Supramolecular Assembly of 2,7-Dimethyldiazapyrenium and Cucurbituril: A New Fluorescent Host for Detection of Catechol and DopamineVladimir Sindelar, Mabel A. Cejas, Françisco M. Raymo, Weizhong Chen, Samantha E. Parker & Angel E. Kaifer
Abstract The formation of a highly stable inclusion complex between 2,7-dimethyldiazapyrenium (Me2DAP2+) and the cucurbituril host (CB8) was demonstrated by X-ray crystallography; MALDI-TOF mass...
Pronounced pH effects on the kinetics of cucurbituril-based pseudorotaxane formation and dissociationAngel E. Kaifer, Wei Li, Serena Silvi & Vladimir Sindelar
Deprotonation of the two terminal COOH groups on a 4,4′-bipyridinium linear derivative leads to a pronounced slow down on the kinetics of threading and unthreading by the cucurbituril host.
Organic flip-flop: Cucurbit[n]uril hosts (where n=7,8) and dipyridinium guests form stable inclusion complexes in which the central carboxyl function can be included inside the host cavity. The pseud...
Abstract Methods for the preparation of anion-free bambusuril (BU6) are presented. They are based on the oxidation of iodide anion, which is bound inside the macrocycle, utilizing dark oxidation...
Remarkable Salt Effect on Stability of Supramolecular Complex between Modified Cucurbituril and Methylviologen in Aqueous MediaMuhammad S. A. Khan, Dominik Heger, Marek Necas & Vladimir Sindelar
The supramolecular complex formed by partial inclusion of methylviologen in MeCB6 was described both in solution and in the solid state. The association constant of the complex was determined using 1H NMR and UV−vis spectrophotometric titration. An extraordinary 2000-fold drop in the association constant of the complex was observed when pure water was replaced by 50 mM NaCl solution.
Dataset for estimation of the biotic and climatic niche breadths and geographic range size of beech (Fagus) species worldwideQiong Cai, Erik Welk, Chengjun Ji, Wenjing Fang, Francesco Maria Sabatini, Jianxiao Zhu, Jiangling Zhu, Zhiyao Tang, Fabio Attorre, Juan Antonio Campos, Andraž Čarni, Milan Chytrý, Süleyman Çoban, Jürgen Dengler, Jiri Dolezal, Richard Field, József Pál Frink, Hamid Gholizadeh, Adrian Indreica, Ute Jandt, Dirk Nikolaus Karger, Jonathan Lenoir, Robert K. Peet, Remigiusz Pielech, Michele De Sanctis … & Helge Bruelheide
This dataset could be used to test whether the commonly observed positive range size–niche breadth relationship, as posited by the “niche breadth hypothesis”, exists for Fagus, one of the most dominant and widespread broad‐leaved deciduous tree genera in temperate forests of the Northern Hemisphere. There are many ways to estimate niche breadth. Here, we estimated biotic and climatic niche breadths per species using plot‐based co‐occurrence data and climate data, respectively. The range sizes of the...
Interaction between hunting strategy, habitat type and stratum drive intraguild predation and cannibalismRadek Michalko, Radek Michalko, Klaus Birkhofer & Stano Pekár
Intraguild predation (IGP) is a common interaction between generalist predators when they competitively exploit similar resources and prey on each other. Theoretical models predict limitations for intraguild predator coexistence unless some mechanisms, such as utilization of alternative prey (i.e., trophic niche partitioning) and cannibalism, increase the relative intraspecific clustering and interspecific segregation. As hunting strategies determine trophic niches of predators and their own vulnerability to predation, the hunting strategies may also determine the relative importance...
Forest understories play a vital role in ecosystem functioning and the provision of ecosystem services. However, the extent to which environmental conditions drive dominant ecological strategies in forest understories at the continental scale remains understudied. Here, we used ~29,500 forest vegetation plots sampled across Europe and classified into 25 forest types to explore the relative role of macroclimate, soil pH, and tree canopy cover in driving abundance-weighted patterns in the leaf economic spectrum (LES) and...
Bambusuril as a One-Electron Donor for Photoinduced Electron Transfer to Methyl Viologen in Mixed CrystalsVladimir Sindelar, Lucie Ludvíková, Michal Babiak, Petr Klán, Dominik Heger, Tomas Fiala, Jan Švec, Tomáš Slanina, L’ubica Vetráková, Marek Nečas & Petr Kulhánek
Methyl viologen hexafluorophosphate (MV2+·2PF6–) and dodecamethylbambusuril (BU6) form crystals in which the layers of viologen dications alternate with those of a 1:2 supramolecular complex of BU6 and PF6–. This arrangement allows for a one-electron reduction of MV2+ ions upon UV irradiation to form MV+• radical cations within the crystal structure with half-lives of several hours in air. The mechanism of this photoinduced electron transfer in the solid state and the origin of the long-lived charge-separated...
The interlocked bambusuril: Reactive hypervalent iodine species possessing dynamic covalent bonds are utilized in a constitutive sense for the near quantitative synthesis of rotaxanes via the stabili...
Cucurbituril (CB) with a substituent attached solely to one methylene bridge was prepared for the first time. The monosubstituted CB undergoes self-assembly to form a cyclic tetramer in the solid state. The affinity of the monosubstituted CB to a series of alkylammonium salts was measured revealing a minor effect of the substituent on the binding properties of the macrocycle.
Abstract Molecular clip 1 remains monomeric in water and engages in host–guest recognition processes with suitable guests. We report the Ka values for 32 1⋅guest complexes measured by 1H NMR, UV/Vi...
Propanediurea-Based Molecular Clips Bind Halide Anions: An Insight into the Mechanism of Cucurbituril FormationTomas Lizal, Lukas Ustrnul, Marek Necas & Vladimir Sindelar
The synthesis and supramolecular properties of the first methylene-bridged propanediurea-based dimers are described. These dimers, bearing an aromatic sidewall, have the shape of molecular clips. Unlike glycoluril-based dimers, these clips neither dimerize nor accept any organic guests, due to their small cavities. Both propanediurea- and glycoluril-based dimers bind halide anions on the convex side of the molecules, even in highly polar organic solvents. This observation brings new insights into the mechanism of cucurbituril formation.
Six- and seven-membered cucurbiturils form inclusion complexes with a lutidine derivative. These inclusion complexes differ in the binding mode, stability, kinetics of complexation, and sensitivity toward basic media.
Electrospray ionization mass spectrometry (ESI-MS) is used to probe the binding of small anions to the macrocycle of bambusuril. For the halide ions, the experimental patterns suggest F– < Cl– < Br– < I–, which is consistent with the order of anion binding found in the condensed phase. Parallel equilibrium studies in the condensed phase establish the association constants of halide anions and bambusuril in mixed solvents. A detailed analysis of the mass spectrometric data...
Abstract Neutral and negatively charged anion receptors functioning in pure water are rare in supramolecular chemistry. Moreover, studies on adjusting the affinity of such receptors toward anions i...
Driving forces of anion binding in water in contrast to nonpolar environments are of high interest because of their relevance to biology and medicine. Here we report a neutral bambusuril macrocycle (1), soluble in both water and nonpolar solvents due to decoration with 12 polyethylene glycol-based substituents. The new bambusuril has the highest affinity for I– in pure water ever reported for a synthetic macrocycle relying on hydrogen bonding interactions rather than metal coordination or...
Department of Physical and Technical Sciences11
University of Miami8
University of the Basque Country3
Central European Institute of Technology3
University of Vienna3
Martin Luther University Halle-Wittenberg3
University of Oviedo2
University of Picardie Jules Verne2