Synthesis,characterization and luminescent properties of three-coordinate copper(I) halide complexes containing diphenylamino monodentate phosphine ligand

Three-coordinate copper halide complexes with a bidentate phosphine ligand have received much attention. Here, a series of three-coordinate dinuclear copper halide complexes containing a diphenylamino monodentate phosphine ligand, [CuX(dpnp)]₂ (dpnp = N-[2-(diphenylphosphino)-4,5-dimethylphenyl]-N-phenylaniline, X = I (1), Br (2) and Cl (3)), were synthesized, and their molecular structures and photophysical properties were investigated. The structural analysis reveals that two copper(I) centers are bridged by two halogen ligands to form a dinuclear structure with a four-membered Cu₂X₂ ring. Crystal structures of 1–3 contain 1-D supramolecular arrays constructed by intermolecular C–H?π interactions. These complexes exhibit blue emission in the solid state at room temperature and have peak emission wavelengths at 483–487 nm with microsecond lifetimes (τ = 13.9–38.1 μs) and low emission quantum yields (<0.01%). The emission of complex 1 mainly originates from intraligand (IL) transition, whereas the emissions of complexes 2 and 3 are from a combination of MLCT, XLCT and IL transitions. The three complexes displayed good thermal stability.     

Synthesis,characterization and luminescent properties of three-coordinate copper(I) halide complexes containing 2-(diphenylphosphino)biphenyl

Highly emissive three-coordinate copper halide complexes with a bidentate phosphine ligand have attracted attention. Here, a series of three-coordinate mono- and dinuclear copper halide complexes, [CuI(dpbp)₂] (1) and [CuX(dpbp)]₂ (dpbp = 2-(diphenylphosphino)biphenyl, X = Br (2), Cl (3)), were synthesized, and their molecular structures and photophysical properties were investigated. In the solid state, these complexes exhibit green photoluminescence with microsecond lifetimes (λ_max = 515–538 nm; τ = 11.8–19.1 μs) at 298 K. The emission of the complexes originates from the (σ + X) → π* transition. All three complexes displayed good thermal stability.     

Synthesis,characterization, and luminescent properties of three-coordinate copper(I) halide complexes containing a carbazolyl monodentate phosphine ligand

Abstract

A series of three-coordinate dinuclear copper halide complexes containing acarbazolyl monodentate phosphine ligand, [CuX(dppc)]₂ (dppc =3,6-di-tert-butyl-9-[2-(diphenylphosphino)phenyl]carbazole, X?=?I (1), Br (2), and Cl (3)), were synthesized, and their molecular structures and photophysical properties were investigated. The structural analysis reveals that two copper(I) centers are bridged by two halogen ligands to form a dinuclear structure with a four-membered Cu₂X₂ ring. Crystal structures of 1-3 contain 1-D supramolecular arrays constructed by intermolecular C–H···π interactions. These complexes exhibit blue to green emission in the solid state at room temperature and have peak emission wavelengths at 492–495?nm with microsecond lifetimes and low emission quantum yields (< 0.01%). The emission of 1-3 mainly originates from MLCT, XLCT, and IL (intraligand) transitions. The three complexes displayed good thermal stability.     

Dinuclear copper(I) complexes of N-methylbenzothiazole-2-thione: synthesis,structures, antibacterial activity and DNA interaction

Three copper(I) halide complexes containing N-methylbenzothiazole-2-thione (mbtt) and triphenylphosphine (PPh₃) have been prepared and structurally characterized by X-ray single-crystal analysis. Copper(I) halide precursors [CuΧ(PPh₃)]₄ (X = Cl, Br, I) react with mbtt in 1 : 4 M ratio to give complexes of formula [CuΧ(mbtt)(PPh₃)]₂. Hereby, dimerization is achieved in case of copper(I) chloride and bromide via halide bridges, while copper(I) iodide gives the binuclear thione-S-bridged dimer. The new complexes show moderate in vitro antibacterial activity against certain bacterial strains. The interaction of the compounds with calf-thymus DNA was monitored via UV–vis spectroscopy, DNA-viscosity measurements and their competition with ethidium bromide for the DNA intercalation sites studied by fluorescence emission spectroscopy. Intercalation was revealed as the probable mode of binding.     

