Cyano-OPVs

Fig. 3 (a) Examples of molecular structures of cyano-OPVs. (b, c) Images of Cl-YB (b) and Cl-RG (c) recorded under excitation with ultraviolet light in chloroform (left) and in the crystalline state (right), (b, c) reprinted with permission from [36]. Copyright 2003 American Chemical Society... 

Although the property of interest in all of the above-mentioned cyano-OPV-containing materials was a mechanically induced change of the photoluminescence color (i.e., a mechanically induced transformation from an excimer-rich to a monomer-dominated emission), certain cyano-OPVs also display a changed of their absorption color upon (dis)assembly. Thus, Kunzelman et al. reported mechanochromic blend films based on C18-RG and either poly(ethylene... 

Beyond cyano-OPVs, several other dyes that form excimers in their aggregated state have also been used for mechanosensing purposes. Pucci and coworkers have reported that poly(propylene) (PP) films containing bis(benzoxazolyl)stilbene (BBS) (Fig. 9a) change photoluminescence color upon tensile deformation [50]. In the as-prepared state, the emission spectrum (Fig. 9b) shows a broad excimer emission band around 500 nm, along with sharper monomer emission bands at 410, 430, and 455 nm. Mechanical deformation lowers the intensity of the excimer band, resulting in a photoluminescence color change (Fig. 9c). 

Scheme 11.3 Chemical structures of various cyano-OPVs l,4-bis(aKyano-4-metho3y-styiyl)-2,5-dimetho3g4)en2ene (BCMDB), l,4-bis(a-cyano -metho>ystyiyl)-benzene fBCMBl and l,4-bisfa-

Blends of cyano-OPVs and amorphous polymers (PMMA and poly(bisphenol A carbonate)) were also produced by melt-processing and rapid quenching. ... 

Figure 5.2 (a) Chemical structures of some of the cyano-OPVs investigated as sensor molecules [24, 35, 36]. 

Many members of the family of cyano-OPVs form excimers due to the specific packing of the planarized molecules in a cofacial arrangement (Figure 5.3) [37]. 

Another interesting example for the use of real-time temperature sensors based on excimer-forming is a multifunctional shape-memory polymer (SMP) with built-in temperature sensing capabilities (Figure 5.13) [66]. This material was prepared by incorporating a fluorescent, chromogenic cyano-OPV dye into a... 

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