Aqueous emissive cyclometalated iridium photoreductants: synthesis, computational analysis and the photocatalytic reduction of 4-nitrophenol.

Herein, we present luminescent mononuclear iridium complexes [1]-[4] using NEt-appended C^N chelating benzimidazole (L1-L4) and semi-flexible phenanthroline-pyrazine-based () ligands exhibiting photocatalytic reduction of 4-nitrophenol (4-NP) in the presence of NEt in an aqueous medium. The formation of [1]-[4] was confirmed by HRMS, H-H COSY, and C and F NMR spectroscopy. The complex [4] is water soluble, whereas the others ([1]-[3]) are partially soluble.

Aggregation induced emission and volatile acid vapour sensing in acridine appended poly (aryl ether) based low molecular weight organogelator.

Considerable research attention has been devoted to the development of portable and rapid fluorescence sensors that can selectively detect volatile acids, due to the harmful effects of acid vapour on the environment and human health. Although various types of fluorophores have been reported for sensing volatile acid vapours, regulation of the sensory response using aggregation induced emissive (AIE) based gelators has rarely been reported. In this study, we present the design and synthesis of a novel organogelator that is capable of sensing volatile acids through AIE.

Asymmetrically Coordinated Heterodimetallic Ir-Ru System: Synthesis, Computational, and Anticancer Aspects.

Herein, we present an unprecedented formation of a heterodinuclear complex [{(ppy)Ir}(μ-phpy){Ru(tpy)}](ClO) {[](ClO)} using terpyridyl/phenylpyridine as ancillary ligands and asymmetric phpy as a bridging ligand. The asymmetric binding mode (NN-∩-NNC) of the phpy ligand in {[](ClO)} is confirmed by H, C, H-H correlated spectroscopy (COSY), high-resolution mass spectrum (HRMS), single-crystal X-ray crystallography techniques, and solution conductivity measurements. Theoretical investigation suggests that the highest occupied molecular orbital (HOMO) and the least unoccupied molecular orbital (LUMO) of [] are located on iridium/ppy and phpy, respectively.

A magnetically retrievable mixed-valent FeO@SiO/Pd/Pd nanocomposite exhibiting facile tandem Suzuki coupling/transfer hydrogenation reaction.

Herein, we report a magnetically retrievable mixed-valent FeO@SiO/Pd/PdNP (5) nanocomposite system for tandem Suzuki coupling/transfer hydrogenation reaction. The nanocomposite 5 was prepared first by making a layer of [Formula: see text] on [Formula: see text] followed by deposition of [Formula: see text] and sorption of [Formula: see text] ions successively onto the surface of FeO@SiONP. The nanocomposite was characterized by powder XRD, electron microscopy (SEM-EDS and TEM-EDS) and XPS spectroscopy techniques.

Fly ash supported Pd-Ag bimetallic nanoparticles exhibiting a synergistic catalytic effect for the reduction of nitrophenol.

Coal fly ash (FA) supported Pd-Ag bimetallic nanoparticles (FA-Pd-Ag) were prepared by reducing Pd(II) and Ag(I) salts together onto the dispersed solid support in aqueous medium. Electron microscope analysis (FE-SEM, HRTEM) in combination with elemental mapping (EDS) suggests that the nanoparticles are well dispersed on fly ash with an average diameter of 6-8 nm. The powder XRD analysis indicates that alloying of the interface occurs between Pd and Ag nanoparticles in FA-Pd-Ag, while XPS reveals that charge transfer takes place between the Pd and Ag moieties that come into contact with each other.

A magnetically separable and recyclable g-CN/FeO/porous ruthenium nanocatalyst for the photocatalytic degradation of water-soluble aromatic amines and azo dyes.

Herein, we present the development of a visible-light-driven magnetically retrievable nanophotocatalyst made of porous ruthenium nanoparticles supported on magnetic carbon nitride (g-CN/FeO/p-RuNP) for the facile removal/degradation of aromatic amines and azo dyes from wastewater. Aromatic amines and azo-based dyes in water bodies are highly toxic and carcinogenic even at very low concentrations and are difficult to separate because of their high solubility. Our nanocatalyst can efficiently degrade/decompose the aromatic amines and azo dyes under visible light (LED/sunlight) at room temperature and in a wide pH range (pH 5.

Alkyl chain-modified cyclometalated iridium complexes as tunable anticancer and imaging agents.

