Hemicyanine, structure

Fig. 2 Examples of the structures of a few fast-response electric filed sensitive dyes N-(4-sulpho-butyl)-4-(4-(4-(dipentylamino)phenyl)butadienyl)pyridinium inner salt (RH421, a styrylpyridinium dye), ANNINE 5 (an annellated hemicyanine dye), merocyanine 540, and N-[(4 -dimethylamino)-3-hydroxy-6-flavonyl mcthyl-N,N-trimcthyl ammonium (F4N1, a 3-hydroxychromone dye)...

Hemicyanine dyes, 9 257 Hemihedrite, 6 471t Hemiisotactic micro structures, 16 108 4,6-Hemiketals, 24 595 Hemimicelle formation, 24 142 Hemins, 14 552... 

The hemicyanine dyes can be represented by structure (5). They may be considered as cyanines in which a benzene ring has been inserted into the conjugated chain. Hemicyanines provide some bright fluorescent red dyes for polyacrylonitrile. 

In contrast to this case, EL spectra presented in Fig. 130 demonstrate the importance of local environment for the energy of excited states. They have been obtained for a multi-component molecular structure comprising of a Nd3+ cation surrounded by four negatively charged pyrazolone ligands. The structure has a permanent dipole moment associated with the hemicyanine unit and this is expected to be enhanced by the rare-earth-containing anion [512]. The... 

Structures 4.1a and 4.1b. These two molecules, one (a) a hemicyanine and the other (b) a nitrostilbene dye can be used to form an organic superlattice displaying a high coefficient for second harmonic generation (see reference 50). 

One can compare the above with another polyurethane preparation where a structure with a hemicyanine dye is attached as a pendant gronp. Following preparation procedure was used ... 

Moreover, there were other reports on the electrospun PI composite Qin et al. reported the fluorescent performance of electrospun PI web mixed with hemicyanine dye (Figure 9), pointed out that the nano fiber structure were helpful to the fluorescence (Qin et al., 2009) Cheng et al. reported the preparation of nonwoven Pl/silica hybrid fabrics by combining electrospinning and controlled in situ sol-gel techniques, their product had better mechanical and thermal properties than ordinary PI electrospun fabrics (Cheng et al., 2009). 

One of the disadvantages of guest-host systems is that usually the LB multilayers deposit in the Y-type centrosymmetric mode, rendering the structure nlo-inactive. By using a second material, which may be either optically active or passive, to form ABAB-type multilayers, non-centro-symmetric films can be produced. Good Y-type deposition has been achieved with the polyethers (64) and (65), to produce four AB layers exhibiting the expected quadratic dependence of second-order nlo response with film thickness [85]. These materials use the hemicyanine-based unit as the pendant side-group, with opposite dipole orientation in the two structures to achieve an additive effect in Y-type LB multilayers. 

As the alternate layer system has a non-centrosym-metric structure, a non-linear optical (NLO) effect may be expected. Several attempts to obtain the NLO effect in alternate LB films of CT complexes have been reported [183-185]. The remarkable feature of this system is that the NLO effect arises from intermole-cular interaction between donor and acceptor fabricated in LB multilayers with a high degree of orientational order. A second harmonic generation of a bilayer of octadecylthiobenzoquinone (acceptor) and 7-(A-octa-decylaminomethyl)-8,16-dioxadibenzo[, g]pyrene (Figure 14.25) was roughly 1/400 of that of a monolayer of a hemicyanine derivative. 

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