Mild pretreatment and enzymatic saccharification of cellulose with recycled ionic liquids towards one-batch process.

The development of second-generation bioethanol involves minimizing the energy input throughout the processing steps. We report here that efficient ionic liquid pretreatments of cellulose can be achieved with short duration times (20 min) at mild temperature (45°C) with [Emim](+)[MeO(H)PO(2)](-) and at room temperature (25 °C) with [Emim](+)[CH(3)COO](-). In these conditions, yields of glucose were increased by a factor of 3. In addition, the recycling of these two imidazolium-based ILs can be performed in maintaining their efficiency to pretreat cellulose. The short time and mild temperature of cellulose solubilization allowed a one-batch processing of [Emim](+)[MeO(H)PO(2)](-) IL-pretreatment and saccharification. In the range from 0 to 100% IL in an aqueous enzymatic medium, the glucose yields were improved at IL proportions between 10 and 40%. The maximum yield at 10% IL is very promising to consider one batch process as efficient as two-step process.

Enzymatic hydrolysis of ionic liquid-pretreated celluloses: contribution of CP-MAS 13C NMR and SEM.

The supramolecular structure of four model celluloses was altered prior to their enzymatic saccharification using two ionic liquid pretreatments: one with the commonly used 1-ethyl-3-methylimidazolium acetate ([Emim](+)[CH(3)COO](-)) and the other with the newly developed 1-ethyl-3-methylimidazolium methylphosphonate ([Emim](+)[MeO(H)PO(2)](-)). The estimation of crystallinity index (CrI) by solid state (13)C nuclear magnetic resonance for each untreated/pretreated celluloses was compared with the performances of their enzymatic hydrolysis. For α-cellulose, both pretreatments led to a significant decrease in CrI from 25% to 5% but had no effect on glucose yields. In contrast, The [Emim](+)[MeO(H)PO(2)](-) pretreatment on the long fibers of cellulose had no significant effect on the CrI although a conversion yield in glucose of 88% is obtained versus 32% without pretreatment. However, scanning electron microscopy analysis suggested a loss of fiber organization induced by both ionic liquid pretreatments leading to a larger accessibility by cellulases to the cellulose surface.

An inconvenient influence of iridium(III) isomer on OLED efficiency.

The recently reported heteroleptic cyclometallated iridium(III) complex [Ir(2-phenylpyridine)(2)(2-carboxy-4-dimethylaminopyridine)] N984 and its isomer N984b have been studied more in detail. While photo- and electrochemical properties are very similar, DFT/TDDFT calculations show that the two isomers have different HOMO orbital characteristics. As a consequence, solution processed OLEDs made using a mixture of N984 and isomer N984b similar to vacuum processed devices show that the isomer has a dramatic detrimental effect on the performances of the device. In addition, commonly used thermogravimetric analysis is not suitable for showing the isomerization process. The isomer could impact performances of vacuum processed OLEDs using heteroleptic cyclometallated iridium(III) complexes as dopant.