Five mononuclear cyclometalated iridium complexes [1](PF6)-[5](PF6) were prepared using imidazole-based ligands of varying alkyl chain length. The complexes were characterised by various analytical techniques. The single crystal X-ray structures of [2](PF6), [3](PF6) and [4](PF6) revealed the expected distorted Oh structures around the metal centre; however, the chain length was found to play a crucial role in deciding the overall geometry.

Preparation and mechanistic aspect of natural xanthone functionalized gold nanoparticle.

Herein, a facile scale up and shape variable synthesis of gold nanoparticle (AuNP) and reaction mechanism by natural xanthone derivative (mangiferin) has been reported. Mangiferin (CHO; 1,3,6,7-tetrahydroxyxanthone-C2-β-d-glucoside), a xanthone derivative is isolated from Mangifera indica L. leaves which efficiently reduces Au ions to Au and stabilizes the formed AuNP.

Long-Lived Polypyridyl Based Mononuclear Ruthenium Complexes: Synthesis, Structure, and Azo Dye Decomposition.

Two mononuclear ruthenium complexes [(bpy)RuL/L](ClO) ([1]/[2]) (bpy-2,2' bipyridine, L = 2,3-di(pyridin-2-yl)pyrazino[2,3-f][1,10]phenanthroline) and L = 2,3-di(thiophen-2-yl)pyrazino[2,3-f][1,10]phenanthroline have been synthesized. The complexes have been characterized using various analytical techniques. The complex [1] has further been characterized by its single crystal X-ray structure suggesting ruthenium is coordinating through the N donors of phenanthroline end.

Cyclometallated iridium complexes inducing paraptotic cell death like natural products: synthesis, structure and mechanistic aspects.

Six mononuclear Ir complexes (1-6) using polypyridyl-pyrazine based ligands (L1 and L2) and {[cp*IrCl(μ-Cl)] and [(ppy)Ir(μ-Cl)]} precursors have been synthesised and characterised. Complexes 1-5 have shown potent anticancer activity against various human cancer cell lines (MCF-7, LNCap, Ishikawa, DU145, PC3 and SKOV3) while complex 6 is found to be inactive. Flow cytometry studies have established that cellular accumulation of the complexes lies in the order 2 > 1 > 5 > 4 > 3 > 6 which is in accordance with their observed cytotoxicity.

A dinuclear [{(p-cym)Ru(II)Cl}2(μ-bpytz˙(-))](+) complex bridged by a radical anion: synthesis, spectroelectrochemical, EPR and theoretical investigation (bpytz = 3,6-bis(3,5-dimethylpyrazolyl)1,2,4,5-tetrazine; p-cym = p-cymene).

The reaction of the chloro-bridged dimeric precursor [{(p-cym)Ru(II)Cl}(μ-Cl)]2 (p-cym = p-cymene) with the bridging ligand 3,6-bis(3,5-dimethylpyrazolyl)-1,2,4,5-tetrazine (bpytz) in ethanol results in the formation of the dinuclear complex [{(p-cym)Ru(II)Cl}2(μ-bpytz˙(-))](+), [1](+). The bridging tetrazine ligand is reduced to the anion radical (bpytz˙(-)) which connects the two Ru(II) centres. Compound [1](PF6) has been characterised by an array of spectroscopic and electrochemical techniques.

Iridium Complexes as a Roadblock for DNA Polymerase during Amplification.

Iridium-based metal complexes containing polypyridyl-pyrazine ligands show properties of DNA intercalation. They serve as roadblocks to DNA polymerase activity, thereby inhibiting the polymerization process. Upon the addition of increasing concentrations of these iridium complexes, a rapid polymerase chain reaction (PCR)-based assay reveals the selective inhibition of the DNA polymerization process.

Synthesis, characterisation and antibacterial activity of [(p-cym)RuX(L)](+/2+) (X = Cl, H2O; L = bpmo, bpms) complexes.

Mononuclear half-sandwiched complexes [(p-cym)RuCl(bpmo)](ClO4) {[1](ClO4)} and [(p-cym)RuCl(bpms)](PF6) {[2](PF6)} have been prepared by reacting heteroscorpionate ligands bpmo = 2-methoxyphenyl-bis(3,5-dimethylpyrazol-1-yl)methane and bpms = 2-methylthiophenyl-bis(3,5-dimethylpyrazol-1-yl)methane, respectively, with a dimeric precursor complex [(p-cym)RuCl(μ-Cl)]2 (p-cym = 1-isopropyl-4-methylbenzene) in methanol. The corresponding aqua derivatives [(p-cym)Ru(H2O)(bpmo)](ClO4)2 {[3](ClO4)2} and [(p-cym)Ru(H2O)(bpms)](PF6)2 {[4](PF6)2} are obtained from {[1](ClO4)} and {[2](PF6)}, respectively, via Cl(-)/H2O exchange process in the presence of appropriate equivalents of AgClO4/AgNO3 + KPF6 in a methanol-water mixture. The molecular structures of the complexes {[1]Cl, [3](ClO4)2 and [4](PF6)(NO3)} are authenticated by their single crystal X-ray structures.

