The aromaticity of all possible substituted fullerene isomers of C18N2, C18B2, C18BN, and their molecular ions which originate from the C20 （Ih） cage were studied by the topological resonance energy （TRE） and the ...The aromaticity of all possible substituted fullerene isomers of C18N2, C18B2, C18BN, and their molecular ions which originate from the C20 （Ih） cage were studied by the topological resonance energy （TRE） and the percentage topological resonance energy methods. The relationship between the aromaticity of C18BxNy isomers and the sites where the heteroatoms dope at the C20 （Ih） cage is discussed. Calculation results show that at the neutral and cationic states all the isomers are predicted to be antiaromatic with negative TREs, but their polyvalent anions are predicted to be aromatic with positive TREs. The most stable isomer is formed by heteroatom doping at the 1,11-sites in C18N2. C18B2, and C18BN. Heterofullerenes are more aromatic than C20. The stability order in the neutral states is C18N2〉C18BN〉C18B2〉C20. The stability order in closed-shell is C18B2^8- 〉C20^6- 〉C18BN^6- 〉C18N2^4-. This predicts theoretically that their polyvalent anions have high aromaticity.展开更多
目的:研究氢火焰气相色谱仪(GC112A)内标法测定反式脂肪酸的实验室最佳条件。方法:采用气相色谱内标-标准曲线法,通过测定反式脂肪酸标准品工作液的标准曲线、重现性和分离度来确定和验证GC112A的最佳色谱条件。结果:实验室最佳色谱条件...目的:研究氢火焰气相色谱仪(GC112A)内标法测定反式脂肪酸的实验室最佳条件。方法:采用气相色谱内标-标准曲线法,通过测定反式脂肪酸标准品工作液的标准曲线、重现性和分离度来确定和验证GC112A的最佳色谱条件。结果:实验室最佳色谱条件:毛细管柱,PC-88(100 m×0.25 mm×0.2μm);进样口温度:260℃;载气:高纯N2,压力220 k Pa,流速41.0 m L/min;检测器(FID)温度:290℃,氢气压力100 k Pa,流速21.0 m L/min;空气压力160 k Pa,流速215.0 m L/min;检测器(FID)灵敏度:1010;手动进样,进样量:1.0μL。结论:该方法避免了外标法(国标方法)的国产仪器局限性和操作者人工进样的不确定性,具有受仪器参数变化的影响较小的特点,适合在基层食品检验机构推广。展开更多
Structures of 2-(naphthalen-2-ylmethyl)-2,3-dihydro-1H-indene-1,2-diol (C20H18O2), compound 1 and 1-(3,4-dimethoxyphenyl)-3-methoxy-3-(4-nitrophenyl)propane-1,2-diol chloroform (C18H21NO7·CHCl3) compound 2 were e...Structures of 2-(naphthalen-2-ylmethyl)-2,3-dihydro-1H-indene-1,2-diol (C20H18O2), compound 1 and 1-(3,4-dimethoxyphenyl)-3-methoxy-3-(4-nitrophenyl)propane-1,2-diol chloroform (C18H21NO7·CHCl3) compound 2 were established by spectral and X-ray diffraction studies. Compound 1 crystallizes in the orthorhombic space group P212121 with unit cell parameters a = 5.2177 (6), b = 13.903 (2), c = 21.121 (2) A, Z = 4. Compound 2 crystallizes in the triclinic space group P-1 with unit cell parameters a = 9.238 (1), b = 9.879 (1), c = 12.636 (1) A, α = 102.004 (1), β = 92.356 (1), γ = 90.779 (1)o, Z = 2. These two new molecules arise from a facile preparation of 1,2-diols from chalcones and have been fully characterized. Based on the crystallographic information obtained for compound 1, the relative configuration for the chiral centers is 1S and 2S. In structure 1, both hydroxyl groups adopt an anti-conformation with a torsion angle O1-C1-C2-O2 value of 93.1 (2)o [in molecule 2, both hydroxyl groups adopt a trans-conformation with a torsion angle O1-C1-C2-O2 value of -171.0 (2)。]. In both structures, the molecules in the crystal are linked by intermolecular hydrogen bonds O-H···O and C-H···O interactions and adjacent molecules are interconnected by intermolecular weak C-H···π and C-H···Cl interactions which give additional support to molecular packing stability.展开更多
