Anhydrosaccharides—A new class of the fragile plastic crystals

Abstract

In this paper, 1,6-anhydro-β-D-glucopyranose (anhGLU), 1,6-anhydro-β-D-mannopyranose (anhMAN), and 1,6-anhydro-β-D-galactopyranose (anhGAL), three new materials that form the Orientationally Disordered Crystal (ODIC) phase, have been thoroughly investigated using various experimental techniques. All measurements clearly indicated that these compounds possess a series of very interesting physical properties that are considerably different than those reported for ordinary plastic crystals. X-Ray diffraction investigations have revealed enormously long-range static correlations between molecules, reaching even 120 Å. Moreover, dielectric studies showed that besides Freon 113, the investigated anhydrosaccharides are the most fragile systems that form the ODIC phase. Further analysis of Fourier transform infrared spectra indicated that such peculiar behavior of anhydrosaccharides might be closely related to multidirectional H-bonds of various strengths that most likely affect the number of available conformations, density states, and the potential barriers in the energy landscape of these compounds. This is consistent with the results from previous reports [L. C. Pardo, J. Chem. Phys. 124, 124911 (2006) and Th. Bauer et al., J Chem. Phys. 133, 144509 (2010)] showing that the higher fragility of Freon 112 as well as a mixture of 60% succinonitrile and 40% glutaronitrile (60SN-40GN) can be closely related to the enhanced conformational ability and additional disorder introduced by various substituents, which further make energy landscape more complex. Finally, by studying the properties of 2,3,4-tri-O-acetyl-1,6-anhydro-β-D-glucopyranose (ac-anhGLU) it was found that besides the shape of the molecules, H-bonds or generally strong intermolecular interactions are extremely important parameters contributing to the ability to form the plastic phase. This is in line with current observations that in most cases the ODIC phase is created in highly interacting compounds.

Pretransitional Effects of the Isotropic Liquid–Plastic Crystal Transition

“…For plastic crystalline materials when cooling below the I-ODIC freezing/melting temperature the translational ordering appears but the orientational freedom remains. Experimental evidence from previously published results [ 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 ] seems to be clear: there are no pretransitional behavior in the surrounding of , contrary to the discussed above case of LC materials. Note that on cooling ODIC forming materials most often terminate in the orientationally disordered solid glass state.…”

“…Indeed, strong pretransitional changes of the Kerr effect (KE) [ 4 , 5 , 6 , 10 , 11 ] and Cotton Mouton effect (CME) [ 4 , 5 , 6 , 12 , 13 ] in the isotropic liquid phase of nematic LCs inspired development of the Landau-de Gennes (LdG) model [ 4 , 5 , 6 , 14 , 15 ], representing important cornerstone for theoretical description of LCs [ 3 , 4 , 5 , 6 , 7 ] and soft matter physics in general [ 16 , 17 ]. On the contrary, in ODIC-forming systems the existing evidence indicates negligible weak pretransitional effect [ 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 ], suggesting the behavior found in systems exhibiting classical liquid-crystal discontinuous phase transitions [ 36 , 37 , 38 , 39 , 40 , 41 ]. The only exception is reported for the optical Kerr effect (OKE) pretransitional effect of in p -terphenyl (1993, [ 42 ]), which could be rather linked to the hidden isotropic-nematic (I-N...…”

“…Such behavior is observed in dielectric constant and its strong electric field counterpart, the nonlinear dielectric effect (NDE), both surprisingly not tested so far. Phase behavior was probed in the extreme range of temperatures in cyclooctanol (C 8 OH), one of the most classical ODIC-forming materials [ 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 ]. As a reference LC system, we studied a rod-like LC material, n -octyloxycyanobiphenyl (8OCB), which also revealed new aspects of pretransitional effects.…”

“…Phase behavior was probed in the extreme range of temperatures in cyclooctanol (C8OH), one of the most classical ODIC-forming materials. [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] As a reference LC system, we studied a rod-like LC material, noctyloxycyanobiphenyl (8OCB), which also revealed new aspects of pretransitional effects.…”

Commodity Chemicals and Fuels from Biomass: Thermodynamic Properties of Levoglucosan Derivatives

“…Compilation of Solid-Solid and Solid-Liquid Phase Transitions Thermodynamics of Levoglucosan (in kJmol -1 ) a 456±1.0 3.2±0.5 [9,10,11] 455.3±0.5 3.2±1.0 [12] 455.4±0.1 3.3±0.2 [13] 454±1 2.9±0.2 [14] 454.9±0.3 3.3±0.1 [15] 456±1 [16] 455.3±0.…”