It is important to know the rate of intra-molecular contact formation in proteins in order to understand how proteins fold clearly. Here we investigate the rate of intra-molecular contact formation in short two-dimens...It is important to know the rate of intra-molecular contact formation in proteins in order to understand how proteins fold clearly. Here we investigate the rate of intra-molecular contact formation in short two-dimensional compact polymer chains by calculating the probability distribution p（r） of end-to-end distance r using the enumeration calculation method and HP model on two-dimensional square lattice. The probability distribution of end-to-end distance p（r） of short two-dimensional compact polymers chains may consist of two parts, i.e. p（r） = p1（r） ＋ p2（r）, where p1（r） and p2（r） are different for small r. The rate of contact formation decreases monotonically with the number of bonds N, and the rate approximately conforms to the scaling relation of k（N）∝ N^-α. Here the value of α increases with the contact radius a and it also depends on the percentage of H （hydrophobic） residues in the sequences of compact chains and the energy parameters of ^εНН、 ^εНН and ^εpp. Some comparisons of theoretical predictions with experimental results are also made. This investigation may help us to understand the protein folding.展开更多
Two-dimensional(2D) materials have been demonstrated to exhibit unique properties originating from its 2D nature. In recent years, the construction of 2D materials has become a topic of great interest. This article su...Two-dimensional(2D) materials have been demonstrated to exhibit unique properties originating from its 2D nature. In recent years, the construction of 2D materials has become a topic of great interest. This article summarizes the recent advance of 2D supramolecular organic frameworks(SOFs) which are homogeneously constructed in solution phase through self-assembly of rationally designed building blocks. These 2D SOFs are soluble and still maintain stable network structures in solutions, which exhibit uniqueness not only in structures but also in properties. In this concise review, the SOFs-related background is briefly introduced firstly, followed by outlining the research progress of soluble 2D SOFs from the perspective of monomer design, assembly, and structural characterization.The article ends with a personal outlook on the future development of this new class of supramolecular polymers.展开更多
Generalized two-dimensional correlation spectroscopy （2DCOS） and its derivate technique, perturbation correlation moving window （PCMW）, have found great potential in studying a series of physico-chemical phenomena...Generalized two-dimensional correlation spectroscopy （2DCOS） and its derivate technique, perturbation correlation moving window （PCMW）, have found great potential in studying a series of physico-chemical phenomena in stimuli-responsive polymeric systems. By spreading peaks along a second dimension, 2DCOS can significantly enhance spectral resolution and discern the sequence of group dynamics applicable to various external perturbation-induced spectroscopic changes, especially in infrared （IR）, near-infrared （NIR） and Raman spectroscopy. On the basis of 2DCOS synchronous power spectra changing, PCMW proves to be a powerful tool to monitor complicated spectral variations and to find transition points and ranges. This article reviews the recent work of our research group in the application of 2DCOS and PCMW in thermoresponsive polymers, mainly focused on liquid crystalline polymers and lower critical solution temperature （LCST）-type polymers. Details of group motions and chain conformational changes upon temperature perturbation can thus be elucidated at the molecular level, which contribute to the understanding of their phase transition nature.展开更多
Over the past decades, two-dimensional（2D） nanomaterials possessing planar layered architecture and unique electronic structures have been being quickly developed, due to their wide potential application in the fiel...Over the past decades, two-dimensional（2D） nanomaterials possessing planar layered architecture and unique electronic structures have been being quickly developed, due to their wide potential application in the fields of chemistry, physics, and materials science. As a new family of 2D nanomaterials, 2D polymerbased nanosheets, featuring excellent characters, such as tunable framework structures, light weight, flexibility, high specific surface, and good semiconducting properties, have been emerging as one kind of promising functional materials for optoelectronics, gas separation, catalysis and sensing, etc. In this review, the recent progress in synthetic approach and characterization of 2D polymer-based nanosheets were summarized, and their current advances in electrochemical energy storage and conversion including second batteries, supercapacitors, oxygen reduction and hydrogen evolution were discussed systematically.展开更多
A series of liquid crystalline polymers with two-dimensional mesogenic units were synthesized by solution polycondensation at low temperature. All the polymers were liquid crystalline. The melting temperature T;（exce...A series of liquid crystalline polymers with two-dimensional mesogenic units were synthesized by solution polycondensation at low temperature. All the polymers were liquid crystalline. The melting temperature T;（except that with substituent of methoxy） and the clearing temperature T;of the polymers change regularly with varying of the length of the alkyl substituent groups.展开更多
