The excited states of bipyridyl and phenanthroline complexes of Fe(III), Ru(II) and Ru(III): A molecular orbital study

The semiempirical zero-differential-overlap molecular orbital model which was shown in earlier papers in this series to give a good account of the charge transfer and -* spectra of Fe(II) complexes with conjugated ligands such as 2,2-bipyridyl and 1,10-phenanthroline is extended to complexes having openshell ground states, such as those of Fe(III), and to complexes of Ru(II) and Ru(III). The results are used to assign the observed charge transfer and intra-ligand absorption bands to specific orbital transitions. Observed and calculated intensities are in good agreement: reasons are advanced for the much lower intensity of the charge transfer bands in Ru(III) compared to Ru(II) complexes.     

Comparative study on the photophysical properties between carbene-based Fe (II) and Ru (II) complexes

The comparative study on the photophysical properties between cheap metal Fe (II) complexes and noble metal Ru (II) complexes with identical ligand coordination is performed by the combination of density functional theory (DFT) and time-dependent density functional theory (TDDFT) to evaluate the potential alternative applications of Fe (II) complexes. RuBIP (BIP = 2,6-bis (imidazol-2- ylidene)pyridine) is theoretically established that the radiative lifetime of the second lowest triplet state is more consistence with experimental value. However, FeBIP retains nonluminous because of low-lying ³MC originated from weak d orbital splitting. FeBIPC (FeBIP with carboxylic acid groups) has twice longer lifetime than its parent complex FeBIP due to the great decrease of the energy gap between ³MLCT and ³MC. What's more, the lifetimes of Fe (II) complexes detected in the experiments are more accessible to nonradiative decay lifetimes of ³MC. The carboxylic acid groups are beneficial for the improvement of luminescent possibility and controllability of Fe (II) complexes, while there is still a huge challenge for effective material replacement comparing with Ru (II) complexes.     

Effect of substituents on DNA-binding behaviors of ruthenium(II) complexes: [Ru(dmb)2(dtmi)]2+ and [Ru(dmb)2(dtni)]2+

Two Ru(II) complexes [Ru(dmb)₂(dtmi)](ClO₄)₂ (1) (dmb = 4, 4′-dimethyl-2, 2′-bipyridine, dtmi = 3-(pyrazin-2-yl)-as-triazino[5, 6-f]-5-methoxylisatin) and [Ru(dmb)₂(dtni)](ClO₄)₂ (2) (dtni = 3-(pyrazin-2-yl)-as-triazino[5, 6-f]-5-nitroisatin) have been synthesized and characterized by elemental analysis, ES-MS, and ¹H NMR. DNA-binding behaviors of these complexes have been investigated by spectroscopic titration, viscosity measurements, and thermal denaturation. The results indicate that the two complexes interact with calf thymus DNA by intercalation.     

The Development of Ru(II)-Based Photoactivated Chemotherapy Agents

Photoactivated chemotherapy (PACT) is a novel cancer treatment method that has drawn increasing attention due to its high selectivity and low side effects by spatio-temporal control of irradiation. Compared with photodynamic therapy (PDT), oxygen-independent PACT is more suitable for treating hypoxic tumors. By finely tuning ligand structures and coordination configurations, many Ru(II) complexes can undergo photoinduced ligand dissociation, and the resulting Ru(II) aqua species and/or free ligands may have anticancer activity, showing their potential as PACT agents. In this mini-review, we summarized the progress in Ru(II)-based PACT agents, as well as challenges that researchers in this field still face.     

Synthesis, characterization and DNA-binding and DNA-photocleavage studies of two Ru(II) complexes containing two main ligands and one ancillary ligand

DNA-binding and DNA-photocleavage properties of two Ru(II) complexes, [Ru(L¹)(dppz)₂](PF₆)₄ (1) and [Ru(L²)(dppz)₂](PF₆)₄ (2) (L¹ = 5,5′-di(1-(triethylammonio)methyl)-2,2′-dipyridyl cation; L² = 5,5′-di(1-(tributylammonio)methyl)-2,2′-dipyridyl cation; dppz = dipyrido[3,2-a:2′,3′-c]phenazine, have been investigated. Experimental results show that the DNA-binding affinity of complex 1 is greater than that of 2, both complexes emit luminescence in aqueous solution, either alone or in the presence of DNA, complex 1 can bind to DNA in an intercalative mode while 2 most likely interacts with DNA in a partial intercalation fashion, and complex 2 serves as a better candidate for enantioselective binding to CT-DNA compared with 1. Moreover, complex 1 reveals higher efficient DNA cleavage activity than 2, during which supercoiled DNA is converted to nicked DNA with both complexes. Theoretical calculations for the two complexes have been carried out applying the density functional theory (DFT) method at the level of the B3LYP/LanL2DZ basis set. The calculated results can reasonably explain the obtained experimental trends in the DNA-binding affinities and binding constants (K_b) of these complexes.     

