Synthesis of Cationic Diacetylene-co-Carbazole-co-Fluorene Polymers and Their Sensitive Fluorescent Quenching Properties with DNA

Two neutral precursor conjugated copolymers based 2,7-diethynylfluorene and 3,6-diethynylcarbazole units in the main chain (PFC and PF2C) were prepared by Hay coupling polymerization. Their cationic copolymers (CPFC and CPF2C) were prepared by the methylation of their diethylpropylamino groups with CH3I. For comparison, neutral conjugated homopolymers of 2,7-diethynylfluorene (PF), 3,6-diethynylcarbazole units (PC) and their cationic polymers (CPF and CPC) were also prepared with the same method. A comparative study on the optical properties of cationic polymers CPFC and CPF2C in DMF and DMF/H2O showed that they underwent water-induced aggregation. The spectral behaviors of CPFC and CPF2C with calf thymus DNA showed that a distinct fluorescent quenching took place with minute addition of CT DNA (3.3 x 10(-13) M). The results showed that the polymers would be promising biosensor materials for sensitive detection of DNA. (c) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 41684177, 2010