0000000001317002
AUTHOR
Ibon Alkorta
Host–Guest Chemistry: Oxoanion Recognition Based on Combined Charge‐Assisted C−H or Halogen‐Bonding Interactions and Anion⋅⋅⋅Anion Interactions Mediated by Hydrogen Bonds
Several bis-triazolium-based receptors have been synthesized and their anion-recognition capabilities have been studied. The central chiral 1,1'-bi-2-naphthol (BINOL) core features either two aryl or ferrocenyl end-capped side arms with central halogen- or hydrogen-bonding triazolium receptors. NMR spectroscopic data indicate the simultaneous occurrence of several charge-assisted aliphatic and heteroaromatic C-H noncovalent interactions and combinations of C-H hydrogen and halogen bonding. The receptors are able to selectively interact with HP2 O7 (3-) , H2 PO4 (-) , and SO4 (2-) anions, and the value of the association constant follows the sequence: HP2 O7 (3-) >SO4 (2-) >H2 PO4 (-) . The …
About the evaluation of the local kinetic, potential and total energy densities in closed-shell interactions
Abstract The local kinetic G( r ) , potential V( r ) and total E( r ) energy densities, calculated at the critical points of 37 H⋯F closed-shell interactions by quantum mechanical methods, have been compared to their estimated values obtained by using an approximate evaluation of G( r ) and the local form of the virial theorem. The results presented here show very small differences between the corresponding quantities, and therefore support the validity of the estimations. Thus, the equations used in this procedure provide useful information for topological studies of experimental electron densities, permitting the evaluation of those energetic properties from the modelling of the topologic…
Comparison of electron density properties in frozen and relaxed electronic distributions.
Two kinds of electron densities for several small molecules (H(2), FH, CH(3)CH(3), CH(3)NH(2), CH(3)OH, and CH(3)F) have been generated for a wide range of bond distances. The first one, as the sum of the electron density of the isolated fragments, and the second one by optimizing the electron density at each given geometrical disposition. A number of properties of this two electronic distributions have been compared (position of the bond critical points, electron density, Laplacian, curvatures, and local energies). The differences, associated to the bond formation, are found to be very important for most of the cases.
The structure of ammonium pyrazolates in the solid state
The crystals obtained by mixing equimolar amounts of diethyl 1H-pyrazole-3,5-dicarboxylate and the primary amines phenethylamine and homoveratrylamine are ammonium pyrazolate salts as determined by 13C and 15N CPMAS NMR. Copyright © 2006 John Wiley & Sons, Ltd.
Correction: A C(π-hole)⋯Cl–Zn tetrel interaction driving a metal–organic supramolecular assembly
Correction for ‘A C(π-hole)⋯Cl–Zn tetrel interaction driving a metal–organic supramolecular assembly’ by Carmen Ramírez de Arellano et al., CrystEngComm, 2020, 22, 6979–6982, DOI: 10.1039/D0CE01272F.
Synthesis, Structure and Anion Sensing Properties of a Dicationic Bis(imidazolium)-Based Cyclophane
The preparation and sensing properties of a tetracyclic cyclophane receptor containing two imidazolium rings as anion binding sites and two fluorene rings as fluorescent signaling units, are reported. The receptor behaves as a selective fluorescent chemosensor molecule for inorganic phosphates. H-NMR spectroscopical data clearly indicate the simultaneous occurrence of charge-assisted aromatic and aliphatic C−H noncovalent interactions. PCM/DFT calculations have been carried out to predict the structures of the complexes formed with one and two molecules of PF , HPO and HPO .
