Hydrogen-bonding liquids

Besides these special physical properties, hydrogen-bonded liquid water also has unique solvent and solution properties. One feature is high proton (H ) mobility due to the ability of individual hydrogen nuclei to jump from one water molecule to the next. Recalling that at temperatures of about 300 K, the molar concentration in pure water of H3O ions is ca. 10 M, the "extra" proton can come from either of two water molecules. This freedom of to transfer from one to an adjacent "parent" molecule allows relatively high electrical conductivity. A proton added at one point in an aqueous solution causes a domino effect, because the initiating proton has only a short distance to travel to cause one to pop out somewhere else. 

Coco, S., Espinet, E., Espinet, P. and Palape, I. (2007) Functional isocyanide metal complexes as building blocks for supramolecular materials hydrogen-bonded liquid crystals. Dalton Transactions, (30), 3267-3272. 

It is the author s view that a chapter such as this needs some sort of context and needs to be self-contained. From this point of view, it will begin with a general introduction to liquid crystals themselves and will then introduce hydrogen-bonded liquid crystals in order to provide some context. The introduction to liquid crystals will not be referenced or illustrated heavily, so those readers requiring more information are directed to reference [1]. 

Kato, T. Mizoshita, N. Kanie, K. Hydrogen-bonded liquid crystalline materials Supramolecular polymeric assembly and the induction of dynamic function. Macromol. Rapid Commun. 2001, 22, 797-814. 

The aim of this study is to investigate the ability of ortho-phosphoric acid to function as the pore-producing additive for the preparation of CA reverse osmosis membranes. Ortho-phosphoric acid (PA) is known to be a strongly hydrogen bonded liquid, and it has been claimed ( ) to be a promising additive for the asymmetric CA membrane formation. To our knowledge, there has not been a thorough study on the problem. 

Osuji C, Chao CY, Bita 1, Ober CK, Thomas EL. Temperature-dependent photonic bandgap in a self-assembled hydrogen bonded liquid-crystalline block copolymer. Adv Funct Mater... 

Liquid polyols are interesting among nonaqueous solvents because, like water and monoalcohols, they are hydrogen-bonded liquids with a high value of relative permittivity (Table 9.2.1), and therefore they are able to dissolve to some extent ionic inorganic compounds. Moreover, reactions can be carried out in such solvents under atmospheric pressure up to 250°C, i.e., at a temperature range higher than in water or monoalcohols such as methanol or ethanol. 

Table I. Low frequency bands in the Raman spectrum of hydrogen bonded liquids...

For bipolar organic liquids, especially for hydrogen-bonding liquids such as alcohols and amines, the tendency to orient in the liquid phase, due to these highly directional intermolecular attractions, is greatly increased by this intermolecular interaction. We can see the effect of this in the significantly larger entropies of vaporization of bipolar chemicals, like aniline, phenol, benzyl alcohol, or ethanol (Table 4.2). 

However, for components A = ethyl acetate and B = C2H5I or CS2, one finds instead that Vj + Vb < Vsoiution (by 1-2%). The deviations from additivity may therefore be of either sign, and are attributable in each case to changes in coordination and packing patterns at the molecular level, particularly dramatic for hydrogen-bonding liquids. 

P. Borowski, J. Jaroniec, T. Janowski, and K. Wolinski. Quantum cluster equilibrium theory treatment of hydrogen-bonded liquids water, methanol and ethanol. Mol. Phys. 101, 1413-21 (2003). [This paper suggests the need for more accurate treatment of free cluster rotations that become hindered librations at normal liquid densities, thus reducing the populations of larger clusters.]... 

Ladanyi BM, Skaf MS. 1993. Computer simulation of hydrogen-bonding liquids. Annu Rev phys Chem 44 335-368. 

S. Goldman and C. Joslin, /. Phys. Cbem., 97, 12349 (1993). Why Hydrogen-Bonded Liquids Tend to Have High Static Dielectric Constants. 

M. S. Skaf, T. Fonseca and B. M. Ladanyi, Wave-vector-dependent dielectric relaxation in hydrogen-bonding liquids a molecular-dynamics study of methanol, J. Chem. Phys., 98 (1993) 8929-45 B. M. Ladanyi and M. S. Skaf, Wave vector-dependent dielectric relaxation of methanol-water mixtures, J. Phys. Chem., 100 (1996) 1368-80 M. S. Skaf, Molecular dynamics simulations of dielectric properties of dimethyl sulfoxide Comparison between available potentials, J. Chem. Phys., 107 (1997) 7996-8003. 

In a system based largely on self-assembly through mesogenic interactions such as the above example by Percec, it can also be beneficial to incorporate hydrogen bonding as well for an added element of organizational control. For instance, Frechet and coworkers demonstrated sequential, hierarchical self-assembly of various levels of order in a small molecule-based system which ultimately resulted in a hydrogen-bonded liquid crystalline network (Fig. 7.9) [53]. 

Luck WAP. A model of hydrogen-bonded liquid. Angew Chem Int Ed Eng 1980 19 28. 

The perturbation theories [2, 3] go a step beyond corresponding states the properties (e.g., Ac) of some substance with potential U are related to those for a simpler reference substance with potential Uq by a perturbation expansion (Ac = Aq + A + Aj + ). The properties of the simple reference fluid can be obtained from experimental data (or from simulation data for model fluids such as hard spheres) or corresponding states correlations, while the perturbation corrections are calculated from the statistical mechanical expressions, which involve only reference fluid properties and the perturbing potential. Cluster expansions involve a series in molecular clusters and are closely related to the perturbation theories they have proved particularly useful for moderately dense gases, dilute solutions, hydrogen-bonded liquids, and ionic solutions. 

POLARIZATION EFFECTS AND CHARGE FLUCTUATIONS IN POLAR HYDROGEN BONDING LIQUIDS... 

It is known that first principles molecular dynamics may overcome the limitations related to the use of an intermolecular interaction model. However, it is not clear that the results for the structure of hydrogen bonding liquids predicted by first principles molecular dynamics simulations are necessarily in better agreement with experiment than those relying on classical simulations, and recent first principles molecular dynamics simulations of liquid water indicated that the results are dependent on the choice of different approximations for the exchange-correlation functional [50], Cluster calculations are an interesting alternative, although surface effects can be important and extrapolation to bulk phase remains a controversial issue. 

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