Thermally activated delayed fluorescence(TADF)molecules have outstanding potential for applications in organic light-emitting diodes(OLEDs).Due to the lack of systematic studies on the correlation between molecular st...Thermally activated delayed fluorescence(TADF)molecules have outstanding potential for applications in organic light-emitting diodes(OLEDs).Due to the lack of systematic studies on the correlation between molecular structure and luminescence properties,TADF molecules are far from meeting the needs of practical applications in terms of variety and number.In this paper,three twisted TADF molecules are studied and their photophysical properties are theoretically predicted based on the thermal vibrational correlation function method combined with multiscale calculations.The results show that all the molecules exhibit fast reverse intersystem crossing(RISC)rates(kRISC),predicting their TADF luminescence properties.In addition,the binding of DHPAzSi as the donor unit with different acceptors can change the dihedral angle between the ground and excited states,and the planarity of the acceptors is positively correlated with the reorganization energy,a property that has a strong influence on the non-radiative process.Furthermore,a decrease in the energy of the molecular charge transfer state and an increase in the kRISC were observed in the films.This study not only provides a reliable explanation for the observed experimental results,but also offers valuable insights that can guide the design of future TADF molecules.展开更多
Hanyu Xu 1,Xuedan Song 1,*,Qing Zhang 1,Chang Yu 1,Jieshan Qiu 1,2,*1 Liaoning Key Lab for Energy Materials and Chemical Engineering,State Key Laboratory of Fine Chemicals,School of Chemical Engineering,Dalian Univers...Hanyu Xu 1,Xuedan Song 1,*,Qing Zhang 1,Chang Yu 1,Jieshan Qiu 1,2,*1 Liaoning Key Lab for Energy Materials and Chemical Engineering,State Key Laboratory of Fine Chemicals,School of Chemical Engineering,Dalian University of Technology,Dalian 116024,Liaoning Province,China.展开更多
Steel-concrete composite beams,due to their superior mechanical properties,are widely utilized in engineering structures.This study systematically investigates the calculation methods for internal forces and load-bear...Steel-concrete composite beams,due to their superior mechanical properties,are widely utilized in engineering structures.This study systematically investigates the calculation methods for internal forces and load-bearing capacity of composite beams based on elastic theory,with a focus on the transformed section method and its application under varying neutral axis positions.By deriving the geometric characteristics of the transformed section and incorporating a reduction factor accounting for slip effects,a computational model for sectional stress and ultimate load-bearing capacity is established.The results demonstrate that the slip effect significantly influences the flexural load-bearing capacity of composite beams.The proposed reduction factor,which considers the influence of the steel beam’s top flange thickness,offers higher accuracy compared to traditional methods.These findings provide a theoretical foundation for the design and analysis of composite beams,with significant practical engineering value.展开更多
Heterostructures of organic semi-conductors and transition metal dichalcogenides(TMDs)are viable candidates for superior optoelec-tronic devices.Photoinduced inter-facial charge transfer is crucial for the performance...Heterostructures of organic semi-conductors and transition metal dichalcogenides(TMDs)are viable candidates for superior optoelec-tronic devices.Photoinduced inter-facial charge transfer is crucial for the performance efficiency of such devices,yet the underlying mecha-nism,especially the roles of optical-ly dark triplets and spatially sepa-rated charge transfer states,is poorly understood.In the present work,we obtain the struc-tures of distinct excited states and investigate how they are involved in the charge transfer process at the Pd-octaethylporphyrin(PdOEP)and WS_(2) interface in terms of their energies and couplings.The results show that electron transfer from the triplet PdOEP formed via intersystem crossing prevails over direct electron transfer from the singlet(two orders of magnitude faster).Further analysis reveals that the relatively higher rate of triplet electron transfer compared to singlet electron transfer is mainly attributed to a smaller reorganization energy,which is dominated by the out-of-plane vibrations of the organic component.The work emphasizes the important roles of the optically dark triplets in the electron transfer of the PdOEP@WS_(2) heterostructure,and provides valuable theoretical insights for further improv-ing the optoelectronic performance of TMD-based devices.展开更多
