Alternated Stacks of Nonpolar Oligo(p-phenyleneethynylene)-BODIPY Systems
Alternated Stacks of Nonpolar Oligo(p-phenyleneethynylene)-BODIPY Systems
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DOI：
10.1002/chem.201203279
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发表时间：
2012-11-01
影响因子：
4.3
通讯作者：
Fernandez, Gustavo
中科院分区：
文献类型：
--
作者：
Florian, Alexander;Mayoral, Maria Jose;Fernandez, Gustavo
4，4-二氟-4-硼杂-3a，4a-二氮杂-s-引达省（BODIPY）[1]染料由于其显著的光学性质（即，高摩尔吸收系数和荧光量子产率、优异的（光）化学稳定性和易于官能化）而在过去两个十年中变得越来越相关。[2]典型的应用领域包括光学化学传感器，[3]激光染料，[4]用于细胞成像的荧光探针，[5]有机发光二极管，[6]光伏器件，[7]或光动力治疗剂。[8]相比之下，尽管BODIPY染料倾向于通过二吡咯亚甲基核心的堆叠自组装成H型或J型二聚体聚集体，[9]但它们的超分子方面迄今为止受到一定限制。最近报道了基于BODIPY的液晶材料的一些实例，[10，12 c-d]或H-[11]或J-型[12]聚集体，其由氢键、[12 c-d]静电相互作用、[12 a]疏水效应、[11b，12 a]或添加离子[11 a，12 b]驱动。然而，很少有人致力于基于π-π芳香族相互作用的BODIPY聚集体的研究，尽管这些相互作用在许多天然超分子组装体或光电器件中的纳米级染料组织中具有相关性。[13]在此，我们描述了oligo（pphenyleneethynylene）（OPE）-BODIPY体系在环己烷中完全由π-π芳香相互作用驱动的高度有序的交替π堆叠的自组装行为。OPEs以其自组装成各种超分子结构的能力而闻名。[14]衍生物1（方案1）通过2，6-二碘-BODIPY（2）[15]和含有长增溶十二烷基链的乙炔基苯基衍生物3的Sonogashira交叉偶联反应合成（有关合成详细信息，请参见支持信息），并通过NMR、IR、MALDI-TOF、高分辨率ESI、UV/维斯、荧光、和元素分析1的UV/维斯光谱显示来自OPE和BODIPY亚基的重要贡献，即，具有中心在约l= 340 nm处的振动图案的跃迁归因于OPE单元的π-π* 跃迁[16]，以及在约l= 340 nm处的强烈尖锐带。577 nm处的一个小的第二跃迁和在约l= 400 nm处的一个小的第二跃迁，其可以被分配给S 0！S1和S 0！分别为BODIPY核心的S2转换（支持信息中的图1和S1）。[17]1与参比化合物2和3在二氯甲烷中的UV/维斯光谱的比较表明，
4, 4-Difluoro-4-bora-3a, 4a-diaza-s-indacene (BODIPY)[1] dyes have become increasingly relevant in the last two dec-ACHTUNGTRENNUNGades due to their remarkable optical properties, that is, high molar-absorption coefficients and fluorescence-quantum yields, excellent (photo) chemical stability, and ease of functionalization.[2] Typical applications encompass fields as diverse as optical chemosensors,[3] laser dyes,[4] fluorescent probes for cell imaging,[5] organic light-emitting diodes,[6] photovoltaic devices,[7] or photodynamic therapy agents.[8] In contrast and despite the tendency of BODIPY dyes to selfassemble into H-or J-type dimer aggregates through stacking of the dipyrromethene core,[9] their supramolecular aspects have thus far been somewhat limited. Some examples of BODIPY-based liquid-crystalline materials,[10, 12c–d] or H-[11] or J-type [12] aggregates driven by hydrogen bonding,[12c–d] electrostatic interactions,[12a] the hydrophobic effect,[11b, 12a] or the addition of ions [11a, 12b] have recently been reported. However, little effort has been devoted to the investigation of BODIPY aggregates based on π–π aromatic interactions, despite the relevance of these interactions in numerous natural supramolecular assemblies or in the nanometer-scale dye organization in optoelectronic devices.[13] Herein, we describe the self-assembly behavior of oligo (pphenyleneethynylene)(OPE)-BODIPY systems into highlyorganized alternated π stacks in cyclohexane exclusively driven by π–π aromatic interactions. OPEs are known for their ability to self-assemble into a wide variety of supramolecular structures.[14] Derivative 1 (Scheme1) was synthesized by Sonogashira cross-coupling reaction of 2, 6-diiodo-BODIPY (2)[15] and ethynylphenyl-based derivative 3 containing long solubilizing dodecyl chains (for synthetic details, see the Supporting Information) and fully characterized by NMR, IR, MALDI-TOF, high-resolution ESI, UV/Vis, fluorescence, and elemental analyses (see the Supporting Information).The UV/Vis spectra of 1 showed important contributions from both OPE and BODIPY subunits, that is, a transition with a vibronic pattern centered at about l= 340 nm attributed to the π–π* transition of the OPE units [16] and an intense sharp band at about l= 577 nm and a small second transition at about l= 400 nm that can be assigned to the S0! S1 and S0! S2 transitions of the BODIPY core, respectively (Figures 1 and S1 in the Supporting Information).[17] Comparison of the UV/Vis spectrum of 1 with those of reference compounds 2 and 3 in dichloromethane showed that