Li-Yi Zhang

Fluoride-enhanced lanthanide luminescence and white-light emitting in multifunctional Al3Ln2 (Ln = Nd, Eu, Yb) heteropentanuclear complexes

Multifunctional heteropentanuclear Al(3)Ln(2) (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 Al(3)Eu(2) complex.

Zn2+ Responsive Bimodal Magnetic Resonance Imaging and Fluorescent Imaging Probe Based on a Gadolinium(III) Complex

A Zn(2+)-responsive bimodal magnetic resonance imaging (MRI) and luminescence imaging probe GdL was synthesized. The relaxivity and luminescence properties were examined. In the presence of 0.5 equiv of Zn(2+), the longitudinal relaxivity is increased from 3.8 mM(-1) s(-1) to 5.9 mM(-1) s(-1) at 23 MHz and 25 °C with 55% enhancement, whereas the fluorescence exhibits a 7-fold increase. The Zn(2+) responsive imaging probe shows favorable selectivity and tolerance over a variety of biologically relevant anions and metal ions in physiological pH range for both relaxivity and luminescence. In vitro phantom images and confocal fluorescence images in living cells show that the bimodal Zn(2+) probe can effectively enhance T(1)-weighted imaging contrast and luminescence imaging effect through Zn(2+) coordination with excellent cellmembrane permeability and biocompatibility. Spectral and electrospray ionization mass spectrometry (ESI-MS) studies indicate that two different Zn(2+)-bound species, (GdL)(2)Zn and GdLZn, are formed when 0.5 and 1 equiv of Zn(2+) are bound to GdL complex, respectively. Crystal structural determination and dysprosium-induced (17)O NMR shift (DIS) experiment demonstrate that the increased molecular weight and the improved molecular rigidity upon complexation of Zn(2+) with GdL is the primary factor for relaxivity enhancement. Significant enhancement of the luminescence is due to a heavy atom effect and much increased molecular rigidity upon Zn(2+) binding to 8-sulfonamidoquinoline chromophore.

Spectroscopic and Phosphorescent Modulation in Triphosphine-Supported PtAg2 Heterotrinuclear Alkynyl Complexes

A series of highly phosphorescent PtAg2 heterotrinuclear 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 π-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 d(8)-d(10) 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 d(8)-d(10) 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 d(8)-d(10) heteronuclear complexes.

Preparation, characterization, and photophysical properties of Pt-M (M = Ru, Re) heteronuclear complexes with 1,10-phenanthrolineethynyl ligands

When 3-ethynyl-1,10-phenanthroline (HCCphen) or 3,8-diethynyl-1,10-phenanthroline (HCCphenCCH) is utilized as a bifunctional bridging ligand via stepwise molecular fabrication, a series of Pt-Ru and Pt-Re heteronuclear complexes composed of both platinum(II) terpyridyl acetylide chromophores and a Ru(phen)(bpy)2/Re(phen)(CO)3Cl subunit were prepared by complexation of one or two Pt((t)Bu3tpy)(2+) units to the mononuclear Ru(II) or Re(I) precursor through platinum acetylide sigma coordination. These Pt-Ru and Pt-Re complexes exhibit intense low-energy absorptions originating from both Pt- and Ru (Re)-based metal-to-ligand charge-transfer (MLCT) states in the near-visible region. They are strongly luminescent in both solid states and fluid solutions with a submicrosecond range of lifetimes and 0.27-6.58% of quantum yields in degassed acetonitrile. For the Pt-Ru heteronuclear complexes, effective intercomponent Pt --> Ru energy transfer takes place from the platinum(II) terpyridyl acetylide chromophores to the ruthenium(II) tris(diimine)-based emitters. In contrast, dual emission from both Pt- and Re-based (3)MLCT excited states occurs because of less efficient intercomponent Pt --> Re energy transfer in the Pt-Re heteronuclear complexes.

Diplatinum alkynyl chromophores as sensitisers for lanthanide luminescence in Pt2Ln2 and Pt2Ln4 (Ln = Eu, Nd, Yb) arrays with acetylide-functionalized bipyridine/phenanthroline

Incorporation of diplatinum complex Pt2(micro-dppm)2(bpyC[triple bond]C)4 or Pt2(mu-dppm)2(phenC[triple bond]C)4 with Ln(hfac)3(H2O)2 (Ln = Nd, Eu, Yb) gave a series of Pt2Ln2 and Pt2Ln4 bimetallic arrays, in which the excitation of d(Pt) -->pi*(R-C[triple bond]C) MLCT absorption induces sensitisation of lanthanide luminescence through efficient d --> f energy transfer from Pt(II) alkynyl chromophores.

