Enantioselective adsorption of ibuprofen enantiomers using chiral-active carbon nanoparticles induced S-α-methylbenzylamine.

The chiral media is crucial to the chiral recognition and separation of enantiomers. In this study, we report the preparation of novel chiral carbon nanoparticles (CCNPs) via surface passivation using glucose as the carbon source and S-(-)-α-methylbenzylamine as the chiral ligand. The structures of the obtained CCNPs are characterized via FT-IR, Raman spectroscopy, DLS, XPS, XRD, TEM, and zeta potential analysis. These CCNPs could be employed as the chiral adsorbent and used for the enantioselective adsorption of the ibuprofen enantiomers. The results demonstrated that the CCNPs could selectively adsorb R-enantiomer from ibuprofen racemate solution and give an enantiomeric excess (e.e.) of about 50% under an optimal adsorption condition. Moreover, the regeneration efficiency of the CCNPs remained above e.e. of 43% after the fifth cycle. The present work confirmed that the prepared CCNPs show great potential in the enantioselective separation of ibuprofen racemate.

The Influence of Special Environments on SiC MOSFETs.

In this work, the influences of special environments (hydrogen gas and high temperature, high humidity environments) on the performance of three types of SiC MOSFETs are investigated. The results reveal several noteworthy observations. Firstly, after 500 h in a hydrogen gas environment, all the SiC MOSFETs exhibited a negative drift in threshold voltage, accompanied by an increase in maximum transconductance and drain current (@ VGS/VDS = 13 V/3 V). This phenomenon can be attributed to that the hydrogen atoms can increase the positive fixed charges in the oxide and increase the electron mobility in the channel. In addition, high temperature did not intensify the impact of hydrogen on the devices and electron mobility. Instead, prolonged exposure to high temperatures may induce stress on the SiO2/SiC interface, leading to a decrease in electron mobility, subsequently reducing the transconductance and drain current (@ VGS/VDS = 13 V/3 V). The high temperature, high humidity environment can cause a certain negative drift in the devices' threshold voltage. With the increasing duration of the experiment, the maximum transconductance and drain current (@ VGS/VDS = 18V (20 V)/3 V) gradually decreased. This may be because the presence of moisture can lead to corrosion of the devices' metal contacts and interconnects, which can increase the devices' resistance and lead to a decrease in the devices' maximum transconductance and drain current.

High Thermoelectric Performance Achieved in Sb-Doped GeTe by Manipulating Carrier Concentration and Nanoscale Twin Grains.

Lead-free and eco-friendly GeTe shows promising mid-temperature thermoelectric applications. However, a low Seebeck coefficient due to its intrinsically high hole concentration induced by Ge vacancies, and a relatively high thermal conductivity result in inferior thermoelectric performance in pristine GeTe. Extrinsic dopants such as Sb, Bi, and Y could play a crucial role in regulating the hole concentration of GeTe because of their different valence states as cations and high solubility in GeTe. Here we investigate the thermoelectric performance of GeTe upon Sb doping, and demonstrate a high maximum zT value up to 1.88 in Ge0.90Sb0.10Te as a result of the significant suppression in thermal conductivity while maintaining a high power factor. The maintained high power factor is due to the markable enhancement in the Seebeck coefficient, which could be attributed to the significant suppression of hole concentration and the valence band convergence upon Sb doping, while the low thermal conductivity stems from the suppression of electronic thermal conductivity due to the increase in electrical resistivity and the lowering of lattice thermal conductivity through strengthening the phonon scattering by lattice distortion, dislocations, and twin boundaries. The excellent thermoelectric performance of Ge0.90Sb0.10Te shows good reproducibility and thermal stability. This work confirms that Ge0.90Sb0.10Te is a superior thermoelectric material for practical application.

Regioselective photocyclization to prepare multifunctional blocks for ladder-conjugated materials.

Multifunctional building blocks 8 and 9 were efficiently synthesized by fusing a perylene-3,4,9,10-tetracarboxylic acid bisimide (PBI) core with o-phenylenediamine, and they were condensed with a pyrenedione and a pyrenetetraone, respectively, to construct new ladder-type conjugated oligomers 12 and 13. In the key photocyclization step, an unusual regioselectivity at the position ortho to the nitro group was discovered in the coupling of the o-nitroaniline functional units at the bay sites of PBI. Bulk-heterojunction solar cells based on 12 and 13 as the acceptors exhibited reasonable performance.

Structures, protonation, and electrochemical properties of diiron dithiolate complexes containing pyridyl-phosphine ligands.

Diiron complexes containing pyridyl-phosphine ligands, that is, (mu-pdt)[Fe(2)(CO)(5)L] (pdt = S(CH(2))(3)S, L = Ph(2)PCH(2)Py, Ph(2)PPy, ) and (micro-pdt)[Fe(CO)(2)(PMe(3))][Fe(CO)(2)L] (L = Ph(2)PCH(2)Py, Ph(2)PPy, ) were prepared as model complexes of the [FeFe]-hydrogenase active site. Protonation of and by HOTf afforded the pyridyl-nitrogen protonated products [H(N)][OTf] and [H(N)][OTf], respectively. The molecular structures of, as well as [H(N)][OTf] and [H(N)][OTf] were confirmed by X-ray diffraction studies, which show that the Ph(2)PCH(2)Py ligand occupies the basal position both in and its protonated species [H(N)][OTf], while the Ph(2)PPy ligand prefers the apical position in and [H(N)][OTf]. The double protonation process of complex was monitored by in situ IR, (1)H and (31)P NMR spectroscopy at low temperature. The spectroscopic evidence indicates that the protonation of occurs first at the Fe-Fe bond and then at the pyridyl-nitrogen atom. Cyclic voltammograms reveal that protonation of and results in a considerable decrease in the overpotential for electrocatalytic proton reduction in the presence of HOTf, while the efficiency is not influenced by protonation. The electrocatalytic efficiency of for proton reduction in the presence of HOAc in CH(3)CN-H(2)O (50 : 1, v/v) is 5 times higher than that in pure CH(3)CN.