A new phase transition compound,2-methoxyanilinium perchlorate-18-crown-6（1） {（oCH3OC6H4NH3）＋（18-crown-6） ClO4 },has been synthesized and separated as crystals.Differential scanning calorimetry（DSC） measureme...A new phase transition compound,2-methoxyanilinium perchlorate-18-crown-6（1） {（oCH3OC6H4NH3）＋（18-crown-6） ClO4 },has been synthesized and separated as crystals.Differential scanning calorimetry（DSC） measurements show a pair of sharp peaks at 225 K（heating） and 210 K（cooling）,indicating the phase transition is first-order.Dielectric anomalies observed at 225 K（heating）and 210 K（cooling） further confirm the phase transition.The crystal structures determined at 298 K and123 K are both triclinic in P 1.The most distinct difference between room-temperature and lowtemperature structures is the order–disorder transition of the host 18-crown-6 molecule,which is the driving force of the phase transition.展开更多
Many phases appear in BaLn 2Mn 2O 7 family (Ln=rare earth) belonging to one of the Ruddlesden-Popper type compounds, depending upon the experimental conditions such as heating conditions when prepared and compositi...Many phases appear in BaLn 2Mn 2O 7 family (Ln=rare earth) belonging to one of the Ruddlesden-Popper type compounds, depending upon the experimental conditions such as heating conditions when prepared and composition. Some of these phases were characterized by powder X-ray diffraction method using Rietveld analysis. These phases have only a little difference in crystal structure which has fundamentally K 2NiF 4 type structure, although the X-ray diffraction patterns are clearly different: a little deformation or tilting of the oxygen octahedron surrounding a central manganese ion composing the main frame of this structure induce these different diffraction patterns. Phase behavior of these compounds, mainly the detailed relation between various phases in BaTb 2Mn 2O 7, was refined including the data of high temperature X-ray diffractometry.展开更多
A novel inorganic-organic hybrid supramolecular compound,[（3-nitroanilinium^＋）（18-crown-6）][IO4]（CH3OH）（1）,was discovered as phase-transition materials displaying dielectric anomalous behaviors.The yellow blo...A novel inorganic-organic hybrid supramolecular compound,[（3-nitroanilinium^＋）（18-crown-6）][IO4]（CH3OH）（1）,was discovered as phase-transition materials displaying dielectric anomalous behaviors.The yellow block crystal formed by N-H…O hydrogen bonding that made contact through the cavity of 18-crown-6 was characterized by single-crystal X-ray diffraction,elemental analysis,infrared analysis,thermogravimetric analysis,differential scanning calorimetry,and potential-energy calculations.Differential scanning calorimetry measurements indicate that the compound experiences a reversible phase transition at around 220 K.Temperature-dependent dielectric measurements further confirm the phase transitions.Potential-energy calculations demonstrate that the phase transition occurs due to the molecular order-disorder rotation of CH3OH,whereas the space grouping of the crystal remains unchanged.展开更多
The crystal structures would directly affect the physical and chemical properties of the surface of the material,and would thus influence the catalytic activity of the material.α-MnO2,β-MnO2 andγ-MnO2 nanorods with...The crystal structures would directly affect the physical and chemical properties of the surface of the material,and would thus influence the catalytic activity of the material.α-MnO2,β-MnO2 andγ-MnO2 nanorods with the same morphology yet different crystal structures were prepared and tested as oxidase mimics using 3,3’,5,5’-tetramethylbenzidine(TMB)as the substrate.β-MnO2 that exhibited the highest activity had a catalytic constant of 83.75μmol·m^−2·s^−1,2.7 and 19.0 times of those ofα-MnO2 andγ-MnO2(30.91 and 4.41μmol·m^−2·s^−1),respectively.The characterization results showed that there were more surface hydroxyls as well as more Mn4+on the surface of theβ-MnO2 nanorods.The surface hydroxyls were conducive to the oxidation reaction,while Mn4+was conducive to the regeneration of surface hydroxyls.The synergistic effect of the two factors significantly improved the activity ofβ-MnO2 oxidase mimic.Usingβ-MnO2,aβ-MnO2-TMB-GSH system was established to detect the content of glutathione(GSH)rapidly and sensitively by colorimetry.This method had a wide detection range(0.11-45μM)and a low detection limit(0.1μM),and had been successfully applied to GSH quantification in human serum samples.展开更多
Ab initio calculations are performed to investigate the structural stability, electronic structure and mechanical properties of rubidium metal hydrides RbMH4（M = B, Al, Ga） for five different crystal structures, nam...Ab initio calculations are performed to investigate the structural stability, electronic structure and mechanical properties of rubidium metal hydrides RbMH4（M = B, Al, Ga） for five different crystal structures, namely hexagonal（P63mc）, tetragonal（P42/nmc）, tetragonal（P421c）, orthorhombic（Pnma） and monoclinic（P21/c）. Among the considered structures, tetragonal（P421c） phase is found to be the most stable one for these metal hydrides at normal pressure. A pressure-induced structural phase transition from tetragonal（P421c） to monoclinic（P21/c） phase is observed in all the three metal hydrides. The electronic structure reveals that these hydrides are wide band gap semiconductors. The calculated elastic constants indicate that these alkali metal tetrahydrides are mechanically stable at normal pressure.展开更多
基金supported by the National Natural Science Foundation of China (No. 21101025)
文摘A new phase transition compound,2-methoxyanilinium perchlorate-18-crown-6（1） {（oCH3OC6H4NH3）＋（18-crown-6） ClO4 },has been synthesized and separated as crystals.Differential scanning calorimetry（DSC） measurements show a pair of sharp peaks at 225 K（heating） and 210 K（cooling）,indicating the phase transition is first-order.Dielectric anomalies observed at 225 K（heating）and 210 K（cooling） further confirm the phase transition.The crystal structures determined at 298 K and123 K are both triclinic in P 1.The most distinct difference between room-temperature and lowtemperature structures is the order–disorder transition of the host 18-crown-6 molecule,which is the driving force of the phase transition.
