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Calixarenes and related macrocycles have been shown to have antimicrobial effects since the 1950s. This review highlights the antimicrobial properties of almost 200 calixarenes, resorcinarenes, and pillararenes acting as prodrugs, drug delivery agents, and inhibitors of biofilm formation. A particularly important development in recent years has been the use of macrocycles with substituents terminating in sugars as biofilm inhibitors through their interactions with lectins. Although many examples exist where calixarenes encapsulate, or incorporate, antimicrobial drugs, one of the main factors to emerge is the ability of functionalized macrocycles to engage in multivalent interactions with proteins, and thus inhibit cellular aggregation.

The ability of p-tert-butyl thiacalix[4]arenes functionalized with tertiary and secondary amide and hydrazide groups at the lower rim in cone, partial cone, and 1,3-alternate conformations to self-assemble and recognize metal ions of s- (Li(+), Na(+), K(+), Cs(+)), p- (Al(3+), Pb(2+)) and d- (Fe(3+), Co(3+), Ni(2+), Cu(2+), Ag(+), Cd(2+), Hg(2+)) elements was investigated by picrate extraction method and dynamic light scattering (DLS). DLS was used for determination of the hydrodynamic diameter, polydispersity index, and molecular weight of nanoscale aggregate systems consisting of p-tert-butyl thiacalix[4]arene molecules and metal nitrates. Also for quantitative determination of the dimer shape from the values of molecular weight and the particles size, the Perrin factor (F) was established. It was shown that in most cases the dimers of stereoisomers of p-tert-butyl thiacalix[4]arenes tetra-substituted at the lower rim by secondary amide groups represent the prolate spheroid.

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.