Facile tandem Suzuki coupling/transfer hydrogenation reaction with a bis-heteroscorpionate Pd-Ru complex.

Design and synthesis of the bis(pyrazol-1-yl)methane based bis-heteroscorpionate Pd-Ru complex results in efficient tandem Suzuki coupling/transfer hydrogenation reaction with a broad range of substrate reactivity.

Dinuclear [{(p-cym)RuCl}2(μ-phpy)](PF6)2 and heterodinuclear [(ppy)2Ir(μ-phpy)Ru(p-cym)Cl](PF6)2 complexes: synthesis, structure and anticancer activity.

Phpy bridged homodinuclear Ru-Ru () and heterodinuclear Ir-Ru complexes () have been developed. Complex induces autophagy towards the cisplatin resistant human breast cancer (MCF7) cell line, whereas is inactive.

Synthesis, characterisation and biological activities of [(p-cym)RuX(pz4lut)]n+ and [{(p-cym)RuX}2(μ-pz4lut)]n+ (X = Cl, H2O and pz4lut = α,α,α',α'-tetra(pyrazol-1-yl)-2,6-lutidine).

Mononuclear [(p-cym)RuCl(pz4lut)]Cl (1) and dinuclear [{(p-cym)RuCl}2(μ-pz4lut)]Cl2 (2) complexes (p-cym = 1-isopropyl-4-methylbenzene) comprising of bis(pyrazol-1-yl)methane based heteroscorpionate ligand α,α,α′,α′-tetra(pyrazol-1-yl)-2,6-lutidine (pz4lut) have been synthesised from pz4lut ligand and dimeric precursor complex [(p-cym)RuCl(μ-Cl)]2 in methanol. The aqua derivatives [(p-cym)Ru(H2O)(pz4lut)](ClO4)2 (3) and [{(p-cym)Ru(H2O)}2(μ-pz4lut)](ClO4)4 (4) are obtained from 1 and 2, respectively, via Cl/H2O exchange process in presence of appropriate equivalents of AgClO4 in methanol–water mixture. The molecular structures of dinuclear complexes, 2 and 4 are authenticated by their single crystal X-ray structures.

An artificial enzyme-based assay: DNA detection using a peroxidase-like copper-creatinine complex.

We report an artificial enzyme-based DNA assay using a peroxidase-like copper (Cu)-creatinine complex as a catalyst for 3,3',5,5'-tetramethylbenzidine (TMB) oxidation. The assay employs double signal amplification and a homogeneous catalytic reaction: (i) fast catalytic growth of Cu on a gold (Au) nanoparticle (NP) label forms a thick Cu layer (first amplification); (ii) dissolution of the Cu layer generates many Cu-creatinine complexes per NP (generation of homogeneous catalysts); (iii) peroxidase-like Cu-creatinine complexes rapidly convert TMB into a colored product (second amplification). To investigate the effect of ligand on the catalytic activities of Cu complexes, the kinetics of catalytic TMB oxidation is tested with and without using imidazole ring-containing ligands (creatinine, imidazole, and poly(l-histidine)).

A facile method of achieving low surface coverage of Au nanoparticles on an indium tin oxide electrode and its application to protein detection.

Low surface coverage of Au nanoparticles on an indium tin oxide electrode for sensitive electrochemical detection was achieved using electrostatic adsorption of AuCl(4)(-) followed by reduction.

Enhancement of the electrocatalytic activity of gold nanoparticles via NaBH4 treatment.

We report on the enhancement of the electrocatalytic activity of Au nanoparticles after NaBH4 treatment and its application to H2O2 detection.

Mixed-valent metals bridged by a radical ligand: fact or fiction based on structure-oxidation state correlations.

