Elaborate Design of d8-d10 Heteronuclear Phosphors for Ultrahigh-Efficiency Solution-Processed Organic Light-Emitting Diodes.

Highly soluble d8-d10 heteronuclear phosphors afford an alternative approach to achieve high-efficiency organic light-emitting diodes (OLEDs) through a solution process. In this work, four highly phosphorescent d8-d10 heteronuclear complexes with significant Pt-Au interactions were prepared. By judicious selection of sterically hindered and π-conjugated substituents in triphosphine ligands, the phosphorescence is dramatically promoted through effectively prohibiting nonradiative thermal relaxation with an efficiency of 0.94-0.99 in doping films. Exploiting highly emissive Pt-Au complexes as phosphorescent dopants, ultrahigh-efficiency solution-processed OLEDs were attained. The peak current efficiency, power efficiency, and external quantum efficiency are 96.2 cd A-1, 65.0 lm W-1, and 26.4% for the green-emitting PtAu2 phosphor and 68.6 cd A-1, 42.5 lm W-1, and 25.1% for the orange-emitting Pt2Au phosphor, which represent the state-of-art for solution-processed OLEDs based on non-iridium phosphors.

Elaborate Design of Ag8Au10 Cluster [2]Catenane Phosphors for High-Efficiency Light-Emitting Devices.

In this work, rational design of highly soluble and phosphorescent Ag-Au cluster complexes with exceptional [2]catenane structures is conducted using 1,8-diethynyl-9H-carbazole (H3decz) as a rigid U-shaped ligand with a distinguished hole-transport character. The self-assembly reaction of H3decz, Au+, and Ag+ generated phosphorescent Ag4Au6 cluster 1 (Φem = 0.22 in CH2Cl2) with H2decz- having a free ethynyl (-C≡CH) group. When the four free C≡CH groups in the Ag4Au6 complex 1 are further bound to four (PPh3)Au+ and four (PPh3)Ag+ moieties through M-acetylide linkages, the formation of Ag8Au10 cluster 2 not only eliminates nonradiative ethynyl C-H vibrational deactivation process but also improves dramatically the molecular rigidity so that the phosphorescent efficiency of the Ag8Au10 cluster 2 (Φem = 0.63) is nearly 3 times that of the Ag4Au6 cluster 1. The Ag8Au10 cluster structure is further rigidified using diphsophine Ph2P(CH2)4PPh2 (dppb) in place of PPh3 so that the phosphorescence of the Ag8Au10 cluster 3 (Φem = 0.77) is more efficient than that of 2. Making use of the Ag8Au10 clusters as phosphorescent dopants, high-efficiency solution-processed organic light-emitting diodes (OLEDs) were achieved with current efficiency (CE) and external quantum efficiency (EQE) of 47.2 cd A-1 and 15.7% for complex 2 and 50.5 cd A-1 and 14.9% for complex 3.

Coordination-Bond-Driven Dissolution-Recrystallization Structural Transformation with the Expansion of Cuprous Halide Aggregate.

Metal-organic frameworks (MOFs) with cuprous-halide-aggregates have shown superiority as organic LED (OLED) and semiconductor materials, while engineering MOF flexibility by involving the expansion of cuprous aggregates remains a great challenge. In this particular work, a dissolution-recrystallization structural transformation (DRST) with the dramatic growth of CuI-I aggregates, from 2D NJNU-100 to 3D NJNU-101 has been successfully realized. The unsaturated coordination nodes (2-positional nitrogen atoms) in NJNU-100 have been demonstrated to be the driven force for DRST to NJNU-101 via the formation of coordination bonds. The structural transformation process was irreversible and observed with optical microscopy and powder XRD. The expansion of CuI-I aggregates was also computational simulated accompanying with the rotation of the neutral tripodal TTTMB ligand (1,3,5-tris(1,2,4-triazol-1-ylmethyl)-2,4,6-trimethylbenzene) and the reduction of CuII to CuI. Moreover, the intermediate product NJNU-102 was captured by adding the planar molecular anthrancene to shut down the reaction, where only partial 2-positional nitrogen atoms coordinated to the aggregates and the anthrancene was oxidized to anthraquinone. NJNU-102 has further confirmed that DRST involved the breakage and recombination of coordination bonds and the electron transfer. NJNU-100 and NJNU-101 could be applied as semiconductor and OLED materials. This work has provided insights for crystal engineering, especially for the construction of the CuIxXy aggregates, and illustrated that DRST could be controlled with a rational design (as the unsaturated coordination modes).

