State Key Laboratory of Optoelectronics Materials and Technologies, Sun Yat-Sen University, Guangzhou 510275, China.
Department of Chemistry, South China University of Technology, Guangzhou 510641, China.
J Phys Chem B. 2021 Jun 10;125(22):5683-5693. doi: 10.1021/acs.jpcb.0c09335. Epub 2021 May 27.
Photophysical properties of five kinds of porphyrins (HTMPyP, ZnTMPyP, PdTMPyP, HTPPS, and ZnTPPS) complexed with model DNAs (ctDNA and dGMP) have been investigated using steady-state absorption, circular dichroism (CD), and femtosecond transient absorption spectroscopy. Upon addition of ctDNA (or dGMP), larger hypochromism and red shifts are observed for HTMPyP and PdTMPyP compared to the other samples. The steady-state measurements have suggested that the binding modes of HTMPyP-ctDNA and PdTMPyP-ctDNA are partial intercalation and full intercalation, respectively, while ZnTMPyP-ctDNA shows outside groove binding. No significant interaction was observed between both HTPPS and ZnTPPS with two kinds of DNA. Upon excitation of the porphyrins into the higher excited state S (Soret band), the appearance of the transient absorption from ∼500 to ∼620 nm at about 0.05 ps in HTMPyP-ctDNA, HTMPyP-dGMP, and PdTMPyP-dGMP indicates the occurrence of the electron transfer (ET) from guanine to HTMPyP and PdTMPyP. The forward ET are extremely fast ( ≥ 1.0 × 10 s), and the backward ET rates are ∼5.6 × 10 and ∼4.0 × 10 s, respectively. The complexation with DNA may lead to the shorter lifetime of the fluorescence of HTMPyP and PdTMPyP.
五种卟啉（HTMPyP、ZnTMPyP、PdTMPyP、HTPPS 和 ZnTPPS）与模型 DNA（ctDNA 和 dGMP）复合物的光物理性质已通过稳态吸收、圆二色性（CD）和飞秒瞬态吸收光谱进行了研究。加入 ctDNA（或 dGMP）后，与其他样品相比，HTMPyP 和 PdTMPyP 的消光值更大，红移更大。稳态测量表明，HTMPyP-ctDNA 和 PdTMPyP-ctDNA 的结合模式分别为部分嵌入和完全嵌入，而 ZnTMPyP-ctDNA 显示为外沟结合。两种 HTPPS 和 ZnTPPS 与两种 DNA 之间均未观察到明显的相互作用。在将卟啉激发到较高的激发态 S（Soret 带）后，在 HTMPyP-ctDNA、HTMPyP-dGMP 和 PdTMPyP-dGMP 中约在 0.05 ps 处观察到从 ∼500 到 ∼620 nm 的瞬态吸收的出现，表明电子转移（ET）从鸟嘌呤到 HTMPyP 和 PdTMPyP 发生。正向 ET 非常快（≥1.0×10 s），反向 ET 速率分别约为 5.6×10 和 4.0×10 s。与 DNA 的络合可能导致 HTMPyP 和 PdTMPyP 的荧光寿命缩短。
