Enantioselective Assembly of a Ruthenium(II) Polypyridyl Complex into a Double Helix

Evolution can increase the complexity of matter by self‐organization into helical architectures, the best example being the DNA double helix. One common aspect, apparently shared by most of these architectures, is the presence of covalent bonds within the helix backbone. Here, we report the unprecedented crystal structures of a metal complex that self‐organizes into a continuous double helical structure, assembled by non‐covalent building blocks. Built up solely by weak stacking interactions, this alternating tread stairs‐like double helical assembly mimics the DNA double helix structure. Starting from a racemic mixture in aqueous solution, the ruthenium(II) polypyridyl complex forms two polymorphic structures of a left‐handed double helical assembly of only the Λ‐enantiomer. The stacking of the helices is different in both polymorphs: a crossed woodpile structure versus a parallel columnar stacking.     

双核钌(II)多吡啶配合物与酵母RNA的相互作用研究

用紫外-可见吸收光谱和荧光光谱滴定、稳态荧光淬灭和反向盐滴定实验研究了双核钌(II)配合物[(bpy)2Ru(ebipcH2)Ru(bpy)2](ClO4)4 {bpy=2,2'-联吡啶; ebipcH2=N-乙基-4,7-二(咪唑-[4,5-f]-(1,10-邻菲啰啉)-2-基)咔唑}与酵母RNA 的相互作用. 结果表明该双核配合物以插入方式与酵母RNA 作用, 在生理盐浓度下(≈150 mmol/L NaCl)该配合物与RNA 的相互作用明显强于DNA.     

双核钌(II)多吡啶配合物与酵母RNA的相互作用研究

用紫外-可见吸收光谱和荧光光谱滴定、稳态荧光淬灭和反向盐滴定实验研究了双核钌(II)配合物[(bpy)₂Ru(ebipcH₂)Ru(bpy)₂](ClO₄)₄ {bpy＝2,2'-联吡啶; ebipcH₂＝N-乙基-4,7-二(咪唑-[4,5-f]-(1,10-邻菲啰啉)-2-基)咔唑}与酵母RNA的相互作用. 结果表明该双核配合物以插入方式与酵母RNA作用, 在生理盐浓度下(≈150 mmol/L NaCl)该配合物与RNA的相互作用明显强于DNA.     

钌(II)多吡啶配合物的合成、荧光性质及与脱氧核糖核酸DNA的 作用机制研究

设计合成含多个配位中心的多吡啶配体ODCIP (3,4-二氯基苯并咪唑并[4,5-f][1,10]邻菲咯啉)及其钌(II)多吡啶配合物[Ru(bpy)2ODCIP]2＋. 运用元素分析、红外光谱、核磁谱和质谱对配体及配合物进行结构表征. 利用紫外吸收光谱、荧光光谱和粘度法研究了[Ru(bpy)2ODCIP]2＋与DNA(脱氧核糖核酸)的作用机制、与Co2＋配位后与DNA的作用机制及其荧光变化情况. 结果表明[Ru(bpy)2ODCIP]2＋与DNA通过部分插入模式作用, [Ru(bpy)2ODCIP]2＋与Co2＋配位形成的双核配合物[Ru(bpy)2(ODCIP)Co]4＋也能与DNA插入结合. 进一步利用稳态荧光发射光谱、荧光淬灭实验等方法研究了单核配合物[Ru(bpy)2ODCIP]2＋和双核配合物[Ru(bpy)2(ODCIP)Co]4＋的荧光性质.     

钌(II)多吡啶配合物光断裂DNA的实验研究

研究了一系列钌(II)多吡啶配合物对pBR 322 DNA 的光断裂作用, 并与光谱法和粘度法的研究结果进行了对比. 实验结果表明, 钌(II)多吡啶配合物光断裂DNA的能力不仅与配合物与DNA相互作用的结合模式和结合强度有关, 还与配合物自身的电子结构有关; 钌(II)多吡啶配合物对DNA的光断裂存在立体选择性; 其断裂机理是激发态的配合物与溶液中的氧分子发生能量转移生成单线态氧活性氧化物种, 将鸟嘌呤碱基氧化而导致DNA断裂. 本研究对于遗传工程中的化学核酸酶以及以DNA为靶标的药物设计有重要的意义.     