The lowest energy structures of peroxynitric acid have been studied with B3LYP/6-311＋ G（2d,2p） method. The potential energy surfaces （PES） along the O-N and O-O bonds have been scanned at CCSD（T）/aug-cc-pVDZ le...The lowest energy structures of peroxynitric acid have been studied with B3LYP/6-311＋ G（2d,2p） method. The potential energy surfaces （PES） along the O-N and O-O bonds have been scanned at CCSD（T）/aug-cc-pVDZ level, respectively. The calculated results show that on the O-N PES, the O3-N4 bond length of the loose transition state is 2.82A^° and the corresponding energy barrier is 25.6 kcal/mol, while on the O-O PES, the loose transition state with of O2-O3 bond length of 2.35A^° has the energy barrier of 37.4 kcal/mol. Thus the primary reaction path for peroxynitric acid is the dissociation into HO2 and NO2.展开更多
Using density functional theory and polarizable continuum models, we study the Raman spectra of aqueous peroxynitric acid. The calculated results indicate that the solvent effect has significant influence on the elect...Using density functional theory and polarizable continuum models, we study the Raman spectra of aqueous peroxynitric acid. The calculated results indicate that the solvent effect has significant influence on the electric dipole transition moments between the ground and excited electronic state and Raman polarizabilities. The theoretical Raman spectra agree well with the experimental results. From the experimental depolarization ratio, we can conclude that peroxynitric acid is not a plane molecule. We also find that the hydrogen bond can enhance IR intensity of hydroxyl group by several times.展开更多
This paper mainly focuses on the theoretical bases of intercultural communication by analyzing reasons of IC studies’emergence,researches done on IC by linguists and English teachers,and some difficulties concerning ...This paper mainly focuses on the theoretical bases of intercultural communication by analyzing reasons of IC studies’emergence,researches done on IC by linguists and English teachers,and some difficulties concerning intercultural communication studies.展开更多
Based on a set of equations established by Duan et al. (1992, 1996) for a geofluid system H2O-CO2-CH4(-N2), a formula is obtained to calculate the heat changes. Combining the geological T-P conditions (geothermal grad...Based on a set of equations established by Duan et al. (1992, 1996) for a geofluid system H2O-CO2-CH4(-N2), a formula is obtained to calculate the heat changes. Combining the geological T-P conditions (geothermal gradients and lithostatic and hydrostatic pressures), the enthalpy of some typical geofluids is figured out. Then the principles of heat transfer of deep-derived supercritical fluids are discussed. The result shows that deep-derived geofluids can bring a large amount of thermal heat and release most heat to the shallow surroundings as they move up, because the molar enthalpies vary very greatly from the deep to shallow, increasing with the increases of T and P. Generally, more than tens of kilojoules heat per molar can be released. Furthermore, the molar enthalpy is affected by the compositions of the geofluids, and the molar enthalpy of CO2, CH4, or N2 is greater than that of H2O, being twice, more than twice, and about 140% of H2O, respectively. Finally, a case study is conducted by investigating a source rock sequence affected hydrothermally by magmatic fluids in the Huimin depression of Shengli Oilfield. The thermal heat calculated theoretically of the fluids related to a diabase intrusion is quite large, which can increase the temperature near the diabase to about 300℃, and that can, to some extent, account for the abnormal rise of the vitrinite reflectance, with the highest of about 3.8% (Ro).展开更多
This article described the characteristics of the liquid nitrogen engine's ideal open cycle.Using two interconnecting strokes to achieve the power output can mitigate the trade-off between high efficiency and the ...This article described the characteristics of the liquid nitrogen engine's ideal open cycle.Using two interconnecting strokes to achieve the power output can mitigate the trade-off between high efficiency and the potential mechanical complexity of multiple-cylinder engines. The total specific energy of the binary media (methane-nitrogen) cycle system could be much higher than the unitary medium (liquid nitrogen) cycle system. By theoretical analysis, the reasonably acceptable driving range proved the feasibility of the liquid nitrogen engine used for supplying power for a lightweight car.展开更多
