Table of Content

01 October 2021, Volume 37 Issue 5

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Editorial

Themed Issue on Women in Chemistry

CHI Lifeng, YU Jihong

2021, 37(5):  0.  doi:10.1007/s40242-021-5000-z

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Contents

Chemical Research in Chinese Universities Vol.37 No.5 October 2021

2021, 37(5):  1-0. 

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Reviews

Recent Progresses on the High Performance Organic Electrochemical Transistors

JIANG Xingyu, WANG Qi, WANG Zi, DONG Bin, HUANG Lizhen, CHI Lifeng

2021, 37(5):  975-988.  doi:10.1007/s40242-021-1306-0

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Organic electrochemical transistor(OECT) with bulk current modulation capability based on the ion penetration into the organic semiconducting channel exhibits unique features, including high transconductance, low voltage and large capacitance. The high current at a low voltage, together with the compatibility with aqueous environment, makes OECT particularly suitable for bioelectronic applications, such as biological interfacing, printed logic circuitry and neuromorphic devices. However, the operation mechanism and structure-performance relationship of OECT are rather complicated and remain unclear to date. One of the critical issues is the ion penetration and transportation process. This review focuses on the research progresses of how to improve the OECT performance specifically through materials design, interfacing and morphology modulation. Different strategies of promoting the ion doping process are compared and discussed in order to optimize the device performance so that a deep understanding of the OECT operation principle could be gained.



Surface-enhanced Raman Scattering of Self-assembled Superstructures

FENG Enduo, TIAN Yang

2021, 37(5):  989-1007.  doi:10.1007/s40242-021-1263-7

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Surface-enhanced Raman scattering(SERS) is a molecular specific spectroscopic technique that amplifies the Raman signal of absorbed molecules for up to 10¹⁰times. Over the past decades, SERS substrates experienced rapid growth, resulting in excellent development for SERS analysis. Because the surface plasmonic resonance coupling between individual materials can form a "hotspot" region to maximize the Raman signal, among many substrate construction strategies, self-assembly attracts more attention in constructing superstructures with strong, uniform and stable SERS activity. In addition, a number of plasmon-free nanomaterials with appropriate superstructures samely show enhanced SERS activity, which is primarily attributed to the formation of the optical resonator. This review aims to provide a scientific synopsis on the progress of self-assembled superstructures for SERS and ignite new dis˗ coveries in the SERS platform, as well as SERS applications in various fields.



Printing High-resolution Micro-patterns by Solution Processes

ZHANG Kejie, ZHANG Min, LIU Huan

2021, 37(5):  1008-1018.  doi:10.1007/s40242-021-1223-2

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The preparation of high-resolution micro-patterns is urgently demanded for developing opto-/electric-devices in various applications. Generally, solution processes have been commonly used for fabricating micro-patterned surfaces for its mild operation conditions, facile operability and low-cost. In this contribution, we reviewed recent processes on preparing micro-/nano-patterns using solution processes based the viewpoint of resolution, including inkjet printing, photolithography, micro-contact printing, dip-pen nanolithography, and fiber direct writing, etc. Specifically, advantages/disadvantages and development prospects of various solution processes for preparing micro-/nano-patterns are also summarized. We envision that the review will provide inspirations for developing and optimizing various high-resolution micro-/nano-patterns using solution processes.



n-Type D-A Conjugated Polymers: Relationship Between Microstructure and Electrical/Mechanical Performance

LIU Xinyu, YAN Ye, ZHANG Qiang, ZHAO Kefeng, HAN Yanchun

2021, 37(5):  1019-1030.  doi:10.1007/s40242-021-1269-1

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Conjugated polymers are widely applied in optoelectronic devices due to their excellent optoelectronic properties, solution processibility, and intrinsic flexibility. High-performance films could be achieved with joint efforts from both molecular structure and film solid microstructure. Herein, research progress of the relationship between microstructure and electrical/mechanical performance of poly{[N,N'-bis(2-octyldodecyl)-representative of n-type donor-acceptor conjugated polymers, is reviewed. Its strong aggregation in solution is underlined and the methods to tune the degree of aggregation, such as solvent quality, molecular weight, and regioregularity, are compared. A liquid-crystalline behavior is evidenced in highly concentrated solutions during film drying, which favors the formation of highly anisotropic structures. Moreover, alignment techniques and thermal annealing are used to regulate molecular orientation and polymorphism in films. These structure characteristics offer great potential for researchers to handle film performances. Up to now, more attention has been paid to optimize the electrical performance of the devices. Achieving high-performance n-type conjugated polymer films with both superior mechanical and electrical properties is a newly emerging focus.



