Zum Fluoreszenzverhalten der isomeren Bis(acridiziniumyl)‐Dikationen

Abstract

Fluorescence Behaviour of the Isomeric Bis(acridizinium‐yl)Dications The fluorescence behaviour of the isomeric bis(acridizinium‐yl)dications is characterized by anomalies of the spectra. At room temperature the emission spectra of the 7,7′‐ and the 8,8′‐isomer show the typical characteristics of a TICT fluorescence band, they are strong red shifted and structureless. The emission wavelength shows the typical dependence on the solvent. At 77 K the expected spectra are obtained. The room temperature spectrum of the 9,9′‐isomer is the result of a plain emitting molecular state. The emission wavelength is only slightly red shifted. The solvent influences the molecular dynamics in the excited state. The differences in the deactivation behaviour of the isomers are caused by different energies of the Frank Condon singlet states.

Radiationless Transitions in Substituted Benzopyrylium Dyes: Competing Adiabatic Photoreactions Towards Nonradiative Funnels

“…the twisted donor groups D1, D 2 or D3 loose an electron and bear the whole positive charge of the ion, the rest of the molecule being neutralized. Other ionic dyes with TICT formation and charge localization are, e.g., triphenylmethane [14, 161, xanthene, rhodamine, oxazine [17, 181, pyrylium [9, 191, stilbazolium [20] dyes and certain doubly charged biaryl systems [21].…”

The benzo[b]quinolizinium ion as a water-soluble platform for the fluorimetric detection of biologically relevant analytes

“…84 In anthracene, both donor and acceptor group have to be introduced as exocyclic substituents (auxochromes) to constitute a push-pull system. But apart from functionalization at the meso positions (C9, C10) 78,85 the synthesis of such anthracene derivatives, especially with donor and acceptor functionalities in the lateral positions, is a rather elaborate project. [86][87][88][89][90] In contrast, the pyridinium unit within the benzo[b]quinolizinium already constitutes an intrinsic acceptor functionality, so that already the introduction of a single electron donating substituent in a "conjugated" position (i.e.…”

“…[77][78][79][80][81] In addition, a set of experimental 82 and computational 83 absorption data of quinolizinium derivatives was compiled. As a general trend, the benzo[b]quinolizinium (2a) absorbs and emits essentially in the same range as anthracene (1) (Figure 1) with an absorption maximum at 396 nm and an emission maximum at 407 nm in methanol, respectively.…”

Μελέτη Της Φωτοχημείας Και Της Φωτοεκκινητικής Ικανότητας Διχρωμοφορικών Αρωματικών Κετονών Σε Σύστημα Φωτοπολυμερισμού ΜΜΑ Τύπου ΙΙ

“…[319,[323][324][325][326][327][328][329][330] Σε άλλη περίπτωση επιχειρήθηκε η προσθήκη βρωμομεθυλενομάδας στα αρχικά υποστρώματα (ξανθένιο ή φλουορένιο). [331][332][333][334] αντίδραση 33: εναλλακτική συνθετική πορεία διβενζοϋλιωμένων προϊόντων Ο στόχος ήταν το διβρωμιωμένο παράγωγο να εισαχθεί σε βενζόλιο, με αντίδραση Friedel-Crafts και να οξειδωθεί τελικά προς τα επιθυμητά προϊόντα Η μεθοδολογία αυτή απέδωσε το επιθυμητό ενδιάμεσο προϊόν, μόνο στην περίπτωση του ξανθενίου, αλλά δεν προτιμήθηκε σε σχέση με την αρχική μεθοδολογία, καθώς λόγω του αριθμού των προσμίξεων, δεν υπήρξε αύξηση της απόδοσης της αντίδρασης.…”