Ru(II)-Catalyzed rearrangement of 2-aryl-2-(phenylthio)penta-3,4-dienyl 2,2,2-trichloroacetimidates

[RuCl₂(p-cymene)]₂ efficiently catalyzes the rearrangement of 2-aryl-2-(phenylthio)penta-3,4-dienyl 2,2,2-trichloroacetimidate to afford (Z)-2,2,2-trichloro-N-(4-aryl-1-(phenylthio)penta-2,4-dien-2-yl)acetamide. Ru carbene is assumed as the reactive intermediate in this rearrangement.     

Synthesis,characterization, antitumor,and cytotoxic activity of mononuclear Ru(II) complexes

In the search for antitumor active metal complexes several ruthenium complexes have been reported to be promising. A series of mononuclear Ru(II) complexes, [Ru(T)₂(S)]²⁺, where T?=?2,2′-bipyridine/1,10-phenanthroline and S?=?CH₃-bitsz, Cl-bitsz, Br-bitsz, tmtsz, dmtsz, have been prepared and characterized by UV-Vis, IR, ¹H-NMR, FAB-mass spectroscopy, and elemental analysis. The complexes were subjected to in vivo anticancer activity against a transplantable murine tumor cell line Ehrlich's ascitic carcinoma (EAC) and in vitro cytotoxic activity against human cancer cell line Molt 4/C₈, CEM, and murine tumor cell line L1210. Ruthenium complexes showed promising biological activity especially in decreasing tumor volume and viable ascitic cell counts. Treatment with these complexes prolonged the life span of EAC-tumor-bearing mice by 10–48%. In vitro evaluation of these ruthenium complexes revealed cytotoxic activity from 0.21 to 24?µmol?L^?1 against Molt 4/C₈, 0.16–19?µmol?L^?1 against CEM, and 0.75–32?µmol?L^?1 against L1210 cell proliferation, depending on the nature of the compound.     

Synthesis,DNA-binding,and photocleavage properties of Ru(II) complexes containing dppz-based ligand

A ligand ipdp (ipdp?=?indeno[1′,2′?:?5,6]pyrazino[2,3-i]dipyrido[3,2-a?:?2′,3′-c]phenazine-8-one) and its ruthenium complexes, [Ru(L)₂(ipdp)]²⁺ (L?=?bpy (2,2′-bipyridine), phen (1,10-phenanthroline)), have been synthesized and characterized by elemental analysis, electrospray mass spectra, and ¹H NMR. The interaction between the complexes and calf thymus DNA (CT-DNA) has been investigated by spectroscopic methods and viscosity measurements. The results indicate that the complexes can bind to CT-DNA in an intercalative mode. In addition, both complexes promote the photocleavage of plasmid pBR322 DNA under irradiation. The mechanistic studies reveal that singlet oxygen ¹O₂ plays a significant role in DNA photocleavage.     

Fe(II) hydrolysis in aqueous solution: A DFT study

Species arising from Fe(II) hydrolysis in aqueous solution have been investigated using density-functional methods (DFT). The different tautomers and multiplicities of each species have been calculated. The solvation energy has been estimated using the UAHF–PCM method. The hydrolysis free energies have been estimated and compared with the available experimental data. The different hydrolysis species have distinct geometries and electronic structures. The estimated ionization potential of the hydrolyzed species is linearly dependent to the number of hydroxyls present in the complex. The estimated Fe(II)/Fe(III) oxidation potential is in good agreement with previously published results about 0.29 V larger than the experimental value. The results highlight the importance of the chemical speciation in describing electron transfer processes at a molecular level. The PBE/TZVP/UAHF–PCM method has been found to describe correctly the hydrolysis free energies of Fe(II) with an average error about 5 kcal mol⁻¹ from the experimental values.     

