Acyclic Congener of Cucurbituril: Synthesis and Recognition Properties.

Abstract

Multi-membered N-heterocycles R 0690Acyclic Congener of Cucurbituril: Synthesis and Recognition Properties. -The recognition properties of the acyclic congener (I) are similar to those of cucurbituril. It undergoes complexation with a range of alkaneammonium and alkanediammonium ions in water, it exhibits length-dependent selectivity, and is competitively bound by alkali metal cations in phosphate buffer. Its binding affinity is only 180-fold lower than that of cucurbituril. -(BURNETT, C. A.; WITT, D.; FETTINGER, J. C.; ISAACS*, L.; J. Org. Chem. 68 (2003) 16, 6184-6191; Dep. Chem. Biochem., Univ. Md.,

Encapsulation of alkyl and aryl derivatives of quaternary ammonium cations within cucurbit[n]uril (n = 6,7) and their inverted diastereomers: density functional investigations

“…The i x -CB[n] diastereomers (x=1 or 2; n=6-8) are found to be stable in gas phase and in different solvents. 1 H NMR patterns of isolated iCB [6] and iCB [7] from the density functional calculations agree well with experimentally measured NMR spectra [44]. Nonetheless, reports on complexation of i x -CB[n] hosts are scanty.…”

“…Furthermore the density functional optimizations based on M06-2X exchange-correlation functional [55] were carried out for the NMR spectra has further been analyzed [38,44]. It has been noticed that the lowest energy inclusion complexes of CB[n] or iCB[n] host reveals HDA in gauche conformation while XYL complexes of CB [6] and iCB [6] show (Fig. 2S of supporting information) one or both ammonium group(s) parallel to aromatic ring of guest.…”

“…A family of cucurbit[n]uril, CB [n], hosts comprising of methylene-bridged glycouril units have attracted considerable attention owing to their potential applications in organic synthesis [1][2][3][4], molecular recognition [5,6], nanoscience [7,8], catalysis [9][10][11], drug delivery vehicles [12] and separation technology [13,14]. The number of glycouril units in cucucrbituril homologues renders varying size to their hydrophobic cavity while portal carbonyl groups on portals provide hydrophilic exterior to these macrocycles.…”

“…Furthermore density functional theory have been successfully applied to characterize the electronic structure and spectral features of CB [n] homologues and modified CB[n] hosts [37][38][39][40][41][42][43][44]. It has been inferred that CB [6] or CB [7] allows binding of various guests of appropriate length and size [45][46][47].…”

“…It is known that the size-complementarities of the host cavity and the guest govern the host-guest binding. The dimensions of CB [6] cavity are comparable to those of para-substituted benzene ring, hence the CB [6] or modified CB [6] macrocycle efficiently encapsulates biologically important amines, para-xylyldiammonium (XYL) cation and quaternary ammonium ions. The interaction of these hosts and quaternary ammonium cations stem from hydrogen bonding.…”