Changes of surface shape, aggregate state, and microstructure of Apocynum fiber before and after irradia-tion were studied by XRD, IR, SEM, ESR, and solid state 13C CP/ MAS NMR. The results show that the surface shape...Changes of surface shape, aggregate state, and microstructure of Apocynum fiber before and after irradia-tion were studied by XRD, IR, SEM, ESR, and solid state 13C CP/ MAS NMR. The results show that the surface shape and microstructure were not spoiled under 50 kGy gamma irradiation, while the crystallization of Apocynum fiber changed under 280 kGy . It also shows that different free radicals appear after irradiation and their concentration increases with the increase of irradiation dose.展开更多
The moisture instability and toxicity of lead have hindered the development of lead organometal halide perovskites(Pb-OHPs).Similar to Pb-OHPs,OHPs based on Pb-free elements,including Group VA metals Bi and Sb(denoted...The moisture instability and toxicity of lead have hindered the development of lead organometal halide perovskites(Pb-OHPs).Similar to Pb-OHPs,OHPs based on Pb-free elements,including Group VA metals Bi and Sb(denoted as M),exhibit optoelectronic properties due to their isoelectronic configuration and close chemistry of the lone-pair ns^(2) state.However,M-OHPs are mostly based on hydrophilic protonated organic countercations and possess low structural dimensionalities,which affect the moisture stability and disrupt continuous carrier transport,respectively.Herein,we demonstrate a“double-free”strategy to realize the rational synthesis of moisture-stable hypotoxic hybrid perovskites.A hydrogen-bond-free alkylated countercation was assembled with Pb-free OHP bearing an extended structure in one molecule.As a proof of concept,two double-free M-OHPs are synthesized,which show greatly improved moisture and photostability compared to their corresponding hydrogen-bond OHPs and the extensively studied MA_(3)M_(2)X_(9)(MA=CH_(3)NH_(3)^(+)).The photoconduction behaviors of both double-free OHPs display short rise and decay recovery time and exhibit excellent photocurrent reproducibility.Importantly,(1-methyl-4-phenylpyridin-1-ium)BiI_(4)(Me4ppi-BiI_(4))displays a comparable switching on/off ratio with MA_(3)Bi_(2)I_(9),and can endure 75% relative humidity(RH)for at least 243 days.The photophysical property measurements and theoretical calculations show that this remarkable photoconversion performance results from the relatively low exciton binding energy and greatly improved carrier mobility and concentration.展开更多
The influence of hydrogen bonds on the physical and chemical properties of hydrogen bonding fluid system of AaDd type is investigated from two viewpoints by the principle of statistical mechanics. In detail, we propos...The influence of hydrogen bonds on the physical and chemical properties of hydrogen bonding fluid system of AaDd type is investigated from two viewpoints by the principle of statistical mechanics. In detail, we proposed two new ways that can be used to obtain the equilibrium size distribution of the hydrogen bonding clusters, and derived the analytical expression of a relationship between the hydrogen bonding free energy and hydrogen bonding degree. For the nonlinear hydrogen bonding systems, it is shown that the sol-gel phase transition can take place under proper conditions, which is further proven to be a kind of geometrical phase transition rather than a thermodynamic one. Moreover, several problems associated with the geometrical phase transition and liquid-solid phase transition in nonlinear hydrogen bonding systems are discussed.展开更多
In separation processes,hydrogen bonding has a very significant effect on the efficiency of isolation of acetic acid (HOAc) from HOAc/H2O mixtures. This intermolecular interaction on aggregates composed of a single HO...In separation processes,hydrogen bonding has a very significant effect on the efficiency of isolation of acetic acid (HOAc) from HOAc/H2O mixtures. This intermolecular interaction on aggregates composed of a single HOAc molecule and varying numbers of H2O molecules has been examined by using ab initio molecular dynamics simulations (AIMD) and quantum chemical calculations (QCC). Thermodynamic data in aqueous solution were obtained through the self-consistent reaction field calculations and the polarizable continuum model. The aggregation free energy of the aggregates in gas phase as well as in aqueous system shows that the 6-membered ring is the most favorable structure in both states. The relative stability of the ring structures inferred from the thermodynamic properties of the QCC is consistent with the ring distributions of the AIMD simulation. The study shows that in dilute aqueous solution of HOAc the more favorable molecular interaction is the hydrogen bonding between HOAc and H2O molecules,resulting in the separation of acetic acid from the HOAc/H2O mixtures with more difficulty than usual.展开更多
