Liu Bin, Bazan Guillermo C
Department of Chemistry, Institute for Polymers and Organic Solids, University of California, Santa Barbara, California 93106, USA.
J Am Chem Soc. 2004 Feb 25;126(7):1942-3. doi: 10.1021/ja038667j.
Interchain interactions modulate the frequency of emission from a cationic water-soluble conjugated polymer. The polymer, PFPB, is obtained by a Suzuki copolymerization of p-phenylenebisboronic acid with a 95:5 mixture of 2,7-dibromo-9,9-bis(6'-bromohexyl)fluorene and 4,7-dibromo-2,1,3-benzothiadiazole, followed by quarternization of the pendant groups by addition of NMe3. The structure of PFPB contains 5% of the 2,1,3-benzothiadiazole (BT) chromophore within a cationic poly(fluorene-co-phenylene) polymer chain. The emission of PFPB is blue under dilute conditions (<1 x 10-6 M in repeat units) and green at higher concentrations. Energy transfer to dye-labeled ss-DNA is more efficient, relative to the parent polymer poly(9,9-bis(6'-N,N,N,-trimethylammonium)hexyl)fluorene-co-alt-1,4-phenylene) dibromide (PFP), as a result of improved spectral overlap. By using a peptide nucleic acid (PNA-C*) labeled with a red-emitting chromophore one can obtain three different emission colors, depending on the nature of the substrate under interrogation. If no ss-DNA is present, the solution emits blue. With a ss-DNA that is noncomplementary to PNA-C*, green emission is observed. Red emission occurs upon addition of ss-DNA complementary to the PNA sequence.
链间相互作用调节阳离子水溶性共轭聚合物的发射频率。聚合物PFPB是通过对苯撑双硼酸与2,7-二溴-9,9-双(6'-溴己基)芴和4,7-二溴-2,1,3-苯并噻二唑的95:5混合物进行铃木共聚，然后通过添加NMe₃使侧基季铵化而得到的。PFPB的结构在阳离子聚(芴-共-亚苯基)聚合物链中含有5%的2,1,3-苯并噻二唑(BT)发色团。PFPB在稀释条件下（重复单元浓度<1×10⁻⁶ M）发射蓝光，在较高浓度下发射绿光。相对于母体聚合物聚(9,9-双(6'-N,N,N,-三甲基铵)己基)芴-共-alt-1,4-亚苯基)二溴化物(PFP)，由于光谱重叠的改善，向染料标记的单链DNA的能量转移更有效。通过使用用红色发射发色团标记的肽核酸(PNA-C*)，根据被检测底物的性质，可以获得三种不同的发射颜色。如果不存在单链DNA，溶液发射蓝光。对于与PNA-C*不互补的单链DNA，观察到绿色发射。加入与PNA序列互补的单链DNA时会出现红色发射。
