Synthesis of Extremely π-Extended Porphyrin Tapes from Hybrid meso-meso Linked Porphyrin Arrays: An Approach Towards the Conjugation Length
Synthesis of Extremely π-Extended Porphyrin Tapes from Hybrid meso-meso Linked Porphyrin Arrays: An Approach Towards the Conjugation Length
复制标题
DOI：
10.1002/asia.200900125
复制
发表时间：
2009-01-01
影响因子：
4.1
通讯作者：
Osuka, Atsuhiro
中科院分区：
文献类型：
--
作者：
Ikeda, Toshiaki;Aratani, Naoki;Osuka, Atsuhiro
直接meso-meso、β-β、β-β三重连接的卟啉阵列是特殊的π共轭分子，其表现出显著的红移吸收带，在IR区域中深深延伸。为了确定有效共轭长度（ECL），我们着手合成远超过12-mer的卟啉带，这是我们迄今为止制备的最长的。在这项研究中，为了找到meso-meso偶联反应到更长阵列的可行性与所得卟啉带的足够溶解性和化学稳定性之间的折衷，我们制备了高达24-mer的杂化meso-meso连接的卟啉阵列BOn，其具有两个不同的芳基，一个2，4，6-三芳基，一个2，4，6-三芳基，一个2，4，6-三芳基，和一个2，4，6-三芳基。（3，5-二叔丁基-苯氧基）苯基（Ar-1）和3，5-二辛氧基苯基（Ar-2）。所有这些阵列通过用DDQ-Sc（OTf）（3）氧化有效地转化为相应的三重连接的卟啉带TBOn。重要的是，TBOn的低能量Q带样吸收带随着卟啉数目n的增加而逐渐红移，直到16，但红移在n=16时饱和，表明卟啉带的ECL为约14-16。有规律地引入的meso-芳基大体积取代基施加面支化，从而导致有效抑制π-π相互作用以及改善TBOn的化学稳定性。
Directly meso-meso, beta-beta, beta-beta triply linked porphyrin arrays are exceptional pi-conjugated molecules exhibiting remarkably red-shifted absorption bands extending deeply in the IR region. In order to determine the effective conjugated length (ECL), we embarked on the synthesis of the porphyrin tapes far beyond the 12-mer, which is the longest we have prepared so far. In this study, to find the compromise between the feasibility of the meso-meso coupling reaction up to longer arrays and the sufficient solubility and chemical stability of the resultant porphyrin tapes, we prepared hybrid meso-meso linked porphyrin arrays BOn up to 24-mer, which have two different aryl groups, a 2,4,6-tris(3,5-di-tert-butyl-phenoxy) phenyl group (Ar-1) and a 3,5-dioctyloxy phenyl group (Ar-2). All these arrays were effectively converted into the corresponding triply linked porphyrin tapes TBOn by oxidation with DDQ-Sc(OTf)(3). Importantly, the low energy Q-band-like absorption bands of TBOn are progressively red-shifted with an increase in the number of porphyrins n until 16 but the red-shift is saturated at n=16, indicating the ECL of the porphyrin tape to be around 14-16. The regularly introduced meso-aryl bulky substituents impose facial encumbrance, hence leading to the effective suppression of pi-pi interactions as well as improvement of the chemical stabilities of TBOn.