Four-coordinate N-heterocyclic carbene (NHC) copper(I) complexes with brightly luminescence properties

Three four-coordinate N-heterocyclic carbene (NHC) copper(I) complexes, [Cu(Py-Im)(POP)](PF₆) (P1), [Cu(Py-BenIm)(POP)](PF₆) (P2), and [Cu(Py-c-BenIm)(POP)](PF₆) (P3) (Py-Im = 3-methyl-1-(pyridin-2-yl)-1H-imidazolylidene, Py-BenIm = 3-methyl-1-(pyridin-2-yl)-1H-benzo[d]imidazolylidene, Py-c-BenIm = 3-methyl-1-(pyridin-2-ylmethyl)-1H-benzo[d]imidazolylidene, POP = bis([2-diphenylphosphino]-phenyl)ether), have been synthesized without transmetalation of the NHC–Ag(I) complex for the first time. The photophysical properties of the resultant NHC–Cu(I) complexes have been systematically investigated via spectroscopic methods. All complexes exhibit good photoluminescence properties with long excited-state lifetimes and moderate quantum yields. Density functional theory and time dependent density functional theory calculations were employed to rationalize the photophysical properties of the NHC–Cu(I) complexes.     

Copper(I)-1,1,1-tris(diphenylphosphinomethyl)ethane complexes with different coordination modes tuned by auxiliary ligands and their spectroscopic properties

Three mono-, bi- and tetranuclear copper(I) complexes, [Cu(phen)(triphos-O)]BF₄ (1) (phen = 1,10-phenanthroline, triphos = 1,1,1-tris(diphenylphosphinomethyl)ethane), [Cu₂(bipy)(triphos)₂](BF₄)₂ (2) (bipy = 4,4′-bipyridine), and [Cu₄(MeOC^N^N)₄(triphos)₂(bipy)](BF₄)₄ (3) (MeOC^N^N = 6-(4-methoxyphenyl)-2,2′-bipyridine), have been synthesized and characterized by NMR spectroscopy, electrospray ionization, and matrix-assisted laser desorption ionization time-of-flight mass spectrometries, elemental analysis, and X-ray crystal analysis. The crystal structure investigation revealed the copper ions of the complexes have pseudo-tetrahedral coordination geometry. The electronic absorption spectra of 1, 2, and 3 contain low-energy bands at 350–500 and 400–650 nm, which are assigned to d(Cu) → π*(phen or bipy) and a mixture of d(Cu) → π*(MeOC^N^N) and d(Cu) → π*(bipy) transitions, respectively. Complex 2 displays a strong, long-lived solid-state emission with a maximum at 555 nm and lifetime of 13.6 μs at room temperature. Photoinduced electron-transfer properties of 2 and 3 involving nanosecond time-resolved absorption spectroscopy and electron spin resonance techniques were studied.     

Synthesis,crystal structure,in vitro anticancer and in vivo acute oral toxicity studies of tetramethylene linked bis-benzimidazolium salts and their respective dinuclear Ag(I)–NHC complexes

