α,α-Difluorophosphonohydroxamic Acid Derivatives among the Best Antibacterial Fosmidomycin Analogues.

Three α,α-difluorophosphonate derivatives of fosmidomycin were synthesized from diethyl 1,1-difluorobut-3-enylphosphonate and were evaluated on Escherichia coli. Two of them are among the best 1-deoxy-d-xylulose 5-phosphate reductoisomerase inhibitors, with IC50 in the nM range, much better than fosmidomycin, the reference compound. They also showed an enhanced antimicrobial activity against E. coli on Petri dishes in comparison with the corresponding phosphates and the non-fluorinated phosphonate.

Innate promiscuity of the CYP706 family of P450 enzymes provides a suitable context for the evolution of dinitroaniline resistance in weed.

Increased metabolism is one of the main causes for evolution of herbicide resistance in weeds, a major challenge for sustainable food production. The molecular drivers of this evolution are poorly understood. We tested here the hypothesis that a suitable context for the emergence of herbicide resistance could be provided by plant enzymes with high innate promiscuity with regard to their natural substrates. A selection of yeast-expressed plant cytochrome P450 enzymes with well documented narrow to broad promiscuity when metabolizing natural substrates was tested for herbicide metabolism competence. The positive candidate was assayed for capacity to confer herbicide tolerance in Arabidopsis thaliana. Our data demonstrate that Arabidopsis thaliana CYP706A3, with the most promiscuous activity on monoterpenes and sesquiterpenes for flower defence, can also oxidize plant microtubule assembly inhibitors, dinitroanilines. Ectopic overexpression of CYP706A3 confers dinitroaniline resistance. We show, in addition, that the capacity to metabolize dinitroanilines is shared by other members of the CYP706 family from plants as diverse as eucalyptus and cedar. Supported by three-dimensional (3D) modelling of CYP706A3, the properties of enzyme active site and substrate access channel are discussed together with the shared physicochemical properties of the natural and exogenous substrates to explain herbicide metabolism.

Synthesis by direct arylation of thiazole-derivatives: regioisomer configurations-optical properties relationship investigation.

The synthesis of thiazole(Tz)-based regioisomer materials using selective direct arylation to avoid any protection steps has been developed. A series of trimers in which the Tz groups sandwich either an electron-rich or an electron-deficient unit, with a regioselective orientation of the respective Tz unit, has therefore been synthesized. This chemical strategy has also been followed to synthesize a second series of pentamers in which the Tz group is used as a π-conjugated bridge between an electron-rich central unit and electron-deficient end-capping groups and vice versa. On both trimers and pentamers, the effect of Tz orientation on the conjugation properties of the synthesized materials was investigated by a combination of experimental measurements and density functional theory calculations. This study highlights that control of the orientation of the Tz unit leads to the synthesis of the most conjugated regioisomer derivative. The present work gives chemical synthesis tools for the synthesis of selectively oriented Tz-based materials as well as a general guideline for the design of Tz-based materials with the highest conjugation length, including the Tz-orientation effect.

Synthesis and thin film phase behaviour of functional rod-coil block copolymers based on poly(para-phenylenevinylene) and poly(lactic acid).

We report the synthesis of a series of block copolymers consisting of a rod-like semiconducting poly(2,5-di(2'-ethylhexyloxy)-1,4-phenylenevinylene) (DEH-PPV) block and a flexible poly(lactic acid) (PLA) block that can be selectively degraded under mild conditions. Such selectively degradable block copolymers are designed as self-assembling templates for bulk heterojunction donor-acceptor layers in organic solar cells. A lamellar microphase-separated domain structure was identified for block copolymers with PLA volume fractions between 29 and 79% in bulk and thin films using SAXS, TEM, and AFM. Depending on the ratio of the two blocks we find either lamellae oriented parallel or perpendicular to the substrate in thin films.