Facile fabrication of asphaltene-derived graphene-polyurethane sponges for efficient and selective oil-water separation

Based on the natural graphene-structure in the raw asphaltene material, a graphene-polyurethane sponge (GPU) oil-absorption material was prepared via a facile and inexpensive route of dip-coated sponge carbonization, which used low-value petroleum asphlatene as the dip-coating reagent and polyurethane sponges as the template. The GPU presents high hydrophobic and super oleophilic properties, as well as the excellent oil absorption performance. And its chloroform absorption capacity could reach 123 times its original mass, which is significantly higher than that of most reported oil absorbents. Furthermore, the GPU exhibits good recyclability. It has the promising applications in the pollution control of spilt oil.     

Structure and coordination environment of the zinc complex with vanillin of double-stranded helix

The structure and coordination environment of unusually double-stranded helix of complex [Zn(C₈H₇O₃)₂(H₂O)₂] are studied experimentally and by the density functional theory (DFT) method. The Zn²⁺ ion coordinates six oxygen atoms of deprotonated vanillin and water molecules forming an octahedron. The intermolecular hydrogen bonds and π interactions of the vanillin fragments contributed to the formation of the double-stranded helical supramolecular structure in the crystal. Counterpoise geometric parameters of the calculation agree with the crystal structure determined by experiment. The stabilization energy between the donor and acceptor obtained from an analysis of natural bond orbitals of the indicated six ligand oxygen atoms act as electron donor to Zn²⁺ ion. The results of the density functional theory on the complex demonstrate that the different coordinated oxygen atoms, which have different chemical environment, distort the coordination octahedron. The text was submitted by the authors in English.     

Copper-mediated chelation-assisted ortho nitration of (hetero)arenes

A novel copper-mediated chelation-assisted ortho C-H nitration of (hetero)arenes has been developed for the first time, which used dioxygen as terminal oxidant and 1,2,3-TCP as solvent, leading to the synthesis of nitroaromatics with excellent regioselectivity and in good yields. Mechanistic investigations indicate a mechanism involving a four-centered transition state, with simultaneous cleavage of an ortho C-H bond and a N-O bond of the nitrate anion on the 2-arylpyridine-coordinated copper(II) complex.     

Similar or different: the same Spiro-core but different alkyl chains with apparently improved device performance of perovskite solar cells

By intelligently utilizing the odd-even effect existing in the melting points of alkanes as presented in the basic textbook of Organic Chemistry, different alkoxy groups were introduced to modify the structure of commercial Spiro-OMeTAD to give new Spiro derivatives of Spiro-OEtTAD, Spiro-OPrTAD, Spiro-OiPrTAD and Spiro-OBuTAD, with the aim to adjust the molecular packing status in perovskite solar cells as hole transporting compounds. Excitedly, with the introduction of ethoxy groups instead of the methoxy ones in Spiro-OMeTAD, Spiro-OEtTAD-based perovskite solar cells demonstrated the highest device performance of 20.16%, higher than that of Spiro-OMeTAD(18.64%).     

Synthesis, spectroscopic and electrochemical characteristics of a novel Schiff-base from saccharin and tryptophan

In the present work, a novel Schiff-base was synthesized by the reaction of saccharin with tryptophan and characterized by elemental analysis as well as UV-Vis, FT-IR, ¹H NMR spectroscopic data. The voltammetric behavior of Schiff-base was also studied on the hanging mercury drop electrode (HMDE) by using Square-Wave Voltammetry (SWV) and Cyclic Voltammetry (CV) techniques. The voltammograms of the Schiff-base exhibited two irreversible reduction peaks in Britton-Robinson buffer (pH 7.0–10.0) for the potential range from 0.0 V to ?1.4 V. These peaks which appeared at more positive potentials than the reduction peaks of tryptophan and saccharin, may be assigned to the cathodic reductions of C-N⁺ and >C=N- moieties of Schiffbase.     

Enantioseparation of amino acid derivatives on an immobilized network polymer derived from L-tartaric acid

Seven structurally related amino acid derivatives were successfully enantioseparated by HPLC with a commercially available column containing a chiral immobilized network polymer derived from L-tartaric acid. The experiments were carried out under normal-phase conditions. All the solutes could be baseline separated using n-hexane/2-propanol (95/5) as eluent at a flow rate of 1 ml/min at 25 degrees C, with reasonable retention time (<12 min). The effects of the polar alcohol modifier (type and content) in the mobile phase and the column temperature on the enantioseparation were studied. Apparent thermodynamic parameters were also calculated from the plots of ln alpha or ln k' versus 1/T. Some mechanistic aspects of chiral recognition were discussed with respect to the structures of the solutes. It was found that the enantioseparations are all enthalpy driven, and the N-acyl groups of the solutes have significant influence on the chiral recognition.     

Efficient subnanometric gold-catalyzed hydrogen generation via formic acid decomposition under ambient conditions

Formic acid (FA) has tremendous potential as a safe and convenient source of hydrogen for sustainable chemical synthesis and renewable energy storage, but controlled and efficient dehydrogenation of FA by a robust solid catalyst under ambient conditions constitutes a major challenge. Here, we report that a previously unappreciated combination of subnanometric gold and an acid-tolerant oxide support facilitates the liberation of CO-free H(2) from FA. Applying an ultradispersed gold catalyst comprising TEM-invisible gold subnanoclusters deposited on zirconia to a FA-amine mixture affords turnover frequencies (TOFs) up to 1590 per hour and a turnover number of more than 118,400 at 50 °C. The reaction was accelerated at higher temperatures, but even at room temperature, a significant H(2) evolution (TOFs up to 252 h(-1) after 20 min) can still be obtained. Preliminary mechanistic studies suggest that the reaction is unimolecular in nature and proceeds via a unique amine-assisted formate decomposition mechanism on Au-ZrO(2) interface.     

Unconventional multiple ring structure formation from evaporation-induced self-assembly of polymers

The formation of multiring deposits of poly(2-vinylpyridine) (P2VP) from the evaporation of a P2VP-(2,6-lutidine + water) drop on a glass substrate does not conform to the conventional pinning-depinning mechanism. Instead, ringlike deposits are formed when the droplet undergoes several cycles of spreading and receding where, for each spreading event, a P2VP ridge is formed at the contact line when the polymer flows toward the outward advancing edge. The complex interplay between an outward solutal-Marangoni flow due to a higher concentration of the polymer at the contact line and an inward solvent-Marangoni flow arising from the differences in volatilities and surface tensions of the pure solvent components plays an important role in enhancing the droplet spreading rate. The newly discovered surface patterning mechanism has important implications in the development of novel techniques for inducing self-assembly of functional materials from evaporating drops.