Qingchen Dong

A Polyferroplatinyne Precursor for the Rapid Fabrication of L1 0 -FePt-type Bit Patterned Media by Nanoimprint Lithography

A polyferroplatinyne polymer can be patterned on the surface of Si wafer in ordered nanoline or nanodot shapes with PDMS molds through nanoimprint lithography (NIL), and subsequent thermal treatment gives rise to the nanopatterned arrays of L1(0) -FePt nanoparticles with the same periodicities. The method offers excellent potential to be utilized in the simple and rapid fabrication of bit patterned media for magnetic data recording.

Investigation of pyrolysis temperature in the one-step synthesis of L10 FePt nanoparticles from a FePt-containing metallopolymer

Ferromagnetic (L10 phase) FePt alloy nanoparticles (NPs) with extremely high magnetocrystalline anisotropy are considered to be very promising candidates for the next generation of ultrahigh-density data storage systems. The question of how to generate L10 FePt NPs with high coercivity, controllable size, and a narrow size distribution is a challenge. We report here a single-step fabrication of L10 FePt NPs by employing one of the two new polyferroplatinyne bimetallic polymers as precursors. The influence of the pyrolysis temperature on the size and magnetic properties of the resulting FePt alloy NPs has been investigated in detail.

Novel hole transport materials based on N,N′-disubstituted-dihydrophenazine derivatives for electroluminescent diodes

A series of novel hole transport materials for organic light-emitting diodes (OLEDs) based on 9,14-diphenyl-9,14-dihydrodibenzo[a,c]phenazine were synthesized and characterized by 1H NMR and 13C NMR, mass spectrometry and single crystal structure analysis methodologies. The crystal structures of three selected molecules reveal large dihedral angles between different functional units. The electro-optical properties of the materials were examined by UV-vis absorption, photoluminescence spectroscopy and cyclic voltammetry. The HOMO of the materials were between 4.83–5.08 eV, indicating a good match between the HOMO of indium tin oxide (ITO) and the HOMO of light-emitting layer, which renders the promising candidates as hole transport materials for organic light-emitting devices. In terms of the device with the structure of ITO/HTM (60 nm)/Alq3 (50 nm)/LiF (1 nm)/Al (200 nm), the device b using N,N-diphenyl-4′-(14-phenyldibenzo[a,c]phenazin-9(14H)-yl)-[1,1′-biphenyl]-4-amine presented a maximum luminance of 17 437 cd m−2 at 10.7 V and kept a high current efficiency (the maximum current efficiency is 2.25 cd A−1) at a high current density (>500 mA cm−2), which illustrates the exploited material possesses good hole transport and stable properties.

Porphyrin-based metallopolymers: synthesis, characterization and pyrolytic study for the generation of magnetic metal nanoparticles

Metallopolymers with different metal centers, pendant groups and linkages exhibit diverse structures and properties, thus giving rise to versatile applications, e.g., as emissive and photovoltaic materials, optical limiters, materials for nano-electronics, information storage, nanopatterning and sensing, macromolecular catalysts and artificial enzymes, and stimuli-responsive materials. Recently, metallopolymers as precursors to generate monometallic or metal alloy nanoparticles are of great interest owing to their advantages of ease of processability, atomic level mixing, and stoichiometric control over composition. By taking advantage of the template effect of porphyrin compounds, a series of monometallic and heterobimetallic polymers are synthesized which are characterized by NMR, IR, HRMS, EA, GPC and TGA, respectively. Photophysical properties of these metallopolymers are also studied by UV-vis spectroscopy. Pyrolytic treatment of these metallopolymers generates various magnetic monometallic and metal alloy nanoparticles which can be used in data storage, catalysis, biomedicine, etc.

Dual Coordination Modes of Ethylene-Linked NP2 Ligands in Cobalt(II) and Nickel(II) Iodides

Here we report the syntheses and crystal structures of a series of cobalt(II) and nickel(II) complexes derived from (R)NP2 ligands (where R = OMe(Bz), H(Bz), Br(Bz), Ph) bearing ethylene linkers between a single N and two P donors. The Co(II) complexes generally adopt a tetrahedral configuration of general formula [(NP2)Co(I)(2)], wherein the two phosphorus donors are bound to the metal center but the central N-donor remains unbound. We have found one case of structural isomerism within a single crystal structure. The Co(II) complex derived from (Bz)NP2 displays dual coordination modes: one in the tetrahedral complex [((Bz)NP2)Co(I)(2)]; and the other in a square pyramidal variant, [((Bz)NP2)Co(I)(2)]. In contrast, the Ni(II) complexes adopt a square planar geometry in which the P(Et)N(Et)P donors in the ligand backbone are coordinated to the metal center, resulting in cationic species of formula [((R)NP2)Ni(I)](+) with iodide as counterion. All Ni(II) complexes exhibit sharp (1)H and (31)P spectra in the diamagnetic region. The Co(II) complexes are high-spin (S = 3/2) in the solid state as determined by SQUID measurements from 4 to 300 K. Solution electron paramagnetic resonance (EPR) experiments reveal a high-spin/low-spin Co(II) equilibrium that is dependent on solvent and ligand substituent.

