Intermolecular Stabilization of 3,3鈥?Diamino-4,4鈥?azoxyfurazan (DAAF) Compressed to 20 GPa

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• 作者：Raja S. Chellappa ; Dana M. Dattelbaum ; Joshua D. Coe ; Nenad Velisavljevic ; Lewis L. Stevens ; Zhenxian Liu
• 刊名：Journal of Physical Chemistry A
• 出版年：2014
• 出版时间：August 7, 2014
• 年：2014
• 卷：118
• 期：31
• 页码：5969-5982
• 全文大小：869K
• ISSN：1520-5215

文摘

The room temperature stability of 3,3鈥?diamino-4,4鈥?azoxyfurazan (DAAF) has been investigated using synchrotron far-infrared, mid-infrared, Raman spectroscopy, and synchrotron X-ray diffraction (XRD) up to 20 GPa. The as-loaded DAAF samples exhibited subtle pressure-induced ordering phenomena (associated with positional disorder of the azoxy 鈥淥鈥?atom) resulting in doubling of the a-axis, to form a superlattice similar to the low-temperature polymorph. Neither high pressure synchrotron XRD, nor high pressure infrared or Raman spectroscopies indicated the presence of structural phase transitions up to 20 GPa. Compression was accommodated in the unit cell by a reduction of the c-axis between the planar DAAF layers, distortion of the 尾-angle of the monoclinic lattice, and an increase in intermolecular hydrogen bonding. Changes in the ring and 鈭扤H₂ deformation modes and increased intermolecular hydrogen bonding interactions with compression suggest molecular reorganizations and electronic transitions at 5 GPa and 10 GPa that are accompanied by a shifting of the absorption band edge into the visible. A fourth-order Birch鈥揗urnaghan fit to the room temperature isotherm afforded an estimate of the zero-pressure isothermal bulk modulus, K₀ = 12.4 卤 0.6 GPa and its pressure derivative K₀^{鈥?/sup> = 7.7 卤 0.3.}