International audienceThe catalytic hydrogenation of levulinic acid (LA) with formic acid (FA) as a hydrogen source into [gamma]-valerolactone (GVL) is considered as one of the crucial sustainable processes in today's biorefinery schemes. In the current work, we investigated the modification of Ru/C as efficient catalysts for both formic acid decomposition and levulinic acid hydrogenation in comparison with Pd and Pt catalysts. In order to better understand what features are responsible for high catalytic performance, we combined experimental tests, DFT calculations together with extensive material characterization. In LA hydrogenation with FA as a hydrogen source, the intermediate surface formate inhibits at least partially the LA hydrogenation. In addition, the FA decomposition is highly sensitive to the kind of the preparation method of the Ru/C catalyst: (i) the process looks structure sensitive favored on larger particles and (ii) residual chlorine decreases significantly the FA decomposition rate

DFT calculations highlight the role of co-adsorbed ammonia in catalytic activity in the amination of alcohols by ammonia.

Bisthienoazepinedione (BTA) has been reported for constructing high-performing p-type conjugated polymers in organic electronics, but the ring extended version of BTA is not well explored. In this work, we report a new synthesis of a key building block to the ring expanded electron-deficient pentacyclic azepinedione (BTTA). Three copolymers of BTAA with benzodithiophene substituted by different side chains are prepared. These polymers exhibit similar energy levels and optical absorption in solution and solid state, while significant differences are revealed in their film morphologies and behavior in transistor and photovoltaic devices. The best-performing polymers in transistor devices contained alkylthienyl side chains on the BDT unit (pBDT-BTTA-2 and pBDT-BTTA-3) and demonstrated maximum saturation hole mobilities of 0.027 and 0.017 cm2 V–1 s–1. Blends of these polymers with PC71BM exhibited a best photovoltaic efficiency of 6.78% for pBDT-BTTA-3-based devices. Changing to a low band gap non-fullerene acceptor (BTP-eC9) resulted in improved efficiency of up to 13.5%. Our results are among the best device performances for BTA and BTTA-based p-type polymers and highlight the versatile applications of this electron-deficient BTTA unit.

We report the evaluation of density-functional-theory (DFT) based procedures for predicting 19F NMR chemical shifts at modest computational cost for a range of molecules with fluorine bonds, to be used as a tool for assisting the characterisation of reaction intermediates and products and as an aid to identifying mechanistic pathways. The results for a balanced learning set of molecules were then checked using two further testing sets, resulting in the recommendation of the ωB97XD/aug-cc-pvdz DFT method and basis set as having the best combination of accuracy and computational time, with a RMS error of 3.57 ppm. Cationic molecules calculated without counter-anion showed normal errors, whilst anionic molecules showed larger errors, possibly due to omission of the counter-cation. The method was applied to the prediction of the conformationally averaged 19F chemical shifts of 2,2,3,3,4,4,5,5-octafluoropentan-1-ol, in which gauche stereoelectronic effects involving fluorine dominate and to determining the position of coordination equilibria of fluorinated boranes as an aid to verifying the relative energies of intermediate species involved in catalytic amidation reactions involving boron catalysts.

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We report the evaluation of density-functional-theory (DFT) based procedures for predicting 19F NMR chemical shifts at modest computational cost for a range of molecules with fluorine bonds, to be used...

We report the evaluation of density-functional-theory (DFT) based procedures for predicting 19F NMR chemical shifts at modest computational cost for a range of molecules with fluorine bonds, to be used as a tool for assisting the characterisation of reaction intermediates and products and as an aid to identifying mechanistic pathways. The results for a balanced learning set of molecules were then checked using two further testing sets, resulting in the recommendation of the ωB97XD/aug-cc-pvdz DFT method and basis set as having the best combination of accuracy and computational time, with a RMS error of 3.57 ppm. Cationic molecules calculated without counter-anion showed normal errors, whilst anionic molecules showed larger errors, possibly due to omission of the counter-cation. The method was applied to the prediction of the conformationally averaged 19F chemical shifts of 2,2,3,3,4,4,5,5-octafluoropentan-1-ol, in which gauche stereoelectronic effects involving fluorine dominate and to determining the position of coordination equilibria of fluorinated boranes as an aid to verifying the relative energies of intermediate species involved in catalytic amidation reactions involving boron catalysts.

We report the evaluation of density-functional-theory (DFT) based procedures for predicting 19F NMR chemical shifts at modest computational cost for a range of molecules with fluorine bonds, to be used as a tool for assisting the characterisation of reaction intermediates and products and as an aid to identifying mechanistic pathways. The results for a balanced learning set of molecules were then checked using two further testing sets, resulting in the recommendation of the ωB97XD/aug-cc-pvdz DFT method and basis set as having the best combination of accuracy and computational time, with a RMS error of 3.57 ppm. Cationic molecules calculated without counter-anion showed normal errors, whilst anionic molecules showed larger errors, possibly due to omission of the counter-cation. The method was applied to the prediction of the conformationally averaged 19F chemical shifts of 2,2,3,3,4,4,5,5-octafluoropentan-1-ol, in which gauche stereoelectronic effects involving fluorine dominate and to determining the position of coordination equilibria of fluorinated boranes as an aid to verifying the relative energies of intermediate species involved in catalytic amidation reactions involving boron catalysts.