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A new sulfonylcalix[4]arene-based dinuclear terbium molecular container (1) was conveniently synthesized and utilized as a fluorescence probe for the detection of a well-known biomarker 1-hydroxypyrene (1-OHP), which is used for the evaluation of polycyclic aromatic hydrocarbons (PAHs). The sulfonylcalix[4]arene ligand could not only serve as an efficient antenna ligand to promote the ligand-to-metal energy transfer but also provide a suitable cavity to accommodate 1-OHP. Promising fluorescence quenching effects were well established during the titration of the compound 1 with 1-OHP, and these effects were due to the enhancement in the host–guest intermolecular charge transfer and the decrease in the ligand-to-metal energy transfer after the formation of the stable host–guest complex. The fluorescence sensing mechanism was clearly understood through the titration experiments, and the data could be fit with the Benesi–Hildebrand and Stern–Volmer models. The TbIII-TBSC-based luminescent sensor exhibited quick response, high sensitivity, and specific selectivity to 1-OHP, even in the presence of other constituents in urine, thus providing a new sensing platform for the clinical diagnosis of human exposure to PAHs. [ABSTRACT FROM AUTHOR]

We have synthesized four Ir(iii) metal complexes (1–4) bearing dual fluorine-free cyclometalates that are derived from 2′,6′-dimethoxy-4-t-butyl-2,3′-bipyridine (pypy)H or 2-(2,4-dimethoxypyrimidin-5-yl)-4-t-butylpyridine (pmpy)H and a third ancillary, e.g. 5-pyridin-2-yl-pyrazolate (Pz) or 5-pyridin-2-yl-pyrrolide (Pr), respectively. The Ir(iii) complexes 3 and 4 were examined by X-ray diffraction studies for providing the structural proofs. Photophysical properties were next measured in CH2Cl2 at RT, among which the pypy complexes 1 and 2 showed an identical structured emission with an E0-0 peak located at 458 nm, while the corresponding pmpy derivative 3 displayed the most blue-shifted E0-0 peak at 444 nm. Organic light-emitting diodes (OLEDs) were fabricated using multiple layered architecture and the aforementioned phosphor at 8 wt% doping level. The associated OLED performances, cf. max. E.Q.E. = 9.0%, 14.3%, 5.8% and 9.4% and CIEx,y coordinates at (0.16, 0.22), (0.16, 0.24), (0.16, 0.17) and (0.16, 0.20) at 100 cd m−2 for phosphors 1–4 in sequence, confirmed their potential to act as blue dopants for phosphorescent OLEDs. [ABSTRACT FROM AUTHOR]

A series of platinum(ii) complexes with 1,3-bis(2-pyridylimino)isoindoline (BPI) derivatives were prepared by substitution of the coordinated Cl in the precursor complex Pt(BPI)Cl with a N-heterocyclic ligand such as pyridine, phthalazine or phenanthridine. These complexes display orange to red luminescence in fluid dichloromethane solutions and in the solid states at room temperature. The photophysical properties were tuned by introducing electron-withdrawing -NO2or electron-donating -NH2to the BPI ligand. The DFT computational studies suggest that the emission in the N-heterocyclic ligand substituted platinum(ii) complexes originates mainly from the 3[π→π*(BPI)] 3IL triplet excited state, mixed with some 3[dπ(Pt)→π*(BPI)] 3MLCT character. Compared with the precursor Pt(BPI)Cl, both the low-energy absorption and the emission in the N-heterocyclic ligand substituted platinum(ii) complexes exhibits a distinct blue-shift due to an obviously enhanced contribution from the 3IL state and a reduced 3MLCT character. [ABSTRACT FROM AUTHOR]

Three new dinuclear lanthanide(iii) complexes {Eu(hfac)3(H2O)}2(μ-HPhMq)2(2) and {Ln(hfac)3(H2O)}2(μ-HMe2NC6H4Mq)2(Ln = Eu, 3; Nd, 4) with 8-hydroxylquinoline derivatives in μ-phenol mode were synthesized and characterized, where hfac−= hexafluoroacetylacetonate, HPhMq = 2-methyl-5-phenylquinolin-8-ol, and HMe2C6H4Mq = 5-(4-(dimethylamino)phenyl)-2-methylquinolin-8-ol. Compared with that (400 nm) for {Eu(hfac)3}2(μ-HMq)2(1, HMq = 2-methy-8-hydroxylquinoline), the excitation wavelength for sensitized lanthanide luminescence is extended to ca.420 nm for 2, and 500 nm for 4by introducing a phenyl or 4-(dimethylamino)phenyl to 8-hydroxylquinoline. These dinuclear lanthanide(iii) complexes exhibit distinctly fluoride-induced lanthanide(iii) emission enhancement in both intensity and lifetime due to replacing coordination water molecules or formation of strong O–HF hydrogen bonds with coordinated H2O and μ-phenol, thus suppressing significantly the non-radiative O–H oscillators. [ABSTRACT FROM AUTHOR]

