Anion-directed self-assembly of a 2,6-bis( 2-anilinoethynyl) pyridine bis( amide) scaffold

Bis(sulfonamide) receptors based on the 2,6-bis(2-anilinoethynyl)pyridine scaffold form persistent dimers with water and halides in solution and in the solid-state. The structurally related bis(amide) receptor derived from 3,5-dinitrobenzoyl chloride is a dimer in the solid-state with two HCl molecules directing the self-assembly. The 2+2 dimer, with a twisted S'-shaped backbone, is held together by six hydrogen bonds. Dissolution of the (H2(+)Cl(-))(2) adduct in CHCl3 results, however, in a monomeric structure. DOSY and H-1 NMR experiments were used to identify the dominance of monomer in solution for both 2 and H2(+)Cl(-). The OFF-ON' fluorescence response of 2,6-bis(2-anilinoethynyl)pyridine is retained with amide arms.