Hydrogen-bonded dimers of a thiacalixarene substituted by carbamoylmethylphosphineoxide groups at the wide rim

Promising advances of thiacalix[4]arene in crystal structures

Thiacalix[4]arenes are one kind of robust scaffolds and extensively applied in supramolecular chemistry and materials science owing to their novel features.

Dimeric capsules formed by tetra-CMPO derivatives of (thia)calix[4]arenes

Thiacalix[4]arene 2, calix[4]arene 3a and its tetraether fixed in the cone conformation 3b form homo- and heterodimeric capsules in apolar solvents, which are held together by a seam of NH...O=P hydrogen bonds between carbamoylmethyl phosphine oxide functions attached to their wide rim. Their internal volume of approximately 370 A(3) requires the inclusion of a suitable guest. Although neutral molecules such as adamantane (derivatives) or tetraethylammonium cations form kinetically stable complexes ((1)H- and (31)P-time scale), the included solvent is rapidly exchanged. The internal mobility of the included tetraethylammonium cation is distinctly higher (DeltaG=42.5 and 49.7 kJ mol(-1) for 3a and 3b) than that for similar capsules of tetraurea calix[4]arenes 1. Mixtures of 1 with 2, 3a, or 3b contain only the two homodimers but the heterodimerization occurs with the tetraloop tetraurea 6, which cannot form homodimers. Two dimers with cationic guests (2.(C(5)H(5))(2)Co(+).2 and 3a.Et(3)NH(+).H(2)O.3a) were confirmed by single-crystal X-ray analysis.

Calixarene receptors of environmentally hazardous and biorelevant molecules and ions

In the paper, a report on the rational design of the calixarene receptors bearing ligating, H-donor, H-acceptor fragments at the wide and/or narrow rim of the macrocycle is presented. The calixarenes form supramolecular complexes with various cations, anions, organic molecules, and biomolecules in solution, in the crystalline state and even in the gas phase. The calixarenes or their complexes can be used as materials for radionuclide extraction, construction of chemosensors, and drug design.