Conjugated oligomers and polymers of cis- and ...
|Title||Conjugated oligomers and polymers of cis- and trans-platinum(II)-para- and ortho-bis(ethynylbenzene)quinone diimine.|
|Author(s)||K. Gagnon, S. Mohammed Aly, A. Brisach-Wittmeyer, D. Bellows, J. Berube, L. Caron, A. Abd-El-Aziz, D. Fortin, P. Harvey|
|Journal||Section Title: Organometallic and Organometalloidal Compounds, Organometallics|
|Abstract||Three platinum coordination conjugated quinonediimine polymers, trans-[Câ‰¡C-1,4-C6H4N:C6(OMe)4:N-1,4-C6H4Câ‰¡CPtL2] (10; L = PEt3), cis-[Câ‰¡C-1,4-C6H4N:C6(OMe)4:N-1,4-C6H4Câ‰¡CPtL2] (11) and trans-[Câ‰¡C-1,2-C6H4N:C6(OMe)4:N-1,2-C6H4Câ‰¡CPtL2] (12) were prepd. by reactions of the corresponding diacetylenes HCâ‰¡C-1,n-C6H4N:C6(OMe)4:N-1,n-C6H4Câ‰¡CH (4, 7; n = 2, 4) with the corresponding cis- and trans-[L2PtCl2]. The three combinations (spacer/PtL2Cl2), ortho/trans, para/trans, and para/cis led to polydispersed polymers, which upon fractionation provided more monodispersed materials with Mn ranging from 3600 to 32400 (GPC). The spacer 4 reacts with cis-PtL2Cl2 to form small oligomers and a chelate cyclic complex (7), which was used as a model compd. All materials along with the aryl-Câ‰¡C-PtL2- Câ‰¡C-aryl models (L = PEt3; aryl = C6H5, 2,4,6-C6H2Me3; 2,4,5-C6H2Me3) were studied by 1H and 31P NMR, IR, UV-vis, TGA, DSC, luminescence spectroscopy, photophysics, and cyclic voltammetry. The UV-vis spectra exhibit an intramol. low-energy and low-intensity charge transfer band (CT) assigned to Ï€(Ph-Câ‰¡C) (for orgs.) and Ï€/dxy((Ph-Câ‰¡C)2Pt) (for organometallics) to the Ï€*(quinone diimine), as demonstrated by comparison with a corresponding amine deriv. (i.e., no CT band) and corroborated by DFT and TDDFT. The polymers and 7 are not luminescent at room temp. However in 2-MeTHF at 77 K, the polymers bearing the combination ortho/trans and para/cis as well as the model compd. 7 exhibit higher energy phosphorescence (Tn â†’ S) originating from the Ï€Ï€*/dxy((Ph-Câ‰¡C)2Pt) excited states. A correlation between the structural parameters, such as angle made by the PtP2(Câ‰¡C)2 vs. the aryl planes, angle made by the aryl and the quinone diimine planes, mol. wt., with the calcd. oscillator strength, absorptivities, and the obsd. position of the lowest energy absorption bands is demonstrated. Finally, upper energy delayed fluorescence (Sn â†’ S) was detected for the polymers and 7 at 77 K and was assigned to T1-T1 interactions via aggregation as its intensity varies with the concn. [on SciFinder(R)]|
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