Flexible Quasi‐Solid State Ionogels with Remarkable Seebeck Coefficient and High Thermoelectric Properties

Thermoelectric materials can be used to harvest low‐grade heat that is otherwise dissipated to the environment. But the conventional thermoelectric materials that are semiconductors or semimetals, usually exhibit a Seebeck coefficient of much less than 1 mV K^?1. They are expensive and consist of toxic elements as well. Here, it is demonstrated environmental benign flexible quasi‐solid state ionogels with giant Seebeck coefficient and ultrahigh thermoelectric properties. The ionogels made of ionic liquids and poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) can exhibit a giant Seebeck coefficient up to 26.1 mV K^?1, the highest for electronic and ionic conductors. In addition, they have a high ionic conductivity of 6.7 mS cm^?1 and a low thermal conductivity of 0.176 W m^?1 K^?1. Their thermoelectric figure of merit (ZT) is thus 0.75. The giant Seebeck coefficient is related to the ion‐dipole interaction between PVDF‐HFP and ionic liquids. Their application in ionic thermoelectric capacitors is also demonstrated for the conversion of intermittent heat into electricity. They are especially important to harvest the low‐grade thermal energy that is abundant on earth.     

Supported Ionic Liquid Gel Membrane Electrolytes for Flexible Supercapacitors

In this work, a novel and easy‐to‐use methodology is developed to prepare supported ionic liquid gel membranes (SILGMs) by incorporating ionogels into commercial porous supports, to use as both electrolytes and separators for supercapacitors. Macroscopic sol–gel transition temperature, Fourier transform infrared spectra, and thermal behaviors of the ionogels are systematically investigated. Ionic conductivities of the ionogels and SILGMs are measured from 25 to 100 °C. The ionic conductivities of the ionogels are lower by one order of magnitude once they are incorporated into the supports. Nonetheless, the ionic conductivity of the SILGMs has reached the practical application level required for energy storage and conversion devices. Furthermore, the stability and flexibility of SILGMs are investigated as flexible electrolytes for supercapacitor devices (see Video in the Supporting Information). Charge–discharge cycling of symmetric supercapacitors based on the SILGMs reveal specific capacitance as high as 153 F g⁻¹ at 0.1 A g⁻¹, and remain at 101 F g⁻¹ at 10 A g⁻¹. The capacitance retention after 10 000 charge–discharge cycles at 5.0 A g⁻¹ is as high as 97%, demonstrating excellent cycle stability of the device. The studies suggest that SILGMs are promising candidates for stable, high performance, and flexible energy storage and conversion devices that could be made by high volume roll‐to‐roll processing.     

Ionogel Electrolytes for High‐Performance Lithium Batteries: A Review

Ionic liquids (ILs) are important electrolytes for applications in electrochemical devices. An emerging trend in ILs research is their hybridization with solid matrices, named ionogels. These ionogels can not only overcome the fluidity of ILs but also exhibit high mechanical strength of the solid matrix. Therefore, they show promise for applications in building lithium batteries. In this review, various types of solid matrices for confining ILs are summarized, including nonmetallic oxides, metal oxides, IL‐tethered nanoparticles, functionalized SiO₂, metal–organic frameworks, and other structural materials. The synthetic strategies for ionogels are first documented, focusing on physical confinement and covalent grafting. Then, the structure, ionic conductivity, thermal stability, and electrochemical stability of ionogels are addressed in detail. Furthermore, the authors highlight the potential applications of state‐of‐art ionogels in lithium batteries. The authors conclude this review by outlining the remaining challenges as well as personal perspectives on this hot area of research.     

