scholarly journals Dihomooxacalix[4]arene-Based Fluorescent Receptors for Anion and Organic Ion Pair Recognition

Molecules ◽  
2020 ◽  
Vol 25 (20) ◽  
pp. 4708
Author(s):  
Alexandre S. Miranda ◽  
Paula M. Marcos ◽  
José R. Ascenso ◽  
Mário N. Berberan-Santos ◽  
Rachel Schurhammer ◽  
...  
Keyword(s):  
Chiral Recognition ◽  
Aminobutyric Acid ◽  
Quantum Mechanical ◽  
Anion Receptor ◽  
Binding Properties ◽  
Cone Conformation ◽  
X Ray ◽  
Biologically Relevant ◽  
Alkylammonium Salts ◽  
Fluorescence Titrations

Fluorescent dihomooxacalix[4]arene-based receptors 5a–5c, bearing two naphthyl(thio)ureido groups at the lower rim via a butyl spacer, were synthesised and obtained in the cone conformation in solution. The X-ray crystal structures of 1,3- (5a) and 3,4-dinaphthylurea (5b) derivatives are reported. Their binding properties towards several anions of different geometries were assessed by 1H-NMR, UV-Vis absorption and fluorescence titrations. Structural and energetic insights of the naphthylurea 5a and 5b complexes were also obtained using quantum mechanical calculations. The data showed that all receptors follow the same trend, the association constants increase with the anion basicity, and the strongest complexes were obtained with F−, followed by the oxoanions AcO− and BzO−. Proximal urea 5b is a better anion receptor compared to distal urea 5a, and both are more efficient than thiourea 5c. Compounds 5a and 5b were also investigated as heteroditopic receptors for biologically relevant alkylammonium salts, such as the neurotransmitter γ-aminobutyric acid (GABA·HCl) and the betaine deoxycarnitine·HCl. Chiral recognition towards the guest sec-butylamine·HCl was also tested, and a 5:2 selectivity for (R)-sec-BuNH3+·Cl− towards (P) or (M) enantiomers of the inherently chiral receptor 5a was shown. Based on DFT calculations, the complex [(S)-sec-BuNH3+·Cl−/(M)-5a] was indicated as the more stable.

scholarly journals The X-ray Crystal Structure and Putative Ligand-derived Peptide Binding Properties of γ-Aminobutyric Acid Receptor Type A Receptor-associated Protein

2001 ◽  
Vol 277 (7) ◽  
pp. 5556-5561 ◽  
Author(s):  
David Knight ◽  
Richard Harris ◽  
Mark S. B. McAlister ◽  
John P. Phelan ◽  
Stella Geddes ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Peptide Binding ◽  
Type A ◽  
Aminobutyric Acid ◽  
Receptor Type ◽  
Binding Properties ◽  
Acid Receptor ◽  
X Ray ◽  
Receptor Associated Protein

Crystal Forms of Semisynthetic Ergot Alkaloid Terguride

2002 ◽  
Vol 67 (4) ◽  
pp. 479-489 ◽  
Author(s):  
Michal Hušák ◽  
Bohumil Kratochvíl ◽  
Ivana Císařová ◽  
Ladislav Cvak ◽  
Alexandr Jegorov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Ergot Alkaloid ◽  
Simplified Model ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
X Ray Diffraction ◽  
Torsion Angles ◽  
Crystal Forms ◽  
X Ray ◽  
Independent Molecules

Two new structures of semisynthetic ergot alkaloid terguride created by unusual number of symmetry-independent molecules were determined by X-ray diffraction methods at 150 K. Form A (monoclinic, P212121, Z = 12) contains three symmetry-independent terguride molecules and two molecules of water in the asymmetric part of the unit cell. The form CA (monoclinic, P21, Z = 8) is an anhydrate remarkable by the presence of four symmetry-independent molecules in the crystal structure. Conformations of twelve symmetry-independent molecules that were found in four already described terguride structures are compared with torsion angles obtained by ab initio quantum-mechanical calculations for the simplified model of N-cyclohexyl-N'-diethylurea.

X-ray Crystallographic Study of Alkylammonium Anthracene-9-carboxylates as a Model for Fibrous Structure of Binary Anthracene Salt Gels

2004 ◽  
Vol 69 (6) ◽  
pp. 1292-1300 ◽  
Author(s):  
Tahahiro Tani ◽  
Kazuki Sada ◽  
Masatsugu Ayabe ◽  
Yuya Iwashita ◽  
Takanori Kishida ◽  
...  
Keyword(s):  
Alkyl Chain ◽  
Columnar Structure ◽  
Hydrogen Bond Network ◽  
One Dimensional ◽  
X Ray ◽  
Crystallographic Study ◽  
Alkylammonium Salts ◽  
Bond Network ◽  
Fibrous Assemblies ◽  
Long Alkyl Chain