A series of 'liquid crystal polymers with two-dimensional mesogeuic units' were synthesized by the polycondensations of the monomer 2, 5-dihydroxybenzylidene-4-phenetidine with a diacid chloride selected from ...A series of 'liquid crystal polymers with two-dimensional mesogeuic units' were synthesized by the polycondensations of the monomer 2, 5-dihydroxybenzylidene-4-phenetidine with a diacid chloride selected from a series of α, ω-bis(4-chloroformylphenyloxy)carbonylalkues. This is the first series of polymers reported under the newly proposed concept 'liquid crystal polymers with two dimensional mesogenic units'.展开更多
A series of liquid crystalline polymers with T-shaped two-dimensional mesogenic unitswere synthesized via low temperature solution polycondensation of 2-(4'-alkoxy-phenyl)hydroquinone with various diacyl dichlorid...A series of liquid crystalline polymers with T-shaped two-dimensional mesogenic unitswere synthesized via low temperature solution polycondensation of 2-(4'-alkoxy-phenyl)hydroquinone with various diacyl dichlorides. The polymers were found to be nematic andshown thermotropic liquid crystalline behaviors through observations using DSC, polarizedmicroscopy and X-ray diffraction. The melting temperature T_m and the isotropizationtemperature T_i of the polymers change regularly with varying of the monomer structures.展开更多
Molecular weaving is a powerful approach to make molecularly woven materials that have showed unprecedented characteristics and properties intrinsically distinct to those of non-woven materials.We here report a facile...Molecular weaving is a powerful approach to make molecularly woven materials that have showed unprecedented characteristics and properties intrinsically distinct to those of non-woven materials.We here report a facile and efficient approach for the synthesis of 2D woven supramolecular polymers by differentiated self-assembly through orthogonal noncovalent interactions.Importantly,the difference in binding strength of two orthogonal noncovalent interactions can be used to control the process of molecular weaving.Consequently,single-layered 2D woven supramolecular polymers were synthesized and fully characterized by various techniques.This study demonstrates a controllable method for molecular weaving,and will significantly hasten the development of molecularly woven materials.展开更多
A new two-dimensional Cd（Ⅱ） coordination polymer, [Cd（2,5-pdch）（H2O）]n·2n（ClO4）·nH2O （2,5-pdch = pyridine-2,5-dicarbohydrazide）, was prepared and characterized by elemental analysis, IR spectra an...A new two-dimensional Cd（Ⅱ） coordination polymer, [Cd（2,5-pdch）（H2O）]n·2n（ClO4）·nH2O （2,5-pdch = pyridine-2,5-dicarbohydrazide）, was prepared and characterized by elemental analysis, IR spectra and single-crystal X-ray diffraction analysis. The crystal belongs to monoclinic, space group P21/c with a = 10.905（2）, b = 11.602（1）, c = 15.034（2） A, β = 117.794 （10°, V = 1682.8（4A3, Z = 4, C7H13CdCl2NsO12, Mr = 542.52, Dc = 2.141 g/cm^3,/μ = 1.691 mm^-1, F（000） = 1072, 2（MoKa） = 0.71073A, the final R = 0.0608 and wR = 0.1329 for 2972 observed reflections with I 〉 2σ（I）. Single-crystal X-ray diffraction analysis reveals that the Cd（Ⅱ） atom displays a distorted pentagonal-bipyramidal geometry coordinated by three N atoms and three O atoms from three different 2,5-pdch ligands, and one water molecule. Interestingly, each two Cd（Ⅱ） atoms are bridged by two carbohydrazide groups of the 2,5-pdch ligands to form a dimeric unit, and such dimeric units are further connected by the 2,5-pdch ligand to generate a two-dimensional （4,4）-network.展开更多
Two series of new liquid crystalline polymers with T-shaped two-dimensional mesogenic units were synthesized by low temperature solution polycondensations of 4-substituted N-2, 5-dihydroxybenzylidene aniline monomers ...Two series of new liquid crystalline polymers with T-shaped two-dimensional mesogenic units were synthesized by low temperature solution polycondensations of 4-substituted N-2, 5-dihydroxybenzylidene aniline monomers with different diacyl dichlorides. The polymers were found to be nematic and shown liquid crystalline behavior. The melting temperature T-m and the clearing temperature T-i of the polymers change regularly with varying of the monomer structures.展开更多
In order to determine a proper compaction temperature that affects the workability and compactibility of the polymer-modified asphalt（PMA）, the effect of compaction temperature was examined on the volumetric propert...In order to determine a proper compaction temperature that affects the workability and compactibility of the polymer-modified asphalt（PMA）, the effect of compaction temperature was examined on the volumetric properties and the compaction energy indices. Change in compaction temperature shows an important influence on the maximum specific gravity of mixture（G_（mm）） by internal volume change of PMA. The change in G_（mm） mainly affects the effective volume of the aggregate（V_（Eff））. Reduction in V_（Eff） from Zero shear viscosity（ZSV） to superpave temperature allows 0.1%-0.15% of the asphalt binder to occupy highly the external voids of aggregates. The volumetric properties for all compaction specimens meet superpave criteria, but the energy efforts were the lowest at ZSV temperature. Lower energy efforts at the ZSV temperature reflect easier compaction than those at excessively high temperature. Clearly, excessive compaction temperature may not be necessary to improve the compactibility and to reduce the compaction efforts.展开更多