The proligands of the series tetramethylenebis(N-n-alkylbenzimidazolium bromide) (where n = 3–10) (1–8) as N-heterocyclic carbene (NHC) precursors have been prepared by reacting the initially synthesized N-n-alkyl benzimidazole with 1,4-dibromobutane in 2 : 1 M ratio. A reaction of Ag₂O with 1–8 resulted in the formation of Ag(I) complexes tetramethylenebis{(N-n-alkylylbenzimidazol-2-ylidene)silver(I)hexafluorophosphate} (9–16), respectively. All the synthesized compounds were characterized by FT-IR, ¹H NMR, ¹³C NMR, atomic absorption and elemental analysis. Single-crystal X-ray diffraction study on tetramethylenebis{(N-n-octylbenzimidazol-2-ylidene)silver(I)hexafluorophosphate} (14) has revealed that the complex exists as a dinuclear compound. All compounds were assessed for their antiproliferation test on human colorectal cancer cell line (HCT 116). Interestingly, increasing the n-alkyl chain length from n = 3 to 10 of the proligands and their respective complexes showed trends in increased cytotoxicity against human colon cancer cell line. Cytotoxicity data showed that tetramethylene linked bis-benzimidazolium salts and their respective dinuclear Ag(I)–NHC complexes can be useful therapeutic agents against colon cancer.     

Ag(I) and Zn(II) isonicotinate complexes: design,characterization, antimicrobial effect,and CT-DNA binding studies

Trinuclear Ag(I) (1) and dinuclear and mononuclear Zn(II) isonicotinate (2 and 3) complexes were prepared and characterized by X-ray crystallography, elemental analysis, IR spectroscopy, and thermal analysis. Single-crystal analysis of the Ag(I) complex reveals two different monodentate carboxylate coordination modes, protonated and deprotonated, respectively. IR spectra showed correlations between isonicotinate coordination modes and Δ(ν_as???ν_s)_IR values. In addition, the hydrogen bonds significantly influence a position of carboxylate absorption bands. Moreover, IC₅₀ and MIC data for bacteria, yeasts, and filamentous fungi were determined and the binding of Ag(I) and Zn(II) complexes to calf thymus DNA was investigated using electronic absorption, fluorescence, and CD measurements. Biological tests showed that the Ag(I) complex is more active than commercially used Ag(I) sulfadiazine against Escherichia coli. The fluorescence spectral results indicate that the complexes can bind to DNA through an intercalative mode. The Stern–Volmer quenching constants for investigated complexes obtained from the linear quenching plot are in the range of 1.67 × 10⁴–3.42 × 10⁴ M^?1.     

Syntheses,crystal structures,and properties of two dinuclear iron(III) complexes constructed with 1,2,3,5-benzenetetracarboxylic acid and chelating N-donor auxiliary coligands

Two dinuclear Fe(III) metal–organic complexes with tetracarboxylate and chelating N-donor ligands, [Fe(Hbtec)(phen)(H₂O)]₂·2H₂O (1) and [Fe(Hbtec)(bpy)(H₂O)]₂·2H₂O (2) (H₄btec = 1,2,3,5-benzenetetracarboxylic acid, phen = 1,10-phenanthroline, bpy = 2,2′-bipyridine) have been prepared and characterized by elemental analysis, IR spectroscopic, and X-ray diffraction methods. Both complexes crystallize in the monoclinic space group P2₁/c with two Fe(III) ions bridged by two Hbtec^3? ligands into a dinuclear unit. Hydrogen bonding connects the dinuclear units into a 3-D framework. The dinuclear units are 10-connected nodes that produce a 3-D framework with topology Schläfli symbol as (3¹²·4²⁸·5⁵). Thermal stabilities and luminescent properties of the two complexes have also been investigated.     

Copper(II) complexes of picolinamide incorporating both tricyanomethanido and 2-(aminomethyl)pyridine moieties

