Two new organic-inorganic hybrid materials based on the polyoxotungstoaluminates

Two new organic-inorganic hybrid compounds, {[Cu(2,2′-bipy)₂]₂(Hbpy)[α-AlW₁₂O₄₀]}·H₂O (1) and {[H₂en][Cu^I(4,4′-bipy)]₃(α-AlW₁₂O₄₀)}·4H₂O (2) (2,2′-bipy = 2,2′-bipyridine, 4,4′-bipy = 4,4′-bipyridine, py = pyridine, en = ethylene dimine) based on Keggin-type α-[AlW₁₂O₄₀]⁵⁻ polyoxoaions and transition-metal organoamine subunits, have been hydrothermally synthesized and characterized by elemental analysis, IR spectroscopy, thermal gravimetric analysis (TG), and single-crystal X-ray diffraction. In addition, the electrochemical properties and photocatalytic activity of compound 1 were studied. The structural analysis reveals that 1 shows a 1D infinite chain structure constructed from [α-AlW₁₂O₄₀]⁵⁻ polyoxoanions and {[Cu^II(2,2′-bipy)₂][Cu^II(2,2′-bipy)(py)]}⁴⁺ fragments, in which the remarkable aspect is that [α-AlW₁₂O₄₀]⁵⁻ polyoxoanion is modified in a fascinating symmetrical mode. Compound 2 displays an unprecedented 2D extended structure constructed from [α-AlW₁₂O₄₀]⁵⁻ polyoxoanions and 4,4′-bipy-Cu^I-4,4′-bipy linear chains, in which three - chain belts formed by three linear chains arranged Cu parallel connect alternately with [α-AlW₁₂O₄₀]⁵⁻ polyoxoanions. As far as we know, compounds 1 and 2 represent the first 1D and 2D extended hybrid materials constructed from 3d transition metals and polyoxotungstoaluminates linked through covalent bonds.     

Two new pH-controlled metal-organic frameworks based on polynuclear secondary building units with conformation-flexible cyclohexane-1,2,4,5-tetracarboxylate ligand

By regulating the pH values, two new zinc(II) coordination polymers, formulated as [Zn₄(μ₇-CTA^I)(μ₃-OH)(μ₂-OH)₃(H₂O)₂]_n·2n(H₂O) (1), [Zn₂(μ₇-CTA^II)(H₂O)₃]_n (2) have been prepared by a flexible ligand, cyclohexane-1,2,4,5-tetracarboxylic acid (H₄CTA) under hydrothermal conditions. Complex 1 exhibits a two-dimensional binodal (3,6)-connected topological network containing rare octanuclear zinc(II) clusters as the secondary building units (SBU1). Complex 2 displays a three-dimensional binodal (4,8)-connected topological network containing unusual Zn₄(COO)₆ secondary building units (SBU2). And importantly, the conformation of H₄CTA in 1 exhibits (a,e,e,a) fashion and transforms to thermodynamically more stable conformation (e,a,e,e) type in 2 by pH-controlled. In addition, both of the complexes show strong photoluminescence at room temperature, and may be good candidates for potential luminescence materials.     

ZSM-5(38)/Al-MCM-41复合分子筛对纤维素催化热解的影响

以纤维素为原料,以自制的不同硅铝比ZSM-5(38)/Al-MCM-41微-介孔复合分子筛为催化剂,在固定床反应器上进行了催化热解实验。采用XRD表征分子筛,采用GC-MS分析生物油成分,考查了催化剂的改变对生物质热解产物及生物油成分的影响。实验结果表明：添加催化剂后,生物油产率降低,且其含水率也有所增加。与未添加催化剂相比,生物油中D L-2,3-丁二醇有明显提高。其中,ZSM-5(38)/Al-MCM-41(20) 最有利于苯酚、愈创木酚 (2-甲氧基-苯酚) 的生成。此外,这几种催化剂均有利于小分子化合物的生成,其中,ZSM-5(38) 有利于C4~C5化合物的生成,微-介孔复合分子筛则有利于C6~C8化合物的生成。     