Synthesis, structures and luminescence properties of amine-bis(N-heterocyclic carbene) copper(i) and silver(i) complexes.

A series of Ag(i) and Cu(i) complexes [Ag3(L1)2][PF6]3 (8), [Ag3(L2)2][PF6]3 (9), [Cu(L1)][PF6] (10) and [Cu(L2)][PF6] (11) have been synthesized by reactions of the tridentate amine-bis(N-heterocyclic carbene) ligand precursors [H2L1][PF6]2 (6) and [H2L2][PF6]2 (7) with Ag2O and Cu2O, respectively. Complexes 10 and 11 can also be obtained by transmetalation of 8 and 9, respectively, with 3.0 equiv. of CuCl. A heterometallic Cu/Ag-NHC complex [Cu2Ag(L1)2(CH3CN)2][PF6]3 (12) is formed by the reaction of 8 with 2.0 equiv. of CuCl. All complexes have been characterized by NMR, electrospray ionization mass spectrometry (ESI-MS), and single-crystal X-ray diffraction studies. The luminescence properties of 10-12 in solution and the solid state have been studied. At room temperature, 10-12 exhibit evident luminescence in solution and the solid state. The emission wavelengths are found to be identical at 483 nm in CH3CN, but they are 484, 480 and 592 nm in the solid state for 10-12, respectively. These results suggest that 12 dissociates into two molecules of 10 and Ag(i) ions in solution. Complex 12 is the first luminescent heterometallic Cu/Ag-NHC complex.

An unprecedented photochromic system with cis-oriented dithienyl-dithiolenes supported by metal chelation.

4,5-Bis(2-methyl-5-phenylthiophen-3-yl)-1,3-dithiol-2-one (L1o) was elaborately designed to afford dithienyl-dithiolene as a new photochromic ligand. We describe herein the preparation and characterization of unprecedented photochromic dithienyl-dithiolene complexes with cis-orientation of dithienylethene (DTE) stabilized by metal chelation instead of conventional cyclopentene. The treatment of L1o with sodium methoxide in methanol afforded a disodium salt of dithiolate dianion, which reacts with M(dppe)Cl2 (dppe = 1,2-bis(diphenylphosphino)ethane, M = Ni, Pd) to give neutral compounds M(dppe)(dithiolate) as established by X-ray crystallography. The reaction of L1o with NiCl2 in the presence of sodium methoxide allows the isolation of an anionic nickel(ii) bis(dithienyl-dithiolene) complex with photochemical inertness. In contrast, the corresponding reaction with ZnCl2 afforded a dianionic zinc(ii) complex chelated by two dianionic dithienyl-dithiolenes, which displays stepwise photocyclization upon irradiation with UV light at 312 nm as demonstrated experimentally and theoretically. Only when dithienyl-dithiolene behaves as a dicationic ligand instead of neutral or monoanionic species, it is possible to achieve reversible photochromism in the corresponding metal complexes.

Syntheses, characterization and electrochemical and spectroscopic properties of ruthenium-iron complexes of 2,3,5,6-tetrakis(2-pyridyl)pyrazine and ferrocene-acetylide ligands.

Heterodimetallic Ru-Fe complexes [(tppz)(PPh3)2RuL](ClO4) (L = C[triple bond, length as m-dash]CFc, [](ClO4); C[triple bond, length as m-dash]C-C6H4-C[triple bond, length as m-dash]CFc), [](ClO4); C[triple bond, length as m-dash]C-C6H4-C6H4-C[triple bond, length as m-dash]CFc, [](ClO4)) were synthesized by the reactions of [(tppz)(PPh3)2RuCl](ClO4) (tppz = 2,3,5,6-tetrakis(2-pyridyl)pyrazine) with ferrocence-acetylide ligands and characterized by ESI-MS, and (1)H and (31)P NMR spectroscopies. The structure of [](PF6) was determined by X-ray crystallography. The electrochemical studies show that compounds [](ClO4)-[](ClO4) possess two widely separated anodic peaks, ascribable to one-electron oxidation of Fc and Ru(II), respectively. This assignment is further corroborated by the results of UV-vis-NIR, XPS, and theoretical calculation studies. Compound [](ClO4) exhibits significant RuFe metal-metal interactions across the Ru-C[triple bond, length as m-dash]C-Fc backbone. As revealed by electrochemical, spectroscopic and theoretical computational studies, one-electron oxidized species [](ClO4)2 is between the electronically delocalized and valence-trapped state and shows a typical Robin-Day class II mixed-valence behavior.