Li₄Mn₅O₁₂Cathode for Both 3 V and 4 V Lithium-ion Batteries

ZHU Ruonan, WANG Jun, LI Jie

2021, 37(5):  1031-1043.  doi:10.1007/s40242-021-1305-1

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Spinel Li₄Mn₅O₁₂ has been of economical and academic interest as cathode material for 3 V lithium-ion batteries(LIBs) since the 1990s. Recent studies also demonstrate that the increase of upper cut-off voltage to 5.0 V can significantly promote the specific capacity and the average operating voltage thus enabling its possibility to be used in 4 V LIBs. It is cost-effective and environmentally benign, shows structural stability without suffering from Jahn-Teller distortion due to the tetravalent oxidation state of Mn ion. However, the undesirable decomposition reactions during high-temperature calcination result in the difficulty of fabricating stoichiometric Li₄Mn₅O₁₂ compounds. Meanwhile, the high capacity led by the enlarged voltage window is combined with fast capacity fading due to the poor reversibility of oxygen redox. In this review, the understanding of the relationship between structure and stochiometric chemistry of Li₄Mn₅O₁₂ is discussed and the ways to improving its electrochemical performance are summarized. Our focus is its recent developments of being used as high voltage cathode or "additive" for layered cathodes. At last, we also provide our perspectives on this material regarding to the target of enabling its application in 4 V LIBs.



Contemporary Approaches to α,β-Dehydroamino Acid Chemical Modifications

ZHANG Mengqian, HE Peiyang, LI Yanmei

2021, 37(5):  1044-1054.  doi:10.1007/s40242-021-1307-z

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As one of the most common unnatural amino acids(uAAs), α, β-dehydroamino acids(α,β-dhAAs) can be found in various ribosomally synthesized and post-translationally modified peptides(RiPPs) and other naturally occurring peptides. In recent years, novel reactions for α,β-dhAA modification continue to emerge. Due to their unique electrophilicity different from 20 natural amino acids, α,β-dhAAs, especially dehydroalanine(Dha), have become powerful tools for site-selective protein modification. In this review, we mainly focus on the latest research progress of C-C and C-heteroatom(C-X, X=S, N, Se, Si, P, B) bond formation methods based on α,β-dhAAs in the past five years. Particularly, we pay much attention to the α,β-dhAA derivatization methodologies used in the late-stage modification for natural peptides and proteins. In addition, we also focus on the downstream functionalization and therapeutic biologic applications of these modifications.



Repair Strategies for Perovskite Solar Cells

LIU Huifen, ZHOU Huanping

2021, 37(5):  1055-1066.  doi:10.1007/s40242-021-1334-9

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In recent years, organic-inorganic hybrid halide perovskite solar cells(PSCs) have obtained rapid development due to their excellent optoelectronic properties and low fabrication cost. However, owing to the environmental sensitivity of perovskite materials, the instability of PSCs is the key issue hindering its commercialization. Developing feasible strategy to repair the degraded PSCs stands for effective and unique means to prolong the operational lifetime of PSCs. Herein, we summarize various methods to repair the degraded PSCs under the influence of different environmental conditions. Along with the repairing process, the optoelectronic properties of perovskite film as well as the corresponding PSCs are discussed. Some suggestions on how to further improve the intrinsic stability of perovskite and repairing effect of PSCs are also provided.



