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abstracts
The first coordination sphere of spin crossover material has been comprehended to play a dominant role to its magnetic property. However, the intermolecular interactions, such as π···π interaction and hydrogen bonding, also play a crucial factor. The contents of the solvent in a 2D layer structure, Fe (μ-atrz)(μ-pyz)(NCS)2·nH2O where n=4, 2 and 0, has been reported to be able to affect the spin transition behavior dramatically.[1] As loss of solvent molecules, the inter-layer distance becomes shorter and the transition temperature shifts to lower temperature and accompanies a larger hysteresis loop. To further understand the correlation between the inter-layer distance and magnetic property, the guest ab/desorption and pressure-induced synchrotron powder diffraction experiments were performed at BL01C2 in NSRRC. Based on the cyclic TGA measurements, the guest molecules, H2O, MeOH and EtOH, all can be removed and retaken repeatedly. The pressure-induced PXRD experiment was performed using a Boehler-Almax design diamond anvil cell (DAC). The detail structural studies attempt to understand not only the spin state changes from HS (high spin state) to LS (low spin state) but also the cooperative effect through the inter-layer distance.
abstracts
We present the high pressure phase transition behavior of a gold(I) -NHCs complex, in which the NHCs include one long N-alkyl substituent and one N-acetamido group, The amide group is an excellent hydrogen bonding motif to provide interaction force between molecule. The gold (I) - NHC series form metallogel in DMSO at room temperature. PXRD studies show that self-assembly of [Au(C16,amide-imy)2 ][NO3] forms a lamellar structure with tubular architecture around the metal ion head core. Through Coulombic, hydrogen bonding, and hydrophobic interactions between solvent and the amide group under ambient environment. In the high pressure PXRD experiment of [Au(C16,amide-imy)2][NO3] complex , the lamellar structure phase become less and less , but the long range order behavior start to reveal by bragg's Debye ring grown up in the 2-D diffraction pattern when the pressure increased, As pressure up to 2GPa, The indexing shown the long range order with 3-D symmetry by monoclinic Laue symmetry. This is the first example that phase transition from lyotropic liquid crystal gel phase to long range order solid phase. The inter-molecule interaction and structure will be presented in this report.
