bent molecular shape that strongly disturbs liquid crystallinity largely affecting the
macroscopic properties of the material upon light excitation as it will be shown
throughout this essay (Zhao and Ikeda 2009; Natansohn and Rochon 2002; Yu and
Ikeda 2011; Yu 2014; Priimagi et al. 2014).
Photochemistry of Azobenzene
The unsubstituted azobenzene molecule presents an absorption spectrum for the
trans isomer, characterized by an intense absorption band in the UV corresponding to
the π-πà transition and a less intense one in the visible region corresponding to the
n-πà transition (Fig. 2). Substitution of the azobenzene chromophores leads to
changes in the described absorption bands. Depending on the relative positions of
these bands, azobenzene chomophores are classified, according to Rau’s criteria, as
azobenzene type molecules, with the spectral properties that were just described,
Fig. 1 Photochromic compounds
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C. Sánchez-Somolinos
macroscopic properties of the material upon light excitation as it will be shown
throughout this essay (Zhao and Ikeda 2009; Natansohn and Rochon 2002; Yu and
Ikeda 2011; Yu 2014; Priimagi et al. 2014).
Photochemistry of Azobenzene
The unsubstituted azobenzene molecule presents an absorption spectrum for the
trans isomer, characterized by an intense absorption band in the UV corresponding to
the π-πà transition and a less intense one in the visible region corresponding to the
n-πà transition (Fig. 2). Substitution of the azobenzene chromophores leads to
changes in the described absorption bands. Depending on the relative positions of
these bands, azobenzene chomophores are classified, according to Rau’s criteria, as
azobenzene type molecules, with the spectral properties that were just described,
Fig. 1 Photochromic compounds
450
C. Sánchez-Somolinos