Structure and dynamics of 1,4-dioxane-water binary solutions studied by X-ray diffraction, mass spectrometry, and NMR relaxation

1999 ◽  
Vol 83 (1-3) ◽  
pp. 163-177 ◽  
Author(s):  
Toshiyuki Takamuku ◽  
Atsushi Yamaguchi ◽  
Masaaki Tabata ◽  
Nobuyuki Nishi ◽  
Koji Yoshida ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Nmr Relaxation ◽  
X Ray Diffraction ◽  
Binary Solutions ◽  
X Ray ◽  
Structure And Dynamics

Structure of Clusters in Methanol-Water Binary Solutions Studied by Mass Spectrometry and X-ray Diffraction

2000 ◽  
Vol 55 (5) ◽  
pp. 513-525 ◽  
Author(s):  
Toshiyuki Takamuku ◽  
Toshio Yamaguchia ◽  
Masaki Asato ◽  
Masaki Matsumoto ◽  
Nobuyuki Nishi
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectra ◽  
Hydration Number ◽  
Heat Of Mixing ◽  
Adiabatic Expansion ◽  
X Ray Diffraction ◽  
Binary Solutions ◽  
X Ray ◽  
Inflection Points ◽  
Submicron Droplets

Abstract The structure of clusters in methanol-water solutions in its dependence on the methanol mole fraction xM has been investigated by mass spectrometry on clusters isolated from submicron droplets by adiabatic expansion in vacuum and by X-ray diffraction on the bulk binary solutions. The mass spectra have shown that the average hydration number, (nm), of m-mer methanol clusters decreases with increasing xM , accompanied by two inflection points at xM = ~0.3 and ~0.7. The X-ray diffraction data have revealed a similar change in the number of hydrogen bonds per water and/or methanol oxygen atom at ~2.8 Å. On the basis of both results, most likely models of clusters formed in the binary solutions are proposed: at 0 < xM < 0.3 the tetrahedral-like water cluster is the main species, at 0.3 < xM < 0.7 chain clusters of methanol molecules gradually evolve with increasing methanol content, and finally, at xM > 7 chain clusters of methanol become predominant. The present results are compared with clusters previously found in ethanol-water binary solutions and discussed in relation to anomalies of the heat of mixing of methanol-water binary solutions.

Structure of Clusters in Ethanol–Water Binary Solutions Studied by Mass Spectrometry and X-Ray Diffraction

1995 ◽  
Vol 68 (7) ◽  
pp. 1775-1783 ◽  
Author(s):  
Masaki Matsumoto ◽  
Nobuyuki Nishi ◽  
Toshiya Furusawa ◽  
Masaru Saita ◽  
Toshiyuki Takamuku ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
X Ray Diffraction ◽  
Binary Solutions ◽  
X Ray

scholarly journals Exploring the Structural Chemistry of Pyrophosphoramides: N,N′,N″,N‴-Tetraisopropylpyrophosphoramide

Chemistry ◽  
2021 ◽  
Vol 3 (1) ◽  
pp. 149-163
Author(s):  
Duncan Micallef ◽  
Liana Vella-Zarb ◽  
Ulrich Baisch
Keyword(s):  
Crystal Structure ◽  
Mass Spectrometry ◽  
Nuclear Magnetic Resonance ◽  
Hydrogen Bonding ◽  
Nmr Spectroscopy ◽  
Ir Spectroscopy ◽  
Room Temperature ◽  
Intermolecular Hydrogen Bonding ◽  
X Ray Diffraction ◽  
X Ray

N,N′,N″,N‴-Tetraisopropylpyrophosphoramide 1 is a pyrophosphoramide with documented butyrylcholinesterase inhibition, a property shared with the more widely studied octamethylphosphoramide (Schradan). Unlike Schradan, 1 is a solid at room temperature making it one of a few known pyrophosphoramide solids. The crystal structure of 1 was determined by single-crystal X-ray diffraction and compared with that of other previously described solid pyrophosphoramides. The pyrophosphoramide discussed in this study was synthesised by reacting iso-propyl amine with pyrophosphoryl tetrachloride under anhydrous conditions. A unique supramolecular motif was observed when compared with previously published pyrophosphoramide structures having two different intermolecular hydrogen bonding synthons. Furthermore, the potential of a wider variety of supramolecular structures in which similar pyrophosphoramides can crystallise was recognised. Proton (1H) and Phosphorus 31 (31P) Nuclear Magnetic Resonance (NMR) spectroscopy, infrared (IR) spectroscopy, mass spectrometry (MS) were carried out to complete the analysis of the compound.

scholarly journals A Covalent Organic Cage Compound Acting as a Supramolecular Shadow Mask for the Regioselective Functionalization of C60

2020 ◽  
Author(s):  
Viktoria Leonhardt ◽  
Stefanie Fimmel ◽  
Ana-Maria Krause ◽  
Florian Beuerle
Keyword(s):  
Mass Spectrometry ◽  
Single Crystal ◽  
High Selectivity ◽  
Shadow Mask ◽  
X Ray Diffraction ◽  
X Ray ◽  
Trigonal Bipyramidal ◽  
Cage Compound ◽  
Vis Spectroscopy ◽  
Regioselective Functionalization

<div><div><div><p>A trigonal-bipyramidal covalent organic cage compound serves as an efficient host to form stable 1:1-complexes with C60 and C70. Fullerene encapsulation has been comprehensively studied by NMR and UV/Vis spectroscopy, mass spectrometry as well as single-crystal X-ray diffraction. Exohedral functionalization of encapsulated C60 via threefold Prato reaction revealed high selectivity for the symmetry-matched all-trans-3 addition pattern.</p></div></div></div>

scholarly journals An N4-Tetradentate Hydrazone Ligand That Binds in a Neutral, Mono- and Bisdeprotonated Form to Iron(II) and Zinc(II) Metal Ions