Marine fouling is a worldwide challenge with huge damages on industrial structures,side effects on economics of industries,and environmental and safety-related hazards.Different approaches have been used for combating...Marine fouling is a worldwide challenge with huge damages on industrial structures,side effects on economics of industries,and environmental and safety-related hazards.Different approaches have been used for combating fouling in the marine environment.Meanwhile,nanocomposite polymer coatings are a novel generation of antifouling coatings with merits of toxin-free chemical composition and ease of large-scale application.Nanomaterials such as nano-metals,nano-metal oxides,metal-organic frameworks,carbon-based nanostructures,MXene,and nanoclays have antibacterial and antifouling properties in the polymer coatings.Besides,these nanomaterials can improve the corrosion resistance,mechanical strength,weathering stability,and thermal resistance of the polymer coatings.Therefore,in this review paper,the antifouling nanocomposite coatings are introduced and antifouling mechanisms are discussed.This review explicitly indicates that the antifouling efficiency of the nanocomposite coatings depends on the properties of the polymer matrix,the inherent properties of the nanomaterials,the weight percent and the dispersion method of the nanomaterials within the coating matrix,and the chemicals used for modifying the surface of the nanomaterials;meanwhile,the hybrids of different nanomaterials and appropriate chemical agents could be used to improve the antifouling behavior of the prepared nanocomposites.Moreover,the theoretical studies are introduced to pave the way of researchers working on theantifouling coatings,and the importance of the theoretical studies and computational modeling along with the experimental research is notified to develop antifouling coatings with high efficiency.展开更多
A novel thiosemicarbazide derivative, （E）-1-（9-（2-（2-methoxyethoxy）ethyl）-9H-carbazol-3-yl） methylene）-thiosemicarbazide （CMT）, was synthesized and structurally characterized by IR, 1H-NMR, EI-MS and single...A novel thiosemicarbazide derivative, （E）-1-（9-（2-（2-methoxyethoxy）ethyl）-9H-carbazol-3-yl） methylene）-thiosemicarbazide （CMT）, was synthesized and structurally characterized by IR, 1H-NMR, EI-MS and single-crystal X-ray diffraction. It crystallizes in monoclinic, space group P21/c with a = 14.769（5）, b = 8.279（5）, c = 17.166（5） , β = 114.391（5）°, V = 1911.6（14） 3, Z = 4, F（000） = 784, Dc = 1.287 g/m3, Mr = 370.47, μ = 0.190 mm-1, the final R = 0.0390 and wR = 0.1358 for 1446 observed reflections with Ⅰ 〉 2σ（Ⅰ）. The UV-vis absorption spectra of CMT were explained based on quantum chemical calculations, using time dependent density functional theory （TD-DFT） at the B3LYP/6-31G （d） level.展开更多
Organic thermoelectric(OTE)materials and devices have garnered significant attention in the past decade for flexible and wearable electronics.Due to the numerous combinations of different backbones,side chains,and fun...Organic thermoelectric(OTE)materials and devices have garnered significant attention in the past decade for flexible and wearable electronics.Due to the numerous combinations of different backbones,side chains,and functional groups for polymer molecules,further efficient developments of high perfor-mance OTEs rely on reverse and rational molecular design as well as fundamental understanding to the structure-property relationship,which both require precise theoretical input.Recently,many theo-retical efforts and progresses have been made to predict TE properties and develop high performance OTE materials.Here,we present first the general methods and principles for OTE theoretical calculations.Subsequently,the latest theoretical advances regarding the effects of molecular design,chemical dop-ing,ambipolar charge transport etc.,to TE conversion are carefully reviewed.These theoretical advances not only significantly deepen the fundamental understanding of OTEs,but also provide precise guidance to the molecular design of OTE materials.Finally,we propose several perspectives for future theoretical investigations of OTEs.展开更多
The bio-mimic reactions of N-phosphoryl amino acids are very important in the study of many biochemical processes. The difference of reactivity between a-COOH and b-COOH in phosphoryl aspartic acid was studied by the...The bio-mimic reactions of N-phosphoryl amino acids are very important in the study of many biochemical processes. The difference of reactivity between a-COOH and b-COOH in phosphoryl aspartic acid was studied by theoretical study (Hartree-Fock and Density Functional methods) in this paper. The intermediates II containing five-membered ring were more stable than III with six-membered ring. While for intermediates III, the isomers with six-membered ring in apical-equatorial spanning arrangement were more stable than those with di-equatorial spanning arrangement. At B3LYP/6-31G** level, it was shown that transition states IV and V involving a-COOH or b-COOH group had energy barriers of DE = 58.67 kJmol-1 and 103.94 kJmol-1, respectively. These results were in agreement with the experimental data. So the a-COOH group was involved in form of the intramolecular penta-coordinate phosphoric-carboxylic mixed anhydride intermediates, but not b-COOH group.展开更多
