Costello Alison M, Duke Rebekah, Sorensen Stephanie, Kothalawala Nadeesha L, Ogbaje Moses, Sarkar Nandini, Kim Doo Young, Risko Chad, Parkin Sean R, Huckaba Aron J
Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States.
Center for Applied Energy Research, University of Kentucky, Lexington, Kentucky 40511, United States.
ACS Omega. 2023 Jun 27;8(27):24485-24494. doi: 10.1021/acsomega.3c02423. eCollection 2023 Jul 11.
To improve the charge-carrier transport capabilities of thin-film organic materials, the intermolecular electronic couplings in the material should be maximized. Decreasing intermolecular distance while maintaining proper orbital overlap in highly conjugated aromatic molecules has so far been a successful way to increase electronic coupling. We attempted to decrease the intermolecular distance in this study by synthesizing cocrystals of simple benzoic acid coformers and dipyridyl-2,2'-bithiophene molecules to understand how the coformer identity and pyridine N atom placement affected solid-state properties. We found that with the 5-(3-pyridyl)-5'-(4-pyridyl)-isomer, the 4-pyridyl ring interacted with electrophiles and protons more strongly. Synthesized cocrystal powders were found to have reduced average crystallite size in reference to the parent compounds. The opposite was found for the intermolecular electronic couplings, as determined via density functional theory (DFT) calculations, which were relatively large in some of the cocrystals.
为了提高薄膜有机材料的电荷载流子传输能力，应使材料中的分子间电子耦合最大化。在高度共轭的芳香族分子中，在保持适当轨道重叠的同时减小分子间距离，是迄今为止增加电子耦合的一种成功方法。在本研究中，我们试图通过合成简单苯甲酸共晶形成物与二吡啶 - 2,2'- 联噻吩分子的共晶体来减小分子间距离，以了解共晶形成物的特性和吡啶氮原子的位置如何影响固态性质。我们发现，对于5-(3-吡啶基)-5'-(4-吡啶基)异构体，4-吡啶环比亲电试剂和质子的相互作用更强。与母体化合物相比，合成的共晶粉末的平均微晶尺寸减小。通过密度泛函理论(DFT)计算确定，分子间电子耦合情况则相反，在一些共晶体中相对较大。
