, it was not evident how these ions access aqueous solution, and the molecular determinants of anion recognition and selectivity have not been elucidated. Using x-ray crystallography, planar bilayer electrophysiology and liposome-based assays, we identify additional binding sites along the permeation pathway. We use this information to develop an oriented system for planar lipid bilayer electrophysiology and observe anion block at one of these sites, revealing insights into the mechanism of anion recognition. We propose a permeation mechanism involving alternating occupancy of anion binding sites that are fully assembled only as the substrate approaches.

scholarly journals Homogeneously N-glycosylated proteins derived from the GlycoDelete HEK293 cell line enable diffraction-quality crystallogenesis

2020 ◽  
Vol 76 (12) ◽  
pp. 1244-1255
Author(s):  
Sandra Kozak ◽  
Yehudi Bloch ◽  
Steven De Munck ◽  
Aleksandra Mikula ◽  
Isabel Bento ◽  
...  
Keyword(s):  
Cell Line ◽  
Protein Interactions ◽  
Successful Implementation ◽  
Structural Studies ◽  
Protein Fragments ◽  
X Ray ◽  
X Ray Crystallography ◽  
Cryo Electron Microscopy ◽  
Acid Protein ◽  
Stimulating Factor

Structural studies of glycoproteins and their complexes provide critical insights into their roles in normal physiology and disease. Most glycoproteins contain N-linked glycosylation, a key post-translation modification that critically affects protein folding and stability and the binding kinetics underlying protein interactions. However, N-linked glycosylation is often an impediment to yielding homogeneous protein preparations for structure determination by X-ray crystallography or other methods. In particular, obtaining diffraction-quality crystals of such proteins and their complexes often requires modification of both the type of glycosylation patterns and their extent. Here, we demonstrate the benefits of producing target glycoproteins in the GlycoDelete human embryonic kidney 293 cell line that has been engineered to produce N-glycans as short glycan stumps comprising N-acetylglucosamine, galactose and sialic acid. Protein fragments of human Down syndrome cell-adhesion molecule and colony-stimulating factor 1 receptor were obtained from the GlycoDelete cell line for crystallization. The ensuing reduction in the extent and complexity of N-glycosylation in both protein molecules compared with alternative glycoengineering approaches enabled their productive deployment in structural studies by X-ray crystallography. Furthermore, a third successful implementation of the GlycoDelete technology focusing on murine IL-12B is shown to lead to N-glycosylation featuring an immature glycan in diffraction-quality crystals. It is proposed that the GlycoDelete cell line could serve as a valuable go-to option for the production of homogeneous glycoproteins and their complexes for structural studies by X-ray crystallography and cryo-electron microscopy.

Synthesis and characterization of new tetra-substituted porphyrins with exo-donor carboxylic groups as building blocks for supramolecular architectures: Catalytic and structural studies of their metalated derivatives

2010 ◽  
Vol 14 (09) ◽  
pp. 804-814 ◽  
Author(s):  
Lucia Carlucci ◽  
Gianfranco Ciani ◽  
Simona Maggini ◽  
Davide M. Proserpio ◽  
Fabio Ragaini ◽  
...  
Keyword(s):  
Building Blocks ◽  
Supramolecular Organization ◽  
Silver Complexes ◽  
Structural Studies ◽  
Polymeric Compound ◽  
X Ray ◽  
X Ray Crystallography ◽  
Supramolecular Architectures ◽  
Carboxylic Groups

We report herein the synthesis of the porphyrins 5,10,15,20-tetrakis(4-carboxybiphenyl)-porphyrin (H2TCBP) and 5,10,15,20-tetrakis(4-carboxy-2,6-dimethylbiphenyl)porphyrin (H2TCDMBP) bearing diphenyl units on meso-positions, and of their cobalt and silver derivatives. The silver complexes of H2TCDMBP and of H2TCPP ( H2TCPP = 5 ,10,15,20-tetrakis(4-carboxyphenyl)porphyrin) were investigated by X-ray crystallography and their supramolecular organization elucidated. Co(TCBP) was reacted with copper formate, yielding a polymeric compound that showed a catalytic activity in the benzylic amination of hydrocarbons using arylazide as aminating agent.

X-ray Crystallography and Structural Studies of Toxins

2021 ◽  
pp. 59-72
Author(s):  
Vinícius Lucatelle da Silva ◽  
Ricardo Barros Mariutti ◽  
Mônika Aparecida Coronado ◽  
Raphael Josef Eberle ◽  
Fábio Rogério de Moraes ◽  
...  
Keyword(s):  
Structural Studies ◽  
X Ray ◽  
X Ray Crystallography

Complexation of Some Phenol Hosts with QuinolineN-Oxide and the Structural Studies of Their Complexes by X-ray Crystallography

2007 ◽  
Vol 36 (10) ◽  
pp. 1272-1273 ◽  
Author(s):  
Bunpei Hatano ◽  
Akiko Aikawa ◽  
Hiroshi Katagiri ◽  
Hideyuki Tagaya ◽  
Hiroki Takahashi
Keyword(s):  
Structural Studies ◽  
X Ray ◽  
X Ray Crystallography

Structural Studies by NMR and X-Ray Crystallography of N-(p-Toluenesulfonyl)-Amino Acids

2004 ◽  
Vol 15 (3) ◽  
pp. 215-221 ◽  
Author(s):  
Liliana Aguilar-Castro ◽  
Margarita Tlahuextl ◽  
Antonio R. Tapia-Benavides ◽  
José Guadalupe Alvarado-Rodríguez
Keyword(s):  
Amino Acids ◽  
Structural Studies ◽  
X Ray ◽  
X Ray Crystallography
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