Rapid and selective detection of biothiols by novel ruthenium(II) complex-based phosphorescence probes.

Considering the excellent photochemical properties of ruthenium(II) complexes, two new ruthenium(II) complexes, RuL1-DNBS and RuL2-DNBS, have been developed as phosphorescence probes for detection of biothiols in 100:1 (v/v) Hepes buffer (20 mM, pH = 7.2)/CH3CN solution. The response rate was highly improved of these two probes toward biothiols because the steric interactions between 1H-imidazo [4, 5-f] [1,10] phenanthroline group and ortho-2, 4-dinitrobenzensulfonate resulted in a relatively rapid thiol-induced SNAr substitution reaction. RuL1-DNBS and RuL2-DNBS were weakly phosphorescent owing to the effectual photoinduced electron transfer from ruthenium(II) luminophore to the sensing group, 2,4-dinitrobenzenesulfonyl. After reacting with biothiols, the 2,4-dinitrobenzenesulfonyl group of RuL1-DNBS and RuL2-DNBS were cleavaged and the RuL1 and RuL2 were obtained. Meanwhile, the phosphorescence were "turn-on". Both of these two probes can detect biothiols sensitively and selectively under physiological conditions with submicromolar detection limits. Furthermore, application of RuL2-DNBS for detecting of intracellular biothiols has been successfully performed in living Glioma cells.

pH-Switchable "Off-On-Off" Near-Infrared Luminescence Based on a Dinuclear Ruthenium(II) Complex.

The pH-switchable room-temperature near-infrared (NIR) phosphorescence emission based on ruthenium(II) polypyridyl complexes has been very rarely reported, even though it is very desirable for applications in sensing, switching, and logic molecular devices and bioimaging. Here we report a novel dinuclear ruthenium(II) complex in an aerated acetonitrile solution featuring a bright NIR emission centered at 760 nm with an absolute quantum yield of 1.03%, a large Stokes shift of 254 nm, and a long emission lifetime of 108.3 ± 0.4 ns. The complex in a Britton-Roberson buffer also exhibited pH-induced "off-on-off" NIR luminescent switches with a maximum intensity enhancement factor of 41 and one of the switching events occurring near the physiological pH range.

Off-on-off pH luminescence switching and DNA binding properties of a free terpyridine-appended ruthenium complex.

A ruthenium(II) complex [Ru(bpy)2(HL(1))](ClO4)2·3H2O {bpy=2,2'-bipyridine and HL(1)=2-(2,6-di(pyridin-2-yl)pyridin-4-yl)-1H-imidazo[4,5-f][1,10]phenanthroline}, denoted as RuHL(1), was synthesized and characterized by elemental analysis, proton nuclear magnetic resonance spectroscopy, and mass spectrometry. The pH effects on the UV-visible (UV-vis) absorption and emission spectra and the luminescence lifetimes of RuHL(1) have been studied, and their ground- and excited-state acid ionization constants were derived. The complex was found to exhibit pH-induced "off-on-off" luminescence switching properties via protonation/deprotonation of the grafted imidazole and terpyridyl groups. A pH-induced emission on-off intensity ratio of 166 was observed as pH was increased from 2.00 to 5.44, which is one of the largest values observed among imidazole-containing Ru(II) complex-based acidic-pH-induced pH luminescence switches. RuHL(1) also strongly binds to calf thymus DNA in mixed binding modes involving classic intercalation and partial intercalation, as determined by UV-vis absorption and emission spectrophotometric DNA titration, ethidium bromide displacement, DNA denaturation and DNA viscosity measurements.

pH luminescence switching, dihydrogen phosphate sensing, and cellular uptake of a heterobimetallic ruthenium(II)-rhenium(I) complex.

A new heterobimetallic ruthenium(II)-rhenium(I) complex of [Ru(bpy)2(HL)Re(CO)3Cl](ClO4)2·6H2O (RuHLRe) {bpy = 2,2'-bipyridine and HL = 2-(4-(2,6-di(pyridin-2-yl)pyridin-4-yl)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline} was synthesised and characterised by elemental analysis, proton nuclear magnetic resonance spectroscopy, and mass spectrometry. The ground- and excited-state acid-base properties of RuHLRe were studied using UV-Vis absorption spectrophotometric and spectrofluorimetric titrations in a 100 : 1 (v/v) Britton-Robinson buffer-CH3CN solution combined with luminescence lifetime measurements. The complex exhibited two-step separate protonation-deprotonation processes in both the ground and excited states. The complex acted as pH-induced "off-on-off" luminescence switches (I(on)/I(off) = 31.0 and 14.6), with one of the switching actions being driven by pH variations over the physiological pH range (5.3-8.0). Importantly, cellular imaging and cytotoxicity experiments demonstrated that RuHLRe rapidly and selectively illuminated the membrane of HeLa cells over fixed cells and exhibited reduced cytotoxicity at the imaging concentration compared to the Re(I)-free parent Ru(II) complex. In addition, RuHLRe acted as an efficient "turn on" emission sensor for H2PO4(-) and "turn off" emission sensor for F(-) and OAc(-).