The reaction mechanism of PCl3/H2 on silicon substrate surface （simulated by Si4 cluster） was investigated with Density Functional Theory （DFT） at the B3LYP/6-311G^＊＊ level. On silicon substrate, PCl3 firstly un...The reaction mechanism of PCl3/H2 on silicon substrate surface （simulated by Si4 cluster） was investigated with Density Functional Theory （DFT） at the B3LYP/6-311G^＊＊ level. On silicon substrate, PCl3 firstly undergoes dissociative adsorption, and then the adsorption product reacts with H2 via a four-step multi-channel mode to give the final product PSi4 cluster. The geometries at each stationary point were fully optimized. The possible transition states were determined by vibrational mode analysis and IRC verification. And finally, the main reaction channel was given.展开更多
Two Pb^Ⅱ coordination polymers [Pb（oba）（2,2′-bipy）]·1.5H2O（1） and [Pb（oba）（phen）]（2）（H2oba = 2,4-oxybis（benzoic acid）, 2,2′-bipy = 2,2′-bipyridine, phen = 1,10-phenanthroline） were synthesized...Two Pb^Ⅱ coordination polymers [Pb（oba）（2,2′-bipy）]·1.5H2O（1） and [Pb（oba）（phen）]（2）（H2oba = 2,4-oxybis（benzoic acid）, 2,2′-bipy = 2,2′-bipyridine, phen = 1,10-phenanthroline） were synthesized by hydrothermal reactions and characterized by single-crystal X-ray diffraction, thermogravimetric analyses, IR spectroscopy and elemental analysis. Structures of compounds 1 and 2 are similar. Compounds 1 and 2 show 1D wavy chains, which are further connected through aromatic π-π stacking interactions to expand into 2D wavelike networks. The crystal structure of 2,4-oxybis（benzoic acid） ligand（3） was obtained, and its full geometry optimization was carried out by using DFT methods at the B3LYP/6-31G（d） level. The calculated data show that the bond distances and bond angles were very close to the experimental data. The values of the frontier orbital energies indicate that this configuration is stable. Moreover, the solid-state fluorescence properties of 1-3 have also been investigated.展开更多
The NaI and IF product rotational alignment of the reactions of Na,F+CH_3I has been theoretically studied in a LEPS PES.The product alignment versus the relative translational energy of the reactants has been obtained.
The mechanism and kinetics for the decomposition of 3-hydroxy-3-methyl-2-butanone have been studied by using the ab initio RHF/3-21G method. The calculated activation barrier of the reaction is 249.6kJ/mol which is in...The mechanism and kinetics for the decomposition of 3-hydroxy-3-methyl-2-butanone have been studied by using the ab initio RHF/3-21G method. The calculated activation barrier of the reaction is 249.6kJ/mol which is in reasonable agreement with the experimental data (222.2±3kJ/mol). The calculated results show that the decomposition is a concerted process with hydrogen transferring and bond breaking via a five-membered cyclic transition state. The thermal rate constants of the decomposition are obtained by calculating microcanonical probability fluxes through transition state1.展开更多
The reaction of Au＋（1S,3D） with CS2 has been investigated at the B3LYP and CCSD（T） levels of theory.The identified reaction pathways revealed that the experimentally observed products,AuS＋ and AuCS＋,can be prod...The reaction of Au＋（1S,3D） with CS2 has been investigated at the B3LYP and CCSD（T） levels of theory.The identified reaction pathways revealed that the experimentally observed products,AuS＋ and AuCS＋,can be produced by the insertion of Au＋ into C-S bond.The calculated energetics shows that the reactions on singlet surface lead to excited-state products,AuS＋（1Σ） ＋ 1CS and AuCS＋（1Σ） ＋ 1S,and have notable energy barriers,whereas the reactions on triplet surface producing the ground state products of AuS＋（3Σ） ＋ 1CS and AuCS＋（1Σ） ＋ 3S are energetically much more favorable.This result suggests that the minor formations of AuS＋ and AuCS＋ observed in the previous experiment under room-temperature condition should result from the reactions of excited-state Au＋（3D） with CS2.Further,the possibility for singlet-triplet surface crossing was also discussed by approximately determining the crossing region.展开更多
Density functional theory B3LYP/6-311 G＊ method was used in the geometry optimization and frequency calculation on Si5X （X = Li, Be, B, C, N, O, E Na, Mg, Al, Si, P, S, Cl） clusters. The influence of the doped seco...Density functional theory B3LYP/6-311 G＊ method was used in the geometry optimization and frequency calculation on Si5X （X = Li, Be, B, C, N, O, E Na, Mg, Al, Si, P, S, Cl） clusters. The influence of the doped second and third period element impurities on the structure and stability of Si5X clusters with C2p symmetry has been investigated, and the thermal stability and dynamic activity have also been discussed.展开更多