We use the pruned-enriched Rosenbluth method to investigate systematically the segment density profiles of compact polymer chains confined between two parallel plane walls. The non-adsorption case of adsorption intera...We use the pruned-enriched Rosenbluth method to investigate systematically the segment density profiles of compact polymer chains confined between two parallel plane walls. The non-adsorption case of adsorption interaction energy ε = 0 and the weak adsorption case of ε= -1 are considered for the compact polymer chains with different chain lengths N and different separation distances between two walls D. Several special entropy effects on the confined compact polymer chains, such as a damped oscillation in the segment density profile for the large separation distance D, are observed and discussed for different separation distances D in the non-adsorption case. In the weak adsorption case, investigations on the segment density profiles indicate that the competition between the entropy and adsorption effects results in an obvious depletion layer. Moreover, the scaling laws of the damped oscillation period Td and the depletion layer width Ld are obtained for the confined compact chains. Most of these results are obtained for the first time so far as we know, which are expected to understand the properties of the confined compact polymer chains more completely.展开更多
In recent years, graphene has been widely employed in the field of metal corrosion protection owing to its outstanding impermeability and chemical stability, with examples of such metal protection including pure graph...In recent years, graphene has been widely employed in the field of metal corrosion protection owing to its outstanding impermeability and chemical stability, with examples of such metal protection including pure graphene coatings and graphene-based composite coatings. But the conductive graphene could promote the electrochemical reaction at the interface and accelerate the corrosion of metal substrates. More emerging graphene-like 2D nanosheets are attracting research attention for the application of metal anticorrosion, because of their barrier properties and poor conductivity, mainly including boron nitride(BN),molybdenum disulfide(MoS_(2)), zirconium phosphate(ZrP), and titanium carbide(MXene). In this review,the application of these graphene-like 2D nanosheets to metal protection is comprehensively reviewed.First, the general preparation methods of 2D nanosheets are briefly introduced. Second, surface functionalization of 2D nanosheets, including covalent and non-covalent modification, is described in detail.Third, the anticorrosion performance and optimization measures of pure 2D nanosheets coatings are summarized. Next, the protection performance, anticorrosive mechanism, and optimizations of 2D nanosheets composite coatings are presented. Finally, the future development of 2D nanosheets-based anticorrosive coatings has been prospected, and the challenges in the industrial application are discussed.展开更多
A new p-PhDTA bridged Cu（II） complex [Cu2（p-PhDTA）（DMSO）2]·4DMSO （p-PhDTA = p-phenylenediamine-N,N,N,N＇-tetraacetic acid） has been synthesized and structurally characterized. The crystal belongs to ortho...A new p-PhDTA bridged Cu（II） complex [Cu2（p-PhDTA）（DMSO）2]·4DMSO （p-PhDTA = p-phenylenediamine-N,N,N,N＇-tetraacetic acid） has been synthesized and structurally characterized. The crystal belongs to orthorhombic, space group Pca21 with a = 19.572（4）, b = 19.552（4）, c = 10.156（2）A, C26H48N2O14CU2S6, Mr = 932.10, V = 3886.4（13）A3, Z = 4, Dc = 1.593 g/cm^3, F（000） = 1936, λ（MoKa） = 0.71073A,μ = 1.480, R = 0.0487 and wR = 0.1151 for 8464 observed reflections （I 〉2σ（I））. In the complex, the oxygen atoms of carboxylate of p-PhDTA connect the Cu atoms in a syn-anti type, giving one-dimensional chains which are further linked by the benzene groups ofp-PhDTA to form a novel two-dimensional structure.展开更多
Two-dimensional mesoporous materials combing ultrathin nanosheet morphology with well-defined mesoporous structures,are now emerging and becoming increasingly important for their promising applications in energy stora...Two-dimensional mesoporous materials combing ultrathin nanosheet morphology with well-defined mesoporous structures,are now emerging and becoming increasingly important for their promising applications in energy storage,electronic devices,electrocatalysts and so on.Here,we synthesized a kind of polypyrrole-based two-dimensional mesoporous materials with uniform pore size,ultrathin thickness and high surface area.Serving for electrochemical NH3 sensor,they exhibited a fast response and high sensitivity.Therefore,our study would promote much interest in design of new materials for gas sensor applications.展开更多
A new zinc polymer, {Zn（O2CC12H8CO2）（H2O）}, or {Zn（DPHA）（H2O）}n （O2CC12H8CO2, DPHA = 1,1′ -biphenyl-2,2′-dicarboxylate dianion） has been synthesized under hydrothermal conditions. The crystal is of monocli...A new zinc polymer, {Zn（O2CC12H8CO2）（H2O）}, or {Zn（DPHA）（H2O）}n （O2CC12H8CO2, DPHA = 1,1′ -biphenyl-2,2′-dicarboxylate dianion） has been synthesized under hydrothermal conditions. The crystal is of monoclinic, space group P21/c with a = 12.8418（5）, b = 5.9505（2）, c = 17.2989（5） A, β = 104.020（2）°, V = 1282.52（8） A^3, C14H10O5Zn, Mr= 323.61, Z = 4, Dc = 1.676 g/cm^3,μ = 1.930 mm^-1, F（000） = 656, R = 0.0766 and wR = 0.1871 for 1775 observed reflections （I 〉 2σ（I））. It consists of Zn2（DPHA）2（H2O）2 units, which are further extended into a one-dimensional double helical-chain polymer via Zn-O bonding. The hydrogen bonding interactions extend the helical chains into a two-dimensional layer structure.展开更多