Layer-by-layer assembly of graphene oxide and a Ru(II) complex and significant photocurrent generation properties.

The multilayer films were fabricated by layer-by-layer electrostatically coassembling graphene oxide and a ruthenium complex of [Ru(bpy)2L](ClO4)2 {L = 2-(2,6-di(pyridin-2-yl)pyridine-4-yl)-1H-imidazo[4,5-f]-1,10-phenanthroline} and characterized using UV-vis absorption spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and cyclic voltammetry. The dependence of redox properties and cathodic photocurrents on the number of layers deposited and the photocurrent generation mechanism and polarity were studied in detail. The homogeneous growth and close packing of the two film-forming components, linear relationships of the dark cyclic voltometry peak currents and photocurrents vs number of layers deposited, and large cathodic photocurrent density of 4.1 µA/cm(2) for a four-layer film make this novel hybrid thin film promising applications ranging from molecular photovoltaic and photocatalytic molecular devices to photoelectrochemical sensing.

Photoelectrochemical properties of electrostatically self-assembled multilayer films formed by a cobalt complex and graphene oxide.

The multilayer films consisting of graphene oxide and a cobalt complex were fabricated though electrostatic layer-by-layer self-assembly technique and characterized by UV-Vis absorption spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and cyclic voltammetry. The results demonstrated that the hybrid films were successfully prepared and exhibited good electrochemical activity. The film was also subjected to photoelectrochemical studies and were found to exhibit large cathodic photocurrent density of 6.1 µA/cm(2) while irradiated with 100 mW/cm(2) polychromatic light (730 nm>λ>325 nm) at an applied potential of -0.4V versus saturated calomel electrode.

pH luminescence switch, DNA binding and photocleavage, and cytotoxicity of a dinuclear ruthenium complex.

The ground- and excited-state acid-base properties of [Ru2(bpy)4(H2bipt)]Cl4 1 {bpy = 2,2'-bipyridine, H2bipt = 2,5-bis[1,10]phenanthrolin[4,5-f]-imidazol-2-yl)thiophene} are investigated by emission and UV-visible absorption spectrophotometric pH titrations. The DNA binding properties of 1 are studied by means of DNA viscosity and optical spectroscopic techniques of UV-visible absorption and emission spectral titrations, steady-state emission quenching with ferrocyanide, ethidium bromide competitive binding, and DNA thermal denaturation as well as density functional theoretical calculations. The DNA photocleavage and singlet oxygen generation properties as well as in vitro anticancer activities against five cancer cell lines are studied as well. The results demonstrated that pH-induced luminescence switching, DNA binding, and anticancer properties of 1 are much improved with respect to those of the mononuclear analog [Ru(bpy)2(Htip)]Cl2 {Htip = 2-(thiophen-2-yl)-1H-imidazo[4,5-f][1,10]phenanthroline}.

Highly sensitive and selective difunctional ruthenium(II) complex-based chemosensor for dihydrogen phosphate anion and ferrous cation.

The anion-interaction properties of a Ru(II) complex of [Ru(bpy)2(Htppip)](ClO4)2·H2O·DMF (RuL) {bpy =2,2'-bipyridine and Htppip =2-(4-(2,6-di(pyridin-2-yl)pyridin-4-yl)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline} were thoroughly investigated in CH3CN and CH3CN/H2O (50:1, v/v) solutions by UV-visible absorption, emission, and (1)H NMR spectra. These analyses revealed that RuL acts as an efficient "turn on" emission sensor for H2PO4(-), and a "turn off" sensor for F(-) and OAc(-); in addition, RuL exhibited slightly disturbed emission spectra in the presence of the other anions studied (Cl(-), Br(-), I(-), NO3(-), and ClO4(-)). The cation-sensing properties of RuL were also studied in both neat CH3CN and aqueous 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid buffer (pH = 7.2)/CH3CN (71/1, v/v) solutions. RuL was found to exhibit a colorimetric sensing ability that was highly selective for Fe(2+), as evidenced by an obvious color change from pale yellow to light red-purple to the naked eye over the other cations studied (Na(+), Mg(2+), Ba(2+), Mn(2+), Fe(3+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+), and Ag(+)). To obtain insights into the possible binding modes and the sensing mechanisms, (1)H NMR spectral analysis, luminescence lifetime measurements, and density functional theoretical calculations were also performed.