Electron-rich Ru(acac)2 (acac- = 2,4-pentanedionato) binds to the pi electron-deficient bis-chelate ligands L, L = 2,2'-azobispyridine (abpy) or azobis(5-chloropyrimidine) (abcp), with considerable transfer of negative charge. The compounds studied, (abpy)Ru(acac)2 (1), meso-(mu-abpy)[Ru(acac)2]2 (2), rac-(mu-abpy)[Ru(acac)2]2 (3), and (mu-abcp)[Ru(acac)2]2 (4), were calculated by DFT to assess the degree of this metal-to-ligand electron shift. The calculated and experimental structures of 2 and 3 both yield about 1.

Metal-induced reductive ring opening of 1,2,4,5-tetrazines: three resulting coordination alternatives, including the new non-innocent 1,2-diiminohydrazido(2-) bridging ligand system.

Reaction of 3,6-diaryl-1,2,4,5-tetrazines (aryl = R = phenyl, 2-furyl or 2-thienyl) with 2 equiv of Ru(acac)2(CH3CN)2 results in reductive tetrazine ring opening to yield diruthenium complexes [(acac)2Ru(III)(dih-R(2-))Ru(III)(acac)2] bridged by the new 1,2-diiminohydrazido(2-) (dih-R(2-) = HNC(R)NNC(R)NH(2-)) ligands. rac/meso diastereoisomers could be detected and separated for the compounds with R = phenyl and 2-thienyl, all species are diamagnetic and were characterized by 1H NMR spectroscopy. Crystal structure determination of the meso isomers with R = phenyl and 2-thienyl confirmed the 1,2-diiminohydrazido formulation through long N-N (approximately 1.

Controlling metal-ligand-metal oxidation state combinations by ancillary ligand (L) variation in the redox systems [L2Ru(mu-boptz)RuL2]n, boptz = 3,6-bis(2-oxidophenyl)-1,2,4,5-tetrazine, and L = acetylacetonate, 2,2'-bipyridine, or 2-phenylazopyridine.

The new compounds [(acac)2Ru(mu-boptz)Ru(acac)2] (1), [(bpy)2Ru(mu-boptz)Ru(bpy)2](ClO4)2 (2-(ClO4)2), and [(pap)2Ru(mu-boptz)Ru(pap)2](ClO4)2 (3-(ClO4)2) were obtained from 3,6-bis(2-hydroxyphenyl)-1,2,4,5-tetrazine (H2boptz), the crystal structure analysis of which is reported. Compound 1 contains two antiferromagnetically coupled (J = -36.7 cm(-1)) Ru(III) centers.

Sensitive oxidation state ambivalence in unsymmetrical three-center (M/Q/M) systems [(acac)2 Ru(mu-Q)Ru(acac)2](n), Q = 1,10-phenanthroline-5,6-dione or 1,10-phenanthroline-5,6-diimine (n = +, 0, -, 2-).

The new redox systems [(acac)2 Ru(mu-Q1)Ru(acac)2](n) (1(n)) and [(acac)2 Ru(mu-Q2)Ru(acac)2](n) (2(n)) with Q1 = 1,10-phenanthroline-5,6-dione and Q2 = 1,10-phenanthroline-5,6-diimine were studied for n = +, 0, -, and 2- using UV-Vis-NIR spectroelectrochemistry and, in part, EPR and susceptometry. The ligands can bind the first metal (left) through the phenanthroline nitrogen atoms and the second metal (right) at the o-quinonoid chelate site. The neutral compounds are already different: Compound 1 is formulated as a Ru(II)(mu-Q1)*- Ru(III) species with partially coupled semiquinone and ruthenium(III) centers.

Isomeric ruthenium terpyridine complexes [Ru(trpy)(L)Cl]n+ containing the unsymmetrically bidentate acceptor L=3-amino-6-(3,5-dimethylpyrazol-1-yl)-1,2,4,5-tetrazine. Synthesis, structures, electrochemistry, spectroscopy and DFT calculations.

The isomeric title complexes were obtained in almost equimolar ratio from the reaction of Ru(trpy)Cl3 and L. Crystal structure analyses of the perchlorate hemihydrates, electrochemical and spectroscopic (NMR, UV/VIS, EPR) studies, supported by DFT calculations, reveal distinct differences between the isomeric redox series [1]n+(tetrazine-Nt trans to Cl) and [2]n+(pyrazolyl-Np trans to Cl; n= 0, 1, 2). The latter system with the pi acceptors trpy and tetrazine in the equatorial plane and the pyrazolyl and chloride donors in the axial positions exhibits facilitated oxidation, lower energy MLCT transitions, more balanced chelate coordination, and a higher g anisotropy in the oxidised (RuIII) state.