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Encapsulation of Photosensitizers in Hexa- and Octanuclear Organometallic Cages: Synthesis and Characterization of Carceplex and Host-Guest Systems in Solution
Cationic arene ruthenium assemblies of the general formulas [Ru6(p-cymene)6(tris-pvb)2(?2-Cl)6]6+, [Ru6(p-cymene)6(tris-pvb)2(OO?OO)3]6+ (tris-pvb = 1,3,5-tris{2-(pyridin-4-yl)vinyl}benzene), and [Ru8(p-cymene)8(NN?NN)2(OO?OO)4]8+ (NN?NN = 1,2,4,5-tetrakis{2-(pyridin-4-yl)vinyl}benzene, 1,2,4,5-tetrakis{2-(pyridin-4-yl)ethynyl}benzene) have been obtained from the corresponding dinuclear arene ruthenium complexes [Ru2(p-cymene)2(?-Cl)2Cl2] and [Ru2(p-cymene)2(OO?OO)Cl2] (OO?OO = oxalato, 2,5-dioxido-1,4-benzoquinonato, 2,5-dichloro-1,4-benzoquinonato, 5,8-dioxido-1,4-naphthoquinonato, 5,8-dioxido-1,4-anthraquinonato, 6,11-dioxido-5,12-naphthacenedionato) by reaction with the multidentate ligands and silver trifluoromethanesulfonate. These cationic hexa- and octanuclear cages have been isolated and characterized as their triflate salts. Addn. of coronene during the synthesis of the large hexanuclear assemblies leads to the direct encapsulation of coronene in the cavity of the trigonal-prismatic complexes. Photosensitizers such as porphin, phthalocyanine, and Zn-phthalocyanine present during the synthesis of these metalla-cages are encapsulated in five of these arene ruthenium complexes to give photosensitizer-encapsulated systems. The host-guest properties of these systems were studied in soln. by DOSY, 2D NOESY and 2D ROESY NMR spectroscopy. The H···H distances between guests and selected metalla-cages were estd. by 2D ROESY NMR spectroscopy and modelization. NMR analyzes indicate that the guest photosensitizers are completely encapsulated in two of these metalla-cages, while in the three other ruthenium cages NMR spectra reveal an equil. between empty and filled cages. [on SciFinder(R)]