Cyclodextrin tubular polymers

Harada, A., Li, J., and Kamachi, M. (1993). Synthesis of a tubular polymer from threaded cyclodextrins. Nature (London) 364 516-518. 

Several other stationary phases made from different proportions of typical phases (methyl, phenyl, cyanopropyl), or from special compounds such as polytrifluropropyl-siloxane, or different columns such as PLOT (porous layer open tubular), columns coated with a modified graphitized carbon or with a silicone based polymer with chiral groups incorporated into the polymeric chain, columns coated with derivatized cyclodextrins (for the separation of chiral compounds), etc. are also utilized. 

Catalytically active supported ionic liquid membranes were used for propylene/propane vapor mixture separation. In this case, the ionic Hquid was immobilized in the pores of an asymmetric ceramic support, displaying sufficient permeability, good selectivity, and long-term stabUity [51]. Porous inorganic membranes were also used as a support for chiral-selective liquid membranes. For this purpose, porous tubular ceramic membranes were impregnated with 3-cyclodextrin polymer. Such SLMs were used for separation of enantiomers of racemic pharmaceutical chlorthahdone [52]. 

Today, there are a number of effective chiral stationary phases suitable for GC, some based on amino acid derivatives, some on polysiloxane polymers and some, probably the more popular, based on cyclodextrin derivatives. Very few chiral columns, if any, are packed, the vast majority being open tubular columns having various lengths and an I.D. that ranges from about 250 pm or 320 pm There has, however, been a recent trend to smaller diameter columns cf. 125 pm) to achieve higher efficiencies and even shorter analysis times. 

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