Influence of Photochromism on Molecular Hyperpolarizabilities

Molecular hyperpolarizabilities of the two isomers of different photochromes are presented in Tables 10.1 and 10.2. As Disperse Red 1 (DRl) is probably the most studied photochrome due to its very interesting NLO properties in polymers, its nonlinear coefficients have also been tabulated. The spiropy-ran/photomerocyanine group has also been investigated in detail in polymers and in solutions as well, and the NLO properties have been described already.More recently, Atassi et al. have shown that it was possible to observe NLO response with a furylfulgide system, and Lehn et al. have shown that some diarylethene compounds can photochemically switch between a low and a high level of NLO response. The first two systems are 

JACQUES A. DELAIRE. ELENA ISHOW AND KEITARO NAK4TAN  

TABLE 10.1 Dipole moinents ) and first hyperpolarizabilities of photochromes 

TABLE 10.2 Dithienylethene derivatives studied for their NLO properties. Conversion ratio under steady-state iiiumination of OF in dtoxan, and products of hyperpoiarisabiiities times dipoie moments of both OF and CF measured at 1.907 jjim in dioxan (from reference 45) 

Recently, another photochromic system based on nitrobenzyl pyridine (NBP) derivatives has been proposed for its potential in switching the second 

---