Excimer-forming dye

These blends have been used for the fabrication of luminogenic mechanochromic thin films. Which films change their emission color upon deformation. The alkyl tails influence fhe solubilify of fhe chromophores in the polymer matrix and effect different aggregation properties. Thus, the mechanochromic fluorescence color change of the blends is related to the self-assembly of the excimer-forming dye in the unperturbed polymer matrix. 

The original idea to exploit excimer-forming dyes as mechanochromic transducers in polymers (as opposed to neat low-molecular-weight compounds) was inspired by the work of Trabesinger et al. [50] who showed that aggregated poly(phenylene ethynylene) guest molecules in a polymeric matrix could be dispersed by simple deformation of the material. This deformation transformed the material from a... 

Chemical Sensing with Excimer-Forming Dyes 133 5.5... 

Makrigiorgos, G. M. (1997) Detection of lipid peroxidation on erythrocytes using the excimer- forming property of a lipophilic BODIPY fluorescent dye. J. Biochem. Biophys. Methods 35(1), 23-35. 

Lott J, Weder C. Luminescent mechanochromic sensors based on poly(vinylidene fluoride) and excimer-forming /7-phenylene vinylene dyes. Macromol Chem Phys 2010 21 l(l) 28-34. 

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... 

Further modification of the above nanostructures is useful for obtaining new functional materials. Thirdly, we apply the dopant-induced laser ablation technique to site-selectively doped thin diblock copolymer films with spheres (sea-island), cylinders (hole-network), and wormlike structures on the nanoscale [19, 20]. When the dye-doped component parts are ablated away by laser light, the films are modified selectively. Concerning the laser ablation of diblock copolymer films, Lengl et al. carried out the excimer laser ablation of diblock copolymer monolayer films, forming spherical micelles loaded with an Au salt to obtain metallic Au nanodots [21]. They used the laser ablation to remove the polymer matrix. In our experiment, however, the laser ablation is used to remove one component of block copolymers. Thereby, we can expect to obtain new functional materials with novel nanostmctures. 

There are many possibilities to use these complex formations in fluorescence sensing. If the excimer is not formed, we observe emission of the monomer only, and upon its formation there appears characteristic emission of the excimer. We just need to make a sensor, in which its free and target-bound forms differ in the ability of reporter dye to form excimers and the fluorescence spectra will report on the sensing event. Since we will observe transition between two spectroscopic forms, the analyte binding will result in increase in intensity of one of the forms and decrease of the other form with the observation of isoemissive point [22]. 

Poly(methyl methacrylate) [PMMA] is an excellent polymer for studying photoresist dissolution because of its minimal swelling characteristic. For this work, PMMA molecules were labelled with phenanthrene (Phe) dye since its fluorescence is quenched by MEK. In addition, this dye has the advantage of forming few excimers (23-241 which results in self-quenching. Thus, the reduction in fluorescence intensity of PMMA-Phe is virtually solely due to MEK quenching. Consequently, the permeation of MEK into a PMMA film can be monitored from fluorescence intensity decay. 

When excited, the molecules of organic dyes tend to form complexes with unexcited molecules like themselves. These excited dimeric complexes are called the excimers. The excimer emission spectrum is easy to observe because it is very different from that of a monomer. It is usually broad and strongly shifted to longer wavelengths, and it does not contain vibrational structure. If the excimer is not formed, we observe emission of the monomer in the fluorescence spectra, and upon its formation there appears a characteristic emission of the excimer. 

---