Enantiomeric Specificity of Biologically Significant Cu(II) and Zn(II) Chromone Complexes Towards DNA

Novel chiral Schiff base ligands (R)/(S)‐2‐amino‐3‐(((1‐hydroxypropan‐2‐yl)imino)methyl)‐4H‐chromen‐4‐one (L₁ and L₂) derived from 2‐amino‐3‐formylchromone and (R/S)‐2‐amino‐1‐propanol and their Cu(II)/Zn(II) complexes ( R1 , S1 , R2 , and S2 ) were synthesized. The complexes were characterized by elemental analysis, infrared (IR), hydrogen (¹H) and carbon (¹³C) nuclear magnetic resonance (NMR), electrospray ionization‐mass spectra (ESI‐MS), and molar conductance measurements. The DNA binding studies of the complexes with calf thymus were carried out by employing different biophysical methods and molecular docking studies that revealed that complexes R1 and S1 prefers the guanine–cytosine‐rich region, whereas R2 and S2 prefers the adenine–thymine residues in the major groove of DNA. The relative trend in K_b values followed the order R1 S1 R2 S2 . This observation together with the findings of circular dichroic and fluorescence studies revealed maximal potential of (R)‐enantiomeric form of complexes to bind DNA. Furthermore, the absorption studies with mononucleotides were also monitored to examine the base‐specific interactions of the complexes that revealed a higher propensity of Cu(II) complexes for guanosine‐5′‐monophosphate disodium salt, whereas Zn(II) complexes preferentially bind to thymidine‐5′‐monophosphate disodium salt. The cleavage activity of R1 and R2 with pBR322 plasmid DNA was examined by gel electrophoresis that revealed that they are good DNA cleavage agents; nevertheless, R1 proved to show better DNA cleavage ability. Topoisomerase II inhibitory activity of complex R1 revealed that the complex inhibits topoisomerase II catalytic activity at a very low concentration (25 μM). Furthermore, in vitro antitumor activity of complexes R1 and S1 were screened against human carcinoma cell lines of different histological origin. Chirality 24:977–986, 2012. © 2012 Wiley Periodicals, Inc.     

Platinum(II) Complexes with 1,10‐Phenanthroline and Hydrophilic Alkoxyacetate Ligands as Potential Antitumor Agents

Four platinum complexes, formulated as [Pt(phen)(OCOCH₂OR)₂] (phen=1,10‐phenanthroline, R=Me, Et, ⁱPr, or ^tBu), have been synthesized and well characterized by elemental analysis, IR, ¹H‐NMR, ¹³C‐NMR and ESI‐MS spectroscopy. Replacing chloride groups of the precursor Pt(phen)Cl₂ with alkoxyacetate anions greatly improved the aqueous solubility and cytotoxicity of the resulting platinum complexes. The in vitro cytotoxicity study revealed that complexes 1 – 3 were active in vitro towards four human tumor cell lines, especially complex 1 which exhibited prominent in vitro cytotoxic activity against HCT‐116 cell lines comparable to cisplatin and oxaliplatin. Flow cytometry assay indicated that representative complexes 1 and 2 exerted cytotoxicity on HCT‐116 cell lines through inducing cell apoptosis and blocking cell cycle progression in the S or G2/M phases. The interaction of representative complexes with pET28a plasmid DNA was tested by agarose gel electrophoresis, which demonstrated that complexes 1 and 2 were capable of distorting plasmid DNA mainly by covalent binding and degradation effect.     

Bifunctional Platinum(II) Complexes with Bisphosphonates Substituted Diamine Derivatives: Synthesis and In vitro Cytotoxicity

A series of N,N′‐dibisphosphonate‐containing 1,3‐propanediamine derivatives ( L1 – L6 ) and their corresponding dichloridoplatinum(II) complexes ( 1 – 6 ) have been synthesized and characterized by elemental analysis, ¹H‐NMR, ¹³C‐NMR, ³¹P‐NMR and HR‐MS spectra. The in vitro antitumor activities of compounds L1 – L6 and 1 – 6 were tested by WST‐8 assay with Cell Counting Kit‐8, indicating that platinum‐based complexes 1 – 6 showed higher cytotoxicity than corresponding ligands L1 – L6 against A549 and MG‐63, especially complex 2 which displayed comparable cytotoxicity to those of cisplatin and zoledronate after 48 h incubation. In addition, complexes 1 – 6 were more active in vitro on osteosarcoma cell line MG‐63 than normal osteoblast cell line hFOB 1.19. The structure‐activity relationship has been summarized based on the in vitro cytotoxicity of three series of platinum complexes from this and our previous studies. The in vitro bone affinity of platinum complexes was also tested by hydroxyapatite (HAP) chromatography in terms of capacity factor K′. Besides, in this paper, representative complex 2 , which has been proved to be a promising antitumor agent with high cytotoxicity and bone HAP binding property, was investigated for its mechanism of action producing cell death against MG‐63.     

