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Dive into the research topics where Ulrich Darbost is active.

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Featured researches published by Ulrich Darbost.


Organic and Biomolecular Chemistry | 2009

Biomimetic and self-assembled calix[6]arene-based receptors for neutral molecules

David Coquière; Stéphane Le Gac; Ulrich Darbost; Olivier Sénèque; Ivan Jabin; Olivia Reinaud

The selective recognition of substrates or cofactors is a key feature of biological processes. It involves coordination bonds, hydrogen bonding, charge/charge and charge/dipole interactions. In this Perspective, we describe how the calix[6]arene core can be functionalized and shaped to act as a biomimetic molecular receptor. The strategy relies on the selective introduction of three amino arms on alternate phenolic positions. Upon metal ion binding or self-assembly via multiple ion-pairing and H-bonding, these amino arms are projected towards each other, thus closing the calixarene small rim. The resulting cone-shaped receptors act as molecular funnels displaying high affinities for a variety of neutral guests. Their hosting properties can be finely tuned by changing the small or the large rim or by allosteric effects. Induced-fit processes are also often observed as the cavity can expand for large guests or shrink for small ones. Hence, the different families of calix[6]arene-based receptors presented here highlight the importance of having a flexible and polarized hydrophobic structure to accommodate the guest.


Supramolecular Chemistry | 2005

A Calix[6]arene Receptor Rigidified by a Self-assembled Triammonium Cap: X-ray and NMR Characterization of the Binding of Polar Neutral Guests

Ulrich Darbost; Michel Giorgi; Nicolas Hucher; Ivan Jabin; Olivia Reinaud

A calix[6]arene has been rigidified by three primary ammonium arms self-assembled with the counter anions. This supramolecular edifice provides a well-defined conic hydrophobic cavity closed at the narrow rim by a tricationic site. X-ray and NMR analyses show that the resulting polarized host behaves as a remarkable endo-receptor for small molecules such as amides, alcohols and even nitriles. This study highlights the efficiency of a system that associates a cationic site with a hydrophobic cavity to host dipolar neutral molecules.


Journal of Organic Chemistry | 2012

Ipso-Nitration of calix[6]azacryptands: intriguing effect of the small rim capping pattern on the large rim substitution selectivity.

Manuel Lejeune; Jean-François Picron; Alice Mattiuzzi; Angélique Lascaux; Stéphane De Cesco; Andrea Brugnara; Grégory Thiabaud; Ulrich Darbost; David Coquière; Benoit Colasson; Olivia Reinaud; Ivan Jabin

The ipso-nitration of calix[6]arene-based molecular receptors is a important synthetic pathway for the elaboration of more sophisticated systems. This reaction has been studied for a variety of capped calixarenes, and a general trend for the regioselective nitration of three aromatic units out of six in moderate to high yield has been observed. This selectivity is, in part, attributed to the electronic connection between the protonated cap at the small rim and the reactive sites at the large rim. In addition, this work highlights the fact that subtle conformational properties can drastically influence the outcome of this reaction.


Journal of Organic Chemistry | 2010

Easy and selective method for the synthesis of various mono-O-functionalized calix[4]arenes: de-O-functionalization using TiCl4.

Joackim Bois; Jeff Espinas; Ulrich Darbost; Caroline Felix; Christian Duchamp; Denis Bouchu; Mostafa Taoufik; Isabelle Bonnamour

An efficient and selective method for the monofunctionalization of p-tert-butylcalix[4]arene is described. A mono-de-O-functionalization of disubstituted p-tert-butylcalix[4]arenes using titanium tetrachloride was developed to synthesize a series of monosubstituted p-tert-butylcalix[4]arenes with the pendant functions being ethoxycarbonylmethyloxy, 3-ethoxycarbonylpropyloxy, cyanomethyloxy, 3-cyanopropyloxy, 4-bromobutyloxy, 3-hydroxypropyloxy, propyloxy, 2-methylpropyloxy, 3-butynyloxy, and 3-cyanopropyloxy groups. The reaction mechanism of the formation of 5,11,17,23-tetra-tert-butyl-26,27,28-trihydroxy-25-(3-ethoxycarbonylpropyloxy) calix[4]arene was studied by (1)H NMR and GC/mass spectroscopy monitoring. Reaction of TiCl4 with the disubstituted p-tert-butylcalix[4]arene produced the corresponding dioxocalix[4]arene titanium dichloride complex, which undergoes elimination of ethyl 4-chlorobutyrate, leading to a trioxocalix[4]arene titanium dichloride complex and to monosubstituted calix[4]arene after hydrolysis. These two complexes were also synthesized, isolated, and fully characterized.


