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1999 | 95 | 3 | 321-334
Article title

Fluorescence Properties of An Electron Acceptor Substituted Bis-Pyrazolo-Pyridine Derivative: NO_{2}-DMPP

Content
Title variants
Languages of publication
EN
Abstracts
EN
The fluorescence properties of 3,5-dimethyl-1,7-diphenyl-4 -(4'-nitro-phenyl)-bis-pyrazolo-[3,4-b;4',3'-e]-pyridine (NO_{2}-DMPP) and its parent compound 3,5-dimethyl-1,7-diphenyl-bis-pyrazolo-[3,4-b;4',3'-e]-pyridine (BPP, without the nitrophenyl substituent) were investigated. BPP is a highly fluorescent blue emitter and the fluorescence properties, the emission wavelength, and the fluorescence quantum yield, depend only slightly on solvent. On the contrary, acceptor substituted NO_{2}-DMPP shows dual fluorescence: A long-wavelength component experiences a red-shift with increasing solvent polarity but is efficiently quenched when the polarity exceeds that of solvents like 1,2-dichloroethane or 1-bromopropane. A weak short-wavelength component changes only slightly its position and intensity upon variation of the solvent but its yield increases strongly at low temperatures. The experimental results are discussed in the context of the results of semiempirical calculations which show that fluorescence originates from two closely lying fluorescent states which change their sequence and properties when the polarity of the solvent is varied. A twisted intramolecular charge transfer (TICT) state does most likely not contribute to the emission properties, because of its high energy.
Keywords
EN
Year
Volume
95
Issue
3
Pages
321-334
Physical description
Dates
published
1999-03
received
1998-08-22
(unknown)
1998-12-14
References
Document Type
Publication order reference
YADDA identifier
bwmeta1.element.bwnjournal-article-appv95z303kz
Identifiers
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