摘要：Three kinds of 4-hydroxyl azobenzene compouds with different substituents varied as -NO2, -H, -OCH3 in the para-position were synthesized and characterized. Their nonlinear optical properties in tetrahydrofuran (THF) and chloroform (CHCl3) solution were determined using Z-scan technique. The results revealed that the nonlinear absorption (β) and nonlinear refraction (γ) values of three azobenzene compounds in THF solution were larger than those in CHCl3 solution. It was mainly due to the regular arrangement and effective π-conjugation of azobenzene molecules caused by the formation of hydrogen bonds between the hydroxyl groups of azobenzene molecules and the oxygen atom of the THF molecules. Among three kinds of azobenzene compounds, the 4-nitro-4′-hydroxyazobenzene (NAzoOH) had the largest coefficients of β and γ values in both THF and CHCl3 solution. It was mainly because that a push-pull (D-π-A) electron system was formed by the electron withdrawing nitro-substituent with electron donating hydroxyl-group in both extremities of azobenzene, resulting in a higher electron delocalization.

摘要：Rational engineering of oxygen vacancy(VO) at atomic precision is the key to comprehensively understanding the oxygen chemistry of oxide materials for catalytic oxidations. Here, we demonstrate that VO can be spatially confined on the surface through a sophisticated surface hydrogen bond(HB) *** HB network is constructed between a hydroxyl-rich Bi OCl surface and polyprotic phosphoric acid,which remarkably decreases the formation energy of surface VO by selectively weakening the metal–oxygen bonds in a short range. Thus, surface-confined VO enables us to unambiguously distinguish the intrafacial and suprafacial oxygen species associated with NO oxidation in two classical catalytic *** randomly distributed bulk VO that benefits the thermocatalytic NO oxidation and lattice O diffusion by the dominant intrafacial mechanism, surface VOis demonstrated to favor the photocatalytic NO oxidation through a suprafacial scheme by energetically activating surface O2, which should be attributed to the spatial confinement nature of surface VO.

摘要：Non-ionic deep eutectic solvents(DESs)are non-ionic designer solvents with various applications in catalysis,extraction,carbon capture,and ***,discovering new DES candidates is challenging due to a lack of efficient tools that accurately predict DES *** search for DES relies heavily on intuition or trial-and-error processes,leading to low success rates or missed *** that hydrogen bonds(HBs)play a central role in DES formation,we aim to identify HB features that distinguish DES from non-DES systems and use them to develop machine learning(ML)models to discover new DES *** first analyze the HB properties of 38 known DES and 111 known non-DES systems using their molecular dynamics(MD)simulation *** analysis reveals that DES systems have two unique features compared to non-DES systems:The DESs have①more imbalance between the numbers of the two intra-component HBs and②more and stronger inter-component *** on these results,we develop 30 ML models using ten algorithms and three types of HB-based *** model performance is first benchmarked using the average and minimal receiver operating characteristic(ROC)-area under the curve(AUC)*** also analyze the importance of individual features in the models,and the results are consistent with the simulation-based statistical ***,we validate the models using the experimental data of 34 *** extra trees forest model outperforms the other models in the validation,with an ROC-AUC of *** work illustrates the importance of HBs in DES formation and shows the potential of ML in discovering new DESs.

摘要：Sluggish water dissociation kinetics severely limits the rate of alkaline electrocatalytic hydrogen evolution reaction(HER).Therefore,finding highly active electrocatalysts and clarifying the mechanism of water dissociation are challenging but *** this study,we report an integrated nanoporous nickel(np-Ni)catalyst with high alkaline HER performance and the origin of the corresponding enhanced catalytic *** 1 mol L^(-1) KOH solution,this np-Ni electrode shows an HER overpotential of 20 mV at 10 mA cm^(-2),along with fast water dissociation *** excellent performance is not only attributed to the large surface area provided by the three-dimensional interconnected conductive network but also from the enhanced intrinsic activity induced by the unique surface *** studies reveal that the types of oxygen species that naturally form on the Ni surface play a key role in water ***,when the lattice oxygen almost disappears,the Ni surface terminates with_(ads)orbed oxygen(O_(ads)),exhibiting the fastest water dissociation *** functional theory calculation suggests that when O_(ads)acts as the surface termination of Ni metal,the orientation and configuration of polar water molecules are strongly affected by O_(ads).Finally,the H–OH bond of interfacial water molecules is effectively activated in a manner similar to hydrogen *** work not only identifies a high-performance and low-cost electrocatalyst but also provides new insights into the chemical processes underlying water dissociation,thus benefiting the rational design of electrocatalysts.

