物理化学学报 >> 2014, Vol. 30 >> Issue (4): 608-622.doi: 10.3866/PKU.WHXB201402181

热力学，动力学和结构化学 上一篇    下一篇

X衍射精细结构和晶体旋光角研究D-, L-, DL-缬氨酸晶格分子间N+H…O-氢键电子库珀对的自旋流超导相变

王文清1, 张玉凤1,2, 龚1,2   

  1. 1 北京大学化学与分子工程学院应用化学系, 北京分子科学国家实验室, 北京100871;
    2 北京服装学院材料科学与工程学院, 北京100029
  • 收稿日期:2013-11-18 修回日期:2014-02-18 发布日期:2014-03-31
  • 通讯作者: 王文清, 龚 E-mail:wangwqchem@pku.edu.cn;clygy@bift.edu.cn
  • 基金资助:

    国家自然科学基金（21002006, 20452002）和国家科技部基础研究重大项目（2004-973-36）资助

Crystal Fine Structure and Optical Rotatory Angle Study on Spin Superfluidity of Intermolecular N+H…O- Hydrogen Bond Electron Cooper Pairing onto D-, L-, and DL-Valine Optical Lattices

WANG Wen-Qing1, ZHANG Yu-Feng1,2, GONG Yan1,2   

  1. 1 Beijing National Laboratory for Molecular Sciences, Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China;
    2 School of Material Science & Engineering, Beijing Institute of Fashion Technology, Beijing 100029, P. R. China
  • Received:2013-11-18 Revised:2014-02-18 Published:2014-03-31
  • Contact: WANG Wen-Qing, GONG Yan E-mail:wangwqchem@pku.edu.cn;clygy@bift.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (21002006, 20452002) and Special Program for Key Basic Research of the Ministry of Science and Technology, China (2004-973-36).

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摘要：

为了解决D-和L-缬氨酸单晶在~270 K相变的机理和分岐，以比热法测定单晶、多晶粉末及Sigma多晶产品发现，只有D-和L-缬氨酸单晶发生相变，且为吸热反应，能差0.18 J·mol-1. 本文以Mo-Kα (λ=0.071073nm)为光源的X衍射精确测定表明，D-/L-缬氨酸单晶属于单斜空间点群P21，Z=4. 在相变温度~270 K，其晶格常数分别为：a=0.96706(5)/0.96737(5) nm，b=0.52680(3)/0.52664(3) nm，c=1.20256(7)/1.20196(6) nm，β=90.724(2)°/90.722(3)°. 在晶体结构的单元细胞中，含有两种转动异构体：A (trans)和B (gauche Ⅰ). 温度为293、270、223、173 K的X衍射精细结构数据表明：在~270 K，D-缬氨酸单晶分子内N―H…O氢键中，N―H、H…O的键长及键角∠N―H…O都发生波动起伏而不可测，但N―H…O总键长变化稳定可测. 说明没有发生构型相变为L-缬氨酸. 根据D-和L-缬氨酸单晶中，NH3→CO2 顺时针和逆时针的相反走向及D-，L-和DL-缬氨酸晶体旋光角的测定，在270-290 K可以观察到晶格分子间N+H…O-氢键电子库珀对的自旋流超导相变.

关键词: D-, L-和DL-缬氨酸晶体, X衍射晶体精细结构, 晶体旋光角, NH3→CO2顺时针与逆时针走向, 晶格表面分子间N+H…O-氢键, 电子库珀对, 自旋流超导相变

Abstract:

With a view to understanding the argument of the phase transition mechanisms of D- and Lvaline around 270 K, the temperature dependences of the heat capacities of single crystals, ground powders, and polycrystalline products were investigated using differential scanning calorimetry. Endothermic transition peaks were observed at phase transition temperatures of 273.59 and 273.76 K for D- and L-valine single crystals, respectively with an energy difference of 0.18 J?mol-1. The X-ray crystal fine structure of chiral valine was determined using Mo-Kα radiation (λ=0.071073 nm) on Nonius Kappa CCD diffractometer. D- and L-valine crystals were monoclinic, with the P21 space group, Z=4, lattice constants a= 0.96706(5)/0.96737(5) nm, b=0.52680(3)/0.52664(3) nm, and c=1.20256(7)/1.20196 (6) nm, and β=90.724(2)°/90.722(3)° at ~270 K. Two crystallographically independent molecules A (trans form) and B (gauche I from) were observed in the unit cell, these were rotational isomers with two different conformations. X ray diffraction at 293, 270, 223, and 173 K showed that the N―H, H…O bond lengths and the N―H…O bond angle of D- valine fluctuated at 270 K，but the intramolecular N―H…O hydrogen bond was stable and measurable. No evidence was obtained for a configuration transformation from D-valine to L-valine. Based on the clockwise and counterclockwise rotations of NH3→CO2 in the chiral valine crystals and the optical rotatory angle measurements, the intermolecular N+H…O- hydrogen bond was electronic Cooper pairing and exhibited the spin superfluidity onto D-, L-, and DL- valine crystal lattices from 270 to 290 K upon the transition to the superconducting state.

Key words: D-, L-, and DL-valine crystal, X-ray crystal fine structure, Optical rotatory angle, Clockwise and counterclockwise rotation of NH3→CO2, Intermolecular N+H…O- hydrogen bond on lattice surface, Electron Cooper pairing, Spin superfluidity in superconducting state

MSC2000: 

  • O641