Color Switching

FIGURE 4.28. Dichroism of solutions of tetracene and bismerocyanine dye in liquid crystalline mixture of cyanophenyl esters (d = 200 / m, T = 20 C) [176]. 

A combination of two dyes (with positive and negative dichroism) has been used [177] for color switching in the guest-host effect. The degree of dye order was 5dye = 0.677 and 0.754 for anthraquinone D /D 1) and tetrazine (T) /D ) dyes, respectively. High values of color contrast were thus achieved on electrooptical switching. 

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Jonas U, Shah K, Norvez S, Charych DH. Reversible color switching and unusual solution polymerization of hydrazide-modified diacetylene hpids. J Am Chem Soc 1999 121 4580-4588. 

The electrochromism of PPy is unlikely to be exploited, mainly due to the degradation of the film on repetitive color switching. 

Recommendation 3. Redesign and relocate crane control devices to one central location on the panel. Eliminate the use of similar dials or pushbuttons as much as the design will permit. Figure 8.3 shows a suggested new layout. In addition, different color switches can be used for critical functions such as crane stop (suggesting a red switch) and crane start (suggesting a green switch). 

Uhlenhaut, D. L Smith, P. Caseri, W., Color Switching in Gold-PolysUoxane Elastomeric Nanocomposites. Adv. Mater. 2006,18,1653-1656. 

Whitesides, GM, Nanoscience, nanotechnology, and chemistry. Small 1 (2005) 172-179. White, SS, Ying, LM, Balasubramanian, S, and Klenerman, D, Individual molecules of dye-labeled DNA act as a reversible two-color switch upon application of an electric field. Angewandte Chemie-InternationalEdition 43 (2004) 5926-5930. 

Kishimura, A. Yamashita, T. Aida, T. Phosphorescent organogels via metallophilic interactions for reversible RGB-color switching. J. Am. Chem. Soc. 2005,127, 179-183. 

Oxidative Eiectropoiymerization of Poiypyridyi Compiexes. Oxidative electropolymerization of suitably substituted [M (bipy)3l + complexes offers an alternative approach to the preparation of electrochromic redox active polymer films. Oxidative eiectropoiymerization has been described for iron(II) and ruthenium(II) complexes containing amino-substituted (31) and pendant aniline-substituted (32) 2,2 -bipyridyl ligands, and amino- and hydroxy-substituted 2,2 6, 2"-terpyridinyl ligands (33) [ligand structures (4) and (5)]. Analysis of IR spectra suggests that the eiectropoiymerization of [Ru(L )2l + [L = (4)], via the pendant aminophenyl substituent, proceeds by a reaction mechanism similar to that of aniline (33). The resulting metallopolymer film reversibly switches from purple to pale pink on oxidation of Fe(II) to Fe(III). For polymeric films formed from [Ru(L )2l + [L = (5)], via polymerization of the pendant hydroxyphenyl group, the color switch is from brown to dark yellow (see Electropolymerization). 

Prom the point of view of the application the electrooptical effect in blue phases may become of interest for relatively low-voltage and relatively fast light modulators [101]. A beautiful color switching in the submillisecond range has been demonstrated on blue phases in [102]. 

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