pH-Controlled recognition of amino acids by urea derivatives of β-cyclodextrin

Stępniak, Paweł; Lainer, Bruno; Chmurski, Kazimierz; Jurczak, Janusz

doi:10.1039/c7ra02127e

Cited by 10 publications

(8 citation statements)

References 30 publications

(28 reference statements)

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confidence: 99%

“…Specific complexants [14,15]; • Ions exchangers [16]; • Surfactants and microemulsions [17,18]; • Ionic liquids [19]; • Adsorbent nanoparticles (polymeric, metallic, oxide) [20][21][22]; • Magnetic nanoparticles [23,24]; • Proteins and enzymes [25,26]. Starting from these results, in the last decade, various membrane reaction systems were addressed, based on polymer and inorganic membranes, but especially on the composite ones, which improve the membrane efficiency in the separation processes, but also add the chemical transformation of the chemical species of interest and developing catalytic or bio-catalytic membrane reactors [27][28][29][30].…”

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confidence: 99%

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Reactional Processes on Osmium–Polymeric Membranes for 5–Nitrobenzimidazole Reduction

et al. 2021

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Membranes are associated with the efficient processes of separation, concentration and purification, but a very important aspect of them is the realization of a reaction process simultaneously with the separation process. From a practical point of view, chemical reactions have been introduced in most membrane systems: with on-liquid membranes, with inorganic membranes or with polymeric and/or composite membranes. This paper presents the obtaining of polymeric membranes containing metallic osmium obtained in situ. Cellulose acetate (CA), polysulfone (PSf) and polypropylene hollow fiber membranes (PPM) were used as support polymer membranes. The metallic osmium is obtained directly onto the considered membranes using a solution of osmium tetroxide (OsO4), dissolved in tert–butyl alcohol (t–Bu–OH) by reduction with molecular hydrogen. The composite osmium–polymer (Os–P)-obtained membranes were characterized in terms of the morphological and structural points of view: scanning electron microscopy (SEM), high-resolution SEM (HR–SEM), energy-dispersive spectroscopy analysis (EDAX), Fourier Transform Infra-Red (FTIR) spectroscopy, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The process performance was tested for reduction of 5–nitrobenzimidazole to 5–aminobenzimidazole with molecular hydrogen. The paper presents the main aspects of the possible mechanism of transformation of 5–nitrobenzimidazole to 5–aminobenzimidazole with hydrogen gas in the reaction system with osmium–polymer membrane (Os–P).

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confidence: 99%

Reactional Processes on Osmium–Polymeric Membranes for 5–Nitrobenzimidazole Reduction

et al. 2021

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“…[27] Based on this design, the same group studied a series of compounds and found binding affinities for non‐polar amino acids from 2300 M −1 for alanine to 54 800 M −1 for tryptophan. Importantly, carboxylates lacking the amino group remained not bound . The binding strength showed to be highly pH dependent with good affinities at pH 8 but almost no binding at pH 6.…”

Section: Cyclodextrinsmentioning

confidence: 96%

“…Importantly, carboxylates lacking the amino group remained not bound. [28] The binding strength showed to be highly pH dependent with good affinities at pH 8 but almost no binding at pH 6.…”

Section: Cyclodextrinsmentioning

confidence: 96%

Molecular Recognition of Zwitterions with Artificial Receptors

Alfonso

Solà

2020

Chemistry An Asian Journal

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Many biomolecules exist as internal ion pairs or zwitterions within a biologically relevant pH range. Despite their importance, the molecular recognition of this type of systems is specially challenging due to their strong solvation in aqueous media, and their trend to form folded or self‐assembled structures by pairing of charges of different sign. In this Minireview, we will discuss the molecular recognition of zwitterions using non‐natural, synthetic receptors. This contribution does not intend to make a full in‐depth revision of the existing research in the field, but a personal overview with selected representative examples from the recent literature.

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“…The enantiodiscrimination and inclusion complex formation of amino acids and amino-acid derivatives by CDs have been experimentally studied with different techniques such as electrospray mass spectrometry, capillary electrophoresis and gas chromatography (Ramanathan and Prokai, 1995 ; Boniglia et al, 2002 ). Experimental results also reveal the influence of organic modifiers and pH conditions on the enantiomer separation of amino acids and inclusion complex formation with CDs (Zia et al, 2001 ; Sebestyén et al, 2012 ; Stepniak et al, 2017 ). In particular, the chiral separation and inclusion complexes formed by valine, leucine, and isoleucine (among other amino acids, but not alanine) with partially methylated β-CD in gas-phase, have been analyzed both experimentally and theoretically (Ramirez et al, 2000 ).…”

Section: Introductionmentioning

confidence: 95%

Molecular Simulation of the Separation of Some Amino Acid Enantiomers by β-Cyclodextrin in Gas-Phase

Alvira

2020

Front. Chem.

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The complexes formed by β-cyclodextrin and some amino acids (alanine, valine, leucine, and isoleucine) in vacuo are studied by molecular mechanics and dynamics simulations. These methods have been improved with respect to our previous studies with amino acids, regarding the determination of molecular structures or initial enantiomer dispositions in the molecular dynamics trajectories. The greatest contribution to the interaction energy is from the van der Waals term, although the discrimination between enantiomers is due mainly to the electrostatic contribution. The lowest energy structures of the complexes obtained from molecular mechanics are inclusion complexes in which the carboxylic end of amino acids is pointing toward the narrow (D-) or wide rim (L-) of β-cyclodextrin. The position probability density provided by molecular dynamics also confirms inclusion complex formation, because the guests spend most time inside the cavity of β-cyclodextrin along its axis, with the carboxylic end pointing toward the narrow rim. The L-amino acids are the first eluted enantiomers in all cases and chiral discrimination increases with the size of guests, except leucine, which has the lowest capacity to discriminate. During the simulation, Ala and Val remain in weakly enantioselective regions, while Leu and Ile stay in zones with great chiral selectivity.

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pH-Controlled recognition of amino acids by urea derivatives of β-cyclodextrin

Abstract: Water soluble amphiphilic urea-substituted β-cyclodextrins were synthesized and applied as amino acid receptors.

Cited by 10 publications

References 30 publications

Reactional Processes on Osmium–Polymeric Membranes for 5–Nitrobenzimidazole Reduction

Reactional Processes on Osmium–Polymeric Membranes for 5–Nitrobenzimidazole Reduction

Molecular Recognition of Zwitterions with Artificial Receptors

Molecular Simulation of the Separation of Some Amino Acid Enantiomers by β-Cyclodextrin in Gas-Phase

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