Two-dimensional conjugated polymers(2DCPs)have received great interest in smart devices due to their unique physical properties associated with flexibility,nanosized thickness,and correlated quantum size effect.Contro...Two-dimensional conjugated polymers(2DCPs)have received great interest in smart devices due to their unique physical properties associated with flexibility,nanosized thickness,and correlated quantum size effect.Control of interlayer interactions of multilayer 2DCPs is crucial for modulating the confinement of charge carriers,heat,and photons to give remarkable properties because of the breaking of symmetry.However,to date,it is unclear how the multilayers of 2DCPs affect their physical properties.In this article,we for the first time perform a density functional theory calculation for the interlayer slipping effect on in-plane electronic properties of few-layer 2DCPs.Based on five homopolymers formed by C-C bonds with various stacking configurations beyond the inclined and serrated ones,results show that a moderate electric field causes the valence(conduction)band of few-layer 2DCPs to exhibit distinctive electrical characteristics which are dominated by the outermost two layers on hole(electron)enriched side.Analysis based on recombined molecular orbitals reveals that band properties are sensitive to the interlayer offsets when they result from the interference among multiple orbitals from each building block.This result provides a new guideline for manipulating charge transfer and spintronic properties of few-layer 2DCPs through an electric field to advance their various applications.展开更多
Achieving molecular self-assembly to produce functional supramolecular polymers with defined dimensions and structural periodicity is crucial,particularly for two-dimensional supramolecular polymers(2DSPs).However,a m...Achieving molecular self-assembly to produce functional supramolecular polymers with defined dimensions and structural periodicity is crucial,particularly for two-dimensional supramolecular polymers(2DSPs).However,a major challenge to their application has been poor electrical conductivity due to weakπ-electron delocalization in existing synthetic methods.Here,we overcome this limitation by demonstrating the controlled construction of conductive 2DSPs through self-aligned brick-like stacking of doubly chargedπ-conjugated monomers driven by aromatic cation-πinteractions.A key feature of this approach is the upright molecular orientation,a notable departure from the horizontal orientation typical of conventional 2D polymers.This versatile method is compatible with various molecular building blocks,enabling modulation of 2DSP conformation from flat to wavy.We have also prepared free-standing single-layer nanosheets of 2DSPs via solution-assisted exfoliation from their crystals.The resulting 2DSPs demonstrate efficient in-planeπ-electron delocalization,leading to impressive electrical conductivity properties,holding significant promise for optoelectronic applications.展开更多
Three two-dimensional like conjugated copolymers PFSDCN,PFSDTA and PFSDCNIO,which consist of alternating fluorene and triphenylamine main chain,and different pendant acceptor groups (malononitrile,1,3-diethtyl-2-thiob...Three two-dimensional like conjugated copolymers PFSDCN,PFSDTA and PFSDCNIO,which consist of alternating fluorene and triphenylamine main chain,and different pendant acceptor groups (malononitrile,1,3-diethtyl-2-thiobarbituric acid and 2-(1,2-dihydro-1-oxoinden-3-ylidene)malononitrile) with thiophene as π-bridge,have been designed,synthesized and characterized.The structure-property relationships of the two-dimensional like conjugated copolymers were systematically investigated.The absorption spectra,band gaps,and energy levels of the polymers were effectively tuned by simply attaching different acceptor groups.As the electron-withdrawing ability of the acceptors increased,the band gaps of the polymers were narrowed from 2.05 to 1.61 eV;meanwhile,the LUMO energy levels of the polymers decreased from -3.27 to -3.75 eV,whereas their relatively deep HOMO energy levels of ～-5.35 eV were preserved.BHJ solar cells were fabricated and characterized by using the three polymers as donor materials and the highest power conversion efficiency of 2.87% was achieved for the device based on PFSDTA:(6,6)-phenyl-C71-butyric acid methyl ester blend.展开更多
A well-designed redox-active organic linker,pyrazine-2,3,5,6-tetracarboxylate(H_4pztc)with brimming active sites for lithium ions storage was utilized to construct coordination polymers(CPs)via a facile hydrothermal r...A well-designed redox-active organic linker,pyrazine-2,3,5,6-tetracarboxylate(H_4pztc)with brimming active sites for lithium ions storage was utilized to construct coordination polymers(CPs)via a facile hydrothermal reaction.Those two isostructural two-dimensional(2D)CPs,namely[M_2(pztc)(H_2O)_6]_n(M=Co for 1 and Ni for 2),delivered excellent reversible capacities and stable cycling performance as anodes in lithium ion batteries.As demonstrated in electrochemical studies,1 and 2 can achieve highly reversible capacities of 815 and 536 mA h g^(-1)at 200 mA g^(-1)for 150 cycles,respectively,best performed for the reported2D-CP-based anode materials.The electrochemical mechanism studies showed that the remarkable performances can be ascribed to the synergistic Li-storage redox reactions of metal centers and organic moieties.Our work highlights the opportunities of using a well-designed organic ligand to construct low-dimensional CPs as new type of electrode materials for advanced lithium ion batteries.展开更多
基金This research was financially supported by the National Natural Science Foundation of China(Nos.20174036,20274074,20574052)the Natural Science Foundation of Zhejiang Province(No.R404047).
