Binding Features of Molecular Clips. Separation of the Effects of Hydrogen Bonding and π−π Interactions

Reek, Joost N. H.; Priem, A.; Engelkamp, Hans; Rowan, Alan E.; Elemans, Johannes A. A. W.; Nolte, Roeland J. M.

doi:10.1021/ja970805f

Cited by 126 publications

(102 citation statements)

References 44 publications

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“…[127][128][129][130] However, it is isolated from natural sources in trace amounts, 130) so that efficient chemical syntheses of 33h are required. 131,132) The starting materials 4-iodophenol (19j) and 3,5-dihydroxystyrene (34e) 133) were protected by benzoyl group to afford 19k and 34f in 82 and 87% yield respectively. The heterogeneous Heck reaction 12) of aryl iodide 19k and alkene 34f proceeded smoothly in the presence of PdAS-V to furnish the coupling 734 Vol.…”

Section: Efficient Synthesis Of Resveratrol Via the Heck Reaction Bymentioning

confidence: 99%

Self-Assembled Complexes of Non-cross-linked Amphiphilic Polymeric Ligands with Inorganic Species: Highly Active and Reusable Solid-Phase Polymeric Catalysts

Yamada

2005

CHEMICAL & PHARMACEUTICAL BULLETIN

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IntroductionDevelopment of immobilized and insoluble metal catalysts is of great interest in recent organic chemistry. [1][2][3][4][5][6][7][8][9] The simple recovery of catalysts by filtration and their reuses resulted in enhancing the economical evaluation of the reaction. At the same time, there is a prospect that the environmental pollution caused by residual metals in the waste fluid will be decreased. Although a great deal of effort has been made to carry out such ideal reactions using immobilized metal catalysts, what seems to be lacking is the efficiency of the catalytic systems. It is obvious that the heterogeneous catalytic systems exhibit generally lower activity than the homogeneous ones. Besides, it is expected that the activity of the catalysts decreases gradually in the recycled systems because the metal species leaches away from their supports. Taking these into consideration, we decided to concentrate on developing insoluble metal catalysts which are highly active and stable. We designed that they were still effective in the use of ppm mol eq, and in the recycled use of many times in any reaction media. To achieve the challenging theme, we have focused on the amphiphilic insoluble catalysts based on a novel concept (Chart 1).Over the past few decades, a considerable numbers of study have been made on solid-phase catalysts which were immobilized with cross-linked polystyrene resins, silica gels or metals. These catalytic systems, however, generally resulted in lower catalytic activity compared with their soluble counterparts, and were often obliged to use hazardous chlorohydrocarbon solvents. [10][11][12][13][14][15] Besides, reuse of these catalysts was often difficult owing to the gradual decline of the catalytic activity. These problems made them less practical.In traditional triphase catalysts, as I have mentioned before, a catalytic species was anchored to a linker that was immobilized to a polymer resin or silica gel (Chart 1, above). In July 2005Chem. Pharm. Bull. 53(7) 723-739 (2005)

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Section: Efficient Synthesis Of Resveratrol Via the Heck Reaction Bymentioning

confidence: 99%

Self-Assembled Complexes of Non-cross-linked Amphiphilic Polymeric Ligands with Inorganic Species: Highly Active and Reusable Solid-Phase Polymeric Catalysts

Yamada

2005

CHEMICAL & PHARMACEUTICAL BULLETIN

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confidence: 99%

“…-Stacking interactions, present in many biological systems and having demonstrated utility in strengthening other types of molecular interactions© [32][33][34][35],© represent© a© novel© means© of© enhanc-ing the formation of macrocycle-metal sandwich complexes. In contrast to the well studied interactions between© metal© ions© and© -orbital© systems© [36© -38],© the inclusion of aromatic moieties on the macrocycles in this report is expected to result in -stacking interactions between the -orbital systems on different macrocycles.…”

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confidence: 99%

Electrospray ionization mass spectrometric detection of self-assembly of a crown ether complex directed by π-stacking interactions