The title compound (C22H18N2O3) has been synthesized by the reaction of 3,4- dimethoxybenzaldehyde, malononitrile and 1-naphthol in ethanol in the presence of piperidine, and its structure was characterized by element...The title compound (C22H18N2O3) has been synthesized by the reaction of 3,4- dimethoxybenzaldehyde, malononitrile and 1-naphthol in ethanol in the presence of piperidine, and its structure was characterized by elemental analysis, IR, 1H NMR and X-ray single-crystal diffraction. The crystal belongs to monoclinic, space group C2/c with a = 24.221(6), b = 9.016(2), c = 17.003(5) ? b = 93.16(1), V = 3707(2) ?, Mr = 358.38, Z = 8, Dc = 1.284 g/cm3, m(MoKa) = 0.087 mm-1, F(000) = 1504, the final R = 0.0432 and wR = 0.1085. X-ray analysis reveals that the atoms of C(1), C(2), C(3), C(4), C(5) and O(1) form a boat-form six-membered ring in which the C(1)C(2) (1.349(3) ? is a C=C double bond.展开更多
In this work,the structure of 4-((2R)-2-(3,4-dibromophenyl)-1-fluorocyclopropyl)-N-(o-tolyl)benzamide(DBFB)has been determined at room temperature using single-crystal X-ray diffraction data.The structure of the compo...In this work,the structure of 4-((2R)-2-(3,4-dibromophenyl)-1-fluorocyclopropyl)-N-(o-tolyl)benzamide(DBFB)has been determined at room temperature using single-crystal X-ray diffraction data.The structure of the compound was solved using 1464 observed reflections with I≥2σ(I).It crystallizes in monoclinic space group P21 with a=20.0820(10),b=10.2770(10),c=4.860(2)?,β=95.9600(10)°,V=997.6(4)?3,Z=2,Dc=1.675 g/m3,F(000)=500,Μr=503.18,μ=4.09 mm-1 and the final R=0.0639.The molecular packing of the title compound exhibits C–H???O and C–H???F hydrogen bonds forming a supramolecular network.Furthermore,conformational analysis has been performed in order to confirm the most stable conformer of the title compound.Geometrical parameters of the keto conformer in the ground state have been obtained using density functional theory(DFT)method with B3LYP/6-31G(d,p)level of theory.In general,a good agreement between the calculated and experimental results was observed.The normal modes of vibration,molecular boundary orbitals(HOMO and LUMO),reactivity descriptors,Mullikan atomic charges and molecular electrostatic potential for the title compound have been evaluated and discussed.展开更多
文摘本文使用密度泛函理论(density functional theory,DFT)中的广义梯度近似(generalized gradient approximation,GGA)研究了经碱金属原子Li、过渡金属原子Ti和Fe原子修饰的富勒烯C18B2M(M=Li,Ti,Fe)的储氢性能.研究发现,C18B2由于B的替代掺杂,比C20对金属原子具有更高的结合能.由平均吸附能分析可知:C18B2Li对H2的吸附能力较弱,C18B2Fe对H2的吸附能力过强,而C18B2Ti对H2的平均吸附能介于0.45—0.59 e V之间,介于物理吸附和化学吸附之间(0.2—0.6 e V),因此可以实现常温下的可逆储氢.C18B2M(M=Li,Ti,Fe)能够吸附的H2数目最多分别为4,6和4.由储氢机理分析可知:C18B2Li主要通过碱金属离子激发的静电场来吸附H2,而C18B2Ti和C18B2Fe主要通过金属原子与H2之间的Kubas作用来吸附H2.由于C18B2Ti既有较大的储氢数目,又可以实现可逆储氢,因此有望开发成新型纳米储氢材料.
文摘The aromaticity of all possible substituted fullerene isomers of C18N2, C18B2, C18BN, and their molecular ions which originate from the C20 （Ih） cage were studied by the topological resonance energy （TRE） and the percentage topological resonance energy methods. The relationship between the aromaticity of C18BxNy isomers and the sites where the heteroatoms dope at the C20 （Ih） cage is discussed. Calculation results show that at the neutral and cationic states all the isomers are predicted to be antiaromatic with negative TREs, but their polyvalent anions are predicted to be aromatic with positive TREs. The most stable isomer is formed by heteroatom doping at the 1,11-sites in C18N2. C18B2, and C18BN. Heterofullerenes are more aromatic than C20. The stability order in the neutral states is C18N2〉C18BN〉C18B2〉C20. The stability order in closed-shell is C18B2^8- 〉C20^6- 〉C18BN^6- 〉C18N2^4-. This predicts theoretically that their polyvalent anions have high aromaticity.
