Azobenzene-based photochromic structures

Blair et al. [9] have carried out film balance measurements on monolayers of photochromic polymers (4) and (5). Figure 7 shows an example of the pressure-area curve for Structure (4). A significant reduction in area per monomer unit was observed on changing from dark to light conditions this was interpreted as being the result of trans-io-cis isomerization of azobenzene chromophores the more extended conformation of the fr 5-isomer would produce a large apparent area. The difference between the pressure-area curves of the meta- and /jaro-polyamide was interpreted based on the assumption that the mcto-azo-polymer chain may have a helical structure, whereas the /jara-azo-polymer has a linear structure. 

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