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Alkylation of thiacalix[4]arenes with ethyl bromoacetate led to high yields (≈60%) of corresponding tetraacetates in various conformations (cone, partial cone, 1,3-alternate) depending strictly on the carbonate (Na, K, Cs) used for the reaction. The complexation ability of new compounds was studied by 1H NMR.

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Mixtures of ibandronate monosodium salt with eleven gluco- and/or galacto-pyranoside derivatives as counterions were designed to prepare co-crystals with improved intestinal absorption. In general, gastrointestinal absorption of bisphosphonates after oral administration is approximately 1%. Co-crystals were generated by means of thermodynamically and/or kinetically controlled crystallization processes. Seventy-seven prepared samples were analyzed by means of FT-NIR, FT-Raman spectrometry and solid state NMR spectroscopy. New entities of ibandronate monosodium salt with phenyl-β-d-galactopyranoside were found and characterized. The absorption of these potential new co-crystals was investigated by means of PAMPA experiments. In the present study the relationships between the chemical structures of the studied compounds required for co-crystal generation are discussed.