A studied tert-butylthiacalix[4]arene derivative with four N-(2-acetoxyethyl)carbamoylmethoxy substituents on its lower rim in partial-cone configuration (calixarene 1) can remember its previous treatment in three essentially different ways by the formation either of a molecular glass or two metastable polymorphs after heating or the removal of an included guest molecule. Guest-induced memory is very selective with a polymorph created only after the release of a few included guests among a large series of those studied and is detected via an exothermic transition. Along with ordinary properties, like glass transition, curing and cold crystallization, the molecular glass from 1 is selective due to its ability to crystallize in solvent vapors and vapor mixtures over a well-defined concentration range. Being cooperative, this property may be used for the visual detection of ethanol content in water solution when it reaches a threshold value.

A problem of controlled (smart) formation of polymorphs was solved for a set of tert-butylthiacalix­[4]­arene derivatives with four N-(2-acetoxyethyl)­carbamoylmethoxy substituents at the lower rim with 1,3-alternate, cone, and partial cone conformations. For this, an effective polymorph screening with a reproducible influence of preparation history was achieved using guest vapor inclusion and a standard state of host glass powder. By this procedure with consequent guest release and heating, the ability of the studied calixarenes for polymorphism was investigated and compared as a function of their macrocycle conformation. The data of simultaneous thermogravimetry and differential scanning calorimetry with mass spectrometry of evolved vapors were determined together with the data of powder X-ray diffraction for the initial host samples, intermediate clathrates, and final polymorphs. In addition, single crystal X-ray diffraction data were obtained for four crystalline forms of the studied calixarenes. The results yielded a structure–property relationship, where 1,3-alternate calixarene without an extended H-bonded supramolecular network at least in one crystalline form has a much higher ability for polymorphism than the other two conformations. Thus, 10 polymorphs with essentially different crystal packing were found for this calixarene including a unique tetramorphism with four consecutive melting points of guest-free polymorph and corresponding three crystallization ranges. This ability of 1,3-alternate calixarene is linked with its other smart property: selective crystallization of its compact glass in vapors of binary liquid mixtures, which can be used for visual detection of very small benzene impurities (0.5% (v/v)) in cyclohexane.

Fast scanning calorimetry with a heating rate of 1000 K s−1 enables successful screening of polymorphs for separate microcrystalline aggregates in thiacalixarene powder.