Mechanochemical reactions of fluorides with hemin

Paneque, Armando; Reguera, E.; Fernández‐Bertrán, J.; Yee‐Madeira, H.

doi:10.1016/s0022-1139(01)00398-0

Cited by 8 publications

(10 citation statements)

References 13 publications

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“…These reactions imply the destruction of intermolecular hydrogen bonds of carboxylic acid dimers. In the case of alkali fluorides [34,36], milling an acid-alkali fluoride mixture in 1:2 stoichiometric ratio was shown to result in a proton transfer with the formation of a carboxylate and a bifluoride acidic ion HF 2 Ϫ . In such reaction, the driving force was reported to be the formation of the HF 2 Ϫ anion [34,36].…”

Section: Solid-state Nmrmentioning

confidence: 99%

“…In the case of alkali fluorides [34,36], milling an acid-alkali fluoride mixture in 1:2 stoichiometric ratio was shown to result in a proton transfer with the formation of a carboxylate and a bifluoride acidic ion HF 2 Ϫ . In such reaction, the driving force was reported to be the formation of the HF 2 Ϫ anion [34,36]. Therefore, grinding a mixture of 2,5-DHB and caesium fluoride in a 1:1 ratio would give rise to a solid in which molecular organization (further referred to as Form I) can be described as 2,5-DHB caesium salt while fluoride anions are in strong interaction with H 3 O ϩ .…”

Section: Solid-state Nmrmentioning

confidence: 99%

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Solid state nuclear magnetic resonance as a tool to explore solvent-free MALDI samples

Pizzala

Barrère

Mazarin

et al. 2009

J. Am. Soc. Mass Spectrom.

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Solid-state Nuclear magnetic resonance (NMR) was used here to explore structural characteristics of samples to be subjected to matrix-assisted laser desorption/ionization (MALDI) and prepared without the use of any solvent. The analytical systems scrutinized in NMR were mixtures of a 2,5-dihydroxybenzoic acid (2,5-DHB) matrix and caesium fluoride (CsF), used as the cationization agent in synthetic polymer MALDI mass analysis, at different molar ratios (1:1, 5:1, and 10:1). Complementary information could be obtained from 13 C, 133 Cs, and 19 F NMR spectra. Grinding the matrix together with the salt in the solid state was shown to induce a strong modification in the molecular organization within the MALDI sample. The evidenced mechano-induced reactions allow strong interactions between the matrix and the cation, up to the formation of a salt, and only occur in the presence of some water molecules. Addition of a poly(ethylene oxide) polymer as the analyte did not further modify the observed molecular organizations. Although relative matrix and salt concentrations in the scrutinized samples were unusual for MALDI analysis, mass spectra of good quality could be obtained and revealed that cation attachment on polymers during the MALDI process is not a matrix-independent event since a lower ionization efficiency was obtained from highly organized solid samples, mostly consisting of 2,5-DHB caesium salt species. (J Am Soc Mass Spectrom 2009, 20, 1906 -1911) © 2009 American Society for Mass Spectrometry M atrix-assisted laser desorption/ionization (MALDI) is widely used as an efficient ionization method to characterize synthetic polymers by time-of-flight mass spectrometry (TOF MS) [1,2]. A key point in the success of a MALDI-MS analysis is sample preparation, that is, proper matrix and cation selection as well as solid-state organization. The matrix actually plays multiple roles in the MALDI process and should accordingly present specific properties. Some criteria are clearly defined, such as a strong absorptivity at the employed laser wavelength or good vacuum stability, while other requirements, such as a good miscibility of the matrix with the analyte in the solid state, are not easily related to physico-chemical parameters of the matrix. As a result, prediction for the optimal matrix-polymer system is still not possible and sample preparation methods are usually developed from published protocols that were shown to work for a given polymeric system [3]. In particular, solvent-free MALDI was recently proposed as an alternative to the conventional dried droplet method [4,5].Despite MALDI being a widely used technique, mechanisms underlying this desorption/ionization process are still not fully understood. To investigate the MALDI process, many studies have focused on sample morphology using different imaging experiments. Sample heterogeneity and distribution of molecules within the MALDI solid sample have been explored using microscopy techniques, such as optical microscopy [6,7], scanning electron microscopy [8 -...

