Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA.
Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208, USA.
Nat Chem. 2017 May;9(5):466-472. doi: 10.1038/nchem.2689. Epub 2016 Dec 19.
Two-dimensional covalent organic frameworks often π stack into crystalline solids that allow precise spatial positioning of molecular building blocks. Inspired by the hydrogen-bonded G-quadruplexes found frequently in guanine-rich DNA, here we show that this structural motif can be exploited to guide the self-assembly of naphthalene diimide and perylene diimide electron acceptors end-capped with two guanine electron donors into crystalline G-quadruplex-based organic frameworks, wherein the electron donors and acceptors form ordered, segregated π-stacked arrays. Time-resolved optical and electron paramagnetic resonance spectroscopies show that photogenerated holes and electrons in the frameworks have long lifetimes and display recombination kinetics typical of dissociated charge carriers. Moreover, the reduced acceptors form polarons in which the electron is shared over several molecules. The G-quadruplex frameworks also demonstrate potential as cathode materials in Li-ion batteries because of the favourable electron- and Li-ion-transporting capacity provided by the ordered rylene diimide arrays and G-quadruplex structures, respectively.
二维共价有机骨架通常会π堆叠成晶体固体，从而可以精确地定位分子构建块的空间位置。受富含鸟嘌呤的 DNA 中经常发现的氢键结合 G-四链体的启发，我们展示了这种结构基元可以被利用来引导萘二酰亚胺和苝二酰亚胺电子受体与两个鸟嘌呤电子供体的自组装，形成基于 G-四链体的晶体有机骨架，其中电子供体和受体形成有序的、分离的π堆叠阵列。时间分辨光和电子顺磁共振光谱表明，在骨架中光生空穴和电子具有长寿命，并表现出典型的离域电荷载流子的复合动力学。此外，还原的受体形成极化子，其中电子在几个分子之间共享。由于有序的 rylene 二酰亚胺阵列和 G-四链体结构分别提供了有利的电子和锂离子传输能力，因此 G-四链体骨架也显示出作为锂离子电池阴极材料的潜力。