Synthesis and chiroptical properties of organometallic complexes of helicenic N‐heterocyclic carbenes

Novel [4, 6]helicenes ( 4a,b ) bearing a fused imidazolium unit have been prepared from [4, 6]helicene‐2,3‐di‐n‐propyl‐amines 3a,b . The in situ formation of N‐heterocyclic carbene (NHC) derivatives followed by their complexation to iridium(I) or rhodium(I) gave access to complexes 1a , 1′a , and 1b , containing mono‐coordinated helicene‐NHC, chloro and COD (COD = 1,5‐cyclooctadiene) ligands. Ir and Rh complexes 1a and 1′a were characterized by X‐ray crystallography. HPLC and NMR analyses showed that Ir(I) complex 1b existed as a mixture of two diastereomeric complexes corresponding to enantiomeric pairs M‐(?)/P‐(+)‐ 1b ¹ and M‐(?)/P‐(+)‐ 1b ² which differ by the position of COD through space. The chiroptical properties (electronic circular dichroism and optical rotation) of the four stereoisomers were measured. These complexes were also tested as catalysts in a transfer hydrogenation reaction.     

Synthesis,Crystal Structure,and Biological Activities of Two Chiral Mononuclear Mn(III) Complexes

Two new chiral mononuclear Mn^(III) complexes, [Mn L ^{( R )}Cl (C₂H₅OH)]?C₂H₅OH ( 1 ) and [Mn L ^{( S )} (CH₃OH)₂]Cl?CH₃OH ( 2 ), {H₂ L = (R,R)‐or (S,S)‐N,N’‐bis‐(2‐hydroxy‐1‐naphthalidehydene)‐cyclohexanediamine} were synthesized and characterized by various physicochemical techniques. Bond valence sum (BVS) calculations and the Jahn‐Teller effect indicate that the Mn centers are in a +3 oxidation state. The statuses of the two complexes in the solution were confirmed as a pair of enantiomers by electrospray ionization, mass spectrometry (ESI‐MS) spectrum. The binding ability of the complexes with calf thymus CT‐DNA was investigated by spectroscopic and viscosity measurements. Both of the complexes could interact with CT‐DNA via an intercalative mode with the order of 1 ( R ‐enantiomer) > 2 ( S ‐enantiomer). Under the physiological conditions, the two compounds exhibit efficient DNA cleavage activities without any external agent, which also follows the order of R ‐enantiomer > S ‐enantiomer. Interestingly, the concentration‐dependent DNA cleavage experiments indicate an optimal concentration of 17.5 μM. In addition, the interaction of the compounds with bovine serum albumin (BSA) was also investigated, which indicated that the complexes could quench the intrinsic fluorescence of BSA by a static quenching mechanism. Chirality 27:142‐150, 2015. © 2014 Wiley Periodicals, Inc.     

Basic polypeptides as histone models. Synthesis, conformation, and interaction with DNA of statistical copolymers (Lys x,Ala y)n.

Statistical copolymers (Lys^x,Ala^y)_n were synthesized by copolymerization of N-carboxyanhydrides of L -amino acids. The conformation of copolymers in aqueous solutions was investigated using circular dichroism (CD). Calculations based on the CD data showed that polymers (Lys^x,Ala^y)_n can exhibit a random conformation, an α-helix, and a β-structure in various ratios. CD spectra of complexes of copolymers with DNA prepared by gradual dialysis from a high ionic strength to 0.15 M NaCl can be correlated with the copolymer conformation in medium and high ionic strength. For copolymers forming an α-helix and β-structure, these spectra show resemblance with similar spectra of complexes of those histones that are able to exhibit ordered conformations.     