文摘Many phases appear in BaLn 2Mn 2O 7 family (Ln=rare earth) belonging to one of the Ruddlesden-Popper type compounds, depending upon the experimental conditions such as heating conditions when prepared and composition. Some of these phases were characterized by powder X-ray diffraction method using Rietveld analysis. These phases have only a little difference in crystal structure which has fundamentally K 2NiF 4 type structure, although the X-ray diffraction patterns are clearly different: a little deformation or tilting of the oxygen octahedron surrounding a central manganese ion composing the main frame of this structure induce these different diffraction patterns. Phase behavior of these compounds, mainly the detailed relation between various phases in BaTb 2Mn 2O 7, was refined including the data of high temperature X-ray diffractometry.
基金supported by National Natural Science Foundation of China (No. 21561030)Prophase-sustentation Fund of Xinjiang Agricultural University (Nos. XJAU201410 and XJAU201511)
文摘A novel inorganic-organic hybrid supramolecular compound,[（3-nitroanilinium^＋）（18-crown-6）][IO4]（CH3OH）（1）,was discovered as phase-transition materials displaying dielectric anomalous behaviors.The yellow block crystal formed by N-H…O hydrogen bonding that made contact through the cavity of 18-crown-6 was characterized by single-crystal X-ray diffraction,elemental analysis,infrared analysis,thermogravimetric analysis,differential scanning calorimetry,and potential-energy calculations.Differential scanning calorimetry measurements indicate that the compound experiences a reversible phase transition at around 220 K.Temperature-dependent dielectric measurements further confirm the phase transitions.Potential-energy calculations demonstrate that the phase transition occurs due to the molecular order-disorder rotation of CH3OH,whereas the space grouping of the crystal remains unchanged.
基金This work was supported by the National Key R&D Program of China(No.2016YFA0202900)China Postdoctoral Science Foundation(No.2018M642021)+1 种基金the National Natural Science Foundation of China(No.21677095)Minhang District Science and Technology Project of Shanghai(No.2019MH-MS02).
文摘The crystal structures would directly affect the physical and chemical properties of the surface of the material,and would thus influence the catalytic activity of the material.α-MnO2,β-MnO2 andγ-MnO2 nanorods with the same morphology yet different crystal structures were prepared and tested as oxidase mimics using 3,3’,5,5’-tetramethylbenzidine(TMB)as the substrate.β-MnO2 that exhibited the highest activity had a catalytic constant of 83.75μmol·m^−2·s^−1,2.7 and 19.0 times of those ofα-MnO2 andγ-MnO2(30.91 and 4.41μmol·m^−2·s^−1),respectively.The characterization results showed that there were more surface hydroxyls as well as more Mn4+on the surface of theβ-MnO2 nanorods.The surface hydroxyls were conducive to the oxidation reaction,while Mn4+was conducive to the regeneration of surface hydroxyls.The synergistic effect of the two factors significantly improved the activity ofβ-MnO2 oxidase mimic.Usingβ-MnO2,aβ-MnO2-TMB-GSH system was established to detect the content of glutathione(GSH)rapidly and sensitively by colorimetry.This method had a wide detection range(0.11-45μM)and a low detection limit(0.1μM),and had been successfully applied to GSH quantification in human serum samples.
文摘Ab initio calculations are performed to investigate the structural stability, electronic structure and mechanical properties of rubidium metal hydrides RbMH4（M = B, Al, Ga） for five different crystal structures, namely hexagonal（P63mc）, tetragonal（P42/nmc）, tetragonal（P421c）, orthorhombic（Pnma） and monoclinic（P21/c）. Among the considered structures, tetragonal（P421c） phase is found to be the most stable one for these metal hydrides at normal pressure. A pressure-induced structural phase transition from tetragonal（P421c） to monoclinic（P21/c） phase is observed in all the three metal hydrides. The electronic structure reveals that these hydrides are wide band gap semiconductors. The calculated elastic constants indicate that these alkali metal tetrahydrides are mechanically stable at normal pressure.
