Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/1236
Title: Tunable photophysical properties of phenyleneethynylene based bipyridine ligands
Authors: James, P V
Yoosaf, K
Jatish Kumar
George Thomas, K
Listorti, A
Accorsi, G
Armaroli, N
Keywords: Organic light emitting diodes (OLED)
Phenyleneethynylene systems
Issue Date: 2009
Publisher: Royal Society of Chemistry
Citation: Photochemical & Photobiological Sciences 8(10):1432-1440;2009
Abstract: A bipyridine-based system with phenyleneethynylene at the 4,4′ positions (1) and its p-methyl (2) and p-methoxy (3) substituted derivatives were synthesized via Sonogashira coupling reactions. The photophysical properties of 1–3 and their related H+ and Zn2+ adducts (1:H+–3:H+ and 1:Zn2+–3:Zn2+) were investigated, as a function of solvent polarity, by using steady-state and time-resolved spectroscopic techniques. Molecular systems 1–3 exhibit trans conformation, whereas adducts with H+ and Zn2+ are conformationally locked cis species. The unsubstituted compound 1 emits at 360 nm with low fluorescence quantum yield (ϕfl = 0.2%) regardless of the solvent polarity. Fluorescence spectra of 2 and 3 are bathochromically shifted in polar solvents, and the p-methoxy (3) derivative possesses ϕfl as high as 12%. Complexation of 1–3 with H+ or Zn2+ in acetonitrile causes red-shift of the lowest energy absorption bands, whereas dramatic changes of the emission properties are found as a function of the electron donating ability of the substituents on the phenyleneethynylene moiety (–CH3 or –OCH3), suggesting a charge-transfer character of the lowest electronic transition of 1–3. 1:H+, 1:Zn2+, 2:H+ and 2:Zn2+ exhibit intense fluorescence with ϕfl up to 33% (1:Zn2+) whilst 3:H+ and 3:Zn2+ are found to be weakly emissive. The singlet radiative and non-radiative rate constants of compounds and complexes were determined, along with triplet parameters, via phosphorescence and transient absorption spectroscopy. More conclusive evidence regarding the protonation of bipyridine nitrogen atoms of compounds 1–3 were obtained through 1H NMR titration studies. These studies indicate that the conjugate molecular systems based on 2,2′-bipyridine and phenyleneethenylenes possess tunable optical properties which can be further utilized for preparing organic and inorganic luminophores with potential application in optoelectronic systems.
URI: http://ir.niist.res.in:8080/jspui/handle/123456789/1236
Appears in Collections:2009

Files in This Item:
File Description SizeFormat 
2009 _ 00115.pdf327.95 kBAdobe PDFView/Open


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.