Multistate and Multicolor Photochromism through Selective Cycloreversion in Asymmetric Platinum(II) Complexes with Two Different Dithienylethene-Acetylides.

Four asymmetric bis(dithienylethene-acetylide) platinum(II) complexes trans-Pt(PEt3)2(L1o)(L5o) (1oo), trans-Pt(PEt3)2(L2o)(L5o) (2oo), trans-Pt(PEt3)2(L3o)(L5o) (3oo), and trans-Pt(PEt3)2(L4o)(L5o) (4oo) with two different dithienylethene-acetylides (L1o-L5o) were designed to modulate stepwise, multistate, and multicolor photochromism by modifying ring-closure absorption wavelengths. Upon irradiation under UV light, 1oo converts only to 1oc without the observation of 1co and dually ring-closed species 1cc. In contrast, both mixed ring-open/closed species oc and co as well as dually ring-closed species cc are observed upon UV light irradiation of 2oo-4oo, implying that a substantial stepwise photochromic process occurs following 2oo-4oo → 2oc-4oc/2co-4co → 2cc-4cc. The conversion percentage of dually ring-closed species at the photostationary state (PSS) is progressively increased following 1cc (0%) → 2cc (40%) → 3cc (86%) → 4cc (>95%), coinciding with the progressive red-shift of ring-closure absorption bands in free L1c (441 nm) → L2c (510 nm) → L3c (556 nm) → L4c (591 nm). Particularly, compound 2 affords four states (2oo, 2co, 2oc, and 2cc) with different colors (colorless, purple, blue, and dark blue, respectively) through a selective photochemical cycloreversion process upon irradiation with appropriate wavelengths of light. Although stepwise photocyclization reactions 3oo → 3co/3oc → 3cc and 4oo → 4co/4oc → 4cc are observed, multicolor photochromism of 3oo and 4oo could not be achieved because ring-closure absorption bands between L3c/L4c and L5c are significantly overlapped. The stepwise photochemical processes are well demonstrated by NMR, UV-vis, and infrared (IR) spectroscopy and time-dependent density functional theory (TD-DFT) computational studies.

Modulating stepwise photochromism in platinum(II) complexes with dual dithienylethene-acetylides by a progressive red shift of ring-closure absorption.

To modulate stepwise photochromism by shifting ring-closure absorption of the dithienylethene (DTE) moiety, trans-Pt(PEt3)2(C≡C-DTE)2 [C≡C-DTE = L1o (1oo), L2o (2oo), L3o (3oo), and L4o (4oo)] and cis-Pt(PEt3)2(L4o)2 (5oo) with two identical DTE-acetylides were elaborately designed. With the gradual red shift of ring-closure absorption for L1c (441 nm) → L2c (510 nm) → L3c (556 nm) → L4c (602 nm), stepwise photochromism is increasingly facilitated in trans-Pt(PEt3)2(C≡C-DTE)2 following 1oo → 2oo → 3oo → 4oo. The conversion percentage of singly ring-closed 2co-4co to dually ring-closed 2cc-4cc at the photostationary state is progressively increased in the order 1cc (0%) → 2cc (18%) → 3cc (67%) → 4cc (100%). Compared with trans-arranged 4oo, stepwise photochromism in the corresponding cis-counterpart 5oo is less pronounced, ascribed to either direct conversion of 5oo to 5cc or rapid conversion of 5co to 5cc. The progressively facile stepwise photocyclization following 2oo → 3oo → 4oo is reasonably interpreted by gradually enhanced transition character involving LUMO+1, which is the only unoccupied frontier orbital responsible for further photocyclization of singly ring-closed 2co-4co.

Aggregation-induced phosphorescence of iridium(III) complexes with 2,2'-bipyridine-acylhydrazone and their highly selective recognition to Cu2+.

Two cationic cyclometallated iridium(III) complexes with 2,2'-bipyridine-acylhydrazone were synthesized and characterized by spectroscopic and photophysical measurements. They exhibit remarkable aggregation-induced phosphorescent emission (AIPE) phenomenon which is caused by the restriction of rapid isomerization of the C=N bond in the acylhydrazone moiety and are supported by TD-DFT studies. They also act as a significant 'off-on' luminescent switch for Cu(2+) which works as both catalyzer and oxidant in the sensing process, resulting in hydrolysis and cyclization products which are highly emissive. The sensing properties of iridium(III) complexes are also investigated by ESI-MS spectrometry and (1)H NMR spectroscopy.

