A twist in the non-slanted H-mers to control π-conjugation in 2-dimensions and optical properties
A twist in the non-slanted H-mers to control π-conjugation in 2-dimensions and optical properties
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DOI：
10.1039/d0ma00424c
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发表时间：
2020-11-01
影响因子：
5
通讯作者：
Gavvalapalli, Nagarjuna
中科院分区：
文献类型：
--
作者：
Das, Mrinal Kanti;Hameed, Fatima;Gavvalapalli, Nagarjuna
理解决定2维中π共轭延伸的结构参数是控制2D π共轭材料的光学、物理和电子性质的关键。在这篇文章中，三个非倾斜的H-聚体，包括一个供体-受体H-聚体（H-聚体-3）与增加二面角（扭曲）之间的链和梯级的合成和研究。这些非倾斜的H-聚体代表2D-π-共轭材料的重复单元。H-mer-3含有供体链和受体横档，是倾斜和非倾斜H-mer中未探索的供体-受体结构。H-聚体显示酸和碱依赖的光学性质。虽然梯级对H-mer吸收光谱的影响很小，但它们对发射和荧光寿命起着关键作用。H-mer-3（即，供体-受体H-mer）显示出比其他两种H-mer更高的Stokes位移和荧光寿命。在H-mer-3中的扭曲和缺电子横档的存在促进了激发态下从链到缺电子横档的分子内电荷转移，因此控制了H-mer发射特性。绝缘侧链的缺乏，薄膜中π-π相互作用的减少，以及较长的荧光寿命使得这些H-mer成为各种电子和光电应用的有趣候选者。
Understanding the structural parameters that determine the extension of pi -conjugation in 2-dimensions is key for controlling the optical, photophysical, and electronic properties of 2D-pi -conjugated materials. In this article, three non-slanted H-mers including a donor-acceptor H-mer (H-mer-3) with an increase in dihedral angle (twist) between the strands and rungs are synthesized and studied. These non-slanted H-mers represent the repeat units of 2D-pi -conjugated materials. H-mer-3, containing donor-strands and an acceptor-rung, is an unexplored donor-acceptor architecture in both slanted and non-slanted H-mers. The H-mers displayed both acid and base dependent optical properties. While the rungs have a little impact on the H-mer absorption spectra they play a key role in the emission and fluorescence lifetime. H-mer-3 (i.e., donor-acceptor H-mer) shows a higher Stokes shift and fluorescence lifetime than the other two H-mers. The twist and the presence of an electron deficient rung in H-mer-3 facilitated an intramolecular charge transfer in the excited state from the strands to the electron deficient rung, and therefore control over the H-mer emission properties. The lack of insulating pendant chains, reduced pi-pi interactions in thinfilms, and longer fluorescence lifetimes make these H-mers interesting candidates for various electronic and optoelectronic applications.