1:1 Adducts of 2,2'-[isopropylidenebis(p-phenyleneoxy)]diacetic acid with dimethylammonium and 4,4'-bipyridine.

The title compounds, dimethylammonium 2-{4-[1-(4-carboxymethoxyphenyl)-1-methylethyl]phenoxy}acetate, C(2)H(8)N(+).C(19)H(19)O(6)(-), (I), and 2,2'-[isopropylidenebis(p-phenyleneoxy)]diacetic acid-4,4'-bipyridine (1/1), C(19)H(20)O(6).C(10)H(8)N(2), (II), are 1:1 adducts of 2,2'-[isopropylidenebis(p-phenyleneoxy)]diacetic acid (H(2)L) with dimethylammonium or 4,4'-bipyridine. The component ions in (I) are linked by N-H...O, O-H...O and C-H...O hydrogen bonds into continuous two-dimensional layers parallel to the (001) plane. Adjacent layers are stacked via C-H...O hydrogen bonds into a three-dimensional network with an -ABAB- alternation of the two-dimensional layers. In (II), two H(2)L molecules, one bipy molecule and two half bipy molecules are linked by O-H...N hydrogen bonds into one-dimensional chains and rectanglar-shaped rings. They are assembled via pi-pi stacking interactions and C-H...O hydrogen bonds into an intriguing zero-dimensional plus one-dimensional poly(pseudo)rotaxane motif.

Chlorido(5-formyl-2-hydroxy-phenyl-κC)mercury(II).

In the planar (r.m.s. deviation = 0.027 Å) title compound, [Hg(C(7)H(5)O(2))Cl], the Hg(II) atom shows a typical linear coordination by a C atom of the benzene ring and a Cl atom. Inter-molecular O-H⋯O hydrogen bonds are present in the crystal structure, resulting in chains propagating along the b axis. The crystal studied was a non-merohedral twin, with a twin ratio of 0.802 (2):0.198 (2).

(2E,5E)-2,5-Difurfurylidenecyclo-penta-none.

In the title mol-ecule, C(15)H(12)O(3), the three five-membered rings are nearly coplanar: the dihedral angles between the cyclopentanone ring and the furan rings are 3.5 (2) and 9.7 (2)°, and the two furan rings form a dihedral angle of 7.2 (2)°. In the crystal structure, weak inter-molecular C-H⋯O hydrogen bonds help to consolidate the crystal packing.

(2E,6E)-2,6-Difurfurylidenecyclo-hexa-none.

The complete mol-ecule of the title compound, C(16)H(14)O(3), is generated by crystallographic mirror symmetry, with two C atoms and one O atom lying on the mirror plane. The mol-ecule adopts an E configuration about the C=C bond and the dihedral angle between the furan rings is 16.1 (2)°.

Sodium (1R,2S,5S)-2-hydr-oxy-6,6-dimethyl-bicyclo-[3.1.1]heptane-2-carboxyl-ate penta-hydrate.

In the title compound, Na(+)·C(10)H(15)O(3) (-)·5H(2)O, the vertices of a distorted octa-hedron centred on the Na(+) cation are defined by six O atoms of water mol-ecules. The edge-sharing Na(H(2)O)(6) octa-hedra form a chain extended along the b-axis direction with adjacent Na(+) cations related by a twofold screw symmetry operation. The organic anion, which is not in close contact with the Na(+ )cation, is hydrogen-bonded to an uncoordinated water mol-ecule and to water mol-ecules of the Na(H(2)O)(6) octa-hedra.

(E)-N'-(4-Pyridylmethyl-ene)-2-(quinolin-8-yl-oxy)acetohydrazide sesquihydrate.

In the title compound, C(17)H(14)N(4)O(2)·1.5H(2)O, the mean planes of the pyridine ring and quinoline group make a dihedral angle of 21.0 (2)°. One water molecule lies on a twofold rotation axis. The organic mol-ecules and the three water mol-ecules are linked into infinite chains by N-H⋯O, O-H⋯O and O-H⋯N hydrogen bonds.