Diverse Structural Ag(I) Supramolecular Complexes Constructed from Multidentate Dicyanoisophorone-Based Ligands: Structures and Enhanced Luminescence

Two multidentate ligands containing a delocalized π-electron system, 2-{5,5-dimethyl-3-[2-(pyridin-3-yl)-ethenyl]­cyclohex-2-enylidene}­propanedinitrile (<b>L1</b>) and 2-{5,5-dimethyl-3-[2-(pyridin-2-yl)-ethenyl]­cyclohex-2-enylidene}­propanedinitrile (<b>L2</b>), were synthesized. By self-assembly of the ligands with silver­(I) salts, six supramolecular complexes, [Ag­(L1)­(TsO)­(H₂O)]₂ (<b>1</b>), {[Ag₃(L1)₂(H₂O)]­(ClO₄)₃}<i>_n</i> (<b>2</b>), {[Ag­(L1)­(NO₃)]·0.5C₆H₆}<i>_n</i> (<b>3</b>), {[Ag­(L2)­(NO₃)]·0.5C₆H₆}_<i>n</i> (<b>4</b>), [Ag­(L2)₂]­(ClO₄) (<b>5</b>), and [Ag­(L2)₂]­(PF₆) (<b>6</b>), with different structures and topologies were obtained. In polymer <b>2</b>, <b>L1</b> acts as a tridentate ligand to bind Ag­(I) ions to form a one-dimensional (1D) supramolecular structure. However, when the ligands adopt bidentate coordination modes to coordinate with Ag­(I) ions through the pyridyl nitrogen atom and one cyano nitrogen atom, the dinuclear supramolecular complex <b>1</b>, 1D coordination polymer <b>3</b>, and two-dimensional (2D) coordination polymer <b>4</b> were obtained. In <b>5</b> or <b>6</b>, only the pyridyl nitrogen atom of <b>L2</b> ligand coordinates with the Ag­(I) ion to form a mononuclear complex. The multiple coordination modes of the multidentate ligands and the effect of anions and solvents play important roles in the structural and topological diversity. The luminescent properties were investigated. Compared with the ligands, the complexes show superior luminescent properties with red-shifted and enhanced emission as well as longer fluorescence lifetimes, which indicates that they may be good candidates for optical materials