Acta Phys. -Chim. Sin. ›› 2014, Vol. 30 ›› Issue (4): 608-622.doi: 10.3866/PKU.WHXB201402181

• THERMODYNAMICS, KINETICS, AND STRUCTURAL CHEMISTRY • Previous Articles     Next Articles

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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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