Palladium-catalyzed polycondensation between p -diethynylbenzene (HC⋮C Ph C⋮CH) and 2,5-diiodo-3-hexylthiophene (I Th(Hex) I) has been carried out under various conditions by changing the polymerization temperature, medium, and added amines. The polycondensation gives the polymer (PAE-1) with a M n of about 3 × 10 4 (by GPC, polystyrene standards) and an [η] value of 0.8 dL g -1 . By using neat NEt 3 as the medium, the polymerization proceeds fast. 1 H-NMR spectroscopic analysis indicates that oligomeric PAE-1 obtained at short polymerization time has a C I bond ( Th(Hex) I bond) as the major terminal group, which is consistent with results of the basic Pd-catalyzed C C coupling reaction. The C I terminal bond of oligomeric PAE-1 reacts with 1,3,5-triethynylbenzene and 1,2,4,5-tetraethynylbenzene to give polymers with M n values of 8.7 × 10 5 and 2.3 × 10 6 (by GPC), respectively, and the polymers are considered to have star-type structures. All the polymers show two (main and sub) photoluminescence PL peaks at 456 ± 3 and 486 ± 2 nm. The C⋮C bond of PAE-1 is susceptible to trans-type hydrogenation with SMEAH (sodium bis(2-methoxyethoxy)aluminum hydride) and DIBAL (diisobutylaluminum hydride) as well as to chlorofluorination by a mixture of N -chlorosuccinic imide and a pyridinium salt of (HF) x F - .
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Yamamoto et al. (1998) studied this question.
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