Synthesis and Characterization of Novel Conjugated Polymer with 4H-Cyclopenta[def]phenanthrene and the Sulfanyl Group

Abstract

A novel 4H-cyclopenta[def]phenanthrene (CPP) derivative with bis-methylsulfanyl-methylene unit was synthesized from CPP, CH(3)I and CS(2). The structure and absolute configuration was determined on the basis of spectroscopic analyses and X-ray diffraction. New electroluminescent polymer with bis-methylsulfanyl-methylene unit in the PCPP backbone, poly-((2,6-(4,4-bis (2-ethylhexyl)-4H-cyclopenta[def]phenanthrene))-alt-(2,6-(4-(bis(methylsulfanyl)methylene)-4H-cyclopenta[def]phenanthrene))) (PCPP-MSC), have been synthesized by the Suzuki coupling reaction. The bis-methylsulfanyl-methylene unit was introduced on the PCPP backbone to affect a red-shifted color change and to increase the electron affinities of the polymer. The HOMO energy level of the polymer was -5.65 eV, and the LUMO energy level was -2.92 eV. The polymer, PCPP-MSC, using this CPP derivative exhibited absorption spectra with maximum peak at 341 nm in chlorobenzene solution and at 344 nm in the solid film state. The PCPP-MSC showed two PL emission peaks at 404 and 522 nm in chloroform Solution with changing concentration. As concentration was growing from 1 x 10(-8) mol/L to 1 x 10(-5) mol/L, the PL peak at 522 nm increased dramatically, and the complete quenching of the host emission at 404 nm was observed, since complete aggregation between the cyclopentaphenanthrene segment and the methylsulfanylmethylene unit was induced by an intermolecular interaction.