Defective hierarchical porous copper-based metal-organic frameworks synthesised via facile acid etching strategy

Introducing hierarchical pore structure to microporous materials such as metal-organic frameworks (MOFs) can be beneficial for reactions where the rate of reaction is limited by low rates of diffusion or high pressure drop. This advantageous pore structure can be obtained by defect formation, mostly via post-synthetic acid etching, which has been studied extensively on water-stable MOFs. Here we show that a water-unstable HKUST-1 MOF can also be modified in a corresponding manner by using phosphoric acid as a size-selective etching agent and a mixture of dimethyl sulfoxide and methanol as a dilute solvent. Interestingly, we demonstrate that the etching process which is time- and acidity- dependent, can result in formation of defective HKUST-1 with extra interconnected hexagonal macropores without compromising on the bulk crystallinity. These findings suggest an intelligent scalable synthetic method for formation of hierarchical porosity in MOFs that are prone to hydrolysis, for improved molecular accessibility and diffusion for catalysis.Comment: 14 pages, 8 figure

Ferrocene-Containing Polycarbosilazanes via the Alkaline-Earth-Catalyzed Dehydrocoupling of Silanes and Amines

We report the use of the alkaline-earth (Ae) metal-catalyzed dehydrocoupling of silanes and amines for the synthesis of ferrocene-containing polycarbosilazanes. The barium complex [Ba(N(SiMe 3) 2) 2·(THF) 2] catalyzed the dehydrocoupling of the hydrosilane FeCp(CpSiPhH 2) (1) with 1,4-(H 2NCH 2) 2C 6H 4 under mild conditions to give a polycarbosilazane with pendant ferrocene groups. The polymer could be readily cross-linked by the addition of phenylsilane to the unquenched reaction mixture. Well-defined polycarbosilazanes with ferrocene in the main chain were also obtained from the dehydrocoupling of hydrosilanes Fe(Cp(SiPhH 2)) 2 (3) and Fe(Cp(SiMe 2H)) 2 (IX) with 1,4-(H(Me)NCH 2) 2C 6H 4 and 1,4-(H 2NCH 2) 2C 6H 4, respectively. Crystalline monomeric analogues, FeCp(Cp(SiPh(NHBn) 2)) (2, Bn = CH 2(C 6H 5)), and Fe(Cp(SiPh(NHBn) 2)) 2 (4), were also obtained via the dehydrocoupling benzylamine with 1 and 3, respectively. The barium-catalyzed dehydrocoupling of diaminoferrocene with Ph 2SiH 2 or Ph(Rc)SiH 2 (6, Rc = (C 5H 4)Ru(C 5H 5)) did not result in polymer, but instead in the formation of the silazane-bridged ansa-[3]ferrocenophanes (Fe(ν-C 5H 4NH) 2SiPh 2) (5) and (Fe(ν-C 5H 4NH) 2SiPh(Rc)) (7), respectively. Both polymeric and molecular products were electrochemically investigated, and the polymers proved to be promising precursors to magnetic iron-containing ceramics in yields of up to 64%. </p

Ferrocene-Containing Polycarbosilazanes via the Alkaline-Earth-Catalyzed Dehydrocoupling of Silanes and Amines

We report the use of the alkaline-earth (Ae) metal-catalyzed dehydrocoupling of silanes and amines for the synthesis of ferrocene-containing polycarbosilazanes. The barium complex [Ba(N(SiMe 3) 2) 2·(THF) 2] catalyzed the dehydrocoupling of the hydrosilane FeCp(CpSiPhH 2) (1) with 1,4-(H 2NCH 2) 2C 6H 4 under mild conditions to give a polycarbosilazane with pendant ferrocene groups. The polymer could be readily cross-linked by the addition of phenylsilane to the unquenched reaction mixture. Well-defined polycarbosilazanes with ferrocene in the main chain were also obtained from the dehydrocoupling of hydrosilanes Fe(Cp(SiPhH 2)) 2 (3) and Fe(Cp(SiMe 2H)) 2 (IX) with 1,4-(H(Me)NCH 2) 2C 6H 4 and 1,4-(H 2NCH 2) 2C 6H 4, respectively. Crystalline monomeric analogues, FeCp(Cp(SiPh(NHBn) 2)) (2, Bn = CH 2(C 6H 5)), and Fe(Cp(SiPh(NHBn) 2)) 2 (4), were also obtained via the dehydrocoupling benzylamine with 1 and 3, respectively. The barium-catalyzed dehydrocoupling of diaminoferrocene with Ph 2SiH 2 or Ph(Rc)SiH 2 (6, Rc = (C 5H 4)Ru(C 5H 5)) did not result in polymer, but instead in the formation of the silazane-bridged ansa-[3]ferrocenophanes (Fe(ν-C 5H 4NH) 2SiPh 2) (5) and (Fe(ν-C 5H 4NH) 2SiPh(Rc)) (7), respectively. Both polymeric and molecular products were electrochemically investigated, and the polymers proved to be promising precursors to magnetic iron-containing ceramics in yields of up to 64%. </p

Green and sustainable devulcanization of ground tire rubber using choline chloride–urea deep eutectic solvent †

This work describes the devulcanization of ground tire rubber (GTR) with particle sizes ranging from 0.6 to 0.122 mm using a non-toxic, biodegradable, and biocompatible deep eutectic solvent (DES) based on choline chloride and urea. In addition to reducing the environmental impact of the process, other goals of this study were to minimize time and energy consumption. To meet these targets, a new de-vulcanization method has been developed. The methodology consists of using probe and bath sonication. The de-vulcanized rubber samples were then characterized using attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), electron dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM). Flory–Rehner and Horikx analyses were also carried out to calculate the devulcanization percentage and investigate the successful devulcanization of the samples through selective crosslink scission. The results showed that rubber samples of 120 mesh (0.122 mm) were devulcanized up to 58% by using 182 W power only during a 30 minutes process

Green and sustainable devulcanization of ground tire rubber using choline chloride–urea deep eutectic solvent †

This work describes the devulcanization of ground tire rubber (GTR) with particle sizes ranging from 0.6 to 0.122 mm using a non-toxic, biodegradable, and biocompatible deep eutectic solvent (DES) based on choline chloride and urea. In addition to reducing the environmental impact of the process, other goals of this study were to minimize time and energy consumption. To meet these targets, a new de-vulcanization method has been developed. The methodology consists of using probe and bath sonication. The de-vulcanized rubber samples were then characterized using attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), electron dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM). Flory–Rehner and Horikx analyses were also carried out to calculate the devulcanization percentage and investigate the successful devulcanization of the samples through selective crosslink scission. The results showed that rubber samples of 120 mesh (0.122 mm) were devulcanized up to 58% by using 182 W power only during a 30 minutes process

Vagus nerve stimulation: State of the art of stimulation and recording strategies to address autonomic function neuromodulation

International audienceObjective. Neural signals along the vagus nerve (VN) drive many somatic and autonomic functions. The clinical interest of VN stimulation (VNS) is thus potentially huge and has already been demonstrated in epilepsy. However, side effects are often elicited, in addition to the targeted neuromodulation. Approach. This review examines the state of the art of VNS applied to two emerging modulations of autonomic function: heart failure and obesity, especially morbid obesity. Main results. We report that VNS may benefit from improved stimulation delivery using very advanced technologies. However, most of the results from fundamental animal studies still need to be demonstrated in humans