Crystal structure of hexylammonium anthracene-9-carboxylate was investigated. The salt was arranged by a one-dimensional hydrogen bond network to form a columnar structure in the crystalline state. This columnar structure should be the model of fibrous assemblies in the organogels of anthracene-9-carboxylate alkylammonium salts having a long alkyl chain.

scholarly journals Chirality, Gelation Ability and Crystal Structure: Together or Apart? Alkyl Phenyl Ethers of Glycerol as Simple LMWGs

Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 732
Author(s):  
Alexander A. Bredikhin ◽  
Aidar T. Gubaidullin ◽  
Zemfira A. Bredikhina ◽  
Robert R. Fayzullin ◽  
Olga A. Lodochnikova
Keyword(s):  
Self Assembly ◽  
Chiral Recognition ◽  
Soft Materials ◽  
Gelling Agent ◽  
Low Molecular Weight ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Types ◽  
Low Molecular Weight Gelators ◽  
Phenyl Ethers

Chiral recognition plays an important role in the self-assembly of soft materials, in particular supramolecular organogels formed by low molecular weight gelators (LMWGs). Out of 14 pairs of the studied racemic and enantiopure samples of alkyl-substituted phenyl ethers of glycerol, only eight enantiopure diols form the stable gels in nonane. The formation of gels from solutions was studied by polarimetry, and their degradation with the formation of xerogels was studied by the PXRD method. The revealed crystalline characteristics of all studied xerogels corresponded to those for crystalline samples of the parent gelators. In addition to those previously investigated, crystalline samples of enantiopure para-n-alkylphenyl glycerol ethers [alkyl = pentyl (5), hexyl (6), heptyl (7), octyl (8), nonyl (9)] and racemic 3-(3,5-dimethylphenoxy)propane-1,2-diol (rac-14) have been examined by single crystal X-ray diffraction analysis. Among 22 samples of compounds 1-14 studied by SC-XRD, seven different types of supramolecular motifs are identified, of which only two are realized in crystals of supramolecular gelators. An attempt was made to relate the ability to gel formation with the characteristics of the supramolecular motif of a potential gelling agent, and the frequency of formation of the motif, required for gelation, with the chiral characteristics of the sample.

scholarly journals Topology of the Electron Density and of Its Laplacian from Periodic LCAO Calculations on f-Electron Materials: The Case of Cesium Uranyl Chloride

Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4227
Author(s):  
Alessandro Cossard ◽  
Silvia Casassa ◽  
Carlo Gatti ◽  
Jacques K. Desmarais ◽  
Alessandro Erba
Keyword(s):  
Electron Density ◽  
Chemical Bonding ◽  
Topological Analysis ◽  
Theoretical Description ◽  
Basis Functions ◽  
Quantum Mechanical ◽  
X Ray Diffraction ◽  
X Ray ◽  
Atomic Orbitals ◽  
Uranyl Chloride

The chemistry of f-electrons in lanthanide and actinide materials is yet to be fully rationalized. Quantum-mechanical simulations can provide useful complementary insight to that obtained from experiments. The quantum theory of atoms in molecules and crystals (QTAIMAC), through thorough topological analysis of the electron density (often complemented by that of its Laplacian) constitutes a general and robust theoretical framework to analyze chemical bonding features from a computed wave function. Here, we present the extension of the Topond module (previously limited to work in terms of s-, p- and d-type basis functions only) of the Crystal program to f- and g-type basis functions within the linear combination of atomic orbitals (LCAO) approach. This allows for an effective QTAIMAC analysis of chemical bonding of lanthanide and actinide materials. The new implemented algorithms are applied to the analysis of the spatial distribution of the electron density and its Laplacian of the cesium uranyl chloride, Cs2UO2Cl4, crystal. Discrepancies between the present theoretical description of chemical bonding and that obtained from a previously reconstructed electron density by experimental X-ray diffraction are illustrated and discussed.

scholarly journals X-ray structure of a molecular basket. Origin of its poor binding properties

1993 ◽  
Vol 112 (6) ◽  
pp. 400-403 ◽  
Author(s):  
C. F. Martens ◽  
R. P. Sijbesma ◽  
R. J. M. Klein Gebbink ◽  
R. J. M. Nolte ◽  
A. L. Spek
Keyword(s):  
Binding Properties ◽  
X Ray

2,3-Ethylene-bridged dihomooxacalix[4]arenes: synthesis, X-ray crystal structures and highly selective binding properties with anions

2018 ◽  
Vol 42 (13) ◽  
pp. 10689-10696 ◽  
Author(s):  
Lin An ◽  
Jia-wei Wang ◽  
Chan Wang ◽  
Shan-shan Zhou ◽  
Jing Sun ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Binding Properties ◽  
Selective Binding ◽  
X Ray

Three novel 2,3-ethylene-bridged p-tert-butyldihomooxacalix[4]arenes 3a–3c were selectively synthesized by direct O-alkylation of p-tert-butyldihomooxacalix[4]arene 1 with excess of 1,2-dibromoethane in controlled basic systems.

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