The reaction mechanism between CC12 and armchair single-walled carbon nanotubes （ASWCNTs） （3,3） and （4,4） has been studied by semiempirical AM1 and ab initio methods. The activation barriers of CC12 adding to AS...The reaction mechanism between CC12 and armchair single-walled carbon nanotubes （ASWCNTs） （3,3） and （4,4） has been studied by semiempirical AM1 and ab initio methods. The activation barriers of CC12 adding to ASWCNT （3,3） and （4,4） are computed and compared. The lower barrier of CC12 forms cycloaddition isomer on （3,3） maybe because the strain energy of （3,3） is larger than that of （4,4）. Our theoretical results are consistent with the experimental results.展开更多
文摘Thermally activated delayed fluorescence(TADF)molecules have outstanding potential for applications in organic light-emitting diodes(OLEDs).Due to the lack of systematic studies on the correlation between molecular structure and luminescence properties,TADF molecules are far from meeting the needs of practical applications in terms of variety and number.In this paper,three twisted TADF molecules are studied and their photophysical properties are theoretically predicted based on the thermal vibrational correlation function method combined with multiscale calculations.The results show that all the molecules exhibit fast reverse intersystem crossing(RISC)rates(kRISC),predicting their TADF luminescence properties.In addition,the binding of DHPAzSi as the donor unit with different acceptors can change the dihedral angle between the ground and excited states,and the planarity of the acceptors is positively correlated with the reorganization energy,a property that has a strong influence on the non-radiative process.Furthermore,a decrease in the energy of the molecular charge transfer state and an increase in the kRISC were observed in the films.This study not only provides a reliable explanation for the observed experimental results,but also offers valuable insights that can guide the design of future TADF molecules.
文摘Hanyu Xu 1,Xuedan Song 1,*,Qing Zhang 1,Chang Yu 1,Jieshan Qiu 1,2,*1 Liaoning Key Lab for Energy Materials and Chemical Engineering,State Key Laboratory of Fine Chemicals,School of Chemical Engineering,Dalian University of Technology,Dalian 116024,Liaoning Province,China.
文摘Steel-concrete composite beams,due to their superior mechanical properties,are widely utilized in engineering structures.This study systematically investigates the calculation methods for internal forces and load-bearing capacity of composite beams based on elastic theory,with a focus on the transformed section method and its application under varying neutral axis positions.By deriving the geometric characteristics of the transformed section and incorporating a reduction factor accounting for slip effects,a computational model for sectional stress and ultimate load-bearing capacity is established.The results demonstrate that the slip effect significantly influences the flexural load-bearing capacity of composite beams.The proposed reduction factor,which considers the influence of the steel beam’s top flange thickness,offers higher accuracy compared to traditional methods.These findings provide a theoretical foundation for the design and analysis of composite beams,with significant practical engineering value.
基金supported by the Fundamental Re-search Funds for the Central Universities(Ganglong Cui)and National Key Research and Development Pro-gram of China(No.2021YFA1500703 to Ganglong Cui)National Natural Science Foundation of China(No.22103067 to Xiao-Ying Xie)and Natural Science Foundation of Shandong Province(No.ZR2021QB105 to Xiao-Ying Xie).
文摘Heterostructures of organic semi-conductors and transition metal dichalcogenides(TMDs)are viable candidates for superior optoelec-tronic devices.Photoinduced inter-facial charge transfer is crucial for the performance efficiency of such devices,yet the underlying mecha-nism,especially the roles of optical-ly dark triplets and spatially sepa-rated charge transfer states,is poorly understood.In the present work,we obtain the struc-tures of distinct excited states and investigate how they are involved in the charge transfer process at the Pd-octaethylporphyrin(PdOEP)and WS_(2) interface in terms of their energies and couplings.The results show that electron transfer from the triplet PdOEP formed via intersystem crossing prevails over direct electron transfer from the singlet(two orders of magnitude faster).Further analysis reveals that the relatively higher rate of triplet electron transfer compared to singlet electron transfer is mainly attributed to a smaller reorganization energy,which is dominated by the out-of-plane vibrations of the organic component.The work emphasizes the important roles of the optically dark triplets in the electron transfer of the PdOEP@WS_(2) heterostructure,and provides valuable theoretical insights for further improv-ing the optoelectronic performance of TMD-based devices.