Reversal of a Single Base‐Pair Step Controls Guanine Photo‐Oxidation by an Intercalating Ruthenium(II) Dipyridophenazine Complex

Small changes in DNA sequence can often have major biological effects. Here the rates and yields of guanine photo‐oxidation by Λ‐[Ru(TAP)₂(dppz)]²⁺ have been compared in 5′‐{CCGG AT CCGG}₂ and 5′‐{CCGG TA CCGG}₂ using pico/nanosecond transient visible and time‐resolved IR (TRIR) spectroscopy. The inefficiency of electron transfer in the TA sequence is consistent with the 5′‐TA‐3′ versus 5′‐AT‐3′ binding preference predicted by X‐ray crystallography. The TRIR spectra also reveal the differences in binding sites in the two oligonucleotides.     

New Amphiphilic Polypyridyl Ruthenium（Ⅱ） Sensitizer and Its Application in Dye-Sensitized Solar Cells

Amphiphilic polypyridyl mthenium（Ⅱ） complex cis-di（isothiocyanato）（4,4＇-di-tert-butyl-2,2＇-bipyridyl）（4,4＇- dicarboxy-2,2＇-bipyridyl）ruthenium（Ⅱ）（K005） has been synthesized and characterized by cyclic voltammetry, ^1H NMR, UV-Vis, and FT-IR spectroscopies. The sensitizer sensitizes TiO2 over a notably broad spectral range due to its intense metal-to-ligand charge-transfer （MLCT） bands at 537 and 418 nm. The photophysical and photochemical studies of K005 were contrasted with those of cis-Ru（dcbpy）2（NCS）2, known as the N3 dye, and the amphiphilic ruthenium（Ⅱ） dye Z907. A reversible couple at E1/2=0.725 V vs. saturated calomel electrode （SCE） with a separation of 0.08 V between the anodic and cathodic peaks, was observed due to the Ru^Ⅱ/Ⅲ couple by cyclic voltammetry. Furthermore, this amphiphilic ruthenium complex was successfully used as sensitizers for dye-sensitized solar cells with the efficiency of 3.72% at the 100 mW·cm^-2 irradiance of air mass 1.5 simulated sunlight without optimization of TiO2 films and the electrolyte.     

Enhanced Electrochemiluminescence from a Stoichiometric Ruthenium(II)–Iridium(III) Complex Soft Salt

Electrochemiluminescence (ECL) and electrochemistry are reported for a heterometallic soft salt, [Ru(dtbubpy)₃][Ir(ppy)₂(CN)₂]₂ ( [Ir][Ru][Ir] ), consisting of a 2:1 ratio of complementary charged Ru and Ir complexes possessing two different emission colors. The [Ru]²⁺ and [Ir]^? moieties in the [Ir][Ru][Ir] greatly reduce the energy required to produce ECL. Though ECL intensity in the annihilation path was enhanced 18× relative to that of [Ru(bpy)₃]²⁺, ECL in the co‐reactant path with tri‐n‐propylamine was enhanced a further 4×. Spooling spectroscopy gives insight into ECL mechanisms: the unique light emission at 634 nm is due to the [Ru]²⁺* excited state and no [Ir]^?* was generated in either route. Overall, the soft salt system is anticipated to be attractive and suitable for the development of efficient and low‐energy‐cost ECL detection systems.     