文摘It is important to know the rate of intra-molecular contact formation in proteins in order to understand how proteins fold clearly. Here we investigate the rate of intra-molecular contact formation in short two-dimensional compact polymer chains by calculating the probability distribution p（r） of end-to-end distance r using the enumeration calculation method and HP model on two-dimensional square lattice. The probability distribution of end-to-end distance p（r） of short two-dimensional compact polymers chains may consist of two parts, i.e. p（r） = p1（r） ＋ p2（r）, where p1（r） and p2（r） are different for small r. The rate of contact formation decreases monotonically with the number of bonds N, and the rate approximately conforms to the scaling relation of k（N）∝ N^-α. Here the value of α increases with the contact radius a and it also depends on the percentage of H （hydrophobic） residues in the sequences of compact chains and the energy parameters of ^εНН、 ^εНН and ^εpp. Some comparisons of theoretical predictions with experimental results are also made. This investigation may help us to understand the protein folding.
基金financially supported by the National Natural Science Foundation of China (Nos. 21472225, 21725404)the Strategic Priority Research Program of the Chinese Academy of Sciences (No. XDAB20000000)
文摘Two-dimensional(2D) materials have been demonstrated to exhibit unique properties originating from its 2D nature. In recent years, the construction of 2D materials has become a topic of great interest. This article summarizes the recent advance of 2D supramolecular organic frameworks(SOFs) which are homogeneously constructed in solution phase through self-assembly of rationally designed building blocks. These 2D SOFs are soluble and still maintain stable network structures in solutions, which exhibit uniqueness not only in structures but also in properties. In this concise review, the SOFs-related background is briefly introduced firstly, followed by outlining the research progress of soluble 2D SOFs from the perspective of monomer design, assembly, and structural characterization.The article ends with a personal outlook on the future development of this new class of supramolecular polymers.
基金financially supported by the National Natural Science Foundation of China(Nos.21274030,51473038 and 21604024)the Natural Science Foundation of Shanghai(No.17ZR1440400)+1 种基金the Open Project of State Key Laboratory of Chemical Engineering(No.SKL-Ch E-16C02)“Chenguang Plan”
文摘Generalized two-dimensional correlation spectroscopy （2DCOS） and its derivate technique, perturbation correlation moving window （PCMW）, have found great potential in studying a series of physico-chemical phenomena in stimuli-responsive polymeric systems. By spreading peaks along a second dimension, 2DCOS can significantly enhance spectral resolution and discern the sequence of group dynamics applicable to various external perturbation-induced spectroscopic changes, especially in infrared （IR）, near-infrared （NIR） and Raman spectroscopy. On the basis of 2DCOS synchronous power spectra changing, PCMW proves to be a powerful tool to monitor complicated spectral variations and to find transition points and ranges. This article reviews the recent work of our research group in the application of 2DCOS and PCMW in thermoresponsive polymers, mainly focused on liquid crystalline polymers and lower critical solution temperature （LCST）-type polymers. Details of group motions and chain conformational changes upon temperature perturbation can thus be elucidated at the molecular level, which contribute to the understanding of their phase transition nature.
基金financially supported by the National Natural Science Foundation of China(51403126,21574080,61306018 and 21504057)Shanghai Committee of Science and Technology(15JC1490500,16JC1400703,and 17ZR1441700)+1 种基金Open Project Program of the State Key Laboratory of Photocatalysis on Energy and Environment(SKLPEE-KF201702,Fuzhou University)State Key Laboratory of Supramolecular Structure and Materials(sklssm201732,Jinlin University)
文摘Over the past decades, two-dimensional（2D） nanomaterials possessing planar layered architecture and unique electronic structures have been being quickly developed, due to their wide potential application in the fields of chemistry, physics, and materials science. As a new family of 2D nanomaterials, 2D polymerbased nanosheets, featuring excellent characters, such as tunable framework structures, light weight, flexibility, high specific surface, and good semiconducting properties, have been emerging as one kind of promising functional materials for optoelectronics, gas separation, catalysis and sensing, etc. In this review, the recent progress in synthetic approach and characterization of 2D polymer-based nanosheets were summarized, and their current advances in electrochemical energy storage and conversion including second batteries, supercapacitors, oxygen reduction and hydrogen evolution were discussed systematically.
基金This work was supported by the FEYUT, SEDC, CHINA and by the National Natural Science Foundation of China.
文摘A series of liquid crystalline polymers with two-dimensional mesogenic units were synthesized by solution polycondensation at low temperature. All the polymers were liquid crystalline. The melting temperature T;（except that with substituent of methoxy） and the clearing temperature T;of the polymers change regularly with varying of the length of the alkyl substituent groups.
