Synthesis of Butadiynyl-Strapped Corona[6]arenes and Their Selective Anion Binding Properties

A number of butadiynylene-strapped O6-corona­[6]­arenes were synthesized straightforwardly through
intramolecular oxidative homocoupling of O6-corona­[6]­arenes,
which contained at least two N-propargyl-phthalimide
segments. The mono-macrocyclic reactants were prepared from the reaction
between 3,6-dichlorotetrazine and N-propargyl-3,6-dihydroxyphthalimide
and another 1,4-dihydroxybenzene derivative with roughly a 3:2:1.3–1.5
ratio in a one-pot reaction manner. The synthesized butadiynylene-strapped
corona[3]­arene[3]­tetrazines acted as highly selective electron-deficient
macrocyclic hosts to form 1:1 complexes with thiocyanate in solution,
and the association constant (Ka) was
up to 1390 M–1. The anion−π noncovalent
interactions provided the driving force for host–guest complexation.