Comparative Study of Structures and Luminescent Properties of Three Ag(I) Complexes Utilizing an Achiral Bipyridyl‑<i>N</i> or Its Axially Chiral <i>N</i>‑Oxide Analogue

An achiral 2,2′-bipyridyl-3,3′-dicarboxylate (H₂L_N) can be oxidized to a <i>C</i>₂ axially chiral <i>N</i>-oxide analogy (<i>R</i>,<i>S</i>)-2,2′-bipyridyl-3,3′-dicarboxylate-1,1′-dioxide ((<i>R</i>,<i>S</i>)-H₂L_NO), converting normal bipyridyl-<i>N</i> to a charge-separated <i>N</i>-oxide group. The achiral H₂L_N connects the Ag­(I) ions into a 4-connected mesomeric 3D network [Ag₄(L_N)₂·(H₂O)]·3H₂O (<b>1</b>). However, as expected, with the introduction of <i>N</i>-oxide groups, {Ag₄­[(<i>R</i>,<i>S</i>)-L_NO]₂·2­(H₂O)}·H₂O (<b>2</b>) and {Ag₂­[(<i>R</i>,<i>S</i>)-L_NO]}·H₂O (<b>3</b>) contain right- and left-handedness homochiral layers. Such opposite handedness layers are linked together to give a racemic compound in <b>2</b> but <i>meso</i> double-layers in <b>3</b>. Notably, both ligands in <b>1</b>–<b>3</b> support argentophilic interactions. Moreover, a luminescent comparison of <b>1</b>–<b>3</b>, pyridyl-<i>N</i>, and its functional <i>N</i>-oxide ligands is also investigated in detail