Reaction of picolinamide (pca) with potassium tricyanomethanide (tcm) and copper(II) perchlorate in 1-propanol gave [Cu(pca)₂(tcm)₂] (1a and 1b) while addition of 2-(aminomethyl)pyridine (2-ampy) provided [Cu(pca)(2-ampy)(tcm)](ClO₄) (2). These compounds have been characterized by IR, powder X-ray diffraction, single crystal X-ray diffraction, combustion analysis, and temperature-dependent magnetic susceptibility. Compound 1a crystallized in the monoclinic space group C2/c whereas 1b and 2 crystallized in the triclinic space group Pī. In 1a, the copper complexes stack alternately with semi-coordinated tcm ions creating layers, further stabilized by hydrogen bonding to neighboring layers. In 1b, the tcm ions are coordinated to complete the octahedral coordination sphere around the copper ions and form staggered layers parallel to the ab face diagonal. In 2, stacks of copper complexes form bilayers, held together by hydrogen bonding between tcm ions and amino groups, parallel to the a axis. Variable temperature magnetic susceptibility data were collected on 1 and 2 from 1.8–310 K. The data were fit to the Curie–Weiss law which showed no significant magnetic exchange as expected based upon the crystal structures [1 ? Curie constant = 0.419(2) emu-K/mol-Oe, θ = ?0.10(6)°; 2 – Curie constant = 0.438(1) emu-K/mol-Oe, θ = 0.05(3)°].     

Tricarbonylrhenium(I) complexes with the N,6-dimethylpyridine-2-carbothioamide ligand: combined experimental and calculation studies

Abstract

A new series of tricarbonyl complexes of rhenium(I) in the “2 + 1” system with the bidentate ligand N,6-dimethylpyridine-2-carbothioamide ((CH₃)NC₅H₄-CS-NH-CH₃, MeLH(Me)_NS) and a monodentate ligand (halides Cl, Br, or I, and the pseudohalide NCS anion) was synthesized. The use of mixed ligands led to the formation of neutral tricarbonylrhenium(I) complexes [Re(CO)₃(MeLH(Me)_NS)X] (X = Cl, Br, I, NCS) (1–4). Single-crystal X-ray diffraction was used to determine the crystal structures of all four compounds and those results were compared with molecular structures obtained from DFT calculations using the PBE0/def2-TZVPD approach. The complexes were also characterized by spectroscopic (FT-IR, NMR, and UV–vis) and analytical (HPLC, TGA, EA, ESI-MS) techniques. IR and UV–vis spectra were also calculated by DFT and TD-DFT methods. The cytotoxicity of these complexes was estimated using human ovarian cancer cell lines (A2780 and A2780cis), cervical cancer cells (HeLa), and non-cancerous human embryonic kidney cells (Hek-293). The toxicity of most complexes was moderate or low toward cancer cell lines (IC₅₀ = 46–231 μM) and similar against non-cancerous cells (IC₅₀ = 41-121 μM). Only the complex with chlorido ligand remarkably inhibited growth of ovarian cancer cells (IC₅₀ = 3 and 12 μM for A2780 and A2780cis, respectively). The cytotoxicity of 1 was higher than that of cisplatin.     

A disparate 3-D silver(I) coordination polymer of pyridine-3,5-dicarboxylate and pyrimidine with strong intermetallic interactions: X-ray crystallography,photoluminescence and antimicrobial activity

A polymeric silver(I) complex, [Ag₄(μ-pydc)₂(μ-pm)₂]_n (1) (pydc = pyridine-3,5-dicarboxylate and pm = pyrimidine), has been synthesized and characterized by elemental analysis, IR spectroscopy, thermal analysis, and single-crystal X-ray diffraction. X-ray crystallographic data of 1 revealed that pydc exhibits two different coordinaton modes that play a key role in the construction of the 3-D crystal network including Ag–carboxylate clusters in which close Ag–Ag distances exist. The magnitudes of close Ag–Ag interactions in second-order energy (E²) have been revealed by natural bond orbital analysis performed with single point energy calculation using the experimental geometry of 1. Furthermore, the luminescent properties of 1 show strong fluorescence with two emission maxima in the visible region. Also, 1 has antifungal activity on Candida albicans (MIC value, 4 μg mL^?1) and good antibacterial activity on micro-organisms (MIC value, 64–256 μg mL^?1).     

