Self-Assembly of a Luminescent Zinc(II) Complex: a Supramolecular Host−Guest Fluorescence Signaling System for Selective Nitrobenzene Inclusion

A luminescent Zn(II) complex, [Zn(bpy)(aba)2] (1) {bpy = 2,2‘-bipyridyl and aba = 4-dimethylaminobenzoate} has been synthesized as a white solid. Complex 1 shows unusually high selectivity
toward nitrobenzene in the presence of other organic guests in
solution, as well as in the vapor phase, resulting in both a dramatic
color change and a concomitant quenching of luminescence. When
crystallized from nitrobenzene, 1 affords deep red crystals with
the composition [Zn(bpy)(aba)2]·C6H5NO2 (2) as a hydrogen-bonded
channel structure via unusual intermolecular C−H···C(sp3) and
H···H interactions. Inside the channels, nitrobenzene molecules
form infinite polar linear tapes through strong C−H···O interactions
in a head-to-tail fashion. The desorption and resorption of
nitrobenzene can be achieved in a thermally reversible manner
that can be monitored by X-ray powder diffraction patterns.