620624-96-6Relevant articles and documents
Cationic polyfluorene- b -neutral polyfluorene rod-rod diblock copolymers
Gutacker, Andrea,Lin, Chi-Yen,Ying, Lei,Nguyen, Thuc-Quyen,Scherf, Ullrich,Bazan, Guillermo C.
, p. 4441 - 4446 (2012)
All-conjugated rod-rod diblock copolymers are an emerging class of polymeric materials of considerable interest for applications in chemical and biological sensors or as components for optoelectronic devices. Here, we report a novel cationic diblock copolymer containing a neutral polyalkylfluorene block covalently bound to a polar polyfluorene counterpart - poly[9,9-bis(6- trimethylammoniumhexyl)-2,7-fluorene]-b-poly(3-hexyl-2,5-thiophene) (PF6NBr-b-PF8) - which was synthesized in a sequential Suzuki-Miyaura polymerization and was made ionic with trimethylamine in a subsequent quaternization step. The optical properties of this material were investigated by UV/vis and photoluminescence spectroscopies in three different solvents: methanol, THF and THF/methanol 1:1. Atomic force microscopic (AFM) imaging experiments provided evidence for solvent-induced aggregation. The formation of vesicles and spherical particles is observed in layers from THF and methanolic solution.
Synthesis, photophysics, and reverse saturable absorption of platinum complexes bearing extended π-conjugated C^N^N ligands
Li, Zhongjing,Sun, Wenfang
supporting information, p. 14021 - 14029 (2013/09/24)
The synthesis of ligands 1-L-6-L that feature the 6-[9,9-di(2-ethylhexyl)- 7-R-9H-fluoren-2-yl]-2,2′-bipyridine (C^N^N) core (R = 4-R′-phenylethynyl with R′ = NO2, benzothiazol-2-yl (BTZ), H and OCH3 or R = 4′-BTZ-phenyl or BTZ) and their platinum complexes 1-6 were reported in this paper. The photophysical properties of these ligands and the Pt(ii) complexes, including the UV-vis absorption spectra, emission characteristics at room temperature and at 77 K, and the triplet transient difference absorption spectra, were systematically investigated in order to understand the effects of the substituent at the 4-position of the 1-ethynylphenyl component and the extension of π-conjugation between the C^N^N core and the BTZ substituent. Reverse saturable absorption (RSA) of complexes 1-6 was demonstrated at 532 nm using 4.1 ns laser pulses. The UV-vis absorption spectra of 1-L-6-L are featured by strong 1π,π* transitions in the blue spectral region, and the absorption bands are effectively red-shifted by substitution at the 4-position of the ethynylphenyl motif and by the extended π-conjugation of the linkage. A similar effect was observed for the fluorescence spectra of these ligands in CH2Cl2 at room temperature, but the nature of the fluorescence varies from 1π,π* fluorescence in 3-L and 6-L, to intraligand charge transfer (1ILCT) fluorescence in 1-L, 2-L and 5-L; while 4-L possesses mixed 1π,π*/ 1ILCT characters. All ligands exhibit moderate triplet transient absorption (TA) in the visible spectral region, with substitution at the 4-position of the ethynylphenyl component broadening of the TA bands, while extended π-conjugation of the linkage inducing red-shifts of the TA bands. For Pt(ii) complexes 1-6, their UV-vis absorption spectra constitute red-shifted 1π,π* transitions and low-energy metal-to-ligand charge transfer (1MLCT/1ILCT) tails. The emission of these complexes at room temperature in CH2Cl2 predominantly originates from the C^N^N core localized 3π,π* state, probably mixed with minor 3MLCT character. 4-Position substitution and extended π-conjugation on the ligands exert a negligible effect on the shape and energy of the emission spectra. Similar to their respective ligands, 1-6 all exhibit broader and red-shifted TA spectra with respect to their ligands and both the 4-position substitution and extended π-conjugation bathochromically shift the TA band maxima. The nonlinear transmission experiments carried out for 1-6 at 532 nm reveal that all complexes exhibit strong reverse saturable absorption (RSA), and the degree of RSA follows this trend: 6 2 and BTZ) and by extending the π-conjugation; while electron-donating substituent (OCH 3 in 4) decreases the RSA at 532 nm.
