Analyzing the n→π* Electronic Transition of Formaldehyde in Water. \ud A Sequential Monte Carlo/Time-Dependent Density Functional Theory

The n→π* absorption transition of formaldehyde in water is analyzed using combined and sequential classical Monte Carlo (MC) simulations and quantum mechanics (QM) calculations. MC simulations generate the liquid solute-solvent structures for subsequent QM calculations. Using time-dependent density functional theory in a localized set of gaussian basis functions (TD-DFT/6-311++G(d,p)) calculations are made on statistically relevant configurations to obtain the average solvatochromic shift. All results presented here use the electrostatic embedding of the solvent. The statistically converged average result obtained of 2300 cm-1 is compared to previous theoretical results available. Analysis is made of the effective dipole moment of the hydrogen-bonded shell and how it could be held responsible for the polarization of the solvent molecules in the outer solvation shells.A transição eletrônica n→π* do formaldeído em água é analisada usando-se um procedimento combinado e seqüencial de Monte Carlo (MC) clássico e mecânica quântica (MQ). MC é usado para gerar configurações do líquido para uso posterior em cálculos de MQ. Usando-se a representação espectral da teoria do funcional da densidade com uma base de funções gaussianas localizadas (TD-DFT/6-311++G(d,p)) cálculos são realizados em configurações estatisticamente descorrelacionadas para se obter o deslocamento solvatocrômico. Todos os resultados são obtidos usando-se uma representação onde o solvente é tratado como um campo eletrostático. O resultado médio obtido de 2300 cm-1 é comparado com resultados teóricos anteriores. Análise é feita do valor do momento de dipolo efetivo da camada associada com as ligações de hidrogênio e como ela pode influenciar as camadas de solvatação mais externas

Fluoroalkenes : synthesis & applications

National audienc

Focus on Fluoroacrylates

International audienc

Fluoroalkenes : synthesis & applications

National audienc

Synthèse et applications des fluoroalcènes : des peptidomimétiques aux hétérocycles

National audienc

Focus on Fluoroacrylates

International audienc

Fluorinated Pseudopeptides

International audienc

Synthesis of tetrasubstituted α-fluoroenones

International audienceWe reported the synthesis of tetrasubstituted α-fluoroenones from tetrasubstituted gem-bromofluoroolefins in good yields. These compounds are scarcely studied in the literature, due to difficulty of synthesis, whereas they could serve as intermediates in the synthesis of biological relevant molecules and could also be envisioned to design new constrained peptidomimetics

Chiral dipeptide mimics possessing a fluoroolefin moiety: a relevant tool for conformational and medicinal studies

International audienceThe replacement of the amide bond in a peptide backbone is a promising strategy in peptidomimetic drug research. Over the various amide bond surrogates, the fluoroolefin moiety has been successfully developed as an effective mimic. Today, fluorine-containing compounds account for a large proportion of new active molecules in life sciences. The synthesis of fluoroolefin peptide mimics is not a trivial task and innovative approaches often need to be addressed, in particular for the stereocontrol of the double bond configuration and the chiral centres adjacent to the fluoroalkene. These fluorinated peptidomimetics have been synthesised and evaluated as metabolically stable and/or conformationally constrained analogs of enzyme inhibitors, and as tools for probing the function, structure, and binding process of receptors

Synthesis of a library of SCF2CO2Et reagents: An access to original (ethoxycarbonyl)difluoromethylthioesters

International audienceA library of original and shelf-stable reagents, source of the (ethoxycarbonyl)difluoromethylthio group, is reported. These reagents are applied to the functionalization of a large panel of aldehydes via a transition metal-free protocol under mild reaction conditions. This approach offers an efficient access to valuable difluoromethylthioester derivatives