Enhancement Of Metal-Metal Interactions Via Host-Guest Interactions

Metal-ligand complexes featuring d⁸ and d¹⁰ transition metals can exhibit non-covalent metal-metal interactions as a result of metallophilic attraction.With the specific physical and chemical properties of metal-metal interactions,such as conductivity,photoluminescence,polymorphism,vapochromism,and vapoluminescence,these complexes have been applied in chemosensing,advanced materials,supramolecular photocatalysis,molecular crystal engineering,and assembly of gold nanorods.In the solid state,these compounds usually exhibit metal-metal interactions due to the short distance between the molecules.But in solution,the strength of metal-metal interactions is affected by several factors as a result of long distance between the molecules.It has been found that metal-metal interactions can be triggered by relevant solvents and counter ions,nucleic acids and peptides,polymers and also host-guest chemistry.In water,enhancement of metal-metal andπ-πstacking interactions was realized by electrostatic interactions between the polyelectrolyte and the platinum（II）-terpyridyl complexes.Herein,wepresentresultsonbindinginteractonsbetweenfour Pt（II）/Au（III）-terpyridyl complexes（guest 1（[Pt（tpy）C≡CCH₂NMe₃][OTf]₂）,guest 2（[Pt（tpy）Cl]Cl）,guest3（[Au（tpy）Cl]Cl₂）andguest4（[{Pt（tpy）（C≡CCH₂）}₂NMe₂][OTf]₃））and cucurbit[10]uril（CB[10]）in water.The results show that CB[10]can encapsulate two guest 1 molecules in pure H₂O viaion-dipole and hydrophobic interactions,enhancingPt（II）···Pt（II）andπ-πstacking interactions.Guest 2without the ammonium group can also be encapsulate in CB[10]also showing metal-metal andπ-πstacking interactions.This approach was extended to Au（III）-containing guest 3 which was also encapsulated in the cavity of CB[10]with stronger emission upon inclusion.Finally,a supramolecular polymer composed of the bis-Pt（II）-terpyridyl complex 4 and CB[10]featuring host-enhanced metal-metal andπ-πstacking interactions was constructed.