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New p-tert-butylthiacalix[4]arenes with several different substituents at the lower rim have been synthesised. A method for the selective introduction of one or two guanidinium fragments into the structure of p-tert-butylthiacalix[4]arenes has been developed. The 1,3-alternate thiacalix[4]arenes containing guanidinium groups interact with silver nitrate and oxalic acid in methanol with a logKassoc of about 3.5 and 1:1 stoichiometry, while the macrocycle in the cone conformation interacts with oxalic acid with logKassoc of 7.4 and 2:1 stoichiometry. The new p-tert-butylthiacalix[4]arenes form nanoscale aggregates with hydrodynamic radii of about 70 nm by self-association and by mediation with silver cations and oxalic acid.