Self-assembly behavior of phenyl modified β-cyclodextrins

Abstract

The self-assembly behavior of mono(6-phenolic-6-deoxy)-β-cyclodextrin (1) both in solution and the solid state is comparatively studied by X-ray crystallography and 1 H NMR spectroscopy. The results obtained show that the phenolic groups in the crystal 1 can successively penetrate into the adjacent β-cyclodextrin cavities from the secondary side to form head-to-tail linear polymeric supramolecule with a 2-fold screw axis. The self-assembly behavior also can be determined in D 2 O solution, giving a self-association constant of 240 mol −1 ⋅L. Using the present and previous structures reported for the relevant β-cyclodextrin derivatives, i.e., mono(6-anilino-6-deoxy)-β-cyclodextrin (2), mono(6-phenylselenyl-6-deoxy)-β-cyclodextrin (3), and mono(6-phenylthio-6-deoxy)-β-cyclodextrin (4), we further reveal the factors governing the formations of supramolecular assemblies.Cyclodextrins(CDs), a cyclic oligosaccharide composed of 6, 7, or 8 α-1,4-linked D-glucopyranose units, are able to form supramolecular complexes with a wide range of guest molecules by the inclusion complexation within the hydrophobic cavities, and therefore have received much attention in the fields of molecular recognition and molecular assembly [1][2][3][4] . The conformations of many modified CDs have been carefully studied both in solution and the solid state, and most studies show that the formation of selfinclusion complexes or supramolecular assemblies mainly depend on the spatial size-fit and/or geometric complementarity between the substituents and CD cavities [5][6][7][8][9][10][11][12][13][14][15][16] . We have recently reported systematical studies on the binding behaviors of mono-modified β-CDs both in solution and the solid state. The obtained results indicated that the assembly modes of polymeric supramolecules might be gov erned through the precise control of structures and chemical properties of substituents [10] . In the present study, we wish to report the self-assembly behavior of mono(6-phenolic-6-deoxy)-β-cyclodextrin (1) both in solution and the solid state by means of X-ray crystallography and 1 H NMR. Using the present and previous structures reported for the relevant β-CD derivatives (Fig. 1), i.e., mono(6-anilino-6-deoxy)-β-CD (2) [11] , mono(6-phenylselenyl-6-deoxy)-β-CD (3) [10] , and mono(6-phenylthio-6-deoxy)-β-CD (4) [16] , the factors governing the formations of supramolecular assemblies are further discussed. It is of our particular interest to investigate how the slight difference of pivot heteroatoms, through which the aromatic substituent is tethered to β-CD, affects the binding behavior of modified β-CDs with phenyl substituents both in solution and the solid state.

Synthesis of phenyl-adducted cyclodextrin through the click reaction

“…In particular, we are interested in derivatizing it in order to produce more customized properties. Previously only one earlier report has appeared on phenyl-modified CD (Zhao & Liu, 2006). We have now shown that the click reaction (e.g., Rostovtsev, Green, Fokin, & Sharpless, 2002;Tornøe, Christensen, & Meldal, 2002;Wu & Fokin, 2007) is an alternative (and convenient) method to place a phenyl derivative on CD.…”

“…It is clear that there is a slight shift upfield for the H-5 peaks. It is well known that such upfield shift is characteristic of the formation of an inclusion compound (e.g., Bilensoy, Vural, Bochot, Renoir, Duchene et al, 2005;Jiang et al, 2007;Zhao, Yang, Hu, & Ma, 2003). Since the phenyl group is hydrophobic, it is not surprising that it gets inserted in the CD cavity.…”

Superstructures of Double Functionalized Host–Guest Acrylmonomers Containing Chiral Phenylalanine-click-cyclodextrin and Polymers

“…13,14 For example Harada et al reported about the formation of supramolecular helical polymers, recently. 15 The self-assembly behavior of phenyl modified β-cyclodextrins has been investigated by Liu et al 16 Also self-assembly of gels through shape selective molecular recognition with CD for linear and cyclic guest molecules was investigated on a macroscopic scale very recently. 17 Furthermore there have been few works dealing with self-assembly of chiral compounds.…”

“…Scientist have been inspired by nature and have investigated various systems mimicking biomolecules by synthetic supramolecular structures with interesting properties and functions. − Superstructures formed by hydrogen bonds were reported for the first time by Lehn et al Many contributions about the formation of supramolecular polymers formed by hydrogen bonding can be found in literature. − However there have been few works dealing with the self-assembly into supramolecular polymeric structures via host–guest interaction. , For example Harada et al reported about the formation of supramolecular helical polymers, recently . The self-assembly behavior of phenyl modified β-cyclodextrins has been investigated by Liu et al…”

Different self-assembly behaviors of mono-modified β-cyclodextrin substituted by benzoic acid derivatives

“…Currently, most investigations of the self-assembly behavior are to establish control over the preparation of self-assemblies so that their architectures and properties are, at least to some extent, predictable. Thus researchers aim to produce controllable self-assembly by using the wide range of possible intermolecular interactions [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]. Some of these approaches are producing more predictable results.…”