Study of the polymorphism of binary solutions of molecular substances in microsamples

Previous studies have shown that certain molecular substances taken in microsamples (droplets of about 1 μm³ in volume dispersed within an emulsion) crystallize into metastable crystalline phases. These compounds are studied in solution with benzene which does not show metastable polymorphism. The binaries benzene-1-2 dichlorobenzene, benzene-chloroform and benzene-nitrobenzene in emulsion are investigated by D.S.C. techniques. Metastable phases appear, too, and it is possible to draw metastable liquidus and locate metastable eutectics in the phase diagrams. In benzene-chloroform solution at least one new metastable phase is detected. In the benzene-nitrobenzene binary a metastable phase is detected, although neither benzene nor nitrobenzene show a metastable crystalline phase when they are pure.