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Oligo( p ‐phenylene ethynylene)–BODIPY Derivatives: Synthesis, Energy Transfer, and Quantum‐Chemical Calculations
Author(s) -
Yin Shouchun,
Leen Volker,
Jackers Carine,
Beljonne David,
Van Averbeke Bernard,
Van der Auweraer Mark,
Boens Noël,
Dehaen Wim
Publication year - 2011
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201100454
Subject(s) - bodipy , phenylene , photochemistry , excited state , chromophore , absorption (acoustics) , acceptor , chemistry , conjugated system , fluorescence , acetylene , absorption spectroscopy , emission spectrum , materials science , crystallography , spectral line , atomic physics , organic chemistry , physics , polymer , quantum mechanics , composite material , condensed matter physics , astronomy
The synthesis and energy‐transfer properties of a series of oligo( p ‐phenylene ethynylene)–BODIPY ( OPEB ) cassettes are reported. A series of oligo( p ‐phenylene ethynylene)s ( OPE s) with different conjugated chain lengths as energy donor subunit in the energy‐transfer system were capped at both ends with BODIPY chromophores as energy‐acceptor subunits. The effect of the conjugated chain of OPE s on energy transfer in the OPEB cassettes was investigated by UV/Vis and fluorescence spectroscopy and modeling. With increasing number n of phenyl acetylene units ( n =1–7), the absorption and emission maxima of OPE n are bathochromically shifted. In the OPEB n analogues, the absorption maximum assigned to the BODIPY moieties is independent of the length of the OPE spacer. However, the relative absorption intensity of the BODIPY band decreases when the number of phenyl acetylene units is increased. The emission spectra of OPEB n are dominated by a band peaking at 613 nm, corresponding to emission of the BODIPY moieties, regardless of whether excitation is at 420 or 550 nm. Furthermore, a very small band is observed with a maximum between 450 and 500 nm, and its intensity relative to that of the BODIPY emission increases with increasing n , that is, the excited state of OPE subunits is efficiently quenched in OPEB n by energy transfer to the BODIPY moieties. Energy transfer (ET) from OPE n to BODIPY in OPEB n is very efficient (all Φ ET values are greater than 98 %) and only slightly decreases with increasing length of the OPE units. These results are supported by theoretical studies that show very high energy transfer efficiency ( Φ ET >75 %) from the OPE spacer to the BODIPY end‐groups for chains with up to 15–20 units.