竹红菌乙素镁、锌配位聚合物的光物理和光生物性质

Photophysical and Photobiological Properties of Coordination Polymers of Hypocrellin B Complexes Containing Magnesium and Zinc

竹红菌乙素(HB)能与Mg^(2+)和Zn^(2+)形成重复单元元数为5-20的配化聚合物(Mg^(2+)-HB,Zn^(2+)-HB),利用紫外-可见(UV-Vis)吸收光谱,傅里叶变换红外(FTIR)光谱,核磁共振氢谱(~1H NMR)对其进行了表征.Mg^(2+)-HB和Zn^(2+)-HB的单重态氧量子产率分别为HB的1.2倍和0.42倍.瞬态吸收实验表明:氧气能够猝灭Mg^(2+)-HB和Zn^(2+)-HB的三重态,其效率可超过96%.系间窜越效率(φ_T)和将能量传递给氧气并能产生单重态氧的三重态光敏剂的比例(f_Δ~T)对HB及其金属配合物的单重态氧量子产率有较大影响.电子自旋共振(EPR)实验结果表明:Mg^(2+)-HB和Zn^(2+)-HB产生半醌负离子自由基的能力较弱,进而降低了Mg^(2+)-HB和Zn^(2+)-HB光敏产生超氧负离子自由基的能力.紫外-可见吸收光谱与小牛胸腺脱氧核糖核酸(CT DNA)熔链温度实验表明:Mg^(2+)-HB和Zn^(2+)-HB可通过静电作用与DNA结合.有氧条件下,Mg^(2+)-HB,HB和Zn^(2+)-HB对小牛胸腺DNA的光敏损伤效率分别为32%,25%和22%.活性氧猝灭实验表明Mg^(2+)-HB主要通过单重态氧光敏损伤DNA.

Hypocrellin B（HB） can chelate with Mg^（2＋） and Zn^（2＋） ions to form the coordination complexes Mg^（2＋）-HB and Zn^（2＋）-HB,which consist of 5-22 repeat units.The structures of these two complexes are characterized by ultraviolet-visible（UV-Vis） spectroscopy,Fourier transform infrared（FTIR） spectroscopy, and ~1H nuclear magnetic resonance（~1H NMR）.The relative quantum yields of singlet oxygen（~1O_2） for Mg^（2＋）-HB and Zn^（2＋）-HB are 1.2 and 0.42 times as high as that of HB,respectively.Transient absorption spectra results indicate that O_2is able to quench the triplet excited state of Mg^（2＋）-HB and Zn^（2＋）-HB with an efficiency higher than 96%.The intersystem crossing efficiency（φ_T） and the fraction of triplet states quenched by O_2 that yield ~1O_2（f_△~T） are considered to be essential for the singlet oxygen quantum yields of HB and its complexes.Electron paramagnetic resonance（EPR） results suggest that Mg^（2＋）-HB and Zn^（2＋）-HB have a weak ability to generate a semiquinone anion radical,which reduces the generation of the superoxide anion radical（O_2^（·-）） by Mg^（2＋）-HB and Zn^（2＋）-HB.The results of the UV-Vis spectra and the deoxyribonucleic acid（DNA） melting temperature experiments indicate that Mg^（2＋）-HB and Zn^（2＋）-HB bind with calf thymus（CT） DNA in an electrostatic interaction mode.Under aerobic conditions,the efficiencies of photoinduced damage to CT DNA by Mg^（2＋）-HB,HB,and Zn^（2＋）-HB are found to be 32%,25%,and 22%, respectively.The reactive oxygen quencher experiments indicate that singlet oxygen is the main component generated by Mg^（2＋）-HB that damages CT DNA.