Two N-Heterocyclic Carbene Silver(I) Cyclophanes: Synthesis, Structural Studies, and Recognition for p-Phenylenediamine

The diimidazolium salt 1,5-bis[1-ethylimidazoliumylethoxy]naphthalene hexafluorophosphate (2) and the dibenzimidazolium salt 1,4-bis[1-(n-butyl)benzimidazoliumylethoxy]benzene hexafluorophosphate (4), as well as their N-heterocyclic carbene silver(I) cyclophanes [naphthalene(OCH2CH2imyEt)2Ag]2(PF6)2 (5) and [benzene(OCH2CH2bimynBu)2Ag]2(PF6)2 (6), have been prepared and characterized. Each cation in complexes 5 and 6 contains a 30-membered macrometallacycle. In the crystal packing of 5 and 6, 3D architectures are formed via intermolecular weak interactions, including π–π interactions, hydrogen bonds, and C–H···π contacts. The recognition of neutral p-phenylenediamine (PDA) molecules using 5 and 6 as receptors via fluorescent and UV/vis spectroscopic titrations have been investigated.