文摘目的:研究氢火焰气相色谱仪(GC112A)内标法测定反式脂肪酸的实验室最佳条件。方法:采用气相色谱内标-标准曲线法,通过测定反式脂肪酸标准品工作液的标准曲线、重现性和分离度来确定和验证GC112A的最佳色谱条件。结果:实验室最佳色谱条件:毛细管柱,PC-88(100 m×0.25 mm×0.2μm);进样口温度:260℃;载气:高纯N2,压力220 k Pa,流速41.0 m L/min;检测器(FID)温度:290℃,氢气压力100 k Pa,流速21.0 m L/min;空气压力160 k Pa,流速215.0 m L/min;检测器(FID)灵敏度:1010;手动进样,进样量:1.0μL。结论:该方法避免了外标法(国标方法)的国产仪器局限性和操作者人工进样的不确定性,具有受仪器参数变化的影响较小的特点,适合在基层食品检验机构推广。
文摘Structures of 2-(naphthalen-2-ylmethyl)-2,3-dihydro-1H-indene-1,2-diol (C20H18O2), compound 1 and 1-(3,4-dimethoxyphenyl)-3-methoxy-3-(4-nitrophenyl)propane-1,2-diol chloroform (C18H21NO7·CHCl3) compound 2 were established by spectral and X-ray diffraction studies. Compound 1 crystallizes in the orthorhombic space group P212121 with unit cell parameters a = 5.2177 (6), b = 13.903 (2), c = 21.121 (2) A, Z = 4. Compound 2 crystallizes in the triclinic space group P-1 with unit cell parameters a = 9.238 (1), b = 9.879 (1), c = 12.636 (1) A, α = 102.004 (1), β = 92.356 (1), γ = 90.779 (1)o, Z = 2. These two new molecules arise from a facile preparation of 1,2-diols from chalcones and have been fully characterized. Based on the crystallographic information obtained for compound 1, the relative configuration for the chiral centers is 1S and 2S. In structure 1, both hydroxyl groups adopt an anti-conformation with a torsion angle O1-C1-C2-O2 value of 93.1 (2)o [in molecule 2, both hydroxyl groups adopt a trans-conformation with a torsion angle O1-C1-C2-O2 value of -171.0 (2)。]. In both structures, the molecules in the crystal are linked by intermolecular hydrogen bonds O-H···O and C-H···O interactions and adjacent molecules are interconnected by intermolecular weak C-H···π and C-H···Cl interactions which give additional support to molecular packing stability.
文摘The title compound (C22H18N2O3) has been synthesized by the reaction of 3,4- dimethoxybenzaldehyde, malononitrile and 1-naphthol in ethanol in the presence of piperidine, and its structure was characterized by elemental analysis, IR, 1H NMR and X-ray single-crystal diffraction. The crystal belongs to monoclinic, space group C2/c with a = 24.221(6), b = 9.016(2), c = 17.003(5) ? b = 93.16(1), V = 3707(2) ?, Mr = 358.38, Z = 8, Dc = 1.284 g/cm3, m(MoKa) = 0.087 mm-1, F(000) = 1504, the final R = 0.0432 and wR = 0.1085. X-ray analysis reveals that the atoms of C(1), C(2), C(3), C(4), C(5) and O(1) form a boat-form six-membered ring in which the C(1)C(2) (1.349(3) ? is a C=C double bond.
文摘In this work,the structure of 4-((2R)-2-(3,4-dibromophenyl)-1-fluorocyclopropyl)-N-(o-tolyl)benzamide(DBFB)has been determined at room temperature using single-crystal X-ray diffraction data.The structure of the compound was solved using 1464 observed reflections with I≥2σ(I).It crystallizes in monoclinic space group P21 with a=20.0820(10),b=10.2770(10),c=4.860(2)?,β=95.9600(10)°,V=997.6(4)?3,Z=2,Dc=1.675 g/m3,F(000)=500,Μr=503.18,μ=4.09 mm-1 and the final R=0.0639.The molecular packing of the title compound exhibits C–H???O and C–H???F hydrogen bonds forming a supramolecular network.Furthermore,conformational analysis has been performed in order to confirm the most stable conformer of the title compound.Geometrical parameters of the keto conformer in the ground state have been obtained using density functional theory(DFT)method with B3LYP/6-31G(d,p)level of theory.In general,a good agreement between the calculated and experimental results was observed.The normal modes of vibration,molecular boundary orbitals(HOMO and LUMO),reactivity descriptors,Mullikan atomic charges and molecular electrostatic potential for the title compound have been evaluated and discussed.