A new Cu2+-responsive MRI contrast agent (Gd-QDOTAMA) with a quinoline-based ligand was synthesized and characterized. Relaxivity studies on Gd-QDOTAMA showed that the relaxivity increased from 4.27 mM−1s−1to 7.29 mM−1s−1in response to equimolar amounts of copper(II) ion, corresponding to ca.71% relaxivity enhancement. Distinct changes in relaxivity were undetected upon addition of physiologically relevant alkali metal cations (K+or Na+), alkaline earth metal cations (Mg2+or Ca2+), or d-block metal cations (Zn2+, Cu+, Fe2+, Fe3+), indicating a high selectivity for Cu2+over other biologically relevant metal ions. Moreover, the influence of common biological anions at physiological levels on the Cu2+-responsive contrast agent was also studied. Luminescence studies on the Eu counterpart Eu-QDOTAMA suggest that the enhancement in relaxivity for Gd-QDOTAMA in response to Cu2+is most likely due to the increased number of inner-sphere water molecules around Gd3+upon Cu2+binding to the 8-amidequinoline moiety. In vitroT1-weighted phantom images of Gd-QDOTAMA confirmed that signal intensity was markedly increased by the addition of equimolar amounts of Cu2+. [ABSTRACT FROM AUTHOR]

An iridium(iii)-containing phosphorescent chemosensor Ir(ppy)2(L)(PF6) (1, ppy = 2-phenylpyridine) containing a 2,2′-bipyridyl ligand (L) functionalized with an α,β-unsaturated ketone for selective detection of thiol was synthesized and characterized by spectroscopic and photophysical measurements. The structure of complex 1was determined by X-ray crystallography. In order to get an insight into 1,4-addition reactions of thiol to complex 1, the adduct 2from reaction of 1with benzenethiol was successfully prepared and characterized. Complex 1shows a lowest energy absorption at ca.450 nm, primarily ascribable to an intraligand charge transfer (ILCT) transition from the HOMO (π) resident on the fragment -C(O)C6H4N(C2H5)2to the LUMO (π*) localized on the 2,2′-bipyridyl moiety in the functionalized 2,2′-bipyridyl ligand as suggested from DFT computational studies. Complex 1is weakly emissive at ca.587 nm at ambient temperature, arising likely from the 3ILCT excited state. Upon addition of thiol to a semi-aqueous solution of complex 1, the lowest energy absorption is obviously blue-shifted and the emission is remarkably enhanced due probably to a conversion from the primary ILCT state to the predominant [π(ppy)→π*(L)] LLCT and the [5d(Ir)→π*(L)] MLCT state caused by the formation of the 1-thiol adduct. The sensing properties of 1to thiol were also investigated by ESI-MS spectrometry and 1H NMR spectroscopy. [ABSTRACT FROM AUTHOR]

A series of oxo-centred triruthenium-acetate complexes with valence iii,iii,iiwere prepared by reactions of [Ru3III,III,III]+precursor [Ru3O(OAc)6(py)2(CH3OH)]+(1) with 3-chloro-6-(pyrazol-1-yl)pyridazine (cppd), 3-chloro-6-(3,5-dimethylpyrazol-1-yl)pyridazine (cmppd), 3,6-bis(pyrazol-1-yl)pyridazine (ppd), 3,6-bis(3,5-dimethylpyrazol-1-yl)pyridazine (mppd) or 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine (bptz). When neutral Ru3III,III,IIprecursor Ru3O(OAc)6(CO)(CH3OH)2(2) was utilized, a stable low-valence Ru3III,II,IIderivative complex was successfully isolated. As established through crystal structural analyses, they were derived from 1or 2by substitution of the axial methanol and one of six bridging acetates in the parent Ru3(μ3-O)(μ-OAc)6cluster core as well as one axial pyridine in some cases. As revealed by electrochemical and spectroscopic studies, substituting one of the six bridging acetates in the parent Ru3(μ3-O)(μ-OAc)6cluster core significantly modifies the electronic and redox characteristics. Compared with those for the parent compound [Ru3O(OAc)6(py)3]+, triruthenium-based redox potentials of these derivatives show remarkable positive shifts. [ABSTRACT FROM AUTHOR]

