Farcas, A;
Tregnago, G;
Resmerita, A-M;
Aubert, P-H;
Cacialli, F;
(2015)
Synthesis and photophysical characteristics of polyfluorene polyrotaxanes.
Beilstein Journal of Organic Chemistry
, 11
pp. 2677-2688.
10.3762/bjoc.11.288.
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Abstract
Two alternating polyfluorene polyrotaxanes (3·TM-βCD and 3·TM-γCD) have been synthesized by the coupling of 2,7-dibromofluorene encapsulated into 2,3,6-tri-O-methyl-β- or γ-cyclodextrin (TM-βCD, TM-γCD) cavities with 9,9-dioctylfluorene-2,7-diboronic acid bis(1,3-propanediol) ester. Their optical, electrochemical and morphological properties have been evaluated and compared to those of the non-rotaxane counterpart 3. The influence of TM-βCD or TM-γCD encapsulation on the thermal stability, solubility in common organic solvents, film forming ability was also investigated. Polyrotaxane 3·TM-βCD exhibits a hypsochromic shift, while 3·TM-γCD displays a bathochromic with respect to the non-rotaxane 3 counterpart. For the diluted CHCl3 solutions the fluorescence lifetimes of all compounds follow a mono-exponential decay with a time constant of ≈0.6 ns. At higher concentration the fluorescence decay remains mono-exponential for 3·TM-βCD and polymers 3, with a lifetime τ = 0.7 ns and 0.8 ns, whereas the 3·TM-γCD polyrotaxane shows a bi-exponential decay consisting of a main component (with a weight of 98% of the total luminescence) with a relatively short decay constant of τ1 = 0.7 ns and a minor component with a longer lifetime of τ2 = 5.4 ns (2%). The electrochemical band gap (ΔEg) of 3·TM-βCD polyrotaxane is smaller than that of 3·TM-γCD and 3, respectively. The lower ΔEg value for 3·TM-βCD suggests that the encapsulation has a greater effect on the reduction process, which affects the LUMO energy level value. Based on AFM analysis, 3·TM-βCD and 3·TM-γCD polyrotaxane compounds exhibit a granular morphology with lower dispersity and smaller roughness exponent of the film surfaces in comparison with those of the neat copolymer 3.
| Type: | Article |
|---|---|
| Title: | Synthesis and photophysical characteristics of polyfluorene polyrotaxanes |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.3762/bjoc.11.288 |
| Publisher version: | http://doi.org/10.3762/bjoc.11.288 |
| Language: | English |
| Additional information: | © 2015 Farcas et al; licensee Beilstein-Institut. This is an Open Access article under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The license is subject to the Beilstein Journal of Organic Chemistry terms and conditions: (http://www.beilstein-journals.org/bjoc) |
| Keywords: | Science & Technology, Physical Sciences, Chemistry, Organic, Chemistry, energy band gaps, fluorescence lifetimes, permethylated cyclodextrins, polyfluorene, polyrotaxanes, BLUE-EMITTING POLYFLUORENE, DISTRIBUTED ELECTRON-DONOR, INSULATED MOLECULAR WIRES, MAIN-CHAIN POLYROTAXANE, OPEN-CIRCUIT VOLTAGE, POLYMER SOLAR-CELLS, CONJUGATED POLYMERS, ALPHA-CYCLODEXTRIN, ELECTROLUMINESCENT PROPERTIES, WHITE ELECTROLUMINESCENCE |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery.ucl.ac.uk/id/eprint/1483286 |
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