文摘A series of 'liquid crystal polymers with two-dimensional mesogeuic units' were synthesized by the polycondensations of the monomer 2, 5-dihydroxybenzylidene-4-phenetidine with a diacid chloride selected from a series of α, ω-bis(4-chloroformylphenyloxy)carbonylalkues. This is the first series of polymers reported under the newly proposed concept 'liquid crystal polymers with two dimensional mesogenic units'.
基金This work was supported by the National Natural Science Foundation of China.
文摘A series of liquid crystalline polymers with T-shaped two-dimensional mesogenic unitswere synthesized via low temperature solution polycondensation of 2-(4'-alkoxy-phenyl)hydroquinone with various diacyl dichlorides. The polymers were found to be nematic andshown thermotropic liquid crystalline behaviors through observations using DSC, polarizedmicroscopy and X-ray diffraction. The melting temperature T_m and the isotropizationtemperature T_i of the polymers change regularly with varying of the monomer structures.
基金supported by the National Natural Science Foundation of China(Nos.92156012 and 22071078).
文摘Molecular weaving is a powerful approach to make molecularly woven materials that have showed unprecedented characteristics and properties intrinsically distinct to those of non-woven materials.We here report a facile and efficient approach for the synthesis of 2D woven supramolecular polymers by differentiated self-assembly through orthogonal noncovalent interactions.Importantly,the difference in binding strength of two orthogonal noncovalent interactions can be used to control the process of molecular weaving.Consequently,single-layered 2D woven supramolecular polymers were synthesized and fully characterized by various techniques.This study demonstrates a controllable method for molecular weaving,and will significantly hasten the development of molecularly woven materials.
文摘A new two-dimensional Cd（Ⅱ） coordination polymer, [Cd（2,5-pdch）（H2O）]n·2n（ClO4）·nH2O （2,5-pdch = pyridine-2,5-dicarbohydrazide）, was prepared and characterized by elemental analysis, IR spectra and single-crystal X-ray diffraction analysis. The crystal belongs to monoclinic, space group P21/c with a = 10.905（2）, b = 11.602（1）, c = 15.034（2） A, β = 117.794 （10°, V = 1682.8（4A3, Z = 4, C7H13CdCl2NsO12, Mr = 542.52, Dc = 2.141 g/cm^3,/μ = 1.691 mm^-1, F（000） = 1072, 2（MoKa） = 0.71073A, the final R = 0.0608 and wR = 0.1329 for 2972 observed reflections with I 〉 2σ（I）. Single-crystal X-ray diffraction analysis reveals that the Cd（Ⅱ） atom displays a distorted pentagonal-bipyramidal geometry coordinated by three N atoms and three O atoms from three different 2,5-pdch ligands, and one water molecule. Interestingly, each two Cd（Ⅱ） atoms are bridged by two carbohydrazide groups of the 2,5-pdch ligands to form a dimeric unit, and such dimeric units are further connected by the 2,5-pdch ligand to generate a two-dimensional （4,4）-network.
基金Tins work was supported by the National Natural Science Foundation of China.
文摘Two series of new liquid crystalline polymers with T-shaped two-dimensional mesogenic units were synthesized by low temperature solution polycondensations of 4-substituted N-2, 5-dihydroxybenzylidene aniline monomers with different diacyl dichlorides. The polymers were found to be nematic and shown liquid crystalline behavior. The melting temperature T-m and the clearing temperature T-i of the polymers change regularly with varying of the monomer structures.
文摘In order to determine a proper compaction temperature that affects the workability and compactibility of the polymer-modified asphalt（PMA）, the effect of compaction temperature was examined on the volumetric properties and the compaction energy indices. Change in compaction temperature shows an important influence on the maximum specific gravity of mixture（G_（mm）） by internal volume change of PMA. The change in G_（mm） mainly affects the effective volume of the aggregate（V_（Eff））. Reduction in V_（Eff） from Zero shear viscosity（ZSV） to superpave temperature allows 0.1%-0.15% of the asphalt binder to occupy highly the external voids of aggregates. The volumetric properties for all compaction specimens meet superpave criteria, but the energy efforts were the lowest at ZSV temperature. Lower energy efforts at the ZSV temperature reflect easier compaction than those at excessively high temperature. Clearly, excessive compaction temperature may not be necessary to improve the compactibility and to reduce the compaction efforts.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.20274040,20574052)the Program for New Century Excellent Talents in Universities(No.NCET-05-0538)+1 种基金the Natural Science Foundation of Zhejiang Province(Nos.R404047,Y405011,Y405553)China Postdoctoral Science Foundation(No.20060401064).
文摘We use the pruned-enriched Rosenbluth method to investigate systematically the segment density profiles of compact polymer chains confined between two parallel plane walls. The non-adsorption case of adsorption interaction energy ε = 0 and the weak adsorption case of ε= -1 are considered for the compact polymer chains with different chain lengths N and different separation distances between two walls D. Several special entropy effects on the confined compact polymer chains, such as a damped oscillation in the segment density profile for the large separation distance D, are observed and discussed for different separation distances D in the non-adsorption case. In the weak adsorption case, investigations on the segment density profiles indicate that the competition between the entropy and adsorption effects results in an obvious depletion layer. Moreover, the scaling laws of the damped oscillation period Td and the depletion layer width Ld are obtained for the confined compact chains. Most of these results are obtained for the first time so far as we know, which are expected to understand the properties of the confined compact polymer chains more completely.