Redox-modulated stepwise photochromism in a ruthenium complex with dual dithienylethene-acetylides.

Achieving stepwise photochromism in a combined molecule to access all of the possible ring-open/closed isomers is a challenge due to facile energy transfer from ring-open dithienylethene (DTE) to an adjacent ring-closed moiety that prohibits further photocyclization. The preparation, characterization, and photochromic properties of a bis(σ-acetylide) bonded ruthenium(II) complex 2oo and its oxidized form 2oo(+) with two identical DTE-acetylides (L1o) are described. Stepwise and dual photochromic reactions are successfully achieved in both 2oo and 2oo(+), in which the ring-closing absorption band of 2oo(+) shows an obvious blue-shift relative to 2oo. It is demonstrated that stepwise photochromic reactions 2oo→2co→2cc are more facile than 2oo(+)→2co(+)→2cc(+). The lower electronic density at the reactive carbon atoms upon oxidation of Ru(II) to Ru(III) causes photocyclization to have more difficulty proceeding in oxidized species 2oo(+)/2co(+). Upon dual ring-closure, 2cc/2cc(+) exhibits significant electronic interaction between two identical ring-closed DTE units across trans-Ru(dppe)(2) spacer. The interconversion processes among six states are unambiguously demonstrated by NMR, UV-vis-NIR, and IR spectroscopic, and electrochemical and computational studies.

Gold(I)-coordination triggered multistep and multiple photochromic reactions in multi-dithienylethene (DTE) systems.

The preparation, characterization, and photochromic properties of a mononuclear gold(I) complex (1oo) with two identical DTE-acetylides and a dinuclear gold(I) complex (2ooo) with both DTE-acetylide and DTE-diphosphine are described. Both gold(I) complexes exhibit multistep and multiple photocyclization/cycloreversion reactions. Particularly, four-state and four-color photochromic switch is successfully achieved for the dinuclear gold(I) complex upon irradiation with appropriate wavelengths of light. In contrast, fully ring-closed form is unattained through multiple photocyclization for the two corresponding model organic compounds coupling with the same DTE units as gold(I) complexes but without gold(I)-participation. It is demonstrated that coordination of gold(I) ion to DTE-acetylides exerts indeed a crucial role in achieving stepwise and selective photocyclization and cycloreversion reactions for both gold(I) complexes, in which the coordinated gold(I) atom acts as an effective "barrier" to prohibit intramolecular energy transfer between multi-DTE moieties.

An iridium(III) complex of oximated 2,2'-bipyridine as a sensitive phosphorescent sensor for hypochlorite.

The designed synthesis of a sensitive phosphorescent chemosensor [Ir(ppy)(2)(L1)](PF(6)) (1) (Hppy = 2-phenylpyridine, L1 = 4'-methyl-2,2'-bipyridyl-4-carbaldehyde oxime) was carried out for selective detection of hypochlorite (ClO(-)). Complex 1 is weakly emissive in solution at ambient temperature due likely to rapid isomerization of C=N-OH as an effective non-radiative decay process. When 1 reacts with ClO(-), however, the emission is remarkably enhanced, in which the oxime in L1 is converted to a carboxylic acid in L2 (4'-methyl-2,2'-bipyridine-4-carboxylic acid). The produced complex [Ir(ppy)(2)(L2)](PF(6)) (2) exhibits bright orange-yellow luminescence originating from [5d(Ir) → π*(bpy)] (3)MLCT and [π(ppy) → π*(bpy)] (3)LLCT triplet excited states as suggested from the DFT computational studies. The selective and competitive experiments reveal that complex 1 shows high sensing selectivity and sensitivity for ClO(-) over other reactive oxygen species (ROS) and metal ions.

Sensitized luminescence in dinuclear lanthanide(III) complexes of bridging 8-hydroxyquinoline derivatives with different electronic properties.

Three new dinuclear lanthanide(III) complexes {Eu(hfac)(3)(H(2)O)}(2)(µ-HPhMq)(2) (2) and {Ln(hfac)(3)(H(2)O)}(2)(µ-HMe(2)NC(6)H(4)Mq)(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 HMe(2)C(6)H(4)Mq = 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 4 by 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-H···F hydrogen bonds with coordinated H(2)O and µ-phenol, thus suppressing significantly the non-radiative O-H oscillators.

A sensitive phosphorescent thiol chemosensor based on an iridium(III) complex with alpha,beta-unsaturated ketone functionalized 2,2'-bipyridyl ligand.