Letter

Chiral Nematic Cellulose Nanocrystals-Magnetite Nanocomposite Films Displaying Magnet-modulated Circular Dichroism Activity

LI Ping, YU Xu, XU Yan

2021, 37(5):  1067-1071.  doi:10.1007/s40242-021-1245-9

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Articles

Esterification of Oleic Acid to Produce Biodiesel over 12-Tungstophosphoric Acid Anchored Two-dimensional Zeolite

PANG Hao, YANG Guoju, LI Lin, YU Jihong

2021, 37(5):  1072-1078.  doi:10.1007/s40242-021-1152-0

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Biodiesel has emerged as a non-toxic, biodegradable, and renewable fuel substitute that can be readily produced via the esterification reaction of free fatty acids. The present work explores the potential of 12-tungstophosphoric acid(TPA) anchored two-dimensional(2D) ITQ-2 zeolite(TPA/ITQ-2) as heterogeneous acid catalysts for biodiesel production. TPA/ITQ-2 material was prepared by swelling, delamination, and subsequent wetness incipient impregnation approach. The prepared catalysts were comprehensively characterized by powder X-ray diffraction, N₂ adsorption/desorption, temperature-programmed desorption of ammonia, flou-rier transform infrared spectroscopy, and transmission electron microscopy. The catalytic activity of TPA/ITQ-2 for biodiesel production was evaluated by the esterification reaction of oleate acid with methanol. Process parameters, such as reactant molar ratio and TPA loading were optimized. Due to the superior mass transfer and adequate stable acid sites, 2D TPA/ITQ-2 showed a higher catalytic activity and a better recyclable stability than the 3D and layered TPA/zeolites. This work will provide new opportunities for the design of 2D zeolite-based acid catalysts for biodiesel production.



Supramolecular Self-assembly of Amphiphilic Alkynyl-platinum(II) 2,6-Bis(N-alkylbenzimidazol-2'-yl) pyridine Complexes

Andy Shun-Hoi CHEUNG, Sammual Yu-Lut LEUNG, Franky Ka-Wah HAU, Vivian Wing-Wah YAM

2021, 37(5):  1079-1084.  doi:10.1007/s40242-021-1309-x

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Alkynylplatinum(II) bzimpy complexes of trimethylammonium-benzylethynyl ligand have been synthesized and characterized. Complexes with long alkyl chains have been found to exhibit interesting self-assembly properties in the acetonitrile solution. The amphiphilic nature of the complexes has led to the formation of nanorods, as revealed by electron microscopy experiments. Further increasing the polarity of the solvent media has given rise to the enhancement of low-energy emission.



A One-pot-synthesized Double-layered Anticoagulant Hydrogel Tube

SUN Di, GAO Wenqing, WU Peng, LIU Jie, LI Shengmei, LI Shilin, YU Meili, NING Meng, BAI Ru, LI Tong, LIU Ying, CHEN Chunying

2021, 37(5):  1085-1091.  doi:10.1007/s40242-021-1267-3

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Extracorporeal membrane oxygenation(ECMO) has emerged as a viable treatment in severe cases of acute respiratory distress syndrome, acute respiratory failure, and adult respiratory distress syndrome. However, thromboembolic events stemming from the use of ECMO devices results in significant morbidity and mortality rates; the inner surface of the ECMO tubing comes into contact with the blood and can readily initiate coagulation. In addition, the tubing needs to be continually replaced due to thromboses on the inner tube wall, which not only increases the risk of infection but also the economic burden. Despite considerable effort, a surface modification strategy that effectively addresses these challenges has not yet been realized. In this study, we developed an integrated hollow core-shell-shell hydrogel tube of gelatin/alginate/acrylamide-bacterial nanocellulose(GAA) that meets the anticoagulant requirements for the inner tubing layer as well as the highly elastic soft material needed for the outer layer. Using static blood from healthy volunteers, we confirmed that the platelets or coagulation is not stimulated by the GAA tubing. Importantly, experiments with dynamic blood also demonstrated that the inner layer of the tubing does not elicit blood clotting. The one-pot-synthesized process may provide guidance for the design of anticoagulation tubes used clinically.