基金This work was supported by the National Natural Science Foundation of China （No.21103003）.
文摘The lowest energy structures of peroxynitric acid have been studied with B3LYP/6-311＋ G（2d,2p） method. The potential energy surfaces （PES） along the O-N and O-O bonds have been scanned at CCSD（T）/aug-cc-pVDZ level, respectively. The calculated results show that on the O-N PES, the O3-N4 bond length of the loose transition state is 2.82A^° and the corresponding energy barrier is 25.6 kcal/mol, while on the O-O PES, the loose transition state with of O2-O3 bond length of 2.35A^° has the energy barrier of 37.4 kcal/mol. Thus the primary reaction path for peroxynitric acid is the dissociation into HO2 and NO2.
基金This work was supported by the National Natural Science Foundation of China （No.20903101 and No.21103003）.
文摘Using density functional theory and polarizable continuum models, we study the Raman spectra of aqueous peroxynitric acid. The calculated results indicate that the solvent effect has significant influence on the electric dipole transition moments between the ground and excited electronic state and Raman polarizabilities. The theoretical Raman spectra agree well with the experimental results. From the experimental depolarization ratio, we can conclude that peroxynitric acid is not a plane molecule. We also find that the hydrogen bond can enhance IR intensity of hydroxyl group by several times.
文摘This paper mainly focuses on the theoretical bases of intercultural communication by analyzing reasons of IC studies’emergence,researches done on IC by linguists and English teachers,and some difficulties concerning intercultural communication studies.
基金supported by the Major State Basic Research Development Program of China(G1999043309)the National Natural Science Foundation of China grant 49973001.
文摘Based on a set of equations established by Duan et al. (1992, 1996) for a geofluid system H2O-CO2-CH4(-N2), a formula is obtained to calculate the heat changes. Combining the geological T-P conditions (geothermal gradients and lithostatic and hydrostatic pressures), the enthalpy of some typical geofluids is figured out. Then the principles of heat transfer of deep-derived supercritical fluids are discussed. The result shows that deep-derived geofluids can bring a large amount of thermal heat and release most heat to the shallow surroundings as they move up, because the molar enthalpies vary very greatly from the deep to shallow, increasing with the increases of T and P. Generally, more than tens of kilojoules heat per molar can be released. Furthermore, the molar enthalpy is affected by the compositions of the geofluids, and the molar enthalpy of CO2, CH4, or N2 is greater than that of H2O, being twice, more than twice, and about 140% of H2O, respectively. Finally, a case study is conducted by investigating a source rock sequence affected hydrothermally by magmatic fluids in the Huimin depression of Shengli Oilfield. The thermal heat calculated theoretically of the fluids related to a diabase intrusion is quite large, which can increase the temperature near the diabase to about 300℃, and that can, to some extent, account for the abnormal rise of the vitrinite reflectance, with the highest of about 3.8% (Ro).
文摘This article described the characteristics of the liquid nitrogen engine's ideal open cycle.Using two interconnecting strokes to achieve the power output can mitigate the trade-off between high efficiency and the potential mechanical complexity of multiple-cylinder engines. The total specific energy of the binary media (methane-nitrogen) cycle system could be much higher than the unitary medium (liquid nitrogen) cycle system. By theoretical analysis, the reasonably acceptable driving range proved the feasibility of the liquid nitrogen engine used for supplying power for a lightweight car.
基金supported financially by the CAS President’s International Fellowship Initiative 2019(PIFI,No.2019PE0059)CAS-VPST Silk Road Science Fund 2021(133137KYSB20200034)INSF’s Project No.99010368。
文摘Marine fouling is a worldwide challenge with huge damages on industrial structures,side effects on economics of industries,and environmental and safety-related hazards.Different approaches have been used for combating fouling in the marine environment.Meanwhile,nanocomposite polymer coatings are a novel generation of antifouling coatings with merits of toxin-free chemical composition and ease of large-scale application.Nanomaterials such as nano-metals,nano-metal oxides,metal-organic frameworks,carbon-based nanostructures,MXene,and nanoclays have antibacterial and antifouling properties in the polymer coatings.Besides,these nanomaterials can improve the corrosion resistance,mechanical strength,weathering stability,and thermal resistance of the polymer coatings.Therefore,in this review paper,the antifouling nanocomposite coatings are introduced and antifouling mechanisms are discussed.This review explicitly indicates that the antifouling efficiency of the nanocomposite coatings depends on the properties of the polymer matrix,the inherent properties of the nanomaterials,the weight percent and the dispersion method of the nanomaterials within the coating matrix,and the chemicals used for modifying the surface of the nanomaterials;meanwhile,the hybrids of different nanomaterials and appropriate chemical agents could be used to improve the antifouling behavior of the prepared nanocomposites.Moreover,the theoretical studies are introduced to pave the way of researchers working on theantifouling coatings,and the importance of the theoretical studies and computational modeling along with the experimental research is notified to develop antifouling coatings with high efficiency.
