Shouquan Huo

Improvement in phosphorescence efficiency through tuning of coordination geometry of tridentate cyclometalated platinum(II) complexes.

A series of tridentate cyclometalated platinum(II) complexes (C(∧)N*N)PtL (L = Cl or acetylide) featuring a fused five-six-membered metallacycle were synthesized. The structure of the complexes was confirmed by X-ray crystallography. In contrast to the C(∧)N(∧)N platinum complexes with a fused five-five-membered metallacycle, the platinum coordination in C(∧)N*N complexes is much closer to a square planar geometry. The photophysical properties of the complexes were studied. The geometrical change from C(∧)N(∧)N to C(∧)N*N led to a substantial improvement in phosphorescence efficiency of the complexes with an acetylide ligand in solution at room temperature. For example, the quantum yield of (C(∧)N*N)PtCCPh was measured to be 56%, demonstrating a big jump from 4% reported for (C(∧)N(∧)N)PtCCPh.

Highly luminescent tridentate N^C*N platinum(II) complexes featured in fused five-six-membered metallacycle and diminishing concentration quenching.

A series of cyclometalating ligands, N-phenyl-N-(3-(pyridin-2-yl)phenyl)pyridin-2-amine (L1), N-(3-(1H-pyrazol-1-yl)phenyl)-N-phenylpyridin-2-amine (L2), N-phenyl-N-(3-(quinolin-2-yl)phenyl)pyridin-2-amine (L3), N-phenyl-N-(3-(pyridin-2-yl)phenyl)quinolin-2-amine (L4), N-(3-(isoquinolin-1-yl)phenyl)-N-phenylpyridin-2-amine (L5), and N-phenyl-N-(3-(pyridin-2-yl)phenyl)isoquinolin-1-amine (L6), were synthesized, which reacted with K(2)PtCl(4) in glacial acetic acid to produce N^C*N-coordinated platinum(II) complexes featured in a fused five-six-membered metallacycle, 1-6, respectively. The structures of 1, 3, 4, and 6 were determined by single crystal X-ray crystallography. The square geometries of the complexes are improved when compared with those of the N^C^N-coordinated complexes as the bite angles for the platinum in N^C*N-coordinated complexes 1, 3, and 4 are increased. The Pt-C bonds (1.94-1.95 Å) are shorter than those of C^N^N-coordinated platinum complexes but longer than those found for N^C^N-coordinated platinum complexes. With the increase of the steric interaction, the distortion of the molecules from a planar coordination geometry becomes more and more severe from 1 to 3 to 4 and 6, and in 6, the N-phenyl ring has to stand up on the coordination sphere to minimize the steric interaction with the N-isoquinolyl ring. The photophysical properties of the complexes were studied, and their absorption and emission spectra were interpreted by relating to the structural features revealed by the X-ray crystal structures and the orbital characters predicted by DFT calculations. All complexes are emissive in fluid at room temperature, and the quantum yields (up to 0.65) are comparable to those of highly emissive N^C^N-coordinated platinum complexes. Self-quenching was not observed in the concentration range of 10(-6) to 10(-4) M. Large rigidochromic shifts for the emissions of 2, 4, and 6 upon cooling from room temperature to rigid glass (77 K) were observed. Two different triplet states that control the emissions were proposed to account for the photophysical properties of 6.

Hydroxycamptothecin-loaded Fe3O4 nanoparticles induce human lung cancer cell apoptosis through caspase-8 pathway activation and disrupt tight junctions.