Synthesis of Catechin‐Rare Earth Complex with Efficient and Broad‐Spectrum Anti‐Biofilm Activity

Biofilm is the crucial reason of clinical infections. Herein, green tea based polyphenol (catechin) and rare earth (RE) metal ions were employed for the preparation of catechin–RE complexes with significant anti‐biofilm properties. The complexes were characterized by FT‐IR, Raman spectroscopy, X‐ray photoelectron spectroscopy (XPS) and dynamic light scattering (DLS), which suggested that catechin coordinated with RE³⁺ through its ortho phenolic hydroxy groups. The prepared catechin‐RE showed significant effects in anti‐biofilm growth against P. aeruginosa (Gram‐negative bacteria), S. sciuri (Gram‐positive bacteria), and A. niger (fungi), which significantly exceeded the utilization of catechin or RE³⁺. Morphological observations indicated that catechin supplied cell affinity to transfer RE³⁺ and helped to damage cell membrane, which act as a carrier to exert cytotoxicity of RE³⁺ to realize anti‐biofilm. Differential gene expression analysis described gene expression changes induced by catechin‐RE, including 56, 272 and 2160 downregulated genes for P. aeruginosa, S. sciuri and A. niger, respectively, which suggested critical changes in cellular metabolism, growth and other processes. These results illustrate the outstanding superiority of catechin‐RE complexes in anti‐infection aspect, i. e., the green tea based rare earth complexes are promising candidates for anti‐biofilm applications to address serious challenges in the prevention of multiple infections.     

Specific ion effects on macromolecular interactions in Escherichia coli extracts

Protein characterization in situ remains a major challenge for protein science. Here, the interactions of ΔTat‐GB1 in Escherichia coli cell extracts were investigated by NMR spectroscopy and size exclusion chromatography (SEC). ΔTat‐GB1 was found to participate in high molecular weight complexes that remain intact at physiologically‐relevant ionic strength. This observation helps to explain why ΔTat‐GB1 was not detected by in‐cell NMR spectroscopy. Extracts pre‐treated with RNase A had a different SEC elution profile indicating that ΔTat‐GB1 predominantly interacted with RNA. The roles of biological and laboratory ions in mediating macromolecular interactions were studied. Interestingly, the interactions of ΔTat‐GB1 could be disrupted by biologically‐relevant multivalent ions. The most effective shielding of interactions occurred in Mg²⁺‐containing buffers. Moreover, a combination of RNA digestion and Mg²⁺ greatly enhanced the NMR detection of ΔTat‐GB1 in cell extracts.     

Separation of hexahistidine fusion proteins with immobilized metal ion affinity chromatographic (IMAC) sorbents derived from MN+‐tacn and its derivatives

The capabilities of a new class of immobilized (im) metal ion chelate complexes (IMCCs), derived from 1,4,7‐triazacyclononane (tacn), bis(1,4,7‐triazacyclononyl) ethane (dtne) and bis(1,4,7‐triazacyclononyl)propane (dtnp) complexed with the borderline metal ions Cu²⁺, Ni²⁺, Zn²⁺, Mn²⁺, Co²⁺, and Cr³⁺, for the purification of proteins have been investigated. In particular, the binding behavior of a model protein, the C‐terminal hexahistidine tagged recombinant fusion protein Schistosoma japonicum glutathione S‐transferase‐Saccharomyces cerevisiae mitochondrial ATP synthase δ‐subunit (GST‐δATPase‐His₆), with these new immobilized metal ion affinity chromatographic (IMAC) sorbents was compared to the properties of a conventional sorbent, derived from immobilized Ni(II)‐nitrilotriacetic acid (im‐Ni²⁺‐NTA). Investigations using the recombinant GST‐δATPase‐His₆ and recombinant S. japonicum glutathione S‐transferase (GST) lacking a hexahistidine tag have confirmed that the C‐terminal tag hexahistidine residues were required for the binding process to occur with these IMAC systems. The results also confirm that recombinant fusion proteins such as GST‐δATPase‐His₆ can be isolated in high purity with these IMAC systems. Moreover, these new macrocyclic systems manifest different selectivity features as a function of pH or ionic strength when compared to the conventional, unconstrained iminodiacetic acid (IDA) or NTA chelating ligands, complexed with borderline metal ions such as Cu²⁺ or Ni²⁺, as IMAC systems. Biotechnol. Bioeng. 2009;103: 747–756. © 2009 Wiley Periodicals, Inc.     

