I am studying an crystalline organic material which shows birefringence and melts at ~75 degree Celsius. But, the material doesn't solidify upon cooling. What could be the reasons?
Dear Kalyan, this is a normal case. Most crystalline organic compounds having more or less large and asymmetrical molecules with flexible fragments do not crystallize upon cooling on the air forming glassy materials. The cooling rate may be too fast. Their crystallization may be induced by equilibration with a saturated solvent vapors, like in paper https://www.researchgate.net/publication/276464359_Twice_as_smart_behavior_of_tert-butylthiacalix4arene_derivative_in_glassy_and_crystalline_form
The solvents used should not dissolve your substance even in vapors and should not be included in its solid phase.
The other way to induce crystallization of your solid is to equilibrate it below the melting point by several degrees.
Dear all, similar problem sometimes happens in recrystallization, which is a purification techniques for solids. This take place when sites of nucleation for crystal growth are lost. One solution is to add minor traces of the solid compound. This induces the starting of crystals formation. My Regards
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