Photophysical and anion sensing properties of platinum(II) terpyridyl complexes with phenolic ethynyl ligands

A series of platinum(II) terpyridyl complexes with phenolic ethynyl ligands have been synthesized and characterized. Their photophysical and sensing properties towards anions such as fluoride, acetate and dihydrogenphosphate have been investigated. These complexes show a colorimetric response and fluorescence quenching in the presence of anions including fluoride, acetate and dihydrogenphosphate, and selective sensing towards fluoride in some cases. The sensing mechanism has been investigated by spectrophotometric and 1H NMR titration.

Synthesis, crystal structure, DNA binding, and oxidative cleavage activity of copper(II)-bipyridyl complexes containing tetraalkylammonium groups

Two copper(II) complexes of disubstituted 2,2′-bipyridine (bpy = 2, 2′-bipyridine) with tetraalkylammonium groups, [Cu(L1)2Br](ClO4)5·2H2O (1) and [Cu(L2)2Br](ClO4)5·H2O (2) (L1 = [4, 4′-(Et3NCH2)2-bpy]2+, L2 = [4, 4′-((n-Bu)3NCH2)2-bpy]2+), have been synthesized and characterized. X-ray crystallographic study of 1 indicates that Cu(II) is a distorted trigonal bipyramidal or square pyramid. DNA binding of both complexes was studied by UV spectroscopic titration. In the presence of reducing reagents, the cleavage of plasmid pBR322 DNA mediated by both complexes was investigated and efficient oxidative cleavage of DNA was observed. Mechanistic study with reactive oxygen scavengers indicates that hydrogen peroxide and singlet oxygen participate in DNA cleavage.

Bis­[μ-bis­(di­phenyl­phosphino)­methane-κ2P:P′]­bis­[diaceto­nitrile­copper(I)] bis­(hexa­fluoro­phosphate)

The title compound, [Cu2(μ2-dppm)2(MeCN)4](PF6)2 or [Cu2(C25H22P2)2(C2H3N)4](PF6)2, crystallizes in the monoclinic space group C2/c, with the cation on a twofold axis. The Cu centers are four-coordinated, exhibiting pseudo-tetrahedral coordination.

Structures and luminescence properties of diethyldithiocarbamate-bridged polynuclear gold(I) cluster complexes with diphosphine/triphosphine

A series of polynuclear gold(I) complexes with bridging diethyldithiocarbamate (Et2dtc) and diphosphine/triphosphine were synthesized, including [{Au2(μ-dpb)(μ-Et2dtc)}SbF6]n (1, dpb = 1,4-bis(diphenylphosphino)benzene), [Au2(μ-dpb)(Et2dtc)2] (2), [Au4(μ-dpn)(μ-Et2dtc)3](SbF6) (3, dpn = 1,4-bis(diphenylphosphino)naphthalene), [Au4(μ-dpn)(μ-Et2dtc)3][Au(Et2dtc)2](SbF6)2 (4), [Au4(μ-dpa)(Et2dtc)3](SbF6) (5, dpa = 9,10-bis(diphenylphosphino)anthracene) and [{Au6(dpep)2(Et2dtc)3}{(SbF6)3}]n (6, dpep = bis(2-diphenylphosphinoethyl)phenylphosphine). The structures of 3·CH2Cl2, 4·2CH2Cl2, 5·2CH2Cl2·H2O and 6 were characterized by X-ray crystallography. The intramolecular Au⋯Au distances across bridging Et2dtc are 2.9376(7)–2.9725(8) A in 3·CH2Cl2, 2.9762(16)–3.1078(14) A in 4·2CH2Cl2, 2.9288(9)–3.0514(10) A in 5·2CH2Cl2·H2O, and 2.9236(12)–3.1914(17) A in 6, implying significant aurophilic interactions. These gold(I) complexes exhibit intense photoluminescence properties in solid state. Upon lowering the temperature from 298 to 77 K, complexes 5 and 6 exhibit an obvious red-shift from 536 nm to 589 nm for 5 and from 538 nm to 564 nm for 6, implying significant luminescence thermochromism due to thermal contraction upon cooling.

(Acetonitrile)(2,2'-bipyridine)tricarbonyl­rhenium(I) perchlorate

The title compound, [Re(C2H3N)(C10H8N2)(CO)3]ClO4, was isolated from the reaction between [ReCl(bpy)(CO)3] (bpy is 2,2′-bipyridine) and AgClO4 in acetonitrile. The Re atom adopts a distorted octahedral geometry.