Cyclodextrins and Their Complexes

Abstract

The ability of cyclodextrins, CyDs, to form inclusion complexes with a wide variety of hydrophobic guest molecules has been used in agriculture. Their ability to alter the physical, chemical, and biological properties of guest molecules has been used for the preparation of new formulations of pesticides. CyDs form complexes with a wide variety of agricultural chemicals including herbicides, insecticides, fungicides, repellents, pheromones, and growth regulators [1,2].Each CyD has its own ability to form inclusion complexes with specific pesticides, depending on a proper fit of the pesticide molecule into the hydrophobic CyD cavity. The principal advantage is that the binding of pesticide molecules within the host molecule is not fixed or permanent but rather is a dynamic equilibrium. Dissociation of the inclusion complex is a relatively rapid process usually driven by a large increase in the number of water molecules in the surrounding environment [3]. aAQ16.3.1aSimilarly to CyD applications in the pharmaceutical (Chapters 14 and 15) and other industries, the most common benefits of CyD applications in agriculture include, among others, alterations of the solubility of the pesticide, stabilization against the effects of light or biochemical degradation, and a reduction of volatility. In some applications, more than one benefit is obtained by complexation with CyDs. However, the application of these hosts in pesticide formulations is very modest, and represents less than 1% of the CyD literature [4]. Moreover, most of these publications are not directly practice oriented. Instead they deal with the preparation of pesticides@CyD complexes using different oligosaccharides and processing methods and their characterization using a wide variety of techniques.Among these papers, some are more or less theoretical papers dealing with the correlation between the properties of the new complexes obtained and the properties of the CyDs, pesticides, or external parameters used. Viernstein et al.

Influence of intramolecular hydrogen bonds on the binding potential of methylated β-cyclodextrin derivatives

“…Cyclodextrins (CDs) are a well-known class of organic hosts able to include various guests, preferably in aqueous solution [1–3]. Inclusion is mainly driven by hydrophobic and van der Waals interactions [4–6].…”

Molecular solubilization of fullerene C60 in water by γ-cyclodextrin thioethers

“…CDs are cyclic oligosaccharides consisting of six, seven, eight or more glucose subunits connected through α-1,4 glycosidic linkages, called α-, β-, and γ-CD, respectively. CD molecules resemble truncated cones comprising a hydrophilic outer surface and a relatively hydrophobic cavity [23–25]. CDs form water-soluble inclusion complexes with many hydrophobic or amphiphilic guest molecules [26], mainly driven by hydrophobic interactions [27].…”

Optical Sensor for Real-Time Detection of Trichlorofluoromethane

“…Generally, cyclodextrin is a cyclic oligosaccharide typically containing six, seven or eight glucopyranose units linked by an α-1,4 glycosidic bond and is referred to as α-, β- and γ-cyclodextrin, respectively [38,39,40]. The interior of the toroid-shaped structures is hydrophobic while the exterior is hydrophilic.…”

“…The interior of the toroid-shaped structures is hydrophobic while the exterior is hydrophilic. Therefore, cyclodextrin can form non-covalent but solid host-guest complexes with hydrophobic molecules of suitable dimension [38,40,41,42]. Other characteristics such as viscosity, solubility, and ICF-selectivity can moreover be modified by sufficient substitution of the CyD’s hydroxyl groups [38,39,43].…”