Search

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]

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]

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]

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]

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]

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]

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]

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]

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: 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]