Wazid Mohd, Misra Rajneesh
Department of Chemistry, Indian Institute of Technology Indore (M.P.), 453552, India.
Dalton Trans. 2024 Sep 18;53(36):15164-15175. doi: 10.1039/d4dt01661k.
A set of ferrocenyl-functionalized perylenediimide (PDI) compounds and their 1,1,4,4-tetracyanobuta-1,3-diene (TCBD) derivatives 1-5 were designed and synthesized using palladium-catalyzed Sonogashira cross-coupling, followed by a thermally activated [2 + 2] cycloaddition-retroelectrocyclization [CA-RE] reaction with a 1,1,2,2-tetracyanoethylene (TCNE) acceptor in good yields. The TCBD group works as an acceptor, whereas the ferrocenyl group acts as a donor at the central PDI core. The effects of varying the number of ferrocenyl and TCNE groups on the photophysical, thermal, electrochemical, and spectroelectrochemical properties were studied. The di-substituted PDI derivatives 3, 4, and 5 exhibit bathochromic shifts in the absorption spectra compared to 1 and 2, attributed to the extended π-conjugation. The electrochemical analysis of derivatives 2, 4, and 5 shows multiple reduction waves in the low potential region due to the presence of TCBD and perylenediimide acceptor units. Spectroelectrochemical studies were performed, showing that upon applying redox potentials, the absorption spectra shifted from the visible to the near-infrared (NIR) region. Computational calculations indicate that in the HOMO, the electron density is localized on the ferrocene unit, while in the LUMO, it is distributed over the PDI-TCBD unit, indicating a strong D-A interaction.
设计并合成了一组二茂铁基功能化苝二酰亚胺（PDI）化合物及其1,1,4,4-四氰基丁-1,3-二烯（TCBD）衍生物1-5，采用钯催化的Sonogashira交叉偶联反应，随后与1,1,2,2-四氰基乙烯（TCNE）受体进行热活化[2 + 2]环加成-逆电环化[CA-RE]反应，产率良好。TCBD基团作为受体，而二茂铁基团在中心PDI核处作为供体。研究了改变二茂铁基和TCNE基团数量对光物理、热、电化学和光谱电化学性质的影响。与1和2相比，二取代的PDI衍生物3、4和5在吸收光谱中表现出红移，这归因于π共轭的扩展。衍生物2、4和5的电化学分析表明，由于存在TCBD和苝二酰亚胺受体单元，在低电位区域出现多个还原波。进行了光谱电化学研究，结果表明施加氧化还原电位时，吸收光谱从可见光区域转移到近红外（NIR）区域。计算计算表明，在最高占据分子轨道（HOMO）中，电子密度定域在二茂铁单元上，而在最低未占据分子轨道（LUMO）中，它分布在PDI-TCBD单元上，表明存在强的给体-受体（D-A）相互作用。
