Pilzak Gregor S, van Gruijthuijsen Kitty, van Doorn Reindert H, van Lagen Barend, Sudhölter Ernst J R, Zuilhof Han
Laboratory of Organic Chemistry, Wageningen University, Dreijenplein 8, 6703 HB Wageningen, The Netherlands.
Chemistry. 2009 Sep 14;15(36):9085-96. doi: 10.1002/chem.200900893.
Novel and highly soluble hybrid conjugated organic oligomers consisting of oligodiacetylene and thiophene units have been synthesized in high purity through iterative and divergent approaches based on a sequence of Sonogashira reactions. The series of thiophene-containing oligodiacetylenes (ThODAs) and homocoupled ThODAs (HThODAs) show--both in solution and in the solid state--a strong optical absorption, which is progressively red shifted with increasing chain length. The linear correlation of the absorption maximum (lambda(A)(max)) with the inverse of conjugation length (CL = number of double and triple bonds) shows that the effective conjugation length of this system is extended up to at least CL = 20. Furthermore, absorption measurements of dropcast thin films display not only a bathochromic shift of the absorption maxima but also a higher wavelength absorption, which is attributed to increased pi-pi interactions. The wavelength of the maximum fluorescence emission (lambda(E)(max)) also increases with CL, and emission is maximal for oligomers with CL=7-12 (fluorescence quantum yield Phi(F) = approximately 0.2). Both longer and shorter oligomers display marginal emission. The calculated Stokes shifts of these planar materials are relatively large (0.4 eV) for all oligomers, and likely due to excitation to the S(2) state, thus suggesting that the presence of enyne moieties dominates the ordering of the lowest excited states. The fluorescence lifetimes (tau(F)) are short (tau(F,max) = <<1 ns) and closely follow the tendency obtained for the fluorescence quantum yield. The anisotropy lifetimes show a near-linear increase with CL, in line with highly rigid oligomers.
通过基于一系列Sonogashira反应的迭代和发散方法，已高纯度合成了由低聚二乙炔和噻吩单元组成的新型且高溶解性的杂化共轭有机低聚物。一系列含噻吩的低聚二乙炔（ThODA）和均偶联的ThODA（HThODA）在溶液和固态中均表现出强烈的光吸收，且随着链长增加，吸收峰逐渐红移。吸收最大值（λA(max)）与共轭长度的倒数（CL = 双键和三键的数量）之间的线性相关性表明，该体系的有效共轭长度至少扩展至CL = 20。此外，旋涂薄膜的吸收测量不仅显示吸收最大值发生红移，还显示出更高波长的吸收，这归因于π-π相互作用的增加。最大荧光发射波长（λE(max)）也随CL增加，对于CL = 7 - 12的低聚物，发射最强（荧光量子产率ΦF≈0.2）。较长和较短的低聚物均表现出微弱的发射。对于所有低聚物，这些平面材料计算出的斯托克斯位移相对较大（0.4 eV），可能是由于激发到S(2)态，因此表明烯炔部分的存在主导了最低激发态的排列。荧光寿命（τF）很短（τF,max << 1 ns），并且紧密遵循荧光量子产率的趋势。各向异性寿命随CL近乎线性增加，这与高度刚性的低聚物一致。
