Synthesis and guest exchange reactions of inclusion compounds of cucurbit[8]uril with nickel(II) and copper(II) complexes

Abstract

Inclusion compounds of the macrocyclic cavitand cucurbit[8]uril (CB[8]) with the nickel(II) complex, {trans-[Ni(en)2(H2O)2]@CB[8]}Cl2 · 23.5H2O, the copper(II) complex, {2[Cu(dien)(bipy)(H2O)]@CB[8]}(ClO4)4 · 11H2O, and the organic molecules, 2(pyCN)@CB[8]} · 16H2O and {2(bpe)@CB[8]} · 17H2O, where bipy is 4,4′-bipyridyl, pyCN is 4-cyanopyridine, and bpe is trans-1,2-bis(4-pyridyl)ethylene, were synthesized. The inclusion compounds with organic molecules were synthesized starting from inclusion compounds of cucurbit[8]uril with cyclam and ethylenediamine complexes of copper(II) and nickel(II) by the guest exchange method, which is based on the replacement of one guest with another in the cavity of the cavitand The resulting compounds were characterized by X-ray diffraction, ESR, 1H NMR, IR, and electronic absorption spectroscopy, and electrospray mass spectrometry. Photochemically induced [2+2]-cycloaddition of two 1,2-bis(4-pyridyl)ethylene molecules included in cucurbit[8]uril was studied.