Synthesis of Fluorinated Urchin-like Serried Hydroxyapatite with Improved Water Sorption-Solubility and Bioactivity for Dental Composites

CHEN Hongyan, WANG Junjun, WANG Ruili, ZHU Meifang

2021, 37(5):  1092-1100.  doi:10.1007/s40242-021-1268-2

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Fluorine is present in the hydroxyapatite mineral in natural tooth enamel, which plays a key role in the prevention of dental caries. The aim of this study is to synthetize the fluorinated urchin-like serried hydroxyapatite(FnUHA) particles with different degrees of fluorine substitution and explore the effect of the fluorine element on the water absorption-solubility, mechanical strength, and biological activity of dental composites. The obtained FnUHA particles were further modified with 3-methacryloxypropyl trimethoxysilane(γ-MPS) to get the silanized FnUHA(SFnUHA) particles, which were then used as the reinforcement for dental composites. The morphology, compositional elements, and structure of the FnUHA were characterized by field-emission scanning electron microscopy(FE-SEM), transmission electron microscopy(TEM), X-ray photoelectron spectroscopy(XPS), X-ray diffractometer(XRD), and Fourier transform infrared spectrometer (FTIR), respectively. The mechanical properties of the SFnUHA reinforced composites with different filler loadings were measured with a universal testing machine. The results demonstrated that the 50%(mass fraction) SF5UHA filled composite exhibited the acceptable flexural strength and compressive strength, giving the respective improvements of 56.3% and 30.8% compared with those of the 50% SUHA filled composite. In addition, this composite also presented lower water absorption-solubility, better in vitro bioactivity, and excellent cell viability. Therefore, fluorinated hydroxyapatite is a promising filler to improve the mechanical properties and functionality of dental composites.



Calcium Ion Coordinated Polyamide Nanofiltration Membrane for Ultrahigh Perm-selectivity Desalination

BIAN Xiangying, ZHANG Yuping, GONG Li, ZHU Yuzhang, JIN Jian

2021, 37(5):  1101-1109.  doi:10.1007/s40242-021-1270-8

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Improving the permeate flux but retaining the rejection of thin-film composite(TFC) polyamide nanofiltration(NF) membrane is a high requirement for desalination. In this work, a calcium ion(Ca²⁺) coordinated polyamide(PA) NF membrane was prepared by directly adding CaCl₂ to the piperazine(PIP) aqueous solution during the interfacial polymerization process. Due to the coordination interaction between Ca²⁺ and the amide bond in PA active layer, the number of hydrogen bonds in the PA active layer was reduced, causing in turn the decrease of physical cross-linking degree. As a consequence, the pore of the PA active layer was enlarged, prominently enhancing the water permeance of NF membrane. With the increase of CaCl₂ concentration, the pure water flux of TFC NF increased significantly while the rejection of Na₂SO₄ decreased sightly. Compared with TFC NF membrane prepared without CaCl₂, the permeate flux of the Ca²⁺ coordinated polyamide NF membrane prepared under optimal conditions was increased by 3-4 folds with Na₂SO₄ rejection of 95.26%. Meanwhile, such a Ca²⁺ coordinated PA NF membrane showed a better SO₄^2-/Cl^- selectivity.



A DFT Investigation on the Electronic Structures and Au Adatom Assisted Hydrogenation of Graphene Nanoflake Array