基金financially supported by the National Natural Science Foundation of China(No.51973231)Guangdong Basic and Applied Basic Research Foundation(Nos.2021A1515012449,2019A1515010743)+1 种基金the Fundamental Research Funds for the Central Universities,Sun Yat-sen University(No.20lgzd17)Open Project from State Key Laboratory of Inorganic Synthesis and Preparative Chemistry(No.2020-31)。
文摘In recent years, graphene has been widely employed in the field of metal corrosion protection owing to its outstanding impermeability and chemical stability, with examples of such metal protection including pure graphene coatings and graphene-based composite coatings. But the conductive graphene could promote the electrochemical reaction at the interface and accelerate the corrosion of metal substrates. More emerging graphene-like 2D nanosheets are attracting research attention for the application of metal anticorrosion, because of their barrier properties and poor conductivity, mainly including boron nitride(BN),molybdenum disulfide(MoS_(2)), zirconium phosphate(ZrP), and titanium carbide(MXene). In this review,the application of these graphene-like 2D nanosheets to metal protection is comprehensively reviewed.First, the general preparation methods of 2D nanosheets are briefly introduced. Second, surface functionalization of 2D nanosheets, including covalent and non-covalent modification, is described in detail.Third, the anticorrosion performance and optimization measures of pure 2D nanosheets coatings are summarized. Next, the protection performance, anticorrosive mechanism, and optimizations of 2D nanosheets composite coatings are presented. Finally, the future development of 2D nanosheets-based anticorrosive coatings has been prospected, and the challenges in the industrial application are discussed.
基金the National Natural Science Foundation of China (No. 20671055)
文摘A new p-PhDTA bridged Cu（II） complex [Cu2（p-PhDTA）（DMSO）2]·4DMSO （p-PhDTA = p-phenylenediamine-N,N,N,N＇-tetraacetic acid） has been synthesized and structurally characterized. The crystal belongs to orthorhombic, space group Pca21 with a = 19.572（4）, b = 19.552（4）, c = 10.156（2）A, C26H48N2O14CU2S6, Mr = 932.10, V = 3886.4（13）A3, Z = 4, Dc = 1.593 g/cm^3, F（000） = 1936, λ（MoKa） = 0.71073A,μ = 1.480, R = 0.0487 and wR = 0.1151 for 8464 observed reflections （I 〉2σ（I））. In the complex, the oxygen atoms of carboxylate of p-PhDTA connect the Cu atoms in a syn-anti type, giving one-dimensional chains which are further linked by the benzene groups ofp-PhDTA to form a novel two-dimensional structure.
基金supported by the research programs from the National Natural Science Foundation of China(Nos.51773062 and 61831021)。
文摘Two-dimensional mesoporous materials combing ultrathin nanosheet morphology with well-defined mesoporous structures,are now emerging and becoming increasingly important for their promising applications in energy storage,electronic devices,electrocatalysts and so on.Here,we synthesized a kind of polypyrrole-based two-dimensional mesoporous materials with uniform pore size,ultrathin thickness and high surface area.Serving for electrochemical NH3 sensor,they exhibited a fast response and high sensitivity.Therefore,our study would promote much interest in design of new materials for gas sensor applications.
基金This work was financially supported by the NNSF of China (No. 20173063), the State Key Basic Research and Development Plan of China (001CB108906) and the NSF of Fujian Province (E0020001)
文摘A new zinc polymer, {Zn（O2CC12H8CO2）（H2O）}, or {Zn（DPHA）（H2O）}n （O2CC12H8CO2, DPHA = 1,1′ -biphenyl-2,2′-dicarboxylate dianion） has been synthesized under hydrothermal conditions. The crystal is of monoclinic, space group P21/c with a = 12.8418（5）, b = 5.9505（2）, c = 17.2989（5） A, β = 104.020（2）°, V = 1282.52（8） A^3, C14H10O5Zn, Mr= 323.61, Z = 4, Dc = 1.676 g/cm^3,μ = 1.930 mm^-1, F（000） = 656, R = 0.0766 and wR = 0.1871 for 1775 observed reflections （I 〉 2σ（I））. It consists of Zn2（DPHA）2（H2O）2 units, which are further extended into a one-dimensional double helical-chain polymer via Zn-O bonding. The hydrogen bonding interactions extend the helical chains into a two-dimensional layer structure.