Synthesis and Biophysical Studies of Bis‐Macrocyclic Cobalt/Copper(II) Complexes Having a Pyridine Spacer with CT DNA and 5′‐GMP

New bis‐macrocyclic complexes of Co^III, 1 , Ni^II, 2 , and Cu^II, 3 , containing pyridyl bridges between 13‐membered macrocyclic subunits, have been synthesized via an in situ one‐pot template condensation reaction (IOPTCR). The proposed structures of these new dinuclear complexes are consistent with the data obtained from elemental analysis, molar conductance, IR, EPR, UV/VIS, ¹H‐ and ¹³C‐NMR, and ESI‐MS. The complexes 2 and 3 possess square‐planar geometry with four secondary N‐atoms coordinated to the metal ion, while complex 1 reveals octahedral geometry in solution due to coordinated H₂O molecules. DNA‐Binding properties of the complexes 1 and 3 were investigated by absorption and emission titrations, cyclic voltammetry, and viscosity measurements. Complexes 1 and 3 are strong DNA binders with binding constants, K_b, of 1.64×10⁵ and 2.05×10⁵ M ^?1, respectively. Hyperchromism, decrease in emission intensity of DNA‐bound ethidium bromide (EB), and changes observed in the viscosity and cyclic voltammograms in the presence of added metal complexes reveals that the complexes bind to DNA predominantly by electrostatic attraction, substantiated by absorption titration with 5′‐GMP.     

Synthesis,Structural Characterization and Antimicrobial Evaluation of Ruthenium Complexes with Heteroaromatic Carboxylic Acids

The antibacterial and antibiofilm activities of two new ruthenium complexes against E. coli, S. aureus, P. aeruginosa PAO1 (laboratory strain) and P. aeruginosa LES B58 (clinical strain) were evaluated. Complexes, mer‐[Ru^III(2‐bimc)₃] ? H₂O ( 1 ) and cis‐[Ru^IVCl₂(2,3‐pydcH)₂] ? 4H₂O ( 2 ), were obtained using aromatic carboxylic acid ligands, namely, 1H‐benzimidazole‐2‐carboxylic acid (2‐bimcH) and pyridine‐2,3‐dicarboxylic acid (2,3‐pydcH₂). Compounds were physicochemically characterized using X‐ray diffraction, Hirshfeld surface analysis, IR and UV/VIS spectroscopies, as well as magnetic and electrochemical measurements. Structural characterization revealed that Ru(III) and Ru(IV) ions in the complexes adopt a distorted octahedral geometry. The intermolecular classical and weak hydrogen bonds, and π???π contacts significantly contribute to structure stabilization, leading to the formation of a supramolecular assembly. Biological studies have shown that the Ru complexes inhibit the growth of bacteria and biofilm formation by the tested strains and the complexes seem to be a potential as antimicrobial agents.     

