Molecular thermodynamic view

Shaikh, S. A., Ahmed, S. R., and Jayaram, B., A molecular thermodynamic view of DNA-drug interactions a case study of 25 minor-groove binders. Arch. Biochem. Biophys. 429, 81-99 (2004). 

In part II of the present report the nature and molecular characteristics of asphaltene and wax deposits from petroleum crudes are discussed. The field experiences with asphaltene and wax deposition and their related problems are discussed in part III. In order to predict the phenomena of asphaltene deposition one has to consider the use of the molecular thermodynamics of fluid phase equilibria and the theory of colloidal suspensions. In part IV of this report predictive approaches of the behavior of reservoir fluids and asphaltene depositions are reviewed from a fundamental point of view. This includes correlation and prediction of the effects of temperature, pressure, composition and flow characteristics of the miscible gas and crude on (i) Onset of asphaltene deposition (ii) Mechanism of asphaltene flocculation. The in situ precipitation and flocculation of asphaltene is expected to be quite different from the controlled laboratory experiments. This is primarily due to the multiphase flow through the reservoir porous media, streaming potential effects in pipes and conduits, and the interactions of the precipitates and the other in situ material presnet. In part V of the present report the conclusions are stated and the requirements for the development of successful predictive models for the asphaltene deposition and flocculation are discussed. 

A Thermodynamic View for Global Understanding of Molecular Recognition. 67... 

A THERMODYNAMIC VIEW FOR GLOBAL UNDERSTANDING OF MOLECULAR RECOGNITION " ... 

In the field of food colloids, the use of molecular thermodynamics provides a set of qualitative and quantitative relationships describing fundamental phenomena occurring in the equilibrium state of systems for which the intermolecular interactions of biopolymers (proteins and polysaccharides) play a key role. The phenomena and processes amenable to discussion from the thermodynamic point of view are ... 

A Thermodynamic View for Clobally Understanding Molecular Recognition 21S... 

In Chapter 1, equilibrium was seen as the most probable way in which a system exists. An equation of state, as introduced in Chapter 2, gives the thermodynamic relationship for a gas system at equilibrium. Our molecular level view, based on statistical arguments, allows that a system does not have to be at equilibrium at any given instant. There can be small fluctuations from equilibrium, which over time average to the equilibrium behavior. There may also be sudden changes, external perturbations, that disrupt equilibrium. 

As we have seen, the third law of thermodynamics is closely tied to a statistical view of entropy. It is hard to discuss its implications from the exclusively macroscopic view of classical themiodynamics, but the problems become almost trivial when the molecular view of statistical themiodynamics is introduced. Guggenlieim (1949) has noted that the usefiihiess of a molecular view is not unique to the situation of substances at low temperatures, that there are other limiting situations where molecular ideas are helpfid in interpreting general experimental results ... 

The solvophobic model of Hquid-phase nonideaHty takes into account solute—solvent interactions on the molecular level. In this view, all dissolved molecules expose microsurface area to the surrounding solvent and are acted on by the so-called solvophobic forces (41). These forces, which involve both enthalpy and entropy effects, are described generally by a branch of solution thermodynamics known as solvophobic theory. This general solution interaction approach takes into account the effect of the solvent on partitioning by considering two hypothetical steps. Eirst, cavities in the solvent must be created to contain the partitioned species. Second, the partitioned species is placed in the cavities, where interactions can occur with the surrounding solvent. The idea of solvophobic forces has been used to estimate such diverse physical properties as absorbabiHty, Henry s constant, and aqueous solubiHty (41—44). A principal drawback is calculational complexity and difficulty of finding values for the model input parameters. 

If A Gx values are sufficiently lower (greater by absolute value) than AG of the rest of the components of free energy change, the process can proceed at all the values of molecular weights from the point of view of thermodynamics. Consequently, the application AG in the definite conditions is unadvisable. 

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