求翻译Transition metal complexes that possess DNA photocleavage

求翻译Transition metal complexes that possess DNA photocleavage
Transition metal complexes that possess DNA photocleavage
activities have drawnmuch attention by virtue of their
utilities as DNA structure probes and as anticancer agents.1
Among them,Ru(II) polypyridyl complexes were extensively
studied owing to their tunable photophysical, photochemical,
and redox properties.2 Ru(II) complex-based DNA
photocleavers generally show two distinct features, high
singlet oxygen (1O2) quantumyield and strong binding ability
to DNA. Both features favor their application in photodynamic
therapy (PDT),3 a tumor treatment strategy that
uses the combination of a photosensitizer and visible or nearinfrared
(NIR) light to generate cytotoxic reactive oxygen
species (ROS), mainly 1O2.4 Besides the high 1O2 quantum
yield, an ideal PDT photosensitizer should have strong
absorptivity within the phototherapeutic window of 600-
900 nm. However, most Ru(II) polypyridyl complexes suffer
from short wavelength absorption, with the metal-to-ligand
charge transfer (MLCT) absorption maximum shorter than
500 nm. Though the ligands having a delocalized π-systemmay
shift the MLCT absorption to longer wavelengths,5,6 shortened
excited state lifetimes accompany them,7 unfavorable for 1O2
generation. For example, [Ru(bpy)2(dpb)]2þ (bpy=2,20-bipyridine,
dpb=2,3-bis(2-pyridyl) benzoquinoxaline, Scheme 1)
exhibits a 1MLCT maximum at 550 nm,8 a 100 nm red shift
compared to its parent complex [Ru(bpy)3]2þ (450 nm). However,
both the 3MLCT lifetime (66 ns) and the 1O2 quantum
yield (0.22) of [Ru(bpy)2(dpb)]2þ9 aremuch lower than those of
[Ru(bpy)3]2þ (900 ns10 and 0.5711). We recently synthesized a
new Ru(II) polypyridyl complex, [Ru(bpy)(dpb)(dppn)]2þ
(dppn=4,5,9,16-tetraaza-dibenzo[a,c]naphthacene), which exhibits
not only a long wavelength 1MLCT band centered at
548 nmbut also a long 3MLCTlifetime of 229 ns and a high 1O2
quantum yield of 0.43.9 The long 3MLCT lifetime of [Ru(bpy)-
(dpb)(dppn)]2þ originates from the long-lived (13 μs) triplet
excited state of the dppn ligand, which is in close proximity
to 3MLCT(Rufdpb) in energy, making an equilibrium
established between the two states, i.e., the reservoir effect.

具有DNA光断裂活性的过度金属络合物由于它们作为DNA结构探测剂,以及作为抗癌药剂的功用,已经引起人们很大的注意1.这些络合物中,Ru（II）多吡啶基络合物得到了广泛研究,因为它们有可调的光物理、光化学性质,以及氧化还原性质2.基于Ru（II）络合物的DNA的光断裂一般显示两个明显的特点,高的单态氧（1O2）量子效率,以及与DNA强的结合能力.这两个特点都有利于它们在光动力学疗法（PDT）3中的应用,PDT是一种肿瘤治疗策略,它利用光增敏剂和可见光或近红外（NIR）光的结合来产生细胞毒素的反应性氧物质（ROS）,主要为1O24.除了高的1O2量子效率外,一种理想的PDT增敏剂应该在600－900nm的光线疗法窗口具有强的吸收性.可是,大多数Ru（II）多吡啶基络合物都苦于短波长吸收,金属到配体电荷转移（MLCT）吸收的最大值短于500nm.虽然具有离位的π体系的配体可能使MLCT吸收移到较长的波长5,6,但缩短的激发态寿命伴随着它们7,对1O2的产生不利.例如,[Ru(bpy)2(dpb)]2+（bpy＝2,2’-二吡啶）dpb＝2,3-双（2-吡啶基）苯骈喹恶啉,方案1）在550nm处呈现一个1MCLT最大值8,相比于其母络合物[Ru(bpy)3]2+（450nm）有100nm的红移.不过[Ru(bpy)2(dpb)]2+9的3MCLT寿命（66ns）和1O2量子效率(0.22)都大大低于[Ru(bpy)3]2+的（900ns10和0.5711）.我们最近合成了一种新的Ru（II）多吡啶基络合物[Ru(bpy)(dpb)(dppn)]2+(dppn=4,5,9,16 tetraaza-dibenzo[a,c]丁省), 它不仅呈现一个中心在548nm处的长波长的1MCLT带,而且呈现出229ns的长3MCLT寿命,以及0.43的高1O2量子效率9.[Ru(bpy)(dpb)(dppn)]2+的长3MCLT寿命起源于dppn配体长寿命（13μs）的三重激发态,这与3MCLT（Ru→dpb）在能量上很接近,使得在两个态之间建立起平衡,即蓄水池效应