SETA BioMedicals, LLC, 2014 Silver Court East, Urbana, Illinois 61801, United States.
SSI "Institute for Single Crystals" of the National Academy of Sciences of Ukraine, 60 Nauky Ave., 61072 Kharkiv, Ukraine.
J Phys Chem Lett. 2022 Nov 24;13(46):10688-10696. doi: 10.1021/acs.jpclett.2c02721. Epub 2022 Nov 10.
While only one enantiomer of chiral biomolecules performs a biological function, access to both enantiomers (or enantiomorphs) proved to be advantageous for technology. Using dye covalent attachment to a DNA Holliday junction (HJ), we created two pairs of dimers of bis(chloroindolenine)squaraine dye that enabled strongly coupled molecular excitons of opposite chirality in solution. The exciton chirality inversion was achieved by interchanging single covalent linkers of unequal length tethering the dyes of each dimer to the HJ core. Dimers in each pair exhibited profound exciton-coupled circular dichroism (CD) couplets of opposite signs. Dimer geometries, modeled by simultaneous fitting absorption and CD spectra, were related in each pair as nonsuperimposable and nearly exact mirror images. The origin of observed exciton chirality inversion was explained in the view of isomerization of the stacked Holliday junction. This study will open new opportunities for creating excitonic DNA-based materials that rely on programmable system chirality.
虽然手性生物分子只有一种对映异构体发挥生物功能，但获得两种对映异构体（或对映体）对技术来说是有利的。我们通过将染料共价连接到 DNA 霍利迪结（HJ）上，创建了两对双（氯吲哚啉） Squaraine 染料的二聚体，使溶液中具有相反手性的强耦合分子激子成为可能。通过交换将每个二聚体的染料连接到 HJ 核心的不等长的单个共价接头，实现了激子手性反转。每对中的二聚体表现出强烈的激子耦合圆二色性（CD）偶对，符号相反。通过同时拟合吸收和 CD 光谱对二聚体的几何形状进行建模，每对中的二聚体都是不可叠加的，并且几乎是完全镜像的。从堆叠的霍利迪结的异构化的角度解释了观察到的激子手性反转的起源。这项研究将为创建依赖于可编程系统手性的基于激子的 DNA 材料开辟新的机会。