C60-多吡啶Ru(II)配合物电子光谱的密度泛函理论研究

应用密度泛函理论(DFT)方法对两种C60-多吡啶Ru(II)衍生物进行理论研究. 在TZP全电子基组优化构型基础上, 通过分析前线轨道组成, 探讨金属及配体对C60母体影响; 以LB及SAOP校正局域密度近似, 用含时密度泛函(TDDFT)方法, 考虑溶剂化效应, 计算化合物1和2的电子吸收光谱. 结果表明, 化合物1和2在气相与丙酮溶液中所对应的光谱值差异较为明显, 溶剂化效应使吸收光谱蓝移. 计算得到化合物1和2在丙酮溶液中电子光谱与实验值吻合较好, 低能跃迁多为金属参与的混合跃迁, 高能跃迁主要由C60与配体部分贡献.     

Highly Charged Ruthenium(II) Polypyridyl Complexes as Lysosome‐Localized Photosensitizers for Two‐Photon Photodynamic Therapy

Photodynamic therapy (PDT) is a noninvasive medical technique that has received increasing attention over the last years and been applied for the treatment of certain types of cancer. However, the currently clinically used PDT agents have several limitations, such as low water solubility, poor photostability, and limited selectivity towards cancer cells, aside from having very low two‐photon cross‐sections around 800 nm, which limits their potential use in TP‐PDT. To tackle these drawbacks, three highly positively charged ruthenium(II) polypyridyl complexes were synthesized. These complexes selectively localize in the lysosomes, an ideal localization for PDT purposes. One of these complexes showed an impressive phototoxicity index upon irradiation at 800 nm in 3D HeLa multicellular tumor spheroids and thus holds great promise for applications in two‐photon photodynamic therapy.     

Photophysical Properties of Ruthenium(II) Polypyridyl DNA Intercalators: Effects of the Molecular Surroundings Investigated by Theory

The environmental effects on the structural and photophysical properties of [Ru(L)₂(dppz)]²⁺ complexes (L=bpy=2,2′‐bipyridine, phen=1,10‐phenanthroline, tap=1,4,5,8‐tetraazaphenanthrene; dppz=dipyrido[3,3‐a:2′,3′‐c]phenazine), used as DNA intercalators, have been studied by means of DFT, time‐dependent DFT, and quantum mechanics/molecular mechanics calculations. The electronic characteristics of the low‐lying triplet excited states in water, acetonitrile, and DNA have been investigated to decipher the influence of the environment on the luminescent behavior of this class of molecules. The lowest triplet intra‐ligand (IL) excited state calculated at λ≈800 nm for the three complexes and localized on the dppz ligand is not very sensitive to the environment and is available for electron transfer from a guanine nucleobase. Whereas the lowest triplet metal‐to‐ligand charge‐transfer (³MLCT) states remain localized on the ancillary ligand (tap) in [Ru(tap)₂(dppz)]²⁺, regardless of the environment, their character is drastically modified in the other complexes [Ru(phen)₂(dppz)]²⁺ and [Ru(bpy)₂(dppz)]²⁺ upon going from acetonitrile (MLCT_dppz/phen or MLCT_dppz/bpy) to water (MLCT_dppz) and DNA (MLCT_phen and MLCT_bpy). The change in the character of the low‐lying ³MLCT states accompanying nuclear relaxation in the excited state controls the emissive properties of the complexes in water, acetonitrile, and DNA. The light‐switching effect has been rationalized on the basis of environment‐induced control of the electronic density distributed in the lowest triplet excited states.     

Nucleic Acid Binding Behavior and Cytotoxicity Properties of a Ruthenium(II) Polypyridyl Complex

The binding of [Ru(IP)₂(dppz-11-CO₂Me)]²⁺ (1) {IP = imidazo[4,5-f][1,10]phenanthroline, dppz-11-CO₂Me = dipyrido[3,2-a:2′,3′-c]phenazine-11-carboxylic acid methyl ester} to calf thymus DNA and yeast tRNA has been investigated by UV–Vis spectroscopy, fluorescence spectroscopy, viscosity, as well as equilibrium dialysis and circular dichroism. In addition, the antitumor activities of complex 1 have been evaluated by the MTT method. On the basis of the spectroscopic results, the binding mode of complex 1 to CT-DNA and yeast tRNA is intercalation. However, DNA binding with complex 1 is stronger than RNA binding with complex 1, and complex 1 is a better candidate for an enantioselective binder to CT-DNA than to yeast tRNA. These results indicate that the structures of DNA and RNA have significant effects on the binding behaviors of complex 1. Furthermore, complex 1 demonstrates different antitumor activities against selected cancer cell lines in vitro.     

