A dual-coded dynamic material was created by the bimodal self-assembly protocol sketched in the scheme. The combination of two orthogonal and reversible interactions, namely solvophobic aggregation (SA) and metal coordination (MC), allows precise control at each step of the self-assembly cycle, leading to the formation of rodlike supramolecular architectures. Eight illustrious organic chemists in one pot! A route from protected monosaccharides to novel C-glycosides and Clinked disaccharides is described which involves tandem Horner-WadsworthEmmons/conjugate addition (Michaeltype), followed by tandem halogenation/Ramberg-Bäcklund reaction using the Meyers-Chan procedure (see scheme, R = protected saccharide). The calculated structures of a supported Rh6 cluster (depicted) demonstrate that protons of surface OH groups of the oxide support migrate onto the cluster. This migration results in the oxidation of metal atoms that are in close contact with the support. The energy released by this reverse hydrogen spillover is estimated to be 120 kmol-1 per OH group. A more sensitive approach: A variation on the heteronuclear multiple-bond correlation technique has been devised which can determine the conformation around the glycosidic bonds in oligosaccharides and glycopeptides. The key section of the studied glycopeptide 1 is shown, for which measurements of the torsion angles φ and ψ derived from 3J(C,H) coupling constants and cross-correlated relaxation rates, compare favorably with those determined by X-ray diffraction or molecular dynamic analysis. Highly unsaturated γ-lactones are formed in good to high yields from 2-(propargyl)allyl phosphates and carbon monoxide in the presence of a palladium catalyst (see scheme). The reaction proceeds efficiently under mild reaction conditions (at 80°C under an ambient pressure of CO). A change in shift! In contrast to the red shift commonly found in organic polyynes and other metal-alkynyl systems, a blue shift in the transition energy was observed in electronic absorption and emission studies on a novel series of structurally characterized dinuclear platinum(II)terpyridyl complexes [{Pt(tBu3-tpy)}2- (CC)n](X)2 (1-3; tBu3-tpy=4,4′,4″-tritert-butyl-2,2′: 6′,2″-terpyridine) upon increasing the extent of π conjugation of the alkynyl bridge.

Dynamic Materials via Metal-Directed and Solvent-Driven Self-Assembly of Cavitands / PIRONDINI L; STENDARDO A.G; GEREMIA S; CAMPAGNOLO M; SAMORI P; RABE J.P; FOKKENS R; DALCANALE E.. - In: ANGEWANDTE CHEMIE. INTERNATIONAL EDITION. - ISSN 1433-7851. - 42:12(2003), pp. 1384-1387. [10.1002/anie.200390355]

Dynamic Materials via Metal-Directed and Solvent-Driven Self-Assembly of Cavitands

PIRONDINI, Laura;DALCANALE, Enrico
2003

Abstract

A dual-coded dynamic material was created by the bimodal self-assembly protocol sketched in the scheme. The combination of two orthogonal and reversible interactions, namely solvophobic aggregation (SA) and metal coordination (MC), allows precise control at each step of the self-assembly cycle, leading to the formation of rodlike supramolecular architectures. Eight illustrious organic chemists in one pot! A route from protected monosaccharides to novel C-glycosides and Clinked disaccharides is described which involves tandem Horner-WadsworthEmmons/conjugate addition (Michaeltype), followed by tandem halogenation/Ramberg-Bäcklund reaction using the Meyers-Chan procedure (see scheme, R = protected saccharide). The calculated structures of a supported Rh6 cluster (depicted) demonstrate that protons of surface OH groups of the oxide support migrate onto the cluster. This migration results in the oxidation of metal atoms that are in close contact with the support. The energy released by this reverse hydrogen spillover is estimated to be 120 kmol-1 per OH group. A more sensitive approach: A variation on the heteronuclear multiple-bond correlation technique has been devised which can determine the conformation around the glycosidic bonds in oligosaccharides and glycopeptides. The key section of the studied glycopeptide 1 is shown, for which measurements of the torsion angles φ and ψ derived from 3J(C,H) coupling constants and cross-correlated relaxation rates, compare favorably with those determined by X-ray diffraction or molecular dynamic analysis. Highly unsaturated γ-lactones are formed in good to high yields from 2-(propargyl)allyl phosphates and carbon monoxide in the presence of a palladium catalyst (see scheme). The reaction proceeds efficiently under mild reaction conditions (at 80°C under an ambient pressure of CO). A change in shift! In contrast to the red shift commonly found in organic polyynes and other metal-alkynyl systems, a blue shift in the transition energy was observed in electronic absorption and emission studies on a novel series of structurally characterized dinuclear platinum(II)terpyridyl complexes [{Pt(tBu3-tpy)}2- (CC)n](X)2 (1-3; tBu3-tpy=4,4′,4″-tritert-butyl-2,2′: 6′,2″-terpyridine) upon increasing the extent of π conjugation of the alkynyl bridge.
Dynamic Materials via Metal-Directed and Solvent-Driven Self-Assembly of Cavitands / PIRONDINI L; STENDARDO A.G; GEREMIA S; CAMPAGNOLO M; SAMORI P; RABE J.P; FOKKENS R; DALCANALE E.. - In: ANGEWANDTE CHEMIE. INTERNATIONAL EDITION. - ISSN 1433-7851. - 42:12(2003), pp. 1384-1387. [10.1002/anie.200390355]
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11381/1452435
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