Bi-functional fluorescent polymer dots: a one-step synthesis via controlled hydrothermal treatment and application as probes for the detection of temperature and Fe3+

A one-step controlled hydrothermal method was described to prepare highly fluorescent polymer dots (PDs) by using polyethylene glycol as the carbon source. The synthesized PDs with an average diameter of 2.5 nm exhibit strong blue fluorescence with high quantum yields (QYs, up to 19%). Further modification of these PDs with glutathione (GSH) endows the resultant GSH–PDs with bi-functional fluorescence responses to temperature and Fe3+. Interestingly, the fluorescence signal of the GSH–PDs is reversibly responsive to the environmental temperature in the range of 20–75 °C. As the GSH–PDs exhibit good biocompatibility, they can pervade the MC3T3-E1 cells and enable the measurement of temperature over the physiological range of 20–45 °C using the confocal fluorescence imaging method. The GSH–PDs were also explored as a fluorescent probe for Fe3+ ion detection, and the linear response range in 0.1–10 μM was observed with a detection limit of 3.7 nM. Thus, the bi-functional measurement of temperature and Fe3+ ions was achieved by the fluorescent PD chemosensor.

Hyperbranched Phosphorescent Conjugated Polymer Dots with Iridium(III) Complex as the Core for Hypoxia Imaging and Photodynamic Therapy

Real-time monitoring of the contents of molecular oxygen (O2) in tumor cells is of great significance in early diagnosis of cancer. At the same time, the photodynamic therapy (PDT) could be realized by highly toxic singlet oxygen (1O2) generated in situ during the O2 sensing, making it one of the most promising methods for cancer therapy. Herein, the iridium(III) complex cored hyperbranched phosphorescent conjugated polymer dots with the negative charges for hypoxia imaging and highly efficient PDT was rationally designed and synthesized. The incomplete energy transfer between the polyfluorene and the iridium(III) complexes realized the ratiometric sensing of O2 for the accurate measurements. Furthermore, the O2-dependent emission lifetimes are also used in photoluminescence lifetime imaging and time-gated luminescence imaging for eliminating the autofluorescence remarkably to enhance the signal-to-noise ratio of imaging. Notably, the polymer dots designed could generate the 1O2 effectively in aqueous solution, and the image-guided PDT of the cancer cells was successfully realized and investigated in detail by confocal laser scanning microscope. To the best of our knowledge, this represents the first example of the iridium(III) complex cored hyperbranched conjugated polymer dots with the negative charges for both hypoxia imaging and PDT of cancer cells simultaneously.

Efficient blue fluorescent organic light-emitting diodes based on novel 9,10-diphenyl-anthracene derivatives

A series of novel 9,10-di(naphthalen-2-yl)anthracene (ADN) derivatives were designed and synthesized as blue fluorescent emissive materials by inducing diverse aromatic groups to the C-2 position of ADN. UV-Vis absorption, fluorescence emission spectroscopy and cyclic voltammetry (CV) were carried out to generally investigate the relationships between the physical properties and molecular structures. Moreover, four non-doped OLED devices adopting OCADN, FA3PADN, FA4PADN and OC4PADN as emitting materials were fabricated to study their electroluminescence (EL) performances. Among them, a device based on OCADN exhibited highly efficient sky-blue emission with a current efficiency of 2.25 cd A−1, power efficiency of 1.13 lm W−1 and CIE(x, y) coordinate of (0.16, 0.30) at 8 V. In addition, the device of OC4PADN showed efficient blue emission with a CIE(x, y) coordinate of (0.16, 0.14) at 8 V.

A novel supramolecular system with multiple fluorescent states constructed by orthogonal self-assembly

A novel supramolecular fluorescent system was successfully constructed by orthogonal self-assembly of host–guest and metal–ligand interactions. By controlling the non-covalent interactions in different ways, the system exhibits diverse fluorescent switching phenomena.

Synthesis, characterization and electrochemistry of some metal carbonyl clusters derived from ferrocenylethynylpyridine

The chemical reactivity of ferrocenylethynylpyridine ligand with some metal complexes has been studied. Ligation of this ferrocenyl-functionalized pyridyl metalloligand with triosmium carbonyl cluster [Os3(CO)10(NCMe)2] via oxidative addition led to a new supramolecular heterobimetallic cluster [Os3(CO)10(μ-H){μ-NC5H3C≡C(η5-C5H4)Fe(η5-C5H5)}] 1 in good yield. Coordination of Co2(CO)8 with the alkