Crystal engineering of a hybrid metal–organic host framework and its single-crystal-to-single-crystal guest exchange using second sphere coordination

Abstract

By means of crystal engineering principles, a new second sphere coordination adduct has been synthesized using charge-assisted hydrogen bonds and self-assembling [CdBr₆]⁴⁻and Br⁻ anions with a V-shaped diprotonated cation. The second sphere adduct is homologous to a copper network, forms a host framework with 1D channels and has good thermal stability (200 °C) upon guest release. The [CdBr₆]⁴⁻ anion shows Jahn–Teller distortion as revealed by X-ray crystallography. Guest exchange via a single-crystal-to-single-crystal manner is reported. The guest behavior is different to that of the homologous Cu adduct due to the pore size effect.