Organic phase-change switch

Organic compounds which show reversible color change by a photochemical reaction are potentially applicable to optical switching and/or memory materials. Azobenzenes and its derivatives are one of the most suitable candidates of photochemical switching molecular devices because of their well characterized photochromic behavior attributed to trans-cis photoisomerization reaction. Many works on photochromism of azobenzenes in monolayers LB films, and bilayer membranes, have been reported. Photochemical isomerization reaction of the azobenzene chromophore is well known to trigger phase transitions of liquid crystals [29-31]. Recently we have found the isothermal phase transition from the state VI to the state I of the cast film of CgAzoCioN+ Br induced by photoirradiation [32]. 

Enantiomeric forms of proteins are not accessible so that a conceptual reversal of the elution order by switching to the enantiomeric CSP is not feasible. However, in some special ca.ses, the elution order can be influenced by the mobile phase conditions. For example, on an ovomucoid CSP a reversal in elution order of the enantiomers of the ketal tosylate intermediate of azalanstat was observed when the organic modifier was changed from ethanol to acetonitrile. This unusual effect has been attributed to a change in binding domains or recognition sites on the ovomucoid protein as a function of the organic modifier of the mobile phase [ 149. ... 

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