A single nucleobase tunes nonradiative decay in a DNA-bound silver cluster
A single nucleobase tunes nonradiative decay in a DNA-bound silver cluster
复制标题
DOI：
10.1063/5.0056836
复制
发表时间：
2021-09-07
影响因子：
4.4
通讯作者：
Kohler, Bern
中科院分区：
文献类型：
--
作者：
Zhang, Yuyuan;He, Chen;Kohler, Bern
DNA 链是聚合物配体，可以保护和调节分子大小的银簇发色团。我们研究了单链 DNA C(4)AC(4)TC(3)XT(4)，其中 X = 鸟苷和肌苷形成绿色荧光 Ag-10(6+) 簇，但这两种宿主的区别在于其结合位点和 Ag-10(6+) 加合物的亮度。这些寡聚物中的核碱基亚基共同协调该簇，并且 fs 时间分辨红外光谱先前确定了 X = 鸟苷的 C2-NH2 之间的一个接触点，这是肌苷所排除的相互作用。此外，该单个核碱基控制簇荧光，因为 X = 鸟苷复合物类似于 2.5x 二聚体。我们使用瞬态吸收光谱在 200 fs-400 mu s 时间窗口内讨论了这两种配合物中的电子弛豫。出现了三个突出的特征：基态漂白、激发态吸收和受激发射。最早延迟时间（200 fs）的受激发射表明发射态在光激发后立即填充。同时，激发态衰变，基态恢复，与 X = 肌苷簇相比，X = 鸟苷的这些变化快了 2 倍，与它们的亮度差异平行。与类似的辐射衰变率相比，X = 鸟苷与肌苷链的非辐射衰变率高 7 倍。讨论了通过暗态的次要衰变通道。非辐射衰变与 X = 鸟苷/肌苷的选择性配位之间可能存在的相关性表明，DNA 链内的特定核碱基亚基可以调节簇-配体相互作用，进而调节簇亮度。由 AIP Publishing 独家许可出版。
DNA strands are polymeric ligands that both protect and tune molecular-sized silver cluster chromophores. We studied single-stranded DNA C(4)AC(4)TC(3)XT(4) with X = guanosine and inosine that form a green fluorescent Ag-10(6+) cluster, but these two hosts are distinguished by their binding sites and the brightness of their Ag-10(6+) adducts. The nucleobase subunits in these oligomers collectively coordinate this cluster, and fs time-resolved infrared spectra previously identified one point of contact between the C2-NH2 of the X = guanosine, an interaction that is precluded for inosine. Furthermore, this single nucleobase controls the cluster fluorescence as the X = guanosine complex is similar to 2.5x dimmer. We discuss the electronic relaxation in these two complexes using transient absorption spectroscopy in the time window 200 fs-400 mu s. Three prominent features emerged: a ground state bleach, an excited state absorption, and a stimulated emission. Stimulated emission at the earliest delay time (200 fs) suggests that the emissive state is populated promptly following photoexcitation. Concurrently, the excited state decays and the ground state recovers, and these changes are similar to 2x faster for the X = guanosine compared to the X = inosine cluster, paralleling their brightness difference. In contrast to similar radiative decay rates, the nonradiative decay rate is 7x higher with the X = guanosine vs inosine strand. A minor decay channel via a dark state is discussed. The possible correlation between the nonradiative decay and selective coordination with the X = guanosine/inosine suggests that specific nucleobase subunits within a DNA strand can modulate cluster-ligand interactions and, in turn, cluster brightness. Published under an exclusive license by AIP Publishing.