一个新型钌(II)配合物对F－的双重光谱识别

采用紫外-可见光谱和荧光光谱滴定方法研究了钌(II)配合物[Ru(bpy)(H2iip)2](ClO4)2 [bpy＝2,2’-联吡啶, H2iip＝2-吲哚基-咪唑并[4,5-f][1,10]-邻菲罗啉]在DMSO溶液中对卤素离子的识别性质. 结果表明该配合物能比色和荧光双重光谱高选择性识别F－.     

Metallomacrocycles with a Difference: Macrocyclic Complexes with Exocyclic Ruthenium(II)‐Containing Domains

The templated synthesis of organic macrocycles containing rings of up to 96 atoms and three 2,2′‐bipyridine (bpy) units is described. Starting with the bpy‐centred ligands 5,5′‐bis[3‐(1,4‐dioxahept‐6‐enylphenyl)]‐2,2′‐bipyridine and 5,5′‐bis[3‐(1,4,7‐trioxadec‐9‐enylphenyl)]‐2,2′‐bipyridine, we have applied Grubbs’ methodology to couple the terminal alkene units of the coordinated ligands in [FeL₃]²⁺ complexes. Hydrogenation and demetallation of the iron(II)‐containing macrocyclic complexes results in the isolation of large organic macrocycles. The latter bind {Ru(bpy)₂} units to give macrocyclic complexes with exocyclic ruthenium(II)‐containing domains. The complex [Ru(bpy)₂(L)]²⁺ (isolated as the hexafluorophosphate salt), in which L=5,5′‐bis[3‐(1,4,7,10‐tetraoxatridec‐12‐enylphenyl)]‐2,2′‐bipyridine, undergoes intramolecular ring‐closing metathesis to yield a macrocycle which retains the exocyclic {Ru(bpy)₂} unit. The poly(ethyleneoxy) domains in the latter macrocycle readily scavenge sodium ions, as proven by single‐crystal X‐ray diffraction and atomic absorption spectroscopy data for the bulk sample. In addition to the new compounds, a series of model complexes have been fully characterized, and representative single‐crystal X‐ray structural data are presented for iron(II) and ruthenium(II) acyclic and macrocyclic species.     

Photo‐Hydrogen‐Evolving Molecular Catalysts Consisting of Polypyridyl Ruthenium(II) Photosensitizers and Platinum(II) Catalysts: Insights into the Reaction Mechanism

The mechanism of photoinduced hydrogen evolution from water driven by the first photo‐hydrogen‐evolving molecular catalyst ( 1 ), given by a coupling of [Ru(bpy)₂(5‐amino‐phen)]²⁺ and [PtCl₂(4,4′‐dicarboxy‐bpy)] (bpy=2,2′‐bipyridine, phen=1,10‐phenanthroline), was investigated in detail. The H₂ evolution rate was found to obey Michaelis–Menten enzymatic kinetics with regard to the concentration of EDTA (ethylenediamine tetra‐acetic acid disodium salt, sacrificial electron donor), which indicates that an ion‐pair formation between the dicationic 1 and the dianionic form of EDTA (pH 5) is a key step leading to H₂ formation. A 2:1 coupling product of 1 and ethylenediamine (i.e., a {Ru^II₂Pt^II₂} complex 2 ) was found to show significantly higher photo‐hydrogen‐evolving (PHE) activity than 1 , which revealed the validity of the bimolecular activation proposed in our previous study. The PHE activity of 2 was also observed to be linear to the concentration of 2 , which indicates that H₂ formation through the intermolecular path competes with the intramolecular path. Molecular orbital diagrams, conformational features, and Pt???H(water or acetic acid) hydrogen bonds were characterized by DFT calculations.     