Synthesis,characterization, and structural determination of copper(II) complexes with alkyl derivatives of hydroxybenzophenones

Four mononuclear copper(II) complexes, [Cu(LFQM-115)₂] (1), [Cu(LFQM-116)₂] (2), [Cu(LFQM-117)₂] (3) and [Cu(octyloxy)₂] (4) [LFQM-115 = 2-hydroxy-4-O-methylbenzophenone (C₁₄H₁₁O₃), LFQM-116 = 2-hydroxy-4-O-butylbenzophenone (C₁₇H₁₈O₃), LFQM-117 = 2-hydroxy-4-O-(33-dimethylallyl)benzophenone (C₁₈H₁₈O₃) and octyloxy = 2-hydroxy-4-O-octylbenzophenone (C₂₁H₂₅O₃)], have been prepared and investigated by infrared spectroscopy, thermal analysis, and powder and single crystal X-ray diffraction. Even though the synthesis and infrared analysis of 1, 2, and 4 have been reported previously, their crystal structures were elucidated for the first time here. In addition, the crystal structures of LFQM-116 and LFQM-117 were also determined by single crystal X-ray diffraction. The pseudo-translational symmetry found in LFQM-116 and the isomorphism between LFQM-115 and LFQM-117 are discussed. The complexes were prepared from a reaction of copper(II) nitrate trihydrate and the respective ligand in a (1:2) molar ratio in methanol (for 1 and 2) or THF (for 3 and 4) with addition of NaOH. Furthermore, crystallographic studies show that each copper(II) exhibits a square planar geometry, coordinated by four oxygens of two ligands. The nature and crystal packing of the intermolecular interactions are discussed. Compounds 2 and 3 are isomorphic crystals and all structures have the same supramolecular synthon.     

Copper complexes with a flexible piperazinyl arm: nuclearity driven catecholase activity and interactions with biomolecules

Three new Cu(II) complexes, [Cu(HL¹)(pyridine)(H₂O)](ClO₄)₂·2MeOH (1), [Cu₂(HL¹)₂(NO₃)₂](NO₃)₂·3H₂O (2) and [Cu(HL₂)(NO₃)₂]·MeCN (3), have been synthesized from two Schiff base ligands [HL¹ = 1-phenyl-3-((2-(piperazin-4-yl)ethyl)imino)but-1-en-1-ol and HL² = 4-((2-(piperazin-1-yl)ethyl)imino)pent-2-en-2-ol] using the chair conformer of a flexible piperazinyl moiety. Structural analysis reveals that 1 and 3 are monomeric Cu(II) complexes consisting of five- and six-coordinate Cu(II), respectively, whereas 2 is a dinuclear Cu(II) complex consisting of two different Cu(II) centers, one square planar with the other distorted octahedral. Screening tests were conducted to quantify the binding of 1–3 towards DNA and BSA as well as the DNA cleavage activity of these complexes using gel electrophoresis. Enzyme kinetic studies were also performed for the complexes mimicking catecholase-like activities. Antibacterial activities of these complexes were also examined towards Methicillin-Resistant Staphylococcus aureus bacteria. The results reflect that 2 is more active than the monomeric complexes, which is further corroborated by density functional theory study.     

Synthesis,crystal structure and fluorescence properties of two dinuclear zinc(II) complexes incorporating tridentate (NNO) Schiff bases

Reactions of hydrated zinc(II) trifluoroacetate and sodium azide with two tridentate Schiff bases HL¹ (2-((E)-(2-(dimethylamino)ethylimino)methyl)-4-chlorophenol) and HL² (2-((E)-(2-(dimethylamino)ethylimino)methyl)-4-bromophenol) under the same reaction conditions yielded two dinuclear isostructural zinc(II) complexes, [Zn(L¹)(N₃)]₂ (1) and [Zn(L²)(N₃)]₂ (2), respectively. The complexes were characterized systematically by elemental analysis, UV–Vis, FT-IR, and ¹H NMR spectroscopic methods. Single-crystal X-ray diffraction studies reveal that each of the dinuclear complexes consists of two crystallographically independent zinc(II) ions connected by double bridging phenoxides. All zinc(II) ions in 1 and 2 are surrounded by similar donor sets and display distorted square–pyramidal coordination geometries. The ligands and complexes reveal intraligand ¹(π → π*) flourescence. The enhancement of the fluorescence intensities for the complexes compared to the ligands indicates their potential to serve as photoactive materials.     

