Guest complexes vitamins

Abstract. The inclusion behavior of the octopus cyclophane constructed with a rigid macrocyclic skeleton and eight hydrocarbon chains was studied in aqueous media by means of fluorescence and electronic absorption spectroscopy. Both hydrophobic and electrostatic interactions came into effect in the host-guest complexation process. The cyclophane acted as an effective apoenzyme model for constitution of an artificial vitamin B -dependent holoenzyme by simultaneous incorporation of pyridoxal-5 -phos-phate and a hydrophobic alkylammonium substrate into the host cavity to give the Schiff-base species, showing the substrate selectivity. 

A 1 2 (guest CD) complex may be formed when the guest molecule is too large to Lnd complete accommodation in one cavity and its other end is also amenable to complex formation. Some examples are the complexesfbCD with prostaglandins, vitamin and indomethacin (IM). 

The central cavity of the cylinder-shaped cyclodextrins behaves as an empty capsule It can accommodate so-called guest molecules of appropriate size, shape, and polarity. This "molecular encapsulation" can be utilized for stabilization and for enhancement of solubility of drugs, vitamins, flavors, etc., and utilizing the selectivity of the inclusion complexation, it can be applied for separation of substances, either by non-chromatographic methods, or chromatographic methods. 

Relatively small guest molecules sometimes show surprisingly unfavourable stoichiometry, E.g. vitamin (menadione, 2-methyl-naphtoquinone) needs 3 POD molecules to form a stable, crystalline complex (24),... 

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