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Fluorescent nanoparticles based on organic chromophores
Čekal, Josef ; Kratochvíl, Matouš (referee) ; Vala, Martin (advisor)
This study aims to create Host-Guest nanoparticle systems exhibiting white light emission (WLE) using organic molecules, achieved through Förster resonance energy transfer (FRET) mechanisms. Substituted stilbene-based compounds were utilized for the preparation of nanoparticle systems, with CA-DPS-V (H2) and CA-DPS-CHO (H1) used as donor/matrix materials, and CA-DPS-DCV (G1) and DPA-DXS-IOO (G2) as acceptor/dopant materials. Three nanoparticle systems were synthesized via nanoprecipitation from common solutions of the compounds in THF: system 1 (H1+G1), which did not achieve WLE, system 2 (H2+G1), and system 3 (H2+G2). Systems 2 and 3 were characterized using fluorescence spectroscopy and FRET parameter calculations. It was found that the Förster distance in system 2 is shorter than in system 3. This variation in Förster distance affects the composition ratios capable of WLE. The closest proximity to the white point (0.33, 0.33) was observed in system 2 at molar ratios of 110:1 (0.32, 0.38) and 164:1 (0.29, 0.32), and in system 3 at ratios of 340:1 (0.34, 0.30) and 476:1 (0.31, 0.28). Thus, the goal of the study was achieved, demonstrating that nanoparticles capable of WLE can be prepared in this manner. However, a drawback of the prepared nanoparticles was their low photostability. Future work could focus on synthesizing more stable nanoparticles from structurally similar compounds. These particles could then be further characterized in terms of structure and other properties for potential applications.
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Host-guest systems for efficient infrared solid-state emission
Rottenberg, Vojtěch ; Smolka, Rastislav (referee) ; Kratochvíl, Matouš (advisor)
The goal of this bachelor thesis is to compile a brief research on solid-phase fluorescence, to find suitable molecules for the preparation of host-guest systems that exhibit high quantum yields of solidphase fluorescence in the infrared region and to analyze them. These systems consist of a predominant molecule (host) that exhibits high quantum yields of fluorescence and a quantitatively less abundant molecule (guest) that exhibits fluorescence in the infrared part of the electromagnetic spectrum. The following molecules were chosen: (E)-N,N-diphenyl-4-(2-(5'-vinyl-[1,1':4',1''-terphenyl]-2'- yl)vinyl)aniline (–V) and (E)-5'-(4-(diphenylamino)styryl)-[1,1': 4',1''-terphenyl]-2'-carbonitrile (–CN) as a guest molecule and (E)-2-((5'-(4-(diphenylamino)styryl)-[1,1':4',1''-terphenyl]-2'- yl)methylene)malononitrile (–DCV) as a guest molecule. For sample analysis, emission and excitation spectra were measured using a fluorophore, quantum yields using an integrating sphere, and fluorescence lifetimes using the time-correlated single photon counting (TCSPC) method. From the spectral analyses and quantum yields, it was determined that the molecule (E)-5'-(4- (diphenylamino)styryl)-[1,1':4',1''-terphenyl]-2'-carbonitrile (–CN) is a suitable guest molecule, (E)-2- ((5'-(4-(diphenylamino)styryl)-[1,1': 4',1''-terphenyl]-2'-yl)methylene)malononitrile (–DCV) is not a suitable guest molecule and the suitability of using (E)-N,N-diphenyl-4-(2-(5'-vinyl-[1,1':4',1''- terphenyl]-2'-yl)vinyl)aniline (–V) as a guest molecule is inconclusive.
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