Abstract: A new bimetallic complex [HNEt3][Cuq2IEu(hfac)3] (q− = 8-hydroxyquinolinato, hfac− = hexafluoroacetylacetonate) was prepared simply with only one step and characterized. Upon excitation of the organic ligand q−, the sensitized europium luminescence was achieved. [Copyright &y& Elsevier]

Multifunctional heteropentanuclear Al3Ln2(Ln = Nd, Eu, Yb) clusters with a novel structure exhibit significantly fluoride-enhanced lanthanide emission intensity and lifetime in both solid state and solution as well as unusual white-light emitting for an Al3Eu2complex. [ABSTRACT FROM AUTHOR]

A platinum(ii) complex of 5,5′-bis(trimethylsilylethynyl)-2,2′-bipyridine displays unusually reversible colour and luminescence changes when exposed to specific organic vapours, correlated well with PtPt distances as well as π–π and C–H(CC) interactions in the stacking of square-planar platinum(ii) moieties. [ABSTRACT FROM AUTHOR]

Abstract: By virtue of versatile coordination modes of 8-hydroxyquinoline and acetate, a new mixed lanthanide complex Er4Yb, {[Er2(hfac)4(μ3-CH3COO)(μ3-OH)]2}{μ-HMq}2{Yb(hfac)(μ4-CH3COO)2} (hfac− =hexafluoroacetylacetonate; HMq=2-methyl-8-hydroxyquinoline) was isolated. The luminescence measurements show that upon irradiation with [n → π*] absorption of HMq at λ ex =400nm, “dual emission” from both erbium (III) and ytterbium (III) has been achieved, respectively. [Copyright &y& Elsevier]

A seriesof ruthenium acetylide complexes [Ru(BPI)(PPh3)2(CCR)] (BPI = 1,3-bis(2-pyridylimino)isoindolate;R = −C6H5(2), −Cp2Fe (3a), −C6H4C6H4CCCp2Fe (3b))and bis(acetylide)-linked binuclear ruthenium complexes [{Ru(BPI)(PPh3)2}2(CCRCC)] (R = none(4), 1,4-benzenediyl (5), 1,4-naphthalenediyl(6), 9,10-anthracenediyl (7)) were synthesizedand characterized by ESI-MS spectrometry, IR, 1H and 31P NMR, and UV–vis–near-IR spectroscopy, andcyclic and differential pulse voltammetry. Oxidation of 3–7with 1 equiv of ferrocenium perchlorate affordedthe corresponding one-electron-oxidized complexes 3+–7+. In contrast to the casefor 3a+, where spin density islocalized at the Fe center due to moderate electronic communicationbetween RuIIand FeIIIcenters along the Ru–CC–Cp2Fe backbone, the spin density is primarily populated on Rufor 3b+without an appreciableelectronic interaction between RuIIIand FeIIacross the quite long bridging system RuCCC6H4C6H4CCCp2Fe. Forbis(acetylide)-linked binuclear ruthenium complexes 4–7, electrochemical, UV–vis–near-IRspectral and TD-DFT computational studies reveal that electronic delocalizationalong the bridging RuCCRCCRu backbone is highly dependenton the R spacer. It is demonstrated that with the gradual increaseof a π-conjugated system in aromatic R spacer, the electronicdelocalization shows progressive enhancement along the Ru–CCRCC–Rubackbone due to an increasing participation of the bridging ligand. 4+displays highly electronically delocalized behavior,whereas 5+–7+are on the borderline of electronic delocalization. [ABSTRACT FROM AUTHOR]

The synthesis, structure, and phosphorescence properties of twofamilies of triphosphine-supported Au(I)–Ag(I) heteronuclearalkynyl cluster complexes with unprecedented Au2Ag2and Au8Ag4cluster structures are described.The phosphorescence emission over the whole visible light region wassystematically tuned through modification of the electronic effectsin aromatic acetylide ligands to attain bright phosphorescence withdifferent luminescent colors. Introduction of electron-withdrawingCF3to phenylacetylides results in the emission spectralblue-shift, while it shows progressive red-shift upon introducingelectron-donating But, OMe, or NMe2. As demonstratedfrom both experimental and theoretical studies, the phosphorescencearises primarily from 3LLCT/3IL and Au2Ag2/Au8Ag4cluster-centered 3[d→p] transitions. [ABSTRACT FROM AUTHOR]