Interaction of Mixed Porphyrin-polypyridyl Ru(II) Complex with Bovine Serum Albumin

The interactions of mixed porphyrin-polypyridyl Ru(II) complexes [m(Py-3′)TPP-Ru(phen) 2 Cl] + (1) and its derivatives [Nim(Py-3′)TPP-Ru(phen) 2 Cl] + (2) and [Cum(Py-3′)TPP-Ru(phen) 2 Cl] + (3)(phen=1,10-phenanthroline; m(Py-3′)TPP=5-(3′-pyridyl)-10,15,20-triphenylporphyrin) with bovine serum albumin(BSA) were investigated by fluorescence, UV-Vis and circular dichroism(CD) spectroscopies. The UV-Vis and CD spectral experiments indicated that the secondary structures of the protein were perturbed in the presence of the porphyrin Ru(II) complex and the perturbation was enhanced under the irradiation with ultra-violet light. The fluorescence quenching mechanism of BSA by the three complexes was determined to be a static process, and the apparent binding constant K values for complexes 1, 2 and 3 measured by fluorescence quenching method were (3.86±0.03)×10 3 L/mol(n=0.94±0.04), (5.69±0.04)×10 3 L/mol(n=1.03±0.06), and (6.54±0.02)×10 3 L/mol(n=1.03±0.05), respectively.     

Synthesis and Characterization of Poly(phenylacetylene)s with Ru(II) Bis‐Terpyridine Complexes in the Side‐Chain

An alkyne‐functionalized ruthenium(II) bis‐terpyridine complex is directly copolymerized with phenylacetylene by alkyne polymerization. The polymer is characterized by size‐exclusion chromatography (SEC), ¹H NMR spectroscopy, cyclic voltammetry (CV) measurements, and thermal analysis. The photophysical properties of the polymer are studied by UV–vis absorption spectroscopy. In addition, spectro‐electrochemical measurements are carried out. Time‐resolved luminescence lifetime decay curves show an enhanced lifetime of the metal complex attached to the conjugated polymer backbone compared with the Ru(tpy)₂²⁺ model complex.

     

Synthesis and Characterization of New Mononuclear Ru (II) PolypyridylComplexes with Catalytic Activity

In this work, we report the synthesis and physicochemical characterization of new chloro and aqua mononuclear Ru (II) complexes of formula [Ru(LLL)(dpp)Cl]PF₆ and [Ru(LLL)(dpp)OH₂](PF₆)₂ (LLL=tpy =2,2’ : 6’,2’’-terpyridine; tptz=2,4,6-tris(2-pyridyl)-1,3,5-triazine and dpp=2,3-bis(2-pyridil)pyrazine). For the complex [Ru(tptz)(dpp)Cl]PF₆, the complete structure was determined by X-ray diffraction. Catalytic studies of aqua-complexes revealed that they are active for the water oxidation reaction at pH 1 using cerium ammonium nitrate (CAN) as a sacrificial oxidant. Also, we were able to establish the reaction mechanism and rate constants of each stage of the catalytic cycle, turnover frequencies (TOFs), and turnover numberes (TONs). The experimental TON values for the aqua complexes were very close to the theoretical value of 7.5, indicating a high degree of recovery. DFT and TD-DFT calculations of electronic states for all complexes were consistent with experimental results and allowed the complete assignment of their UV-Visible bands and redox states.     

Synthesis,characterization and DNA-binding properties of Ru(II) complexes coordinated by ofloxacin as potential antitumor agents

Three Ru complexes coordinated by oxfloxacin, [Ru(L)₂(OFX)]Cl·2H₂O (L = bpy, 1; dmbpy, 2; phen, 3; and OFX = ofloxacin), were synthesized and characterized. These complexes can inhibit the growth of cervical cancer HeLa cells efficiently. Furthermore, these three complexes exhibited excellent binding affinities with DNA, as confirmed by spectroscopy methods and viscosity experiments. Therefore, the synthesized Ru(II) complexes have excellent DNA-binding abilities with potential applications in cancer chemotherapy.     

介孔有机金属Ru(Ⅱ)非均相催化剂的制备及其催化性能的研究

采用正硅酸乙酯和有机金属Ru(II)硅烷在模板剂P123作用下共聚,合成出有序介孔Ru(II)有机金属催化剂,通过FTIR、NMR、XRD、TEM、N2吸附脱附等对催化剂进行了系统表征;将该催化剂应用于水介质中烯丙醇型异构化反应,结果表明,其具有高活性和高选择性,催化效率接近均相催化剂,且能够多次重复使用,有望在绿色化工中推广应用.     