10‐Hydroxycamptothecin (HCPT) elicits strong anti‐cancer effects and is less toxic than camptothecin (CPT), making it widely used in recent clinical trials. However, its low solubility limits its application as an effective anti‐cancer therapy. In the present study we investigate the hypothesis that the unique water dispersible oleic acid‐Triton X‐100‐coated Fe3O4 nanoparticles loaded with HCPT disrupt epithelial cell–cell junctions and induce human lung cancer cell apoptosis through the caspase‐8 pathway. We characterized the HCPT‐loaded nanoparticles and determined their effects on lung cancer cell viability and apoptosis by using immunofluorescence light microscopy and SDS‐PAGE/immunoblots. We found that HCPT‐loaded nanoparticles elicited an anti‐proliferative effect in a dose‐dependent manner. HCPT‐loaded nanoparticles reduced the expression of cell–cell junction protein claudins, E‐cadherin and ZO‐1, and transmission electron microcopy demonstrated a disrupted tight junction ultrastructure. Transepithelial electric resistance was also reduced, indicating the reduction of tight junction functions. The HCPT‐loaded nanoparticles increased phosphorylation of p38 and SAPK/JNK while it showed no effects on p42/44 MAP kinase. Compared with void Fe3O4 nanoparticles or HCPT drug alone, HCPT drug‐loaded nanoparticles evoked synergistic effects by increasing cell apoptosis with enhanced activation of the caspase‐8 pathway. Therefore, our current study highlights the potential of HCPT drug‐loaded nanoparticles as a chemotherapeutic agent for increasing anti‐cancer drug efficacy. (Cancer Sci 2011; 102: 1216–1222)

Acridinone/amine(carbazole)-based bipolar molecules: efficient hosts for fluorescent and phosphorescent emitters.

Three acridinone-based molecules ADBP, ACBP, and DABP were synthesized, and their application to the OLED devices was investigated. When used as the host for either the deep blue singlet or the green triplet emitter in OLED devices, the bipolar molecules ADBP and ACBP demonstrated superior performance compared to either DABP or commonly used host CBP, remarkably lowering the drive voltage and improving efficiencies.

Zirconium-catalyzed enantioselective carboalumination of unactivated alkenes as a new synthetic tool for asymmetric carbon-carbon bond formation

The discovery, methodological developments, including those for separationpurification of chiral flexible primary alcohols, and their applications to the syntheses of some natural products of the titled reaction are discussed.

Negishi coupling in the synthesis of advanced electronic, optical, electrochemical, and magnetic materials

Negishi coupling is one of the most important modern organic synthetic methods for selective C–C bond formation, and has been extensively applied in the synthesis of organic electronic, optical, electrochemical, and magnetic materials. This report provides a critical overview of the efficiency and versatility of Negishi coupling as applied for synthesizing polymers, oligomers, and small molecules with a wide variety of structural features and various desirable functions for organic electronic, optoelectronic, and other advanced technologies.

Platinum-Catalyzed Double Acylation of 2-(Aryloxy)pyridines via Direct C-H Activation

A unique, platinum-catalyzed, direct C-H acylation of 2-(aryloxy)pyridines with acyl chlorides is discovered. The reaction requires neither an oxidant nor other additives. When both ortho positions of the aryl group are accessible, the double acylation occurs readily to produce the diacylated products. Aliphatic, aromatic, and α,β-unsaturated acyl groups can all be introduced. The acylation reaction may proceed through an analogous aromatic electrophilic substitution triggered by the nucleophilic attack of the platinum at the acyl chloride.

A general method for the synthesis of E and/or Z oligoisoprenoids based on Pd-catalyzed homoallyl-alkenyl and homopropargyl-alkenyl cross coupling and Zr-catalyzed carboalumination

A truly general, versatile, and highly regioselective and stereoselective methodology for the synthesis of terpenoids containing 1,5-diene units of E and/or Z geometry critically involves (a) Pd-catalyzed homoallyl-alkenyl and homopropargyl-alkenyl coupling and (b) Zr-catalyzed carboalumination of alkynes. In each introduction of an E or Z trisubstituted C5 alkene unit, the yield is excellent, and the regioselectivity and stereoselectivity level is >98%. As such, this appears to represent the first general synthetic method accommodating Z alkene units in >95% regioselectivity and stereoselectivity. Its application to some representative terpenoids of both natural and unnatural geometries is discussed.

P-189: Vapor Pressures of Homo- and Heteroleptic Orthometalated Complexes of Iridium

Tris-orthometalated complexes of iridium are the leading class of phosphorescent dopants for use in harvesting triplet state emission in OLEDs. Here we report vapor pressures of a group of homo- and heteroleptic orthometalated iridium complexes and derive the enthalpies and entropies of sublimation. Molecular features influencing these thermodynamic properties are discussed. Keywords: phosphorescent emitter, iridium complexes, sublimation, vapor pressures, enthalpy, entropy.