摘要：High-energy-density(HED)fuels(***-10)are of great importance in safeguarding territorial air security,since they can increase the flight range and payload of military *** reduce the reliance on limited petroleum source,the production of HED fuel with renewable biomass feedstocks is highly *** currently,most of the synthetic biofuels,due to their intrinsic ring structure,are incapable of competing with JP-10 in terms of energy density and freezing *** emulating the structural characteristic of JP-10,we herein design and prepare a special C16 fused tetracyclic biofuel using renewable cyclopentanone and benzoquinone as *** to success depends on selective dehydration of vicinal diol(dimer of cyclopentanone)over Amberlyst-15 in[Hmim]*** Amberlyst-15/[Hmim]Cl system effectively suppresses the dominant pinacol-type rearrangement pathway and also exhibits good reusability for the *** hydrogen-bonding interaction between vicinal diol and imidazolium ring,as well as electrostatic force between carbocation intermediate and chloride anion contribute to the high diene *** compact ring framework gives rise to a density of 0.966 g/mL,combustion heat of 43.1 MJ/L,freezing point of‒67℃,and kinematic viscosity of 12.4 cSt,which are comparable to the properties of *** is expected that this as-prepared HED biofuel may potentially serve as a renewable alternative to petroleum fuel JP-10.

摘要：Three 3,3＇-di（4-substituted-phenyl）-1,1＇-isophthaloylbis（thiourea） compounds were designed as novel neutral anion receptors, and synthesized by simple steps in good yields. The single crystal structure of receptor 1 shows that a solvent molecule was captured by the host molecule through intermolecular hydrogen bonding. Moreover, it was self-assembled as a supramolecular system for the presence of abundant inter- and intramolecular hydrogen bonding and π-π interactions between phenyl groups. Their application as anion receptors has been examined by UV-Vis and ^1H NMR spectroscopy, showing that they had a higher selectivity for fluoride than other halides. The host and guest formed a 1 ： 1 stoichiometry complex through hydrogen bonding interactions in the first step, then following a process of deprotonation in presence of an excess of F^- in the solvent of DMF.

摘要：The interaction between a gas molecule and photocatalyst is vital to trigger photocatalytic *** surface state of photocatalyst affects much in this ***,adsorption of H2O molecules on s-triazine-based g-C3N4 was thoroughly studied by first-principle *** various initial adsorption models with multifarious locations of H2O molecules were built,the optimized models with strong adsorption energy pointed to the same adsorption configuration,in which the H2O molecule hold an upright orientation above the corrugated g-C3N4 *** intermolecular O-H…N hydrogen bond formed via the binding of a polar O-H bond in H2O molecule and a two-coordinated electron-rich nitrogen atom in *** the bridging effect of this intermolecular hydrogen bond,electrons would transfer from g-C3N4 to the H2O molecule,thereby lowering the Fermi level and enlarging work function of ***,regardless of the substitute,i.e.g-C3N4 multilayer,large supercell and nanotube,this adsorption system was highly reproducible,as its geometry structure and electronic property remained *** addition,the effect of nonmetal element doping on adsorption energy was *** work not only disclosed a highly preferential H2O adsorbed g-C3N4 architecture established by intermolecular hydrogen bond,but also contributed to the deep understanding and optimized design in water-splitting process on g-C3N4-based photocatalysts.

摘要：The history of antiparallel coiled coil dimer design is briefly reviewed and the main principles governing the successful designs are explained. They include analysis of the inter subunit electrostatic repulsion for determining partners for dimerization and of the buried polar interaction for determining the relative orientation of the partners. A theory is proposed to explain the lack of antiparallel coiled coil homodimers in nature. 