基金supported by the National Natural Science Foundation of China(52233010)CAS Project for Young Scientists in Basic Research(YSBR-053)。
文摘Two-dimensional conjugated polymers(2DCPs)have received great interest in smart devices due to their unique physical properties associated with flexibility,nanosized thickness,and correlated quantum size effect.Control of interlayer interactions of multilayer 2DCPs is crucial for modulating the confinement of charge carriers,heat,and photons to give remarkable properties because of the breaking of symmetry.However,to date,it is unclear how the multilayers of 2DCPs affect their physical properties.In this article,we for the first time perform a density functional theory calculation for the interlayer slipping effect on in-plane electronic properties of few-layer 2DCPs.Based on five homopolymers formed by C-C bonds with various stacking configurations beyond the inclined and serrated ones,results show that a moderate electric field causes the valence(conduction)band of few-layer 2DCPs to exhibit distinctive electrical characteristics which are dominated by the outermost two layers on hole(electron)enriched side.Analysis based on recombined molecular orbitals reveals that band properties are sensitive to the interlayer offsets when they result from the interference among multiple orbitals from each building block.This result provides a new guideline for manipulating charge transfer and spintronic properties of few-layer 2DCPs through an electric field to advance their various applications.
基金supported by the National Natural Science Foundation of China(grant nos.22475171,22471219,22175142,22071197,22022107,22072103,51821002,and 22161132026)the Key Research and Development Program of Shaanxi(grant no.2024GX-YBXM-380)+1 种基金the Shaanxi Fundamental Science Research Project for Chemistry and Biology(grant nos.22JHQ019 and 23JHZ002)the Fundamental Research Funds for the Central Universities(grant nos.G2023KY0603 and D5000230114).
文摘Achieving molecular self-assembly to produce functional supramolecular polymers with defined dimensions and structural periodicity is crucial,particularly for two-dimensional supramolecular polymers(2DSPs).However,a major challenge to their application has been poor electrical conductivity due to weakπ-electron delocalization in existing synthetic methods.Here,we overcome this limitation by demonstrating the controlled construction of conductive 2DSPs through self-aligned brick-like stacking of doubly chargedπ-conjugated monomers driven by aromatic cation-πinteractions.A key feature of this approach is the upright molecular orientation,a notable departure from the horizontal orientation typical of conventional 2D polymers.This versatile method is compatible with various molecular building blocks,enabling modulation of 2DSP conformation from flat to wavy.We have also prepared free-standing single-layer nanosheets of 2DSPs via solution-assisted exfoliation from their crystals.The resulting 2DSPs demonstrate efficient in-planeπ-electron delocalization,leading to impressive electrical conductivity properties,holding significant promise for optoelectronic applications.
基金supported by the National Natural Science Foundation of China (50990065,51010003,51073058 and 20904011)the National Basic Research Program of China (973 Program) (2009CB623601)+1 种基金the Fundamental Research Funds for the Central Universities,South China University of Technology (2009220012,2009220043)the supported UGC grant (#400897) of the University of Hong Kong and Hong Kong Research Grants Council (HKU#712108 and HKU#712010) from the Research Grants Council of the Hong Kong Special Administrative Region,China
文摘Three two-dimensional like conjugated copolymers PFSDCN,PFSDTA and PFSDCNIO,which consist of alternating fluorene and triphenylamine main chain,and different pendant acceptor groups (malononitrile,1,3-diethtyl-2-thiobarbituric acid and 2-(1,2-dihydro-1-oxoinden-3-ylidene)malononitrile) with thiophene as π-bridge,have been designed,synthesized and characterized.The structure-property relationships of the two-dimensional like conjugated copolymers were systematically investigated.The absorption spectra,band gaps,and energy levels of the polymers were effectively tuned by simply attaching different acceptor groups.As the electron-withdrawing ability of the acceptors increased,the band gaps of the polymers were narrowed from 2.05 to 1.61 eV;meanwhile,the LUMO energy levels of the polymers decreased from -3.27 to -3.75 eV,whereas their relatively deep HOMO energy levels of ～-5.35 eV were preserved.BHJ solar cells were fabricated and characterized by using the three polymers as donor materials and the highest power conversion efficiency of 2.87% was achieved for the device based on PFSDTA:(6,6)-phenyl-C71-butyric acid methyl ester blend.
基金supported by the National Natural Science Foundation of China(21622105,21501071,21421001)Shenzhen Fundamental Research Project(JCYJ20160525164227350)+1 种基金the Ministry of Education of China(B12015)the Natural Science Foundation of Tianjin(18JCJQJC47200)
文摘A well-designed redox-active organic linker,pyrazine-2,3,5,6-tetracarboxylate(H_4pztc)with brimming active sites for lithium ions storage was utilized to construct coordination polymers(CPs)via a facile hydrothermal reaction.Those two isostructural two-dimensional(2D)CPs,namely[M_2(pztc)(H_2O)_6]_n(M=Co for 1 and Ni for 2),delivered excellent reversible capacities and stable cycling performance as anodes in lithium ion batteries.As demonstrated in electrochemical studies,1 and 2 can achieve highly reversible capacities of 815 and 536 mA h g^(-1)at 200 mA g^(-1)for 150 cycles,respectively,best performed for the reported2D-CP-based anode materials.The electrochemical mechanism studies showed that the remarkable performances can be ascribed to the synergistic Li-storage redox reactions of metal centers and organic moieties.Our work highlights the opportunities of using a well-designed organic ligand to construct low-dimensional CPs as new type of electrode materials for advanced lithium ion batteries.
