Synthesis And Post-Assembly Modification Of Concentric Cyclinder-in-Cyclinder Architectures Bearing Exclusively Metal-Carbene Bonds

Over the last decades,the chemistry of N-heterocyclic carbenes?NHCs?has become a field of intensive research.This is not only due to their interesting properties,but also for their wide-ranging applications in catalytically-active metal complexes,organocatalysis,material science and also in the pharmaceutical chemistry.The application of NHCs has been extended to metallosupramolecular chemistry where the poly-NHC ligands are employed as building blocks for the construction of varieties of metallosupramolecular assemblies.However,due the non-reversible nature of carbene-metal bonds,the post-synthetic modification of such assemblies are found to be rather difficult in compared to coordination complexes.Recently,it has been demonstrated that NHC-Ag bonds are exceptions to the generally obtained transition metal-carbene bonds.Thus,taking the advantages of reversible NHC-Ag bonds,here we investigated the preparation of a gigantic dodecakisimidazolium cages bearing a remarkably large cavity.This covalent organic cage is synthesized from its concentric cylinder-in-cylinder organometallic assemblies,where the three silver?I?ions remain inside forming a smaller cylindrical structure and the other three peripheral silver?I?ions remain outside resulting in a larger cylindrical architecture.This paper mainly includes the following aspects:1.Design and synthesis of nitrogen heterocyclic carbene with concentric circles structure precursor H₆-L?PF₆?₆?L=1a,1b?,using conventional construction method of nitrogen heterocyclic metal silver carbene,get a central atom by six metal respectively connect the two contains six imidazole ligand of new metal carbene framework[Ag₆?L?₂]?PF₆?₆?L=1a,1b?,according to the nitrogen heterocyclic carbene metal exchange way for the gold carbene of corresponding compounds[Au₆?L?₂]?PF₆?₆?L=1a,1b?.Finally,a series of new compounds will be characterized by NMR and MS.2.After the successful synthesis of nitrogen heterocyclic metal carbene framework complexes with concentric ring structure,this part mainly focuses on how to modify the nitrogen heterocyclic metal carbene framework with concentric ring structure.Based on our group long-term studies of photochemical reaction[2+2],we can success will occur[2+2]photochemical reaction of functional groups of cinnamic esters is introduced into the concentric ring structure of ligand imidazole salt H₆-L?PF₆?₆?L=2a,2b?,then use the terminal group for cinnamic esters groups of six imidazoles salt react with silver oxide to prepare nitrogen heterocyclic silver carbene with functional groups[Ag₆?L?₂]?PF₆?₆?L=2a,2b?,further through metal exchange to get the nitrogen heterocyclic gold carbene of the corresponding complexes[Au₆?L?₂]?PF₆?₆?L=2a,2b?.Then,the nitrogen heterocyclic metal carbene frame was used as the template.Under the UV irradiation of365 nm,the metal carbene complexes underwent intramolecular[2+2]photochemical reaction,to obtain a closed three-dimensional cage compound with six metal centers[M₆?L?]?PF₆?₆?M=Ag,Au;L=3a,3b?.Finally,the organic cage compounds dodecakisimidazolium were obtained for the first time by simple removal of the silver atoms in silver carbene complexes after ring closure H₁₂-L?PF₆?₁₂?L=3a,3b?.