Sherman

Brodbelt

Marchand

et al. 2005

J. Am. Soc. Mass Spectrom.

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The self-assembly of ligand-metal-ligand sandwich complexes involving a novel quinoxalinecontaining crown ether, 1, was studied by electrospray ionization mass spectrometry (ESI-MS). Donor-acceptor -stacking interactions between the electron-poor quinoxaline group of 1 and electron-rich benzene groups from benzo-or dibenzo-18-crown-6 were found to significantly enhance the formation of mixed-ligand sandwich complexes with a free energy gain of up to 17 kJ/mol relative to sandwich formation involving macrocycles without such aromatic functionalities. The relative intensities of the sandwich complexes were greatest with the alkali metals Na In the present report, we present electrospray ionization mass spectrometry (ESI-MS) results on a novel crown ether which demonstrate that donor-acceptor -stacking interactions can be used to direct the self-assembly of noncovalent macrocycle-metal complexes.For probing metal complexation of macrocyclic systems, ESI-MS has proven to be an invaluable tool. Since ESI© is© capable© of© transferring© even© very© weakly© bound noncovalent complexes to the gas phase, mass spectrometry can be used to qualitatively and quantitatively evaluate the binding selectivities of the hosts or the relative binding constants of the resulting host-guest complexes© [4© -22].©Furthermore,©many©studies©have demonstrated that the results of ESI-MS analysis of these host-guest complexes correlate well with mea- Although binding of the second ligand in a ligandmetal-ligand sandwich complex in solution is typically not as strong as for the first ligand for unsubstituted crown©ethers© [27],©it©is©expected©that©the©addition©of certain functional groups on the macrocycle could enhance the formation of sandwich complexes. An analogous result has been observed for the formation of bis-crown ether-metal complexes studied by ESI-MS [13,© 23,© 28].© For© these© macrocycles,© the© preorganization offered by the covalently linked crown ethers results in very strong metal complexation in which the metal cation is simultaneously coordinated by both crown ethers.Rather than rely on covalently linked structures, such as those used in bis-crown ethers, other chemical interactions must be leveraged to create sandwich complexes which can self-assemble. -Stacking interactions, present in many biological systems and having demonstrated utility in strengthening other types of molecular interactions© [32][33][34][35],© represent© a© novel© means© of© enhanc-

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“…It is known that the association constant of an aromatic guest with clips and baskets increases with decreasing electron density on the guest. [39,40] An increase was found in the acidity of the hydroxy groups as well as the strength of the π-π stacking interactions of dihydroxybenzene substrates in the presence of electron-withdrawing groups. The observed downfield shift of the signal of the side-wall protons of 6 can be a result of the expulsion of this pyridyl group from the cavity of the Cu I 3 complex, induced by the less dynamic overall structure described above.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Characterization of PY2‐ and TPA‐Appended Diphenylglycoluril Receptors and Their Bis‐Cu^I Complexes

et al. 2006

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Binding Features of Molecular Clips. Separation of the Effects of Hydrogen Bonding and π−π Interactions

Cited by 126 publications

References 44 publications

Self-Assembled Complexes of Non-cross-linked Amphiphilic Polymeric Ligands with Inorganic Species: Highly Active and Reusable Solid-Phase Polymeric Catalysts

Self-Assembled Complexes of Non-cross-linked Amphiphilic Polymeric Ligands with Inorganic Species: Highly Active and Reusable Solid-Phase Polymeric Catalysts

Electrospray ionization mass spectrometric detection of self-assembly of a crown ether complex directed by π-stacking interactions

Synthesis and Characterization of PY2‐ and TPA‐Appended Diphenylglycoluril Receptors and Their Bis‐Cu^I Complexes

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Binding Features of Molecular Clips. Separation of the Effects of Hydrogen Bonding and π−π Interactions

Cited by 126 publications

References 44 publications

Self-Assembled Complexes of Non-cross-linked Amphiphilic Polymeric Ligands with Inorganic Species: Highly Active and Reusable Solid-Phase Polymeric Catalysts

Self-Assembled Complexes of Non-cross-linked Amphiphilic Polymeric Ligands with Inorganic Species: Highly Active and Reusable Solid-Phase Polymeric Catalysts

Electrospray ionization mass spectrometric detection of self-assembly of a crown ether complex directed by π-stacking interactions

Synthesis and Characterization of PY2‐ and TPA‐Appended Diphenylglycoluril Receptors and Their Bis‐CuI Complexes

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Synthesis and Characterization of PY2‐ and TPA‐Appended Diphenylglycoluril Receptors and Their Bis‐Cu^I Complexes