Fluorescence small molecule materials

During the last two decades, there has been an enormous increase in the use of photophysical methods in supra-molecular chemistry. Until recently, photophysical methods, such as transient spectrometry and time-resolved fluorescence spectrometry, were primarily research tools in the arenas of photokinetics of small molecules, materials physics, and biophysics. This situation changed dramatically with the introduction of commercial, user-friendly electro-optical components such as charge-coupled detector (ED)-based spectrometers, solid-state pulsed lasers, and other instrumentation necessary for time-resolved measurements. As a result, time-resolved spectrometry became more available to the community of supramolecular chemists, who now reached the level of sophistication that can benefit from the new horizons offered. 

Xue, S.,Yao, L., Shen, E, Gu, C., Wu, H., Ma,Y, 2012. Highly efficient and fully solution-processed white electroluminescence based on fluorescent small molecules and a polar conjugated polymer as the electron-injection material. Adv. Funct. Mater. 22,1092-1097. 

SMOLEDs contain small-molecule emissive materials that can be processed by either vacuum deposition (evaporative) techniques or solution coating. The emissive small molecule may be a fluorescent (singlet excited state) or a phosphorescent (triplet excited state) emitter. 

The phenomenon of organic EL was first demonstrated using a small-molecule fluorescent emitter in a vapor-deposited OLED device. The Kodak group first used metal oxinoid materials such as the octahedral complex aluminum tris-8-hydroxyquinoline (Alq3) (discussed above as an ETM) as the fluorescent green emitter in their pioneering work on OLED architectures [167],... 

So, what s next Of course, research on all fronts will advance, with the approaches in Sect. 4 receiving perhaps the highest attention. The rapid development of nanoscopic and nanostructured materials has specially opened the path to sophisticated sensing ensembles Sousa and Vogtle would not even have dreamed about [228, 229]. However, for many applications, small molecules as reporters are indispensible, simply because of their size and the possibilities of interaction at the molecular level so that their future exploration is also essential. Finally, since technology will advance, new instrumental techniques and possibilities will appear and automatically fuel research on powerful fluorescent reporters. 

The photochemistry of small molecule LC materials has been an active area of research for many years and has been reviewed recently [9]. The photochemistry of LC polymers, per se, has received much less attention although two brief reviews have appeared [5,10], and there has been a considerable effort to apply some simple photochemical transformations such as trans-cis photoisomerization, to the development of practical devices [1-6]. This section is divided into three parts. In Part A, chromophore aggregation, which seems to be important in almost all the cases in which careful UV-Vis and/or fluorescence studies of films of pure LC polymers have been made, is explicitly discussed. Part B is devoted to a thorough review, organized by chromophore type, of the photochemistry and related photophysics of LC polymers. No attempt has been made to extensively cross-reference the work on LC polymers to the hundreds of papers and reviews on analogous non-LC compounds. However, when it seemed particularly appropriate or interesting, experiments related to optical applications of the photochemistry of LC polymers are briefly described. In Part C, a few experiments are described in which a classical photophysical method, fluorescence spectroscopy, is used to probe the microstructures of some LC polymers. 

Summary A synthetic route to highly fluorescent organic semiconductors with rigid connections to curable alkoxysilanes is described. The title compounds are prepared via Heck reactions of monodisperse bromo-OPVs with allyl-alkoxysilanes. A combined extension of the Jt-system and coimection with alkoxysilanes is possible when an alkoxysilyl-styrene is used as a substrate. Hydrolysis and condensation of alkoxysilanes yields linear and cyclic oligo-OPV-siloxanes or three-dimensional networks, thus allowing the transformation of small molecules into luminescent materials with well-defined chromophores. 

Three classes of polymers are amenable to study by fluorescence techniques. The first class of materials is that consisting of extrinsic fluorescent molecules incorporated into the polymer solution. This class has applications in the study of solubilization of small molecules in block copolymer micelle cores (6) but is not of interest for configurational studies such as the present work. 

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