New Journal of Chemistry | 2016

Copper complexes bearing an NHC–calixarene unit: synthesis and application in click chemistry

Benjamin Ourri; Olivier Tillement; Tao Tu; Erwann Jeanneau; Ulrich Darbost; I. Bonnamour

The synthesis of N-heterocyclic carbene (NHC) copper complexes supported by calix[4]arene is reported. Mono-substituted calix[4]arene was prepared through conventional procedures, followed by the attachment of an imidazolyl group to create the precursor of NHC ligands. Alkylation with two alkyl bromides followed by metalation resulted in fully characterized original complexes. The X-ray structure showed an “out” conformation for copper. The catalytic activity of the complexes was studied in click chemistry, and revealed good performances. In particular, three new triazoles were synthesized in high yields, under solvent-free conditions and a fast reaction time. The newly synthesized chiral complex was tested in the kinetic resolution of racemic azide.


Chemistry: A European Journal | 2014

Eaton’s Reagent‐Mediated Domino π‐Cationic Arylations of Aromatic Carboxylic Acids to Iasi‐Red Polymethoxylated Polycyclic Aromatic Hydrocarbons: Products with Unprecedented Biological Activities as Tubulin Polymerization Inhibitors

Alina Ghinet; Philippe Gautret; Nathalie Van Hijfte; Bertrand Ledé; Jean-Pierre Hénichart; Elena Bîcu; Ulrich Darbost; Benoît Rigo; Adam Daïch

A rapid domino π-cationic arylation of aromatic carboxylic acids, mediated by Eatons reagent, has been developed for the synthesis of Iasi-red polymethoxylated polycyclic aromatic hydrocarbons (PAHs). This route is currently the easiest method to obtain such popular PAH compounds, which bear in addition numerous methoxy groups. The domino process was generalized, the structure of the obtained red products and the mechanism of their formations were elucidated, and some of their photophysical properties were determined. Newly synthesized polymethoxylated-PAHs were tested for their interaction with tubulin polymerization as well as for their cytotoxicity on a panel of NCI-60 human cancer cell lines. Interestingly, one of these rubicene derivatives exhibited remarkable cytotoxicity in vitro, including inhibition of leukemia, colon, melanoma, CNS, and ovarian cancer cell lines with GI50 values in the low nanomolar range (GI50 < 10 nM).


Transition Metal Chemistry | 2016

Synthesis and crystal structures of palladium(II) complexes of bis-(N-heterocyclic carbenes) on a calix[4]arene platform

Hui Ren; Benjamin Ourri; Erwann Jeanneau; Tao Tu; Isabelle Bonnamour; Ulrich Darbost

A series of calix[4]arene supported N-heterocyclic carbene palladium complexes were successfully prepared and characterised. Their X-ray crystal structures were obtained and are discussed. Notably, the dimeric compound b[5-(3-N-4,5-diphenylimidazol-2-yliden-1-yl)-25,26,27,28-tetrapropyloxy calix[4]arene] palladium(II) dibromide (cone) showed pseudo-polymorphism.


Chemistry: A European Journal | 2011

Selectivity among Two Lectins: Probing the Effect of Topology, Multivalency and Flexibility of “Clicked” Multivalent Glycoclusters

Samy Cecioni; Sophie Faure; Ulrich Darbost; I. Bonnamour; Hélène Parrot-Lopez; Olivier Roy; Claude Taillefumier; Michaela Wimmerová; Jean-Pierre Praly; Anne Imberty; Sébastien Vidal


Journal of the American Chemical Society | 2005

Polarizing a Hydrophobic Cavity for the Efficient Binding of Organic Guests: The Case of Calix[6]tren, a Highly Efficient and Versatile Receptor for Neutral or Cationic Species

Ulrich Darbost; Marie-Noëlle Rager; Samuel Petit; Ivan Jabin; Olivia Reinaud


Journal of Organic Chemistry | 2005

Optically pure calix[6]tris-ammoniums: syntheses and host-guest properties toward neutral guests.

Ulrich Darbost; Xianshun Zeng; Michel Giorgi; Ivan Jabin

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Isabelle Bonnamour

Centre national de la recherche scientifique

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Ivan Jabin

Université libre de Bruxelles

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Olivia Reinaud

Paris Descartes University

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Guy Royal

Centre national de la recherche scientifique

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Mostafa Taoufik

Centre national de la recherche scientifique

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