基金supported by the National Natural Science Foundation of China (51142011)Natural Science Foundation of Anhui Province (1208085MB22)Education Department of Anhui Province (KJ2010A030)
文摘A novel thiosemicarbazide derivative, （E）-1-（9-（2-（2-methoxyethoxy）ethyl）-9H-carbazol-3-yl） methylene）-thiosemicarbazide （CMT）, was synthesized and structurally characterized by IR, 1H-NMR, EI-MS and single-crystal X-ray diffraction. It crystallizes in monoclinic, space group P21/c with a = 14.769（5）, b = 8.279（5）, c = 17.166（5） , β = 114.391（5）°, V = 1911.6（14） 3, Z = 4, F（000） = 784, Dc = 1.287 g/m3, Mr = 370.47, μ = 0.190 mm-1, the final R = 0.0390 and wR = 0.1358 for 1446 observed reflections with Ⅰ 〉 2σ（Ⅰ）. The UV-vis absorption spectra of CMT were explained based on quantum chemical calculations, using time dependent density functional theory （TD-DFT） at the B3LYP/6-31G （d） level.
基金support from the National Natural Science Foundation of China(Nos.22125504,22305253,62205347)the Beijing Natural Science Foundation(No.Z220025)the K.C.Wong Education Foundation(No.GJTD-2020-02).
文摘Organic thermoelectric(OTE)materials and devices have garnered significant attention in the past decade for flexible and wearable electronics.Due to the numerous combinations of different backbones,side chains,and functional groups for polymer molecules,further efficient developments of high perfor-mance OTEs rely on reverse and rational molecular design as well as fundamental understanding to the structure-property relationship,which both require precise theoretical input.Recently,many theo-retical efforts and progresses have been made to predict TE properties and develop high performance OTE materials.Here,we present first the general methods and principles for OTE theoretical calculations.Subsequently,the latest theoretical advances regarding the effects of molecular design,chemical dop-ing,ambipolar charge transport etc.,to TE conversion are carefully reviewed.These theoretical advances not only significantly deepen the fundamental understanding of OTEs,but also provide precise guidance to the molecular design of OTE materials.Finally,we propose several perspectives for future theoretical investigations of OTEs.
基金the National Natural Science Foundation of China (No. 29802006) the Teaching and Research Award Program for Outstanding Young Teachers in Higher Education Institutions of MOE P.R.C. and Tsinghua University.
文摘The bio-mimic reactions of N-phosphoryl amino acids are very important in the study of many biochemical processes. The difference of reactivity between a-COOH and b-COOH in phosphoryl aspartic acid was studied by theoretical study (Hartree-Fock and Density Functional methods) in this paper. The intermediates II containing five-membered ring were more stable than III with six-membered ring. While for intermediates III, the isomers with six-membered ring in apical-equatorial spanning arrangement were more stable than those with di-equatorial spanning arrangement. At B3LYP/6-31G** level, it was shown that transition states IV and V involving a-COOH or b-COOH group had energy barriers of DE = 58.67 kJmol-1 and 103.94 kJmol-1, respectively. These results were in agreement with the experimental data. So the a-COOH group was involved in form of the intramolecular penta-coordinate phosphoric-carboxylic mixed anhydride intermediates, but not b-COOH group.
基金supported by the Foundation of Education Committee of Liaoning Province (990321076)
文摘The reaction mechanism of PCl3/H2 on silicon substrate surface （simulated by Si4 cluster） was investigated with Density Functional Theory （DFT） at the B3LYP/6-311G^＊＊ level. On silicon substrate, PCl3 firstly undergoes dissociative adsorption, and then the adsorption product reacts with H2 via a four-step multi-channel mode to give the final product PSi4 cluster. The geometries at each stationary point were fully optimized. The possible transition states were determined by vibrational mode analysis and IRC verification. And finally, the main reaction channel was given.