Synthesis,characterization and catalytic,cytotoxic and antimicrobial activities of two novel cyclotriphosphazene‐based multisite ligands and their Ru(II) complexes

Two novel cyclotriphosphazene ligands ( 2 and 3 ) bearing 3‐oxypyridine groups and their corresponding Ru(II) complexes ( 4 and 5 ) were synthesized and their structures were characterized using Fourier transform infrared, ¹H NMR and ³¹P NMR spectroscopic data and elemental analysis. The Ru(II) complexes were used as catalysts for catalytic transfer hydrogenation of p‐substituted acetophenone derivatives in the presence of KOH. Additionally, the cytotoxic activities of compounds 2 , 3 , 4 , 5 were evaluated against PC3 (human prostate cancer), DLD‐1 (human colorectal cancer), HeLa (human cervical cancer) and PNT1A (normal human prostate) cell lines. Finally the antimicrobial activities of compounds 2 , 3 , 4 , 5 were evaluated against a panel of Gram‐positive and Gram‐negative bacteria and yeast cultures. The complexes showed efficient catalytic activity towards transfer hydrogenation of acetophenone derivatives, especially those bearing electron‐withdrawing substituents on the para‐position of the aryl ring. The compounds were found to have moderate to high cytotoxic and antimicrobial activities, and Ru(II) complexation enhanced both cytotoxic and antimicrobial activities in comparison with the parent compounds. Copyright © 2015 John Wiley & Sons, Ltd.     

Effects of the substituting groups and proton abstraction on the nonlinear optical properties of heteroleptic bis-tridentate Ru(II) complexes

The second-order nonlinear optical (NLO) properties have been carried out on a series of Ru(II) complexes with different 4′-substituted terpyridine derivatives and the tridentate ligand 2,6-bis(benzimidazole-2-yl)pyridine by using density functional theory (DFT). The introduction of different substituents enhances the static first hyperpolarizabilities in various degrees. Time-dependent density functional theory (TD-DFT) calculations indicate that the additional metal-to-ligand charge transfer (MLCT) transition, which is vectorially opposite to the intraligand charge transfer (ILCT) transition, could contribute to the smaller β_vec in species with electron-withdrawing groups compared to ones with electron-donating groups. The stepwise deprotonation brings about a change in electron density of the benzimidazole moiety and finally makes the moiety turn to be as donor, which subsequently leads to an efficient second-order NLO switching. For the species 3 with electron-donating group, the β_vec value of the mono-deprotonated system is 49.9 and 11.1 times as small as that of its diprotonated and fully deprotonated ones.     

X-ray crystal structures of novel platinum(II) and palladium(II) complexes of dialkyl phosphonated phosphines

Two diethyl phosphonated phosphine ligands of formula Ph₂P(CH₂)₃PO₃Et₂ (ligand L) and Ph₂P(4-C₆H₄PO₃Et₂) (ligand L′) were used to prepare different complexes of platinum(II) (1, cis-PtCl₂L₂; 2, trans-PtCl₂L₂·H₂O; 3A and 3B, cis- and trans-PtCl₂L′₂) and palladium(II) (4, [PdCl₂L]₂; 5, trans-PdCl₂L₂·H₂O; 6, trans-PdCl₂L′₂·CH₂Cl₂). The single-crystal X-ray structure analyses of complexes 1, 2, 4-6 indicate that complexation involved only the phosphine end, whereas the strong polarization of the PO bond was highlighted by the formation of hydrogen bonds with a water molecule in 2 and 5, and with a dichloromethane molecule in 6, with an exceptionally short CH?O hydrogen bond length (C?O separation 3.094(3) Å).     

钌(II)-吡啶基NNN配合物催化酮的室温(不对称)氢转移反应

合成了一种基于吡啶骨架含有苯并咪唑和手性咪唑啉基团的三齿NNN配体及其二价钌(II)配合物,通过核磁共振波谱学和X射线单晶晶体结构测定确认了钌(II)配合物的分子结构.这些配合物在室温下催化酮的氢转移反应,表现出了优异的催化活性,收率和ee值最高分别可达99%和97%.     

NNN pincer Ru(II)-catalyzed dehydrogenative coupling of 2-aminoarylmethanols with nitriles for the construction of quinazolines

An efficient NNN pincer Ru(II)-catalyzed preparation of quinazolines via acceptorless dehydrogenative strategy has been developed. Under the optimized conditions, a broad range of substituted o-aminobenzyl alcohols and (hetero)aryl or alkyl nitriles were well tolerated to afford various 2-substituted quinazolines in high yields. Subsequently, a set of control experiments have been performed to elucidate the reaction mechanism, which underwent alcohol oxidation, nitrile hydration, and cyclocondensation steps. The current protocol is featured with several advantages, such as environmental benignity, operational simplicity, broad substrate scope (compatible with aliphatic nitriles, up to 87% yield), and short reaction time (mostly in 2?h).