Search results for "resorcinarene"
showing 10 items of 166 documents
Hierarchical Ordering in Ternary Co-Crystals of C60, N-Benzyl Ammonium Resorcinarene Bromide and Solvent Molecules
2014
Co-crystallization of C60 together with an N-benzyl ammonium resorcinarene bromide from toluene:1,2-dichloroethane mixture results in ternary co-crystals where the modulated C60 lattice entraps dimeric resorcinarene assemblies, which, in turn, have 149 and 280 A3 cavities filled with 1,2-dichloroethane molecules.
Methylresorcinarene: a reaction vessel to control the coordination geometry of copper(II) in pyridine N-oxide copper(II) complexes
2015
Pyridine and 2-picolinic acid N-oxides form 2 : 2 and 2 : 1 ligand : metal (L : M) discrete L2M2 and polymeric complexes with CuCl2 and Cu(NO3)2, respectively, with copper(ii) salts. The N-oxides also form 1 : 1 host-guest complexes with methylresorcinarene. In combination, the three components form a unique 2 : 2 : 1 host-ligand-metal complex. The methylresorcinarene acts as a reaction vessel/protecting group to control the coordination of copper(ii) from cis-see-saw to trans-square planar, and from octahedral to square planar coordination geometry. These processes were studied in solution and in the solid state via(1)H NMR spectroscopy and single crystal X-ray diffraction.
Solvent driven formation of silver embedded resorcinarene nanorods
2012
Silver complexes of resorcinarene bis-crown-5 were observed to arrange into nanorods of 2.4 nm in diameter. The left- and right-handed isomers of the inherently chiral resorcinarene host are separated into their own entity in the self-assembly process with the periphery of the nanorods consisting of silver cations included in the cavity.
Size- and Structure-Selective Noncovalent Recognition of Saccharides by Tetraethyl and Tetraphenyl Resorcinarenes in the Gas Phase
2008
The noncovalent complexation of tetraethyl and tetraphenyl resorcinarenes with mono-, di-, and oligosaccharides was studied with negative-polarization electrospray ionization quadrupole ion trap and electrospray ionization Fourier-transform ion cyclotron resonance mass-spectrometric analysis. The saccharides formed 1:1 complexes with deprotonated resorcinarenes, which exhibited clear size and structure selectivity in their complexation. In the case of the monosaccharides, hexoses formed much more abundant and kinetically stable complexes than pentoses or deoxyhexoses. A comparison of the mono-, di-, and oligosaccharides revealed that both the relative abundance and stability of the complexe…
Piperazine bridged resorcinarene cages.
2010
The one-pot Mannich condensation of resorcinarenes with piperazine and an excess of formaldehyde under high dilution conditions results in a helical cage, namely, a covalently linked dimer of two resorcinarenes connected via four piperazine bridges in yields ranging from 20 to 40%. The compounds were analyzed by NMR spectroscopy, ESI mass spectrometry, and single crystal X-ray diffraction. The helical cages can encapsulate small guest molecules by adapting the cavity volume by changing the helical pitch according to the guest size.
Synthesis and structure of mono-bridged resorcinarene host: a ditopic receptor for ammonium guests.
2009
The synthesis and structural properties of tetramethoxy resorcinarene mono-crown-5 (1) are described. The binding characteristics of 1 toward acetylcholine and tetramethylammonium salts were investigated by 1H NMR titration. It was observed that the cavity of 1 provides a better fit to acetylcholine compared to the smaller tetramethylammonium cation, as acetylcholine is able to interact with both the crown ether moiety and the free hydroxyl groups of receptor 1 simultaneously.
Ion-Pair Recognition of Tetramethylammonium Salts by Halogenated Resorcinarenes
2011
The non-covalent interactions of different upper-rim-substituted C(2)-resorcinarenes with tetramethylammonium salts were analyzed in the gas phase in an Electrospray Ionization Fourier-transform ion-cyclotron-resonance (ESI-FTICR) mass spectrometer and by (1)H NMR titrations. The order of binding strengths of the hosts towards the tetramethylammonium cation in the gas phase reflects the electronic nature of the substituents on the upper rim of the resorcinarene. In solution, however, a different trend with particularly high binding constants for halogenated resorcinarenes has been observed. This trend can be explained by a synergetic effect originating from the interaction of the halogenate…
The Recognition of Viologen Derivatives in Water by N-Alkyl Ammonium Resorcinarene Chlorides
2017
Three water-soluble N-alkyl ammonium resorcinarene chlorides decorated with terminal hydroxyl groups at the lower rims were synthesized and characterized. The receptors were decorated at the upper rim with either terminal hydroxyl, rigid cyclohexyl, or flexible benzyl groups. The binding affinities of these receptors toward three viologen derivatives, two of which possess an acetylmethyl group attached to one of the pyridine nitrogens, in water were investigated via 1H NMR spectroscopy, fluorescence spectroscopy, and isothermal titration calorimetry (ITC). ITC quantification of the binding process gave association constants of up to 103 M-1. Analyses reveal a spontaneous binding process whi…
Conformational changes in Cmethyl-resorcinarene pyridine N -oxide inclusion complexes in the solid state
2016
Aromatic N-oxides interact with Cmethyl-resorcinarene resulting in marked changes in the conformation of the host resorcinarene. In the solid state, 2- and 3-methylpyridine N-oxides form pseudo-capsular 2 : 2 endo host-guest complexes with Cmethyl-resorcinarene stabilized by C-H⋯π interactions. The Cmethyl-resorcinarene·2-methylpyridine N-oxide complex has a C4v crown conformation, while the Cmethyl-resorcinarene·3-methylpyridine N-oxide complex has a slightly open C2v boat conformation. On the contrary, other para-substituted and benzo-fused pyridine N-oxides form only exo complexes with Cmethyl-resorcinarene. In the exo complexes, the asymmetry of the guest, conformational flexibility and…
N-Alkyl Ammonium Resorcinarene Salts as High-Affinity Tetravalent Chloride Receptors.
2016
N-Alkyl ammonium resorcinarene salts (NARYs, Y=triflate, picrate, nitrate, trifluoroacetates and NARBr) as tetravalent receptors, are shown to have a strong affinity for chlorides. The high affinity for chlorides was confirmed from a multitude of exchange experiments in solution (NMR and UV/Vis), gas phase (mass spectrometry), and solid-state (X-ray crystallography). A new tetra-iodide resorcinarene salt (NARI) was isolated and fully characterized from exchange experiments in the solid-state. Competition experiments with a known monovalent bis-urea receptor (5) with strong affinity for chloride, reveals these receptors to have a much higher affinity for the first two chlorides, a similar af…