Abiotic guanidinium containing receptors for anionic species

Best, Michael D.; Tobey, Suzanne L.; Anslyn, Eric V.

doi:10.1016/s0010-8545(02)00256-4

Cited by 376 publications

(193 citation statements)

References 79 publications

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“…The hydrogen bond-reinforced salt bridge is weak in water but has binding constants as high as 10 4 M À1 at the lipid/water interface 61 and even higher in nonpolar environments. 62 We expect compound 4 to easily migrate into a nonpolar lipid bilayer if the internal salt bridge is formed. Even with the ionic groups, 4 is insoluble in water, due to the dominance of hydrophobic groups.…”

Section: Cf Leakage Measurement Preparation Of Cf-containing Luvsmentioning

confidence: 99%

Translocation of Hydrophilic Molecules across Lipid Bilayers by Salt-Bridged Oligocholates

Cho

Zhao

2011

Langmuir

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Macrocyclic oligocholates were found in a previous work (Cho, H.; Widanapathirana, L.; Zhao, Y. J. Am. Chem. Soc.2011, 133, 141−147) to stack on top of one another in lipid membranes to form nanopores. Pore formation was driven by a strong tendency of the water molecules in the interior of the amphiphilic macrocycles to aggregate in a nonpolar environment. In this work, cholate oligomers terminated with guanidinium and carboxylate groups were found to cause efflux of hydrophilic molecules such as glucose, maltotriose, and carboxyfluorescein (CF) from POPC/POPG liposomes. The cholate trimer outperformed other oligomers in the transport. Lipid-mixing assays and dynamic light scattering ruled out fusion as the cause of leakage. The strong dependence on chain length argues against random intermolecular aggregates as the active transporters. The efflux of glucose triggered by these compounds increased significantly when the bilayers contained 30 mol % cholesterol. Hill analysis suggested that the active transporter consisted of four molecules. The oligocholates were proposed to fold into "noncovalent macrocycles" by the guanidinium−carboxylate salt bridge and stack on top of one another to form similar transmembrane pores as their covalent counterparts. Disciplines Chemistry CommentsReprinted ( Synthetic transmembrane pores with an inner diameter of 1 nm or larger have attracted a great deal of attention in recent years. 1,2 Part of the motivation comes from the fact that their biological congeners, membrane-associated pore-forming proteins, are involved in critical functions such as signaling, metabolism, and bacterial or viral infection. 3À7 Since it is notoriously difficult to obtain detailed structural information for complex membrane proteins, chemists have sought to construct simpler biomimetic nanopores and study their behavior under more easily controlled conditions. Knowledge generated from such studies not only is useful to the understanding of biological pore formation but also helps create materials with potential applications ranging from single-molecule detection of DNAs and RNAs 8À14 to drug delivery. 15 Crown ethers and open chain compounds, which worked extremely well for ion channels, 16À21 normally are too flexible for nanopore formation. To keep the pore open, the structure must be able to withstand the external membrane pressure when incorporated into a bilayer. 22 Despite the significant efforts devoted to synthetic nanopores, limited designs exist currently. An early example was Ghadiri's cyclic D/L-peptides, which self-assembled into transmembrane pores large enough for glucose and glutamic acid to pass through. 23,24 In recent years, the β-barrel pores constructed from oligo(phenylene) derivatives by Matile and coworkers 25À27 proved particularly versatile and useful in many applications including sensing 26 and catalysis. 27 Other examples include the porphyrin-based nanopores by Satake and Kobuke, 28 Gong's π-stacked aromatic heterocycles, 29 the metal-coordinated nanopores by Fy...

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Section: Cf Leakage Measurement Preparation Of Cf-containing Luvsmentioning

confidence: 99%

Translocation of Hydrophilic Molecules across Lipid Bilayers by Salt-Bridged Oligocholates

Cho

Zhao

2011

Langmuir

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“…Klassische Beispiele dafür sind synthetische Rezeptoren wie 17 für die selektive Komplexierung von Nitrat. [326] In DMSO werden durch 18 Carboxylate mit K > 10 3 m À1 , gebunden, Sulfate oder Halogenide dagegen mit K < 50 m À1 . [327] Wasserstoffbrücken können Enolate wie bei 19 so stark komplexieren, dass die Acidität entsprechender 1,3-Dicarbonylverbindungen um bis zu drei pK-Einheiten sinkt.…”

Section: Grundlagenunclassified

Bindungsmechanismen in supramolekularen Komplexen

Schneider

2009

Angewandte Chemie

185

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Kräfte‐Sammelsurium: Supramolekulare Komplexe, wie der gezeigte, beruhen meist auf einer Kombination unterschiedlichster Wechselwirkungen, wie Ionenpaarbildung, Wasserstoffbrücken und Stapelwechselwirkungen. Die nicht immer einfache Charakterisierung von Natur und Stärke der intermolekularen Kräfte liefert Beiträge zum Verständnis biomimetischer Systeme wie auch zum Design von synthetischen Rezeptoren, Wirkstoffen und intelligenten Materialien. Die supramolekulare Chemie hat in den letzten Jahren eine enorme Ausdehnung erfahren, sowohl mit Blick auf mögliche Anwendungen wie auch auf analoge biologische Systeme. Bildung und Funktion supramolekularer Komplexe werden durch eine Vielzahl von oft schwer zu differenzierenden nichtkovalenten Kräften bestimmt. Ziel dieses Aufsatzes ist es, die entscheidenden Wechselwirkungsmechanismen zusammenhängend darzustellen und das Gesamtgebiet auf diese Weise zu klassifizieren. Als Beispiele werden meist organische Wirt‐Gast‐Komplexe gewählt, unter Berücksichtigung auch von biologisch relevanten Fragestellungen. Das Verständnis und die Quantifizierung der intermolekularen Wechselwirkungen ist für die rationale Planung neuer supramolekularer Systeme, einschließlich intelligenter Materialien, ebenso von Bedeutung wie für die Entwicklung neuer Wirkstoffe.

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“…Anion supramolecular chemistry involves the development and use of selective anion receptors. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] In fact, today a large number of coordination studies can be found in the literature describing a wide range of different ligands for anion coordination mainly involving hydrogen bonding, [15][16][17][18][19] electrostatic interactions [20][21][22][23][24][25][26][27] or coordination with suitable metal cations. [28][29][30][31][32][33] The nature of the binding sites and their specific spatial arrangement determine the binding constant with a certain anion and usually selective coordination can be found when a large host-guest complementarity is reached.…”

Section: -Introductionmentioning

confidence: 99%