A series of mono-functional benzoxazine monomers with different N-substituents were synthesized from phenol, formaldehyde, and various amines （ammonia, methylamine, n-butylamine, dodecylamine）, named P-am, P-m, P-b,...A series of mono-functional benzoxazine monomers with different N-substituents were synthesized from phenol, formaldehyde, and various amines （ammonia, methylamine, n-butylamine, dodecylamine）, named P-am, P-m, P-b, and P-da, respectively. The surface properties of these polybenzoxazine films were proven by contact angle measurements. The hydrogen bond network of the polybenzoxazine systems was studied using the FTIR spectra. And the results showed that the surface free energy increased with increasing the fraction of intermolecular hydrogen bonding when the N-substituent was an alkyl chain. However, the rule was not suitable when the N-substituent was H. That was because there was one more kind of intramolecular hydrogen bond in the poly（P-am）. Based on these findings, we proposed that both the N-substituent alkyl group and the fraction of intermolecular hydrogen bonding had effects on the surface free energy.展开更多
Gallic acid and its alkyl and phenyl gallate usually exist in gall and tea. They have very good properties in antioxygenation, antisepsis, astringency, etc., there-fore they are generally used in the industries of gre...Gallic acid and its alkyl and phenyl gallate usually exist in gall and tea. They have very good properties in antioxygenation, antisepsis, astringency, etc., there-fore they are generally used in the industries of grease, dyestuff, spinning and weaving, metallurgy, chemistry, petroleum, food, medicine, etc. It has been known展开更多
基金Supported by National National Science Foundation (20464002)
文摘Changes of surface shape, aggregate state, and microstructure of Apocynum fiber before and after irradia-tion were studied by XRD, IR, SEM, ESR, and solid state 13C CP/ MAS NMR. The results show that the surface shape and microstructure were not spoiled under 50 kGy gamma irradiation, while the crystallization of Apocynum fiber changed under 280 kGy . It also shows that different free radicals appear after irradiation and their concentration increases with the increase of irradiation dose.
基金the financial support by the Natural Science Foundation of Shandong Province(no.ZR2020MB014)the National Natural Science Foundation of China(no.21201080)+1 种基金the Fund of State Key Laboratory of Structural Chemistrythe Jinan Research Leader’s Studio(no.2019GXRC053)for financial support.
文摘The moisture instability and toxicity of lead have hindered the development of lead organometal halide perovskites(Pb-OHPs).Similar to Pb-OHPs,OHPs based on Pb-free elements,including Group VA metals Bi and Sb(denoted as M),exhibit optoelectronic properties due to their isoelectronic configuration and close chemistry of the lone-pair ns^(2) state.However,M-OHPs are mostly based on hydrophilic protonated organic countercations and possess low structural dimensionalities,which affect the moisture stability and disrupt continuous carrier transport,respectively.Herein,we demonstrate a“double-free”strategy to realize the rational synthesis of moisture-stable hypotoxic hybrid perovskites.A hydrogen-bond-free alkylated countercation was assembled with Pb-free OHP bearing an extended structure in one molecule.As a proof of concept,two double-free M-OHPs are synthesized,which show greatly improved moisture and photostability compared to their corresponding hydrogen-bond OHPs and the extensively studied MA_(3)M_(2)X_(9)(MA=CH_(3)NH_(3)^(+)).The photoconduction behaviors of both double-free OHPs display short rise and decay recovery time and exhibit excellent photocurrent reproducibility.Importantly,(1-methyl-4-phenylpyridin-1-ium)BiI_(4)(Me4ppi-BiI_(4))displays a comparable switching on/off ratio with MA_(3)Bi_(2)I_(9),and can endure 75% relative humidity(RH)for at least 243 days.The photophysical property measurements and theoretical calculations show that this remarkable photoconversion performance results from the relatively low exciton binding energy and greatly improved carrier mobility and concentration.
