Acta Phys. -Chim. Sin. ›› 2011, Vol. 27 ›› Issue (01): 25 -31.doi: 10.3866/PKU.WHXB20110123

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

Structure and Photochromic Properties of a Histidine Salt of 12-Silicotungstate Supramolecular Compound

SUN De-Hui1, ZHANG Ji-Lin2, SUN De-Xin3   

  1. 1. Faculty of Science, Changchun Institute of Technology, Changchun 130012, P. R. China;
    2. State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China;
    3. The Amour Technology Institute of PLA, Changchun 130117, P. R. China
  • Received:2010-07-23 Revised:2010-10-21 Published:2010-12-31
  • Contact: SUN De-Hui E-mail:dhsun998@gmail.com
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (20871083).

Abstract:

We synthesized a novel histidine salt of 12-silicotungstate supramolecular compound ((HisH2)2SiW12O40·6H2O) by a solution method. Its composition, thermostability, and structure were characterized by elemental analysis, thermal gravimetric and differential thermal analysis (TG-DTA), and single crystal X-ray diffraction, respectively. The experimental results show that the supramolecular compound has a composition of C12H34N6O50SiW12 and it is stable under 135 °C in air. It belongs to a monoclinic system (space group C2/c) with a=2.44005(18) nm, b=1.29788(10) nm, c=1.86898(14) nm, β=124.0380(10)°, V= 4.9048(6) nm3, Z=4, and Dc=4.465 g·cm-3. The final statistics based on F2 are goodness-of-fit (GOF) = 1.268, R1=0.0344 and wR2=0.0851 for (I>2σ(I)). X-ray diffraction analysis further reveals that this supramolecular compound mainly consists of polyoxometalate anions [SiW12O40]4-, protonated histidine cations [HisH2]2+ and lattice water. A three-dimensional (3D) network is formed through hydrogen bonding. The resulting sample shows photochromism under UV irradiation. We propose a possible photochromic mechanism by an analysis of the chromic sample′s electron spin resonance (ESR) spectrum.

Key words: Supramolecular compound, Polyoxometalate, Histidine, Photochromism

MSC2000: 

  • O641