Efekt protonace na dynamiku excitovaného stavu pyrimidinových chromoforů

The effect of protonation on the photophysics and especially on the excited state dynamics of two pyrimidine chromophores, bearing the A-(pi-D)(2) and A-(pi-D)(3) structure, is studied by means of fs-ps and ns time resolved fluorescence spectroscopy. Three different acids, namely camphorsulphonic (CSA), acetic (AcOH) and trifluoroacetic acid (TFA) were used. The chromophores bear the pyrimidine electron deficient heterocycle as electron-withdrawing group, used as protonation site, as well as diphenylamino electron donors. Protonation is revealed through the emergence of red-shifted absorption and fluorescence bands accompanied by a quenching of the fluorescence of the neutral molecules. Time-resolved dynamics reveal that protonation with CSA and TFA do not influence the excited state lifetime of the chromophores, pointing to a static quenching process. On the other hand, the lifetime is decreased upon protonation with AcOH. Further investigation based on the Stern-Vollmer plots showed that addition of AcOH leads to both dynamic and static quenching.Byl studován efekt protonace na fotofyziku dvou pyrimidinových chromoforů prostřednictvím fluorescenční spektroskopie. Byly využity tři kyseliny, kafrsulfonová, octová a trifluoroctová

Fotofyzikální vlastnosti 9,9-dimethylakridanem substituovaných fenylstyrylpyrimidinů – charakteristiky dlouhotrvající intramolekulární charge-transfer fluorescence a agregací indukované emise

Six pyrimidine-based push-pull systems substituted at positions C2 and C4/6 with phenylacridan and styryl moieties, employing methoxy or N,N-diphenylamino donors, have been designed and synthesized through cross-coupling and Knoevenagel reactions. X-ray analysis confirmed that the molecular structure featured the acridan moiety arranged perpendicularly to the residual pi system. Photophysical studies revealed significant differences between the methoxy and N,N-diphenylamino chromophores. Solvatochromic studies revealed that the methoxy derivatives showed dual emission in polar solvents. Time-resolved spectroscopy revealed that the higher energy band involved very fast (<80 ps) fluorescence, whereas the lower energy one included long components (approximate to 30 ns) due to long-lived intramolecular charge-transfer fluorescence. In contrast to N,N-diphenylamino chromophores, the methoxy derivatives also showed aggregation-induced emission in mixtures of THF/water, as well as dual emission in thin films, covering almost the whole visible spectrum with corresponding chromaticity coordinates not far from that of pure white light. These properties render the methoxy derivatives as very promising organic materials for white organic light-emitting diodes.Cross-couplingovými reakcemi a Knoevenagelovou kondenzací bylo připraveno šest push-pull molekul na bázi pyrimidinu substituovaných v polohách C2 a C4/6 fenylakridanem a styrenovými fragmenty, dekorované methoxy nebo N,N-difenylamino substituenty jako donory. X-ray analýzy potvrdily strukturu látek, akridanová část je orientována kolmo ke zbývajícími pi-systému. Fotofyzikální studie potvrdily významné rozdíly mezi methoxy s N,N-difenylamino chromofory. Při solvatochromních studiích vykazovaly methoxy deriváty duální emisi v polárních rozpouštědlech

Overview of people localization systems for safe evacuation of large passenger ships

Maritime disasters in recent years are a stark reminder of the imperative need for timely and effective evacuation of large passenger ships during emergency. Tragedies at sea, notably the 2014 South Korean ferry Sewol and the 2012 Costa Concordia incidents, have magnified the urgent need for improvements in the mustering, evacuation, and abandoning procedures, and have led to a series of new global safety initiatives and measures. Driven by this need, several technologies and systems for people localization have been considered, studied and demonstrated over the past decade, which would enable tracking of passengers and crew either on-board, in case of an emergency in order to improve mustering, evacuation, and abandoning procedures, or overboard, after ship abandoning. In this work, we present an overview of these initiatives, evaluating various aspects of such systems, their advantages and disadvantages. Key factors that are considered in our study have been retrieved after extensive analysis of end-user data, acquired over the past three years in the framework of the Lynceus2Market EU funded project (H2020), which has brought together European global players in the field aiming at implementing the first market replication of these technologies and products