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 982
Author(s):  
Devaraj Pandiarajan ◽  
Thomas Fox ◽  
Bernhard Spingler
Keyword(s):  
Mass Spectrometry ◽  
Coordination Chemistry ◽  
Transition Metals ◽  
Metal Ions ◽  
Elemental Analysis ◽  
X Ray Diffraction ◽  
Hydrazone Ligand ◽  
X Ray

The coordination chemistry of butane-2,3-dione bis (2′-pyridylhydrazone) towards the divalent first-row transition metals zinc and iron has been explored. Depending upon the conditions, the ligand in the six complexes was found to be either neutral, mono, or doubly deprotonated. The zinc(II) and iron(II) complexes were fully characterized by elemental analysis, mass spectrometry, and X-ray diffraction methods.

Synthesis, characterization, and structures of zircona- and boracyclosiloxanes with ferrocenyl substituents

2002 ◽  
Vol 80 (11) ◽  
pp. 1469-1480 ◽  
Author(s):  
Karena Thieme ◽  
Sara C Bourke ◽  
Juan Zheng ◽  
Mark J MacLachlan ◽  
Fojan Zamanian ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Differential Scanning Calorimetry ◽  
Thermogravimetric Analysis ◽  
Ring Opening ◽  
Ring Opening Polymerization ◽  
The Novel ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Multinuclear Nmr Spectroscopy

The novel zirconatetraferrocenylcyclotrisiloxane Cp2Zr(OSiFc2)2O (6), dizirconatetraferrocenylcyclotetrasiloxane [Cp2Zr(OSiFc2)O]2 (7), boratetraferrocenylcyclotrisiloxane (C6H5)B(OSiFc2)2O (8), and diboratetraferrocenylcyclotetrasiloxane [(C6H5)B(OSiFc2)O]2 (9) with ferrocenyl (Fc = Fe(η-C5H4)(η-C5H5)) substituents at silicon have been prepared from the reactions of Cp2Zr(NMe2)2 and PhBCl2 with diferrocenylsilanediol Fc2Si(OH)2 (3) and tetraferrocenyldisiloxanediol [Fc2SiOH]2O (5). The compounds were characterized by mass spectrometry, elemental analysis, UV–vis, IR, Raman, and multinuclear NMR spectroscopy, as well as single crystal X-ray diffraction. Thermogravimetric analysis and differential scanning calorimetry investigation of 6–9 showed that the cycles decompose before they can undergo any thermal ring-opening polymerization. In addition, no polymerization was detected in the presence of either KOSiMe3 or HOTf. The bulky ferrocenyl substituents on the Si atoms are likely to be at least partially responsible for the inability of these heterocycles to undergo ring-opening polymerization. Key words: heterocyclosiloxanes, ferrocenyl.

scholarly journals Slow cooling of protein crystals

2009 ◽  
Vol 42 (5) ◽  
pp. 944-952 ◽  
Author(s):  
Matthew Warkentin ◽  
Robert E. Thorne
Keyword(s):  
Ice Nucleation ◽  
Glycerol Solution ◽  
X Ray Diffraction ◽  
Slow Cooling ◽  
Sodium Potassium ◽  
X Ray ◽  
Structure And Dynamics ◽  
Potassium Tartrate ◽  
Flash Cooling ◽  
Diffraction Patterns

Cryoprotectant-free thaumatin crystals have been cooled from 300 to 100 K at a rate of 0.1 K s−1– 103–104times slower than in conventional flash cooling – while continuously collecting X-ray diffraction data, so as to follow the evolution of protein lattice and solvent properties during cooling. Diffraction patterns show no evidence of crystalline ice at any temperature. This indicates that the lattice of protein molecules is itself an excellent cryoprotectant, and with sodium potassium tartrate incorporated from the 1.5 Mmother liquor ice nucleation rates are at least as low as in a 70% glycerol solution. Crystal quality during slow cooling remains high, with an average mosaicity at 100 K of 0.2°. Most of the mosaicity increase occurs above ∼200 K, where the solvent is still liquid, and is concurrent with an anisotropic contraction of the unit cell. Near 180 K a crossover to solid-like solvent behavior occurs, and on further cooling there is no additional degradation of crystal order. The variation ofBfactor with temperature shows clear evidence of a protein dynamical transition near 210 K, and at lower temperatures the slope dB/dTis a factor of 3–6 smaller than has been reported for any other protein. These results establish the feasibility of fully temperature controlled studies of protein structure and dynamics between 300 and 100 K.

scholarly journals 2.2.5.5-Tetraorganyl-1.4-dioxa-2.5-disilacyclohexane/2,2,5,5-Tetraorganyl-1,4-dioxa-2,5-disilacyclohexanes

1983 ◽  
Vol 38 (2) ◽  
pp. 190-193 ◽  
Author(s):  
Reinhold Tacke ◽  
Hartwig Lange ◽  
Anke Bentlage ◽  
William S. Sheldrick ◽  
Ludger Ernst
Keyword(s):  
Molecular Structure ◽  
Mass Spectrometry ◽  
Diffraction Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Elemental Analyses

Abstract The 2,2,5,5-tetraorganyl-1,4-dioxa-2,5-disilacyclohexanes 2a-2c were prepared by condensation of the corresponding (hydroxymethyl)diorganylsilanes 1 a-1 c. The constitution of the heterocycles was confirmed by elemental analyses, cryoscopic measurements, mass spectrometry, and NMR-spectroscopic (1H, 13C) investigations. The molecular structure of 2 b was determined by X-ray diffraction analysis.

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