SONG Yang, TAO Lei, ZHANG Yanfang, PAN Jinbo, DU Shixuan

2021, 37(5):  1110-1115.  doi:10.1007/s40242-021-1163-x

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Graphene nanoribbons with zigzag edges(ZGNRs) have attracted much attention for their spin-polarized edge states predicted more than 15 years ago. Since the ZGNRs are fabricated on metal substrates using molecular precursors, due to their strong coupling with metal substrates, experimental detection of the spin-polarized edge states is still difficult. Here, we design a partially hydrogenated graphene(PHGr), in which periodic hexagonal graphene nanoflakes(GNFs) with zigzag boundaries are embedded in a hydrogenated graphene layer. Using density functional theory(DFT) based first-principles calculations, we find that the hexagonal GNFs exhibit spin-polarized boundary states at their opposite zigzag boundaries, which is similar with the bow-tie-shaped GNFs and ZGNRs. DFT calculations demonstrate that the PHGr is a semiconductor with an antiferromagnetic ground state. Moreover, the antiferromagnetic boundary states and semiconduc-ting properties keep unchanged when the size of GNF varies from 1.4 nm to 2.3 nm. The robustness of the spin-polarized boundary states enables this PHGr as a robust material for detecting spin-polarized boundary states coming from zigzag boundaries. In addition, we find that single Au atoms selectively adsorbed on boundaries catalyze H₂ dissociation and therefore lower the barrier of graphene hydrogenation. Therefore, the PHGr can be used not only in carbon-based spintronic devices but also as a platform for single atom catalyst.



A Green Approach to Producing Polymer Microparticles for Local Sustained Release of Flavopiridol

Matthew J. OWEN, Jasper H. N. YIK, Congwang YE, Brianca NETTO, Dominik R. HAUDENSCHILD, Gang-yu LIU

2021, 37(5):  1116-1124.  doi:10.1007/s40242-021-1262-8

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Poly(lactic-co-glycolic acid)(PLGA) microparticles represent an important class of materials used for drug delivery. Current synthesis frequently uses conventional emulsion, where dichloromethane(DCM) is used as the organic phase solvent. Due to the health and environmental toxicity of DCM and its slow degradation, this work replaces DCM with a greener solvent, dimethyl carbonate(DMC). To attain narrow distribution of PLGA particle size, microfluidic flow focusing was chosen over conventional emulsion. This new approach successfully produced PLGA microparticles encapsulated with flavopiridol, a kinase inhibitor. These particles exhibit sustained release profile more desirable than the conventional counterparts. The cytotoxicity and activity tests have demonstrated high biocompatibility and efficacy of these PLGA particles. The high sustainability is also evaluated using simple E-Factor(sEF) and complete E-Factor(cEF). The lower health and environmental toxicities of DMC than DCM are evidenced by approximately one order of magnitude higher in lethal dose, i. e., 50%(LD₅₀) values in rat, 5-fold faster degradation rate, and 30% higher GlaxoSmithKline(GSK) combined greenness value. The approach reported in this work shall provide a new and green means for drug delivery in general. The products enable local sustained delivery of flavopiridol for prevention of post-traumatic osteoarthritis, and anti-cancer therapy.



Growth of Single-walled Carbon Nanotubes on Substrates Using Carbon Monoxide as Carbon Source

ZHAO Xue, ZHANG Xinrui, LIU Qidong, ZHANG Zeyao, LI Yan

2021, 37(5):  1125-1129.  doi:10.1007/s40242-021-1277-1

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The growth of single-walled carbon nanotubes(SWCNTs) on substrates has attracted great interests because of the potential applications in various fields. Carbon monoxide(CO) was used as the carbon source for the growth of SWCNTs on silicon substrates. Random or oriented SWCNTs can be produced by varying the CO flow rate. When the flow rate of CO was as low as 20 sccm(sccm:standard cubic centimeter per minute), dense SWCNT networks with clean surface were produced. When the flow rate was above 50 sccm, vertically aligned SWCNT(VA-SWCNT) arrays were grown. Well-aligned VA-SWCNT arrays were obtained in the temperature range of 650-800℃ and the content of large-diameter(above 1.7 nm) tubes in the array increased with the temperature. The height of the array was affected by the growth temperature, the CO flow rate, and the growth time. These findings indicate CO can be used as an efficient carbon source for the growth of SWCNTs on substrates under low flow rates.