An iridium(III)-containing phosphorescent chemosensor Ir(ppy)(2)(L)(PF(6)) (1, ppy = 2-phenylpyridine) containing a 2,2'-bipyridyl ligand (L) functionalized with an alpha,beta-unsaturated ketone for selective detection of thiol was synthesized and characterized by spectroscopic and photophysical measurements. The structure of complex 1 was determined by X-ray crystallography. In order to get an insight into 1,4-addition reactions of thiol to complex 1, the adduct 2 from reaction of 1 with benzenethiol was successfully prepared and characterized. Complex 1 shows a lowest energy absorption at ca. 450 nm, primarily ascribable to an intraligand charge transfer (ILCT) transition from the HOMO (pi) resident on the fragment -C(O)C(6)H(4)N(C(2)H(5))(2) to the LUMO (pi*) localized on the 2,2'-bipyridyl moiety in the functionalized 2,2'-bipyridyl ligand as suggested from DFT computational studies. Complex 1 is weakly emissive at ca. 587 nm at ambient temperature, arising likely from the (3)ILCT 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 [pi(ppy)-->pi*(L)] LLCT and the [5d(Ir)-->pi*(L)] MLCT state caused by the formation of the 1-thiol adduct. The sensing properties of 1 to thiol were also investigated by ESI-MS spectrometry and (1)H NMR spectroscopy.

Square structures and photophysical properties of Zn(2)Ln(2) complexes (Ln = Nd, Eu, Sm, Er, Yb).

Heterotetranuclear Zn(2)Ln(2) (Ln = Nd , Eu , Sm , Er , Yb ) complexes {Zn(2)(Mq)(2)(tpyO)(2)}{(Ln(hfac)(3))(2)} (HMq = 2-methyl-8-hydroxylquinoline, tpyOH = [2,2':6'2'']terpyridin-4'-ol, hfac = hexafluoroacetylacetonate) display novel square structures ligated by bifunctional ligands tpyO (mono- and tridentate) and Mq (chelating and bridging mu-phenoxo). These compounds exhibit sensitized lanthanide emission upon photo-excitation of ZnMq/tpy antenna chromophores. By virtue of the dual luminescence with complementary colors, the ZnMq/tpyO-based cyan emission and Sm(III)-centered orange luminescence are combined to generate a white-light emission in Zn(2)Sm(2) (4) complex.

Photochromic and electrochromic properties of oxo-centred triruthenium compounds with a dithienylethene bis(phosphine) ligand.

The reaction of 1,2-bis(5-(diphenylphosphino)-2-methylthien-3-yl) cyclopentene (PPh(2)-DTE-PPh(2)) with the triruthenium cluster precursor [Ru(3)O(OAc)(6)(py)(2)(CH(3)OH)](PF(6)) (1) gave monomeric or dimeric derivatives [Ru(3)O(OAc)(6)(py)(2){PPh(2)-DTE-PPh(2)}](PF(6)) ([2]PF(6)) and [{Ru(3)O(OAc)(6)(py)(2)}(2){mu-PPh(2)-DTE-PPh(2)}](PF(6))(2) ([3]PF(6)). Reduction of [2](+) and [3](2+) afforded one- or two-electron-reduced neutral products Ru(3)O(OAc)(6)(py)(2){PPh(2)-DTE-PPh(2)} (2) and {Ru(3)O(OAc)(6)(py)(2)}(2){mu-PPh(2)-DTE-PPh(2)} ()3, respectively. These triruthenium complexes show remarkable photochromism through photochemical ring-closing (UV light irradiation) and ring-opening (Vis light irradiation) processes as well as electrochromic properties through oxidation/reduction in the triruthenium cluster. Both the photochromic and electrochromic properties of 2 and 3 are highly reversible.

Systematic investigation on the coordination chemistry of a sulfonated monoazo dye: ligand-dominated d- and f-block derivatives.

