Towards polypeptides bearing luminescent side-chains as materials for organic light-emitting devices

• Main Author: Brunner, Pierre-Louis Marc
• Language: English
• Published: 2009
• Online Access: http://hdl.handle.net/2429/11218

Two different routes, using the Wittig reaction to obtained compound 2.5 are described. The O-benzyl-N-CBZ-L-serine cyclohexyl ammonium salt (2.7b) and the OstilbeneTN- CBZ-L-serine cyclohexyl ammonium salt (2.8b) were then prepared by coupling benzyl bromide or compound 2.5 respectively to iV-CBZ-Z-serine, as precursors to novel polypeptides containing a conjugated chromophore as a side-chain. Compound 2.9 was also obtained as a side-product by elimination of the side-chain in a basic media. The route toward these new materials involved the synthesis of the corresponding NCAs of 2.7b and 2.8b. Three different routes using SOCl₂ , Oxalyl chloride or PBr3 as halogenating agents were tried in an attempt to form the 5-membered ring of the NCAs from 2.7a, 2.7b and 2.8b. It was shown that the vinylic bond of the PPV oligomer-like side-chain of 2.8b got chlorinated when SOCI2 was used to form compound 2.11. Attempted syntheses of the polypeptides 2.12a and 2.12b using 4- methylmorpholine or diisopropylamine as initiator are also described. The photoisomerisation of 2.8a and 2.8b were explored. Excitation at 300 nm lead to a 57% conversion of the trans isomer to the cis isomer of the stilbene-like sidechain, where a broader excitation at wavelength greater than 290 nm lead to a 10 % conversion of the trans isomer to the cis isomer of the stilbene-like side-chain.