2‐Hydroxynaphthalene‐1‐carbaldehyde‐ and 2‐(Aminomethyl)pyridine‐Based Schiff Base CuII Complexes for DNA Binding and Cleavage

Three mononuclear Cu^II complexes, [CuCl(naph‐pa)] ( 1 ), [Cu(bipy)(naph‐pa)]Cl ( 2 ), and [Cu(naph‐pa)(phen)]Cl ( 3 ) ((naph‐pa)=Schiff base derived from the condensation of 2‐hydroxynaphthalene‐1‐carbaldehyde and 2‐picolylamine (=2‐(aminomethyl)pyridine), bipy=2,2′‐bypiridine, and phen=1,10‐phenanthroline) were synthesized and characterized. Complex 1 exhibits square‐planar geometry, and 2 and 3 exhibit square pyramidal geometry, where Schiff base and bipy/phen act as NNO and as NN donor ligands, respectively. CT (Calf thymus)‐DNA‐binding studies revealed that the complexes bind through intercalative mode and show good binding propensity (intrinsic binding constant K_b: 0.98×10⁵, 2.22×10⁵, and 2.67×10⁵ M ^?1 for 1 – 3 , resp.). The oxidative and hydrolytic DNA‐cleavage activity of these complexes has been studied by gel electrophoresis: all the complexes displayed chemical nuclease activity in the presence and absence of H₂O₂. From the kinetic experiments, hydrolytic DNA cleavage rate constants were determined as 2.48, 3.32, and 4.10 h^?1 for 1 – 3 , respectively. It amounts to (0.68–1.14)×10⁸‐fold rate enhancement compared to non‐catalyzed DNA cleavage, which is impressive. The complexes display binding and cleavage propensity to DNA in the order of 3 > 2 > 1 .     

Synthesis,Characterization, and Biological Activities of Pendant Arm‐Pyridyltetrazole Copper(II) Complexes: DNA Binding/Cleavage Activity and Cytotoxic Studies

2‐(1H‐Tetrazol‐5‐yl)pyridine ( L ) has been reacted separately with Me₂NCH₂CH₂Cl?HCl and ClCH₂CH₂OH to yield two regioisomers in each case, N,N‐dimethyl‐2‐[5‐(pyridin‐2‐yl)‐1H‐tetrazol‐1‐yl]ethanamine ( L1 )/N,N‐dimethyl‐2‐[5‐(pyridin‐2‐yl)‐2H‐tetrazol‐2‐yl]ethanamine ( L2 ) and 2‐[5‐(pyridin‐2‐yl)‐1H‐tetrazol‐1‐yl]ethanol ( L3 )/2‐[5‐(pyridin‐2‐yl)‐2H‐tetrazol‐2‐yl]ethanol ( L4 ), respectively. These ligands, L1 – L4 , have been coordinated with CuCl₂?H₂O in 1 : 1 composition to furnish the corresponding complexes 1 – 4 . EPR Spectra of Cu complexes 1 and 3 were characteristic of square planar geometry, with nuclear hyperfine spin 3/2. Single X‐ray crystallographic studies of 3 revealed that the Cu center has a square planar structure. DNA binding studies were carried out by UV/VIS absorption; viscosity and thermal denaturation studies revealed that each of these complexes are avid binders of calf thymus DNA. Investigation of nucleolytic cleavage activities of the complexes was carried out on double‐stranded pBR322 circular plasmid DNA by using a gel electrophoresis experiment under various conditions, where cleavage of DNA takes place by oxidative free‐radical mechanism (OH ^? ). In vitro anticancer activities of the complexes against MCF‐7 (human breast adenocarcinoma) cells revealed that the complexes inhibit the growth of cancer cells. The IC₅₀ values of the complexes showed that Cu complexes exhibit comparable cytotoxic activities compared to the standard drug cisplatin.     