3-(Pyridin-2-yl)[1,2,3]triazolo[1,5-a]quinoline: A Theoretical and Experimental Analysis of Ring-Chain Isomerisation
In the course of the synthesis of new fluorophores for molecular recognition an experimental (1H NMR) and theoretical (DFT) study of the ring-chain isomerism of 3-(pyridin-2-yl)[1,2,3]triazolo[1,5-a]quinoline derivatives (A) into 2-([1,2,3]triazolo[1,5-a]pyridin-3-yl)quinoline derivatives (B) has been carried out. The rearrangement is influenced by steric and electronic effects of the substituents present on the quinoline ring. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
3-(2-Pyridyl)-[1,2,3]triazolo[1,5-a]pyridines. An experimental and theoretical (DFT) study of the ring-chain isomerization
An experimental (1H NMR) and theoretical (DFT) study of the ring-chain-ring isomerization of 3-(2-pyridyl)-[1,2,3]triazolo[1,5-a]pyrid-7-yl derivatives (A) into 6-{[1,2,3]triazolo[1,5-a]pyrid-3-yl}-2-pyridyl derivatives (B) has been carried out. Based on the calculations, a mechanism of several steps will be proposed. The experimental results as well as the calculations lead to the conclusion that the A-B ratio depends on the electronic properties of the substituents. © The Royal Society of Chemistry 2005.
[1,2,3]Triazolo[1,5-a]pyridines. A theoretical (DFT) study of the ring-chain isomerization
The ring opening isomerization of [1,2,3]triazolo[1,5-a]pyridines to the corresponding 2-pyridyl derivatives has been studied by means of DFT calculations at the B3LYP/6-31+G(d,p) computational level. The effect of the substitution as well as those of protonation, deprotonation, and lithiation on different positions has been studied. The electronic characteristics of the optimized structures have been analyzed by means of the Atoms In Molecules (AIM), Electron Localization Function (ELF), Molecular Electrostatic Potential (MEP), and Natural Bond Orbital (NBO) methodologies. © 2008 Elsevier Ltd. All rights reserved.
A C(π-hole)⋯Cl-Zn tetrel interaction driving a metal-organic supramolecular assembly
A brominated pyrimidinyl triazolopyridine ligand (bptpy) forms a C(π-hole)⋯Cl-Zn tetrel interaction that plays a determining role in the formation of supramolecular layers through chain assembly in 18 membered metallacycle [(ZnCl2)2(μ-bptpy)2] crystals. Supramolecular chains are formed through C-H⋯X interactions. The observed interactions are supported by DFT calculations using model dimers. This journal is
[1,2,3]Triazolo[1,5-a]pyridyl phosphines reflecting the influence of phosphorus lone pair orientation on spectroscopic properties
A series of new triazolopyridine-based phosphines has been prepared. These compounds revealed unexpected spectroscopic patterns. In particular, the NMR spectra are highly dependent on the relative conformational preference of the phosphine substituent at C7. Here, we report on their complete NMR analysis, X-ray structures and DFT calculations that confirm the particular arrangement of the phosphorus lone pair orbital related to the substituent pattern of the chosen phosphine.
A theoretical and experimental study of the racemization process of hexaaza[5]helicenes
A dynamic 1H NMR study, together with DFT calculations, of bis-([1,2,3]triazolo)[1,5-a:5′,1′-k][1,10]phenanthroline 2 has allowed to identify the ring and open forms of a new example of ring/chain tautomerism, as well as their interconversion barriers (ring/ring and ring/open). The barrier of the exchange process between the chain forms and the ring form was found higher than the 'racemization' process in the closed form, so the ring opening does not contribute to the 'racemization'. The di-1,10-methyl and di-1,10-iodo derivatives have been prepared and their properties calculated.
CCDC 1821490: Experimental Crystal Structure Determination
Related Article: Paula Sabater, Faviola Zapata, Pedro Molina, Ibon Alkorta, Jose Elguero, Antonio Caballero, Carmen Ramirez de Arellano|2018|Chem. Sel.|3|3855|doi:10.1002/slct.201800809
CCDC 1448934: Experimental Crystal Structure Determination
Related Article: Lidia Gonzalez, Fabiola Zapata, Antonio Caballero, Pedro Molina, Carmen Ramirez de Arellano, Ibon Alkorta, Jose Elguero|2016|Chem.-Eur.J.|22|7533|doi:10.1002/chem.201600379
CCDC 1448935: Experimental Crystal Structure Determination
Related Article: Lidia Gonzalez, Fabiola Zapata, Antonio Caballero, Pedro Molina, Carmen Ramirez de Arellano, Ibon Alkorta, Jose Elguero|2016|Chem.-Eur.J.|22|7533|doi:10.1002/chem.201600379