Enhanced Electrochemical Performance of Na_0.67Fe_0.5Mn_0.5O₂Cathode with SnO₂ Modification

YE Peng, LIU Yongchao, MA Jian, WANG Yueda, FENG Xuyong, XIANG Hongfa, SUN Yi, LIANG Xin, YU Yan

2021, 37(5):  1130-1136.  doi:10.1007/s40242-021-1287-z

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P2-type layered oxide Na_0.67Fe_0.5Mn_0.5O₂ is recognized as a very promising cathode material for sodium-ion batteries due to the merits of high capacity, high voltage, low cost, and easy preparation. However, its unsatisfactory cycle and rate performances remain huge obstacles for practical applications. Here, we report a strategy of SnO₂ modification on P2-type Na_0.67Fe_0.5Mn_0.5O₂ to improve the cycle and rate performance. Scanning electron microscope(SEM) and transmission electron microscope(TEM) images indicate that an insular thin layer SnO₂ is coated on the surface of Na_0.67Fe_0.5Mn_0.5O₂ after medication. The coating layer of SnO₂ can protect Na_0.67Fe_0.5Mn_0.5O₂ from corrosion by electrolyte and the cycle performance is well enhanced. After 100 cycles at 1 C rate(1 C=200 mA/g), the capacity of SnO₂ modified Na_0.67Fe_0.5Mn_0.5O₂ retains 83 mA·h/g(64% to the initial capacity), while the capacity for the pristine Na_0.67Fe_0.5Mn_0.5O₂ is only 38 mA·h/g(33.5% to the initial capacity). X-Ray photoelectron spectroscopy reveals that the ratio of Mn⁴⁺ increases after SnO₂ modification, leading to less oxygen vacancy and expanded lattice. As a result, the capacity of Na_0.67Fe_0.5Mn_0.5O₂ increases from 178 mA·h/g to 197 mA·h/g after SnO₂ modification. Furthermore, the rate performance of Na_0.67Fe_0.5Mn_0.5O₂ is enhanced with SnO₂ coating, due to high electronic conductivity of SnO₂ and expanded lattice after SnO₂ coating. The capacity of SnO₂ modified Na_0.67Fe_0.5Mn_0.5O₂ at 5 C increases from 21 mA·h/g(pristine Na_0.67Fe_0.5Mn_0.5O₂) to 35 mA·h/g.



Effect of Sodium Concentration on the Synthesis of Faujasite by Two-step Synthesis Procedure

ZHAO Lei, YANG Ge, GUO Hailing, WANG Chunzheng, WANG Lijuan, Svetlana MINTOVA

2021, 37(5):  1137-1142.  doi:10.1007/s40242-021-1292-2

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The relationship between the concentration of sodium cations and the properties of faujasite(FAU) zeolite was investigated using a two-step synthesis procedure including (1) formation of amorphous aluminosilicate precursors and separation of amorphous nanoparticles, and (2) transformation of these amorphous particles into zeolite crystals by treatment with alkali solutions(NaOH). Three representative samples including two nano-sized zeolites and one micron-sized zeolite were prepared using different concentrations of sodium hydroxide. The crystallization process of these zeolites was studied in detail by Fourier transform infrared(FTIR) spectrometry, nuclear magnetic resonance spectroscopy(NMR), X-ray diffraction(XRD), scanning electron microscopy (SEM), transmission electron microscopy(TEM), and N₂ adsorption. The results indicated that minor changes in the concertation of inorganic cations can significantly shorten the induction period and crystallization time and thus affect the morphology, size and chemical composition of the zeolite crystals.



Glaser Coupling of Substituted Anthracene Diynes on a Non-metallic Surface at the Vapor-Solid Interface

FANG Yuan, HEYDARI Zahra, LIU Chenghao, ZHANG Nianyue, CUCCIA Louis A., IVASENKO Oleksandr, PEREPICHKA Dmitrii F.

2021, 37(5):  1143-1148.  doi:10.1007/s40242-021-1324-y

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The direct polymerization via irreversible C-C coupling on inert substrates will give access to new low-dimensional advanced functional materials and simplify their industrial fabrication. In this work, we present our initial results in the application of Glaser coupling to the direct on-surface polymerization of a model diacetylene compound at the solid-vapor interface. The self-assembly of the monomer and polymerization products was characterized using scanning tunneling microscopy (STM). In addition, selected optical properties and the electronic structure of all compounds were investigated.