Computational Solid Form Screening

Computational methods could, therefore, potentially impact on polymorph screening, salt or co-crystal selection, as well as the avoidance of solvates. The outline of such a possibility should not be viewed as an over-optimistic assessment of current capabilities, but rather a goal towards which developments should aim. Given that progress is being made on flexible molecules and multi-component crystal structures, the methods that are necessary for such in silico screens are attainable, although it is difficult to predict the rate of progress and, therefore, when such calculations will be practical for the typical pharmaceutical molecule. Moreover, results will always need to be interpreted with care and a realistic view of the approximations and limitations of the methods. This is where continued assessment of methods on well-characterized systems is needed, to inform our level of confidence in the calculations. 

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Computational Crystal Structure Prediction Towards In Silico Solid Form Screening... 

Phase-equilibrium calculations were discussed for vapor-liquid equilibria (VLB), liquid-liquid equilibria (LLE), and solid-solid equilibria (SSE). Results from VLE calculations often take the form of K-factors and relative volatilities, especially when thermodynamic calculations serve as intermediate steps in computer-aided process-design programs. In those situations, K-factors are routinely provided to subprograms that size distillation columns and gas-liquid absorbers. Similarly, the distribution coefficients computed for LLE serve as bases for sizing solvent-extraction columns moreover, liquid-liquid distribution coefficients may be helpful in screening candidate solvents for use in an extraction. 

Even the colours of television screens and computer monitors make use of solids that have been developed by chemists. Gone are the days of power-hungry, bulky cathode-ray tubes. Now we are in the world of liquid crystals, plasma displays, and OLEDs (organic light-emitting diodes). The liquid crystals and OLEDs are formed of molecules built by chemists that respond in special... 

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