基金supported by the Natural Scientific Research and Overall innovation plan major project of Shaanxi Provincial Education Office of China(No.2012KTCL03-16)the National Natural Science Foundation of China(No.21373178)+2 种基金the Natural Scientific Research Foundation of Shaanxi Provincial Education Office(No.2013Jk0668)the National College Students'innovation and entrepreneurship training program(201310719002)the special fund of Yan’an University(No.YDZ2013-10)
文摘Two Pb^Ⅱ coordination polymers [Pb（oba）（2,2′-bipy）]·1.5H2O（1） and [Pb（oba）（phen）]（2）（H2oba = 2,4-oxybis（benzoic acid）, 2,2′-bipy = 2,2′-bipyridine, phen = 1,10-phenanthroline） were synthesized by hydrothermal reactions and characterized by single-crystal X-ray diffraction, thermogravimetric analyses, IR spectroscopy and elemental analysis. Structures of compounds 1 and 2 are similar. Compounds 1 and 2 show 1D wavy chains, which are further connected through aromatic π-π stacking interactions to expand into 2D wavelike networks. The crystal structure of 2,4-oxybis（benzoic acid） ligand（3） was obtained, and its full geometry optimization was carried out by using DFT methods at the B3LYP/6-31G（d） level. The calculated data show that the bond distances and bond angles were very close to the experimental data. The values of the frontier orbital energies indicate that this configuration is stable. Moreover, the solid-state fluorescence properties of 1-3 have also been investigated.
文摘The NaI and IF product rotational alignment of the reactions of Na,F+CH_3I has been theoretically studied in a LEPS PES.The product alignment versus the relative translational energy of the reactants has been obtained.
文摘The mechanism and kinetics for the decomposition of 3-hydroxy-3-methyl-2-butanone have been studied by using the ab initio RHF/3-21G method. The calculated activation barrier of the reaction is 249.6kJ/mol which is in reasonable agreement with the experimental data (222.2±3kJ/mol). The calculated results show that the decomposition is a concerted process with hydrogen transferring and bond breaking via a five-membered cyclic transition state. The thermal rate constants of the decomposition are obtained by calculating microcanonical probability fluxes through transition state1.
基金Supported by the General Program of the Applied Basic Research of Science and Technology Department of Yunnan Province (No.2008ZC095)the Scientific Research Fund of Yunnan Provincial Education Department (No.08Y0195)supported by the Key Laboratory of Forest Resources Conservation and Use in the Southwest Mountains of China (Southwest Forestry University)
文摘The reaction of Au＋（1S,3D） with CS2 has been investigated at the B3LYP and CCSD（T） levels of theory.The identified reaction pathways revealed that the experimentally observed products,AuS＋ and AuCS＋,can be produced by the insertion of Au＋ into C-S bond.The calculated energetics shows that the reactions on singlet surface lead to excited-state products,AuS＋（1Σ） ＋ 1CS and AuCS＋（1Σ） ＋ 1S,and have notable energy barriers,whereas the reactions on triplet surface producing the ground state products of AuS＋（3Σ） ＋ 1CS and AuCS＋（1Σ） ＋ 3S are energetically much more favorable.This result suggests that the minor formations of AuS＋ and AuCS＋ observed in the previous experiment under room-temperature condition should result from the reactions of excited-state Au＋（3D） with CS2.Further,the possibility for singlet-triplet surface crossing was also discussed by approximately determining the crossing region.
基金This work was supported by Foundation of Education Committee of Liaoning Province (No. 990321076)
文摘Density functional theory B3LYP/6-311 G＊ method was used in the geometry optimization and frequency calculation on Si5X （X = Li, Be, B, C, N, O, E Na, Mg, Al, Si, P, S, Cl） clusters. The influence of the doped second and third period element impurities on the structure and stability of Si5X clusters with C2p symmetry has been investigated, and the thermal stability and dynamic activity have also been discussed.
基金This work was supported by the National Natural Science Foundation of China (No. 20303010), NKStar HPC Program and the Science Foundation of Nankai University
文摘The reaction mechanism between CC12 and armchair single-walled carbon nanotubes （ASWCNTs） （3,3） and （4,4） has been studied by semiempirical AM1 and ab initio methods. The activation barriers of CC12 adding to ASWCNT （3,3） and （4,4） are computed and compared. The lower barrier of CC12 forms cycloaddition isomer on （3,3） maybe because the strain energy of （3,3） is larger than that of （4,4）. Our theoretical results are consistent with the experimental results.
