title: Self-assembled hexanuclear organometallic cages: synthesis, characterization, and host-guest properties.
abstract: A series of iridium- and rhodium-based hexanuclear organometallic cages containing 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone, 9,10-dihydroxy-1,4-anthraquinone, and 6,11-dihydroxynaphthacene-5,12-dione ligands were synthesized from the self-assembly of the corresponding molecular "clips" and 2,4,6-tri(4-pyridyl)-1,3,5-triazine ligands in good yields. These organometallic cages can form inclusion systems with a wide variety of π-donor substrates, including coronene, pyrene, [Pt(acac)(2)], and hexamethoxytriphenylene. The 1:1 complexation of the resulting supramolecular assemblies was confirmed by (1)H NMR spectroscopy. Large complexation shifts (Δδ>1 ppm) were observed in the (1)H NMR spectra of guests in the presence of cage [Cp*(6)M(6)(μ-DHNA)(3)(tpt)(2)](OTf)(6) (6a; M=Ir, tpt=2,4,6-tri(4-pyridyl)-1,3,5-triazine). The formation of discrete 1:1 donor-acceptor complexes, pyrene⊂6b (M=Rh), coronene⊂6a, coronene⊂6b, and [Pt(acac)(2)]⊂6a was confirmed by their single-crystal X-ray analyses. In these systems, the most important driving force for the formation of guest-host complexes is clearly the donor-acceptor π···π stacking interaction, including charge-transfer interactions between the electron-donating and electron-accepting aromatic components. These structures provide compelling evidence for the existence of strong attractive forces between the electron-deficient triazine core and electron-rich guest. The results presented here may provide useful guidance for designing artificial receptors for functional biomolecules.
authors.affiliation: Shanghai Key Laboratory of Molecular Catalysis and Innovative Material, Department of Chemistry, Fudan University, 220 Handan Road, Shanghai, 200433 P.R. China.
authors.forename: Ying-Feng
authors.initials: YF
authors.lastname: Han
authors.forename: Hao
authors.initials: H
authors.lastname: Li
authors.forename: Zhi-Fang
authors.initials: ZF
authors.lastname: Zheng
authors.forename: Guo-Xin
authors.initials: GX
authors.lastname: Jin
mesh_terms: D000880:Anthraquinones / Q000737:chemistry; D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry; D018360:Crystallography, X-Ray; D007495:Iridium / Q000737:chemistry; D008024:Ligands; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D012238:Rhodium / Q000737:chemistry
chemical_list: D000880:Anthraquinones; D056831:Coordination Complexes; D008024:Ligands; D009942:Organometallic Compounds; D007495:Iridium; C416442:1,4-anthraquinone; D012238:Rhodium