Progress in molecular modelling of DNA materials

The unique molecular recognition properties of DNA molecule, which store genetic information in cells, are responsible for the rise of DNA nanotechnology. In this article, we review the recent advances in atomistic and coarse-grained force fields along with simulations of DNA-based materials, as applied to DNA–nanoparticle assemblies for controlled material morphology, DNA–surface interactions for biosensor development and DNA origami. Evidently, currently available atomistic and coarse-grained representations of DNA are now at the stage of successfully reproducing and explaining experimentally observed phenomena. However, there is a clear need for the development of atomistic force fields which are robust at long timescales and in the improvement of the coarse-grained models.     

Triple‐Layer Structured Composite Separator Membranes with Dual Pore Structures and Improved Interfacial Contact for Sustainable Dye‐Sensitized Solar Cells

A composite separator membrane (CSM) with an A/B/A type layered structure, composed of a microporous electrolyte‐philic poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVdF‐HFP) gel layer (A) and a submicrometer porous polyethylene (PE) or a macroporous poly(ethylene terephthalate) (PET) non‐woven matrix (B), is introduced in a dye‐sensitized solar cell (DSSC). Commercially available PE and PET separator membranes (SMs) act as matrices that provide mechanical stability to the DSSC and permanent pore structures for facilitated ion transport. PVdF‐HFP is used as a microporous gelator for improved interfacial contact between the solid SM and the electrodes. The PVdF‐HFP gel impedes the charge recombination process between electron and I₃ ^? at the TiO₂/electrolyte interface, resulting in improved electron lifetimes. The DSSC assembled with the CSM exhibits high initial solar energy conversion efficiency (η, 6.1%) and stable η values over 1400 h, demonstrating good long term stability. The behaviors of the DSSC are attributed to the synergistic factors of the CSM, such as improved ion conductivity, electrolyte affinity, electrolyte retention capability, effective interfacial contact, and plausible passivation of the dyes. This study demonstrates a practical combination of short‐ and long‐term DSSC performance through the introduction of the CSM.     

Decreased Recombination Through the Use of a Non‐Fullerene Acceptor in a 6.4% Efficient Organic Planar Heterojunction Solar Cell

An optimization of several aspects of planar heterojunction solar cells based on boron subnaphthalocyanine chloride (SubNc) as a donor material is presented. The use of hexachlorinated boron subphthalocyanine chloride (Cl₆SubPc) as an alternative acceptor to C₆₀ allows for the simultaneous increase of the short‐circuit current, fill factor, and open‐circuit voltage compared to cells with fullerene acceptors. This is due to the complementary absorption of Cl₆SubPc versus SubNc, reduced recombination at the heterointerface, and improved energetic alignment. Furthermore, insertion of a thin diindeno[1,2,3‐cd:1′,2′,3′‐lm]perylene (DIP) layer at the anode results in a very significant 60% increase in photocurrent owing to reduced exciton quenching at the anode. The simultaneous improvement of all three solar cell para­meters results in a power conversion efficiency of 6.4% for a non‐fullerene planar heterojunction cell.     

High Performance Na0.5[Ni0.23Fe0.13Mn0.63]O2 Cathode for Sodium‐Ion Batteries

The synthesis of a new layered cathode material, Na_0.5[Ni_0.23Fe_0.13Mn_0.63]O₂, and its characterization in terms of crystalline structure and electrochemical performance in a sodium cell is reported. X‐ray diffraction studies and high resolution scanning electron microscopy images reveal a well‐defined P2‐type layered structure, while the electrochemical tests demonstrate excellent characteristics in terms of high capacity and cycle life. This performance, the low cost, and the environmental compatibility of its component poses Na_0.5[Ni_0.23Fe_0.13Mn_0.63]O₂ to be among the most promising materials for the next generation of sodium‐ion batteries.