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Section: Solid-state Nmrmentioning

confidence: 99%

Section: Solid-state Nmrmentioning

confidence: 99%

Solid state nuclear magnetic resonance as a tool to explore solvent-free MALDI samples

Pizzala

Barrère

Mazarin

et al. 2009

J. Am. Soc. Mass Spectrom.

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“…[246] 2-aminopyrimidine (2-Apy) may be ground with either one or two equivalents of CuCl 2 to form the complexes CuCl 2 (2-apy) and CuCl 2 (2-apy) 2 respectively, [248] and dimethylglyoxime (H 2 dmg) will react with NiX 2 (X = Cl, NO 3 ) to form [Ni(H 2 dmg) 2 ]X 2 . [249] Grinding thiourea or a derivative with silver salts AgX (X = NO 3 , SO 4 , ClO 4 ) gave compounds with various silver:thiourea ratios depending upon the stoichiometry used, [250] and whilst grinding PtCl 2 with imidazole (Him) gave [245] It is also possible to use more complicated metal precursors than simple salts; the iron(III) centre of the protoporphyrin complex hemin will coordinate two imidazole molecules [253] or two fluoride ions [254] upon co-grinding, and reaction of M(en)(NO 3 ) 2 (M = Pd, Pt; en = ethan-1,2-diamine) with 4,4′-bipyridine forms the tetranuclear square [M(bipy)(en)] 4 (NO 3 ) 8 (Scheme 26). [255] This last reaction illustrates the benefits that solid-state reactions can have over the equivalent solution reactions -formation of the platinum complex takes 4 weeks at 100 ºC in solution, but is complete in 10 minutes by grinding.…”

Section: Introductionmentioning

confidence: 99%

Mechanochemistry: opportunities for new and cleaner synthesis

et al. 2012

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Citation for published item:tmesD F vF nd edmsD gF tF nd folmD gF nd frgD hF nd gollierD F nd pri § s § i¡ D F nd qrepioniD pF nd rrrisD uF hF wF nd ryettD qF nd tonesD F nd uresD eF nd wkD tF nd winiD vF nd yrpenD eF qF nd rkinD sF F nd herouseD F gF nd teedD tF F nd ddellD hF gF @PHIPA 9wehnohemistry X opportunities for new nd lener synthesisF9D ghemil soiety reviewsFD RI @IAF ppF RIQERRUF Further information on publisher's website: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details.

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“…It seems that the basicity of the other amino acids is too low to remove a proton from the carboxylic groups of hemin in a solid state reaction. [21] The relatively low reactivity of His, which was expected to have a behavior similar to that reported for Imd, [17] may be due to its intra-and intermolecular hydrogen bonding interactions in the crystalline state. His crystallizes in two polymorphic forms, monoclinic and orthorhombic.…”

Section: Reactions Of Amino Acid Ligands With the Acidic Propionic Grmentioning

confidence: 86%

Mechano‐chemical Synthesis and Spectroscopic Characterization of Hemin Complexes with Some Amino Acids

Paneque¹,

Fernández‐Bertrán²,

Reguera

et al. 2003

Synthesis and Reactivity in Inorganic and Metal-Organic Chemist

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The mechano-chemical reactions of hemin with arginine (Arg), histidine (His), lysine (Lys), methionine (Met) and tryptophan (Trp) were monitored using IR and Mössbauer spectroscopies. According to IR spectra, with exception of Arg, these basic amino acids don´t react at the peripheral propionic acid groups of hemin which is related with their relatively low basicity. Arg also forms a penta-coordinated complex with hemin at the iron site, as revealed by the Mössbauer spectra of the hemin -Arg milled mixtures. The hemin -Arg solid state reaction is completed in 1:3 molar ratio suggesting that this is the stoichiometry of

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Mechanochemical reactions of fluorides with hemin

Cited by 8 publications

References 13 publications

Solid state nuclear magnetic resonance as a tool to explore solvent-free MALDI samples

Solid state nuclear magnetic resonance as a tool to explore solvent-free MALDI samples

Mechanochemistry: opportunities for new and cleaner synthesis

Mechano‐chemical Synthesis and Spectroscopic Characterization of Hemin Complexes with Some Amino Acids

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