A series of highly phosphorescent PtAg2 heterotrinu-clear alkynyl complexes with bis(diphenylphosphinomethyl)-phenylphosphine (dpmp) were prepared and characterized structurally. The solution phosphorescence with various emitting colors is systematically modulated by modifying substituents as well as n-conjugated systems in aromatic acetylides. The crystals, powders, or films exhibit reversible stimuli-responsive phosphorescence changes upon exposure to vapor of MeCN, pyridine, DMF, etc., resulting from perturbation of d8-d10 metallophilic interaction in the excited states as a consequence of the formation/disruption of Ag--solvent bonds. Both experimental and time-dependent density functional theory (TD-DFT) studies demonstrate that d8-d10 metallophilic interaction exerts a crucial role on phosphorescent characteristics due to the PtAg2 cluster-based ³[d → p] state. This study affords a paradigm for phosphorescence modulation in d8--d10 heteronuclear complexes. [ABSTRACT FROM AUTHOR]

Abstract: Two novel mixed-ligand dicopper(I) halide complexes, [{Cu(PPh3)X}2(μ-HL)] (HL=3,5-bis{6-(2,2′-dipyridyl)}pyrazole, X=I (1); Br (2)), have been synthesized by a straightforward double-layer diffusion approach and structurally characterized by single-crystal X-ray diffraction. The multi-site HL acts as a bridging bis-bidentate chelate, assembling two Cu(PPh3)X moieties into copper(I) dimers possessing the triple-decker “organic” sandwich structure of phenyl/pyrazolyl/phenyl through π···π interactions. Complexes 1 and 2 exhibit photoluminescence in the solid state at ambient temperature, ascribed to a combination of intraligand charge transfer (ILCT) and metal-to-ligand charge transfer (MLCT) transitions. The emission of 2 is red-shifted 18nm relative to that of 1 due to substitution of the iodides of 1 by the weaker electron-donating bromides. [Copyright &y& Elsevier]

Abstract: A new ligand L, 6-hydroxy chromone-3-carbaldehyde thiosemicarbazone, and its Ni(II) complex have been synthesized and characterized. The crystal structure of Ni(II) complex was determined by single crystal X-ray diffraction. Ni(II) complex and ligand L were subjected to biological tests in vitro using THP-1, Raji and Hela cancer cell lines. Compared with the ligand, Ni(II) complex showed significant cytotoxic activity against these three cancer cell lines. The interactions of Ni(II) complex and ligand L with calf thymus DNA were then investigated by spectrometric titration, ethidium bromide displacement experiments and viscosity measurements methods. The experimental results indicated that Ni(II) complex bound to DNA by intercalative mode via the ligand L. The intrinsic binding constants of Ni(II) complex and ligand L with DNA were (1.10±0.65)×106 M−1 and (1.48±0.57)×105 M−1, respectively. [Copyright &y& Elsevier]

Abstract: The Zn(II) complexes of two bipyridyl derivatives with trimethylaminomethyl groups, [Zn(L1)3](ZnBr4)(ClO4)2Br4 ·12H2O (1) and [Zn(L2)3](ClO4)8 ·H2O (2) (L1 =[4,4′-(Me3NCH2)2-bpy]2+, L2 =[5,5′-(Me3NCH2)2-bpy]2+ and bpy=2,2′-bipyridyl), were synthesized and characterized. The structure of complex 1 has been determined by X-ray diffraction, and the configuration of ligand-coordinated Zn(II) ion can be well described as distorted octahedral. Species distribution of both complexes in aqueous solution was investigated by potentiometeric titration. DNA-binding ability of both complexes was studied by UV spectroscopy titration. Under hydrolytic condition, both complexes (150μM) can effectively cleave plasmid pBR322 DNA from supercoiled to nicked form, giving hydrolysis rate constants of 2.63×10−5 and 9.92×10−5 s−1, respectively (pH 7.75, 37°C). The result shows that complex 2 is one of the most active artificial nucleases based on zinc. [Copyright &y& Elsevier]