Study of SOD Mimic and Nucleic Acid Interaction Activity Exerted by Enrofloxacin‐Based Copper(II) Complexes

Five new copper(II) complexes of type [Cu(erx)( L )Cl] (erx, enrofloxacin; thiophene‐2‐carbaldehyde ( L ¹ ); pyridine‐2‐carbaldehyde ( L ² ); 2,2′‐dipyridylamine ( L ³ ); 4,5‐diazafluoren‐9‐one ( L ⁴ ); bis(3,5‐dimethyl‐1‐pyrazolyl)methane ( L ⁵ )) have been synthesized and characterized by elemental analysis, reflectance, IR, and FAB‐MS. Complexes have been investigated for their interaction with calf thymus (CT) DNA utilizing the absorption‐titration method, viscometric and DNA thermal denaturation studies. The cleavage reaction on pUC19 DNA has been monitored by agarose gel electrophoresis. The results indicated that the Cu^II complexes can more effectively promote the cleavage of plasmid DNA at physiological pH and superoxide dismutase. The (SOD) activity of the complexes has been evaluated by the nitroblue tetrazolium assay, and the complexes catalyzed the dismutation of superoxide at pH 7.8 with IC₅₀ values of 0.35–1.25 μM . The complexes have also been screened for their antibacterial activity against five pathogenic bacteria.     

Synthesis,Structure, DNA‐Binding Properties,and Cytotoxicity of Ruthenium(II) Polypyridyl Complexes

Many ruthenium(II) complexes show high antitumor activities, and the in vitro antitumor activities are usually related to DNA binding. We designed and synthesized two Ru^II polypyridyl complexes, [Ru(dmp)₂(fpp)]²⁺ (dmp=2,9‐dimethyl‐1,10‐phenanthroline; fpp=2‐[3,4‐(difluoromethylenedioxy)phenyl]imidazo[4,5‐f] [1,10]phenanthroline and [Ru(phen)₂(fpp)]²⁺ (phen=1,10‐phenanthroline). The DNA‐binding properties of these complexes have been investigated by spectroscopic titration, DNA melting experiments, viscosity measurements, and photoactivated cleavage. The mechanism studies of photocleavage revealed that singlet oxygen (¹O₂) and superoxide anion radical (O$\rm{{_{2}^{{^\cdot} -}}}$ ) may play an important role in the photocleavage. The cytotoxicity of complexes 1 and 2 have been evaluated by MTT (3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl‐2H‐tetrazolium bromide) method; complex 2 shows slightly higher anticancer potency than 1 does against all the cell lines screened.     

Electronic Effect of Substituents on the DNA Intercalation of Ruthenium(II)?Polypyridyl Complexes

Five ruthenium(II) complexes, i.e., [Ru(bpy)₂(TIP)]²⁺ (bpy=2,2′‐bipyridine; TIP=2‐thiophenimidazo[4,5‐f] [1,10]phenanthroline; 1 ), [Ru(bpy)₂(5‐NTIP)]²⁺ (5‐NTIP=2‐(5‐nitrothiophen)imidazo[4,5‐f] [1,10]phenanthroline; 2 ), [Ru(bpy)₂(5‐MOTIP)]²⁺ (5‐MOTIP=2‐(5‐methoxythiophen)imidazo[4,5‐f] [1,10]phenanthroline; 3 ), [Ru(bpy)₂(5‐BTIP)]²⁺ (5‐BTIP=2‐(5‐bromothiophen)imidazo[4,5‐f] [1,10]phenanthroline; 4 ), and [Ru(bpy)₂(4‐BTIP)]²⁺ (4‐BTIP=2‐(4‐bromothiophen)imidazo[4,5‐f] [1,10]phenanthroline; 5 ), were synthesized and characterized by elemental analysis and UV/VIS, IR, and ¹H‐NMR spectroscopic methods. The photophysical and DNA‐binding properties were investigated by means of UV and fluorescence spectroscopic methods and viscosity measurements, respectively. The results suggest that all five complexes can bind to CT‐DNA with various binding strength. Complexes 2 and 3 showed the strongest and the weakest binding affinity, respectively, among these five complexes. Due to the substituent position of the Br‐atom in the ligand, complex 5 interacted stronger with CT‐DNA than complex 4 . The binding affinities of the complexes decreased in the order 2, 5, 4, 1 , and 3 .