新型三齿多吡啶钴(II)、钌(II)配合物的合成、表征及其与DNA的作用研究

合成了两种新型三齿多吡啶钴(II)和钌(II)的混配配合物[Co(TolylTPy)(H₂Bzimpy)]Cl₂ [TolylTPy＝4'-对甲基苯 基-2,2':6',2'-三联吡啶, H₂Bzimpy＝2,6-二(苯并咪唑-2)吡啶] (A)和Ru(TolylTPy)(Bzimpy) (B). 用元素分析, IR, ¹H NMR等对它们进行了表征, 测定了配合物B的晶体结构, 用电子吸收光谱、荧光光谱等研究了配合物与小牛胸腺DNA(CTDNA)的相互作用及其对pBR322 DNA的断裂作用. 结果表明, 配合物A和B与CTDNA的作用属静电结合, 凝胶电泳实验说明配合物A在310 nm光辐射15 min, 可使超螺旋pBR322 DNA断裂为开环缺口型和线型DNA.     

A New Heteroleptic Ruthenium(II) Polypyridyl Complex with Long‐Wavelength Absorption and High Singlet‐Oxygen Quantum Yield

Ruthenium(II) polypyridyl complexes with long‐wavelength absorption and high singlet‐oxygen quantum yield exhibit attractive potential in photodynamic therapy. A new heteroleptic Ru^II polypyridyl complex, [Ru(bpy)(dpb)(dppn)]²⁺ (bpy=2,2′‐bipyridine, dpb=2,3‐bis(2‐pyridyl)benzoquinoxaline, dppn=4,5,9,16‐tetraaza‐dibenzo[a,c]naphthacene), is reported, which exhibits a ¹MLCT (MLCT: metal‐to‐ligand charge transfer) maximum as long as 548 nm and a singlet‐oxygen quantum yield as high as 0.43. Steady/transient absorption/emission spectra indicate that the lowest‐energy MLCT state localizes on the dpb ligand, whereas the high singlet‐oxygen quantum yield results from the relatively long ³MLCT(Ru→dpb) lifetime, which in turn is the result of the equilibrium between nearly isoenergetic excited states of ³MLCT(Ru→dpb) and ³ππ*(dppn). The dppn ligand also ensures a high binding affinity of the complex towards DNA. Thus, the combination of dpb and dppn gives the complex promising photodynamic activity, fully demonstrating the modularity and versatility of heteroleptic Ru^II complexes. In contrast, [Ru(bpy)₂(dpb)]²⁺ shows a long‐wavelength ¹MLCT maximum (551 nm) but a very low singlet‐oxygen quantum yield (0.22), and [Ru(bpy)₂(dppn)]²⁺ shows a high singlet‐oxygen quantum yield (0.79) but a very short wavelength ¹MLCT maximum (442 nm).     

Turn On of a Ruthenium(II) Photocatalyst by DNA-Templated Ligation

Here, the synthesis of a Ru^II photocatalyst by light-directed oligonucleotide-templated ligation reaction is described. The photocatalyst was found to have tremendous potential for signal amplification with >15000 turnovers measured in 9 hours. A templated reaction was used to turn on the activity of this ruthenium(II) photocatalyst in response to a specific DNA sequence. The photocatalysis of the ruthenium(II) complex was harnessed to uncage a new precipitating dye that is highly fluorescent and photostable in the solid state. This reaction was used to discriminate between different DNA analytes based on localization of the precipitate as well as for in cellulo miRNA detection. Finally, a bipyridine ligand functionalized with two different peptide nucleic acid (PNA) sequences was shown to enable template-mediated ligation (turn on of the ruthenium(II) photocatalysis) and recruitment of substrate for templated photocatalysis.