Ten coordination compounds based on a sulfonated monoazo dye, formulated as M(H(2)O)(2)(4,4'-abs)(2) (M = Mn , Co , Cu , Zn , Cd and Pb ; 4,4'-abs = 4-aminoazobenzene-4'-sulfonic anion), Ag(4,4'-abs) (), [Ln(H(2)O)(phen)(2)(4,4'-abs)(3)].3H(2)O (Ln = Gd , Tb , and Ho ; phen = 1,10-phenanthroline), as well as the parent ligand L [(4,4'-Habs)(2).4H(2)O] and precursor NaL.HL [Na(4,4'-abs)(4,4'-Habs)] were successfully isolated. Structural analyses revealed that the structures of compounds, and vary according to the coordination geometries of the metal ions, and vary from double-strand chain structures () to a 3-D pillared-layer framework to mononuclear complexes. The double-strand chain structures of are isostructural, and are built on octahedral metal centers and double bridging 4,4'-abs ligands coordinating via terminal N- and O-donors. The silver-containing compound displays a pillared-layer structure constructed from 4.8(2) silver sulfonate nets pillared by the linear backbones of 4,4'-abs ligands. Compounds , which are also isostructural, possess mononuclear structures consisting of a metal cation, three 4,4'-abs anions, two auxiliary phen ligands, one aqua ligand and three non-coordinated water molecules. Evidence on two series of isostructural compounds indicates that structures of d- and f-block metal derivatives are dominated by the coordination mode of the ligands. The surface chemistry of compound has been investigated based on the LBL (layer-by-layer) technique. The as-synthesized multilayer films with different composite components exhibit different surface behaviours.

Sensitization of lanthanide luminescence by two different Pt-->Ln energy transfer pathways in PtLn3 heterotetranuclear complexes with 5-ethynyl-2,2'-bipyridine.

Reactions of 5-[2-(trimethylsilyl)-1-ethynyl]-2,2'-bipyridine (Me3SiC-Cbpy) with Pt(bpy)C12 (bpy = 2,2'-bipyridine) and Pt(bpyC[triple bond]C-C[triple bond]Cbpy)Cl2 (bpyC[triple bond]C-C[triple bond]Cbpy=bis(2,2'-bipyridin-5-yl)butadiyne) induced isolation of Pt(bpy)(C[triple bond]Cbpy)2 (1) and Pt(bpyC[triple bond]C-C[triple bond]Cbpy)(C[triple bond]Cbpy)2 (5), respectively. Incorporating Ln(hfac)3(H2O)2 (hfac = hexafluoroacetylacetone) with 1 or 5 gave the corresponding PtLn2 (Ln = Nd (2), Eu (3), Yb (4)) or PtLn3 arrays (Ln=Nd (6), Eu (7), Gd (8), Yb (9)). With excitation at 360 < or = lamda(ex)0 < or =480 nm, which is the MLCT absorption region of the Pt(2,2'-bipyridyl)(acetylide)2 chromophore, sensitized lanthanide luminescence is successfully attained by efficient Pt-->Ln energy transfer from the Pt(II) antenna chromophores. In contrast with quite efficient Pt-->Ln energy transfer in the Pt-C[triple bond]Cbpy-Ln(Pt...Ln = 8.6 A) array, energy transfer transmitted across the Pt-bpyC[triple bond]C-C[triple bond]Cbpy-Ln(Pt...Ln = 13.3 A) array is less efficient owing to the much longer Pt...Ln separation in the latter.

Reversal effect of tyroservatide (YSV) tripeptide on multi-drug resistance in resistant human hepatocellular carcinoma cell line BEL-7402/5-FU.

Tyroservatide (YSV) is an active, low-molecular-weight polypeptide that has been shown to have antitumor effects on human hepatocellular carcinoma BEL-7402 cells in vitro and in vivo. Multi-drug resistance (MDR) represents a major obstacle to the success of cancer chemotherapy. To enhance the chemosensitivity of tumor cells, attention has been focused on MDR modulators. In this study, we evaluated the reversal effect of YSV on MDR, and explored its mechanism of action in vitro. Administration of YSV reversed the multi-drug resistance of human hepatocellular carcinoma BEL-7402/5-FU cells significantly. The intracellular accumulation of doxorubicin and Rhodamine-123 (Rh123) were increased, which implied that the function of the P-glycoprotein (P-gp) efflux pump was inhibited by YSV. Moreover, the mRNA and protein expression of multi-drug resistance gene (MDR1) were also decreased by YSV. We observe that lung-resistance protein (LRP) and multi-drug resistance-associated protein (MRP1) each contribute to MDR in BEL-7402/5-FU cells as well. The mRNA and protein expression of LRP were decreased by YSV. No significant change was observed in mRNA expression of MRP1. However, we observe that the MRP1 protein level was reduced after treatment with YSV. These data demonstrate that YSV effectively reverses MDR in BEL-7402/5-FU cells, and that its mechanism of action is associated with the down-regulation of MDR1, MRP1 and LRP expression, as well as the inhibition of P-gp function.

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.