基金This work was supported by the National Natural Science Foundation of China (Grant Nos. 20303006 and 20574016) the Natural Science Foundation of Hebei Province (Grant Nos. B2006000959 and B2004 000093)the Natural Science Foundation of Education Committee of Hebei Province (Grant No. 2003101).
文摘The influence of hydrogen bonds on the physical and chemical properties of hydrogen bonding fluid system of AaDd type is investigated from two viewpoints by the principle of statistical mechanics. In detail, we proposed two new ways that can be used to obtain the equilibrium size distribution of the hydrogen bonding clusters, and derived the analytical expression of a relationship between the hydrogen bonding free energy and hydrogen bonding degree. For the nonlinear hydrogen bonding systems, it is shown that the sol-gel phase transition can take place under proper conditions, which is further proven to be a kind of geometrical phase transition rather than a thermodynamic one. Moreover, several problems associated with the geometrical phase transition and liquid-solid phase transition in nonlinear hydrogen bonding systems are discussed.
基金Supported by the Jiangsu Planned Projects for Postdoctoral Research Funds (No. 0901001C)the National Natural Science Foundation of China (Grant No. 20876072)the Natural Science Foundation of Jiangsu Province (No. KB2008023)
文摘In separation processes,hydrogen bonding has a very significant effect on the efficiency of isolation of acetic acid (HOAc) from HOAc/H2O mixtures. This intermolecular interaction on aggregates composed of a single HOAc molecule and varying numbers of H2O molecules has been examined by using ab initio molecular dynamics simulations (AIMD) and quantum chemical calculations (QCC). Thermodynamic data in aqueous solution were obtained through the self-consistent reaction field calculations and the polarizable continuum model. The aggregation free energy of the aggregates in gas phase as well as in aqueous system shows that the 6-membered ring is the most favorable structure in both states. The relative stability of the ring structures inferred from the thermodynamic properties of the QCC is consistent with the ring distributions of the AIMD simulation. The study shows that in dilute aqueous solution of HOAc the more favorable molecular interaction is the hydrogen bonding between HOAc and H2O molecules,resulting in the separation of acetic acid from the HOAc/H2O mixtures with more difficulty than usual.
基金financially supported by the Nanotech Foundation of Science and Technology Commission of Shanghai Municipality(No.0652nm001)the National Natural Science Fundation of China(No.u1162110)+1 种基金the Fundamental Research Funds for the Central Universities(No.WA1514015)and China Postdoctoral Science Foundation(No.2015M571509)
文摘A series of mono-functional benzoxazine monomers with different N-substituents were synthesized from phenol, formaldehyde, and various amines （ammonia, methylamine, n-butylamine, dodecylamine）, named P-am, P-m, P-b, and P-da, respectively. The surface properties of these polybenzoxazine films were proven by contact angle measurements. The hydrogen bond network of the polybenzoxazine systems was studied using the FTIR spectra. And the results showed that the surface free energy increased with increasing the fraction of intermolecular hydrogen bonding when the N-substituent was an alkyl chain. However, the rule was not suitable when the N-substituent was H. That was because there was one more kind of intramolecular hydrogen bond in the poly（P-am）. Based on these findings, we proposed that both the N-substituent alkyl group and the fraction of intermolecular hydrogen bonding had effects on the surface free energy.
基金Project supported by the National Natural Science Foundation of China.
文摘Gallic acid and its alkyl and phenyl gallate usually exist in gall and tea. They have very good properties in antioxygenation, antisepsis, astringency, etc., there-fore they are generally used in the industries of grease, dyestuff, spinning and weaving, metallurgy, chemistry, petroleum, food, medicine, etc. It has been known