Reactions of Pt(diimine)(tdt) (tdt = 3,4-toluenedithiolate) with [M2(dppm)2(MeCN)2]²+ (M = CuΙ or AgΙ, dppm = bis(diphenylphosphino)methane) gave heterotrinuclear complexes [PtCu2(tdt)(μ-SH)(dppm)3](CIO4)(1) and [PtCu2-(diimine)a(tdt)(dppm)2](CIO4)2 (diimine = 2,2′-byridine (bpy) 2; 4,4′-dimethyl-2,2′-bipyridine (dmbpy) 3; phenanthroline (phen) 4, 5-bromophenanthroline (Brphen) 5) for M - CuΙ, but [PtAg2(tdt)(μ-SH)(dppm)3](SbF6) (6) and [PtAg2(diimine)(tdt)(dppm)2](SbF6)2 (diimine = bpy 7; dmbpy 8; phen 9; Brphen 10) for M = AgΙ. While the complexes [PtAg2(diimine)(tdt)(dppm)2](SbF6)2 (7–10) result from linkage of Pt(diimine)(tdt) and [M2(dppm)2(MeCN)2]²+ by tdt sulfur donors, formation of [PtCu2(diimine)2(tdt)(dppm)2](ClO4)2 (2–5) is related to rupture of metal-ligand bonds in the metal components and recombination between the ligands and the metal atoms by self-assembly. The formation of 1 and 6 is involved not only in dissociation and recombination of the metal components, but also in disruption of C-S bonds in the dithiolate (tdt). The dithiolate tdt adopts a chelating and bridging coordination mode in anti conformation for [PtCu2(diimine)2(tdt)(dppm)2](CIO4)2 (2–5), whereas there is the syn conformation for other complexes. Compounds 1 and 6 represent sparse examples of μ-SH-bridged heterotrinuclear PtΙΙMΙ2 complexes, in which PtΙΙ-MΙ centers are bridged by dppm and sulfur donors of tdt, whereas MΙ-MΙ (M = Cu for 1; Ag for 6) centers are linked by dppm and the μ-SH donor. The 31P NMR spectra show typical platinum satellites (JPt-P = 1450–1570 Hz) for 1–6 and Ag-P coupling for PtΙΙ-AgΙ (JAg-P = 350–450 Hz) complexes 6–10. All of the complexes show intense emission in the solid state and in frozen glasses at 77 K. The complexes [PtAg2(diimine)(tdt)(dppm)2](SbF6)2 (7–10) also afford emission in fluid acetonitrile solutions at room temperature. Solid-state emission lifetimes at room temperature are in the microsecond range. It is revealed that emission energies of the trinuclear heterometallic complexes [PtAg2(diimine)(tdt)(dppm)2](SbF6)2 (7–10) exhibit a remarkable blue shift (0.10–0.35 eV) relative to those of the precursor compounds Pt(diimine)(tdt). The crystal structures of 1, 2, 4, 6, 8, and 9 were determined by X-ray crystallography. [ABSTRACT FROM AUTHOR]

Abstract: Reaction of cyclometallated iridium(III) complex Ir(ppy)2(PPh3)Cl (2, ppy=2-phenylpyridine) with dicyanamide or tricyanomethanide gave neutral mononuclear complexes Ir(ppy)2(PPh3)N(CN)2 (3a) or Ir(ppy)2(PPh3)C(CN)3 (3b), and dicyanamide/tricyanomethanide-linked binuclear iridium(III) complexes [{Ir(ppy)2(PPh3)}2N(CN)2]+ (4a) or [{Ir(ppy)2(PPh3)}2C(CN)3]+ (4b). Substitution of coordinated chloride in the precursor 2 with dicyanamide or tricyanomethanide improved significantly the luminescence properties of 3a–4b. Compared with that in the precursor 2 (1.6%), 2.2 to 9.3-fold enhancement of emission quantum yields was detected in 3a–4b. [Copyright &y& Elsevier]

Abstract: The preparation, characterization and photophysical properties of heterobinuclear complexes {Pt(C^N^N)(Chfac)3 (C^N^N=2-(6-(naphthalen-3-yl)-4-phenylpyridin-2-yl)pyridine; HCsp sp="0.25" />=5-ethynyl-2,2′-bipyridine; Ln=Nd, Eu, Yb; hfac=hexafluoroacetylacetonate) are described. With excitation at 390⩽ λ ex ⩽500nm which is the MLCT/LLCT absorption region of the Pt(C^N^N)(Comophore, lanthanide luminescence is successfully attained by Pt→Ln energy transfer from the platinum(II) antenna chromophore to the lanthanide center across the bridging Cnd. [Copyright &y& Elsevier]