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Permanent Encapsulation or Host-Guest Behavior of Aromatic Molecules in Hexanuclear Arene Ruthenium Prisms
Cationic arene Ru metallaprisms [Ru6(p-cymene)6(tpt)2(OO?OO)3]6+ {tpt = 2,4,6-tris(4-pyridyl)-1,3,5-triazine; OO?OO = 9,10-dioxo-9,10-dihydroanthracene-1,4-diolato [1]6+, 6,11-dioxo-6,11-dihydronaphthacene-5,12-diolato [2]6+} were obtained from the corresponding dinuclear arene Ru complexes [Ru2(p-cymene)2(OO?OO)Cl2] by reaction with tpt and Ag trifluoromethanesulfonate. Arom. mols. (phenanthrene, pyrene, triphenylene, coronene) present during the synthesis of these metallaprisms are permanently encapsulated to give carceplex systems. All empty cages ([1]6+ and [2]6+) and carceplex systems ([guest?1]6+ and [guest?2]6+) were isolated in good yield as trifluoromethanesulfonate salts and characterized by NMR, UV, and IR spectroscopy. The host-guest properties of [1]6+ and [2]6+ were studied in soln. in the presence of small arom. mols. (phenanthrene and pyrene). The stability const. of assocn. (Ka) was estd. by NMR spectroscopy for the following host-guest systems: [phenanthrene?1]6+, [pyrene?1]6+ and [phenanthrene?2]6+, [pyrene?2]6+. All Ka values are larger than 2.0 × 104 M-1 for these host-guest systems ([D3]acetonitrile, 21°). [on SciFinder(R)]
Designing the host-guest properties of tetranuclear arene ruthenium metalla-rectangles to accommodate a pyrene molecule
Cationic tetranuclear rectangular macrocyclic arene ruthenium complexes [Ru4(p-cymene)4(?-N-N)2(?-dhnq)2](CF3SO3)4 [1-3, dhnq = 5,8-dihydroxy-1,4-naphthoquinonato(2-); N-N = pyrazine, 4,4'-bipyridine, 1,2-bis(4-pyridyl)ethene], featuring Ru-dhnq-Ru-N-N-Ru-dhnq-Ru rectangle structures with adjustable Ru-Ru distances (7.0 Ã…, 11.2 Ã…, 13.6 Ã…, resp.), are obtained in methanol from the reaction of the dinuclear arene ruthenium precursor [Ru2(p-cymene)2(dhnq)2Cl2] with pyrazine or bipyridine linkers in the presence of AgCF3SO3. All complexes 1-3, isolated in good yield as triflate salts, have been characterized by NMR and IR spectroscopy. The interaction of these rectangular complexes with pyrene as a guest mol. has been studied in soln. by various NMR techniques (1D, DOSY, ROESY). In CD3CN, the pyrazine-contg. metalla-rectangle 1 shows no meaningful interactions with pyrene. On the other hand, the 4,4'-bipyridine- and 1,2-bis(4-pyridyl)ethylene-contg. metalla-rectangles 2 and 3 clearly interact with pyrene. DOSY measurements suggest that, in the case of the 4,4'-bipyridine complex 2, the interactions occur on the outside of the rectangular assembly, while in the case of dipyridylethylene complex 3 the pyrene mol. is found inside the hydrophobic cavity of the metalla-rectangle, thus giving rise to a host-guest system. [on SciFinder(R)]
Designing the Host-Guest Properties of Tetranuclear Arene Ruthenium Metalla-Rectangles to Accommodate a Pyrene Molecule
Cationic tetranuclear arene ruthenium complexes of the general formula [Ru4(p-cymene)4(N∩N)2(dhnq)2]4+ comprising rectangular structures are obtained in methanol from the reaction of the dinuclear arene ruthenium precursor [Ru2(p-cymene)2(dhnq)2Cl2] (dhnq = 5,8-dihydroxy-1,4-naphthoquinonato) with pyrazine or bipyridine linkers [N∩N = pyrazine, 1; 4,4-bipyridine, 2; 1,2-bis(4-pyridyl)ethylene, 3] in the presence of AgCF3SO3. All complexes 1-3, isolated in good yield as triflate salts, have been characterised by NMR and IR spectroscopy. The interaction of these rectangular complexes with pyrene as a guest molecule has been studied in solution by various NMR techniques (1D, DOSY, ROESY). In [D3]acetonitrile, the pyrazine-containing metalla-rectangle 1 shows no meaningful interactions with pyrene. On the other hand, the 4,4-bipyridine- and 1,2-bis(4-pyridyl)ethylene-containing metalla-rectangles 2 and 3 clearly interact with pyrene in [D3]acetonitrile. DOSY measurements suggest that, in the case of [Ru4p-cymene)4(4,4-bipyridine)2(dhnq)2]4+ (2), the interactions occur on the outside of the rectangular assembly, while in the case of [Ru4(p-cymene)4{1,2-bis(4-pyridyl)ethylene}2 (dhnq)2]4+ (3), the pyrene molecule is found inside the hydrophobic cavity of the metalla-rectangle, thus giving rise to a host-guest system.