配体尺度对配合物结构及光催化降解活性的调节:从零维到一维的Cu(Ⅱ)配合物

合成了桥联吡啶类配体2,6-二(3′-吡啶乙炔基)-4-甲基苯胺(L1)和未见文献报道的尺度更短的桥联吡啶配体2,6-二(3′-吡啶基)-4-甲基苯胺(L2),在常温下分别将其与一水合醋酸铜(Cu(OAc)2·H2O,OAc-=CH3CO2-)进行配位反应获得零维的配位大环分子[Cu2(L1)(OAc)4]2(1)和一维的配位聚合物{[Cu2(L2)(OAc)4]·2CH2Cl2·CH3CN}n(2)。对获得的2个配合物进行了X射线单晶衍射、傅里叶红外光谱、元素分析等方面的结构表征。对比其结构可以发现,配合物1和2中均存在{Cu2(OAc)4}的二核铜簇,不同的是2个配合物中配体的配位取向不同:配位大环化合物1中的配体L1以U型构型与二核铜簇形成了“2+2”的平面配位大环结构,而化合物2中的配体L2则以Z型构型连接相邻的二核铜簇形成一维链状结构。2个化合物的结构差异是由于配体的尺度导致的,更短的尺度使得配位氮原子取向发生改变而产生不同的配位构型,这显示了结构调控中配体尺度的影响作用。通过测定配体与配合物在固态下的荧光发射性质,证实了铜的引入会猝灭配体自身的荧光发射;同时,采用亚甲基蓝(MB)为底物的光催化降解实验证明,大环配位分子的光催化降解活性明显优于一维配位聚合物,两者的催化活性均远远强于醋酸铜本身的催化活性。     

Syntheses,characterizations, crystal structures,antibacterial and SOD-like activities of nickel(II) and copper(II) complexes with 2-((Z)-(4-methoxyphenylimino)methyl)-4,6-dichlorophenol

Three mononuclear nickel(II) and copper(II) complexes, [Ni(L)₂(py)₂] (1), [Ni(L)₂(DMF)(H₂O)] (2), and [Cu(L)₂] (3), where HL = 2-((Z)-(4-methoxyphenylimino)methyl)-4,6-dichlorophenol, py = pyridine and DMF = N,N-dimethylformamide, have been synthesized and their structures determined by single crystal X-ray analysis. Complexes 1–3 crystallized in the monoclinic system of the space groups C2/c, P2_1/n, and P2_1/c, respectively. The crystal structures of 1 and 2 present an octahedral geometry at the metal center and 3 shows a square-planar geometry. The FT-IR spectra, UV–vis spectra, and magnetic susceptibility measurements agree with the observed crystal structures. EPR spectra indicate a d_x2–y2 ground state (g_|| > g_⊥ > 2.0023 and A_|| > A_⊥) for 3 at RT and LNT. The results of simultaneous TG-DTA analyses of 1 and 3 showed the final degradation products are NiO for 1 and CuO for 3. The Schiff base (HL) behaves as monobasic bidentate ligand possessing N and O donor atoms. Electrochemical properties for the complexes are similar and involve two irreversible redox processes. Complex 3 exhibits the ability to inhibit jack bean urease, although its Schiff base has no ability to inhibit urease. Complex 1 exhibits more active scavenging effects against O₂^? than HL, 2 and 3 under the same conditions. Antibacterial screening activities of these complexes were also investigated.     

New polynuclear compounds based on N-benzyliminodipropionic acid: solution studies,synthesis, and X-ray crystal structures

Three new polynuclear compounds based on a dicarboxylic acid ligand are reported. In particular, two Cu(II) coordination compounds, [Cu₂(H₂O)₆(Hbzlidp)₂](CF₃SO₃)₂·2H₂O (1) and [Cu(NO₃)(Hbzlidp)]_∞ (2) (bzlidp^2? = N-benzyliminodipropionate anion), and a Ni(II) dinuclear compound, [Ni₂(H₂O)₄(bzlidp)₂] (3), were synthesized and characterized by IR spectroscopy, elemental analysis and single crystal X-ray diffraction. Different structures were obtained depending on the reaction conditions. The structural analyses reveal that 1 was formed by dinuclear [Cu₂(H₂O)₆(Hbzlidp)₂]²⁺ units built by two copper(II) ions joined through two Hbzlidp^? ligands, while 2 was formed by pairs of Cu(II) centers bridged by four syn,syn carboxylate groups to generate “paddle wheel” units. The dinuclear copper units are arranged in a rhombus type grid, in a 2-D layer structure. In both cases, the N was protonated and not coordinated to the metal center. Compound 3 was formed by [Ni₂(H₂O)₄(bzlidp)₂] neutral dinuclear units, with octahedral Ni(II) centers. Solution studies of the ligand–M(II) systems (M(II) = Mn, Co, Ni, Cu, Zn, Cd, and Pb) were also carried out.     

Synthesis,crystal structures,and DNA-binding studies of two silver(I) complexes with 1,3-bis(1-ethylbenzimidazol-2-yl)-2-thiapropane

Two new silver(I) complexes, [Ag(bebt)(methacrylate)] (1) and [Ag₂(bebt)₂](pic)₂ (2) (bebt = 1,3-bis(1-ethylbenzimidazol-2-yl)-2-thiapropane, pic = picrate), have been synthesized and characterized by physico-chemical and spectroscopic methods. Single-crystal X-ray diffraction revealed that the structure of 1 was four-coordinate in a distorted tetrahedral geometry, while in 2, it may be described as a 2 + 1 coordinated silver(I) compound with a nearly linear N–Ag–N backbone and a weak Ag–S interaction. Two ligands are arranged in a face-to-face syn conformation to coordinate to two Ag(I) ions from opposite directions in 2, generating a U-type double layer structure around the metal ions. Experimental studies of the DNA-binding properties indicated that free bebt and both complexes bind to DNA via intercalation, and the order of the binding affinity is 2 > 1 > bebt.     

Synthesis,structural, electrochemical,and spectroscopic studies of some (diimine)ruthenium nitrile complexes

The syntheses of cationic ruthenium(II) complexes [Ru(Me₂-bpy)(PPh₃)₂RR?][PF₆]_x {Me₂-bpy = 4,4?-dimethyl-2,2?-bipyridine, (3) R = Cl, R? = N≡CMe, x = 1, (4) R = Cl, R? = N≡CPh, x = 1, (5) R = R? = N≡CMe, x = 2} and [Ru(Me₂-bpy)(κ²-dppf)RR?][PF₆]_x {dppf = 1,1?-bis(diphenylphosphino)ferrocene, (6) R = Cl, R? = N≡CMe, x = 1, (7) R = Cl, R? = N≡CPh, x = 1, (8) R = R? = N≡CMe, x = 2} are reported, together with their structural confirmation by NMR (³¹P, ¹H) and IR spectroscopy and elemental analysis, and, in the case of trans-[Ru(Me₂-bpy)(PPh₃)₂(N≡CCH₃)Cl][PF₆] (3), by X-ray crystallography. Electronic absorption and emission spectra of the complexes reveal that all complexes except 4 and 6 are emissive in the range 370–400 nm with 8 exhibiting an emission in the blue. Cyclic voltammetry studies of 3–8 show reversible or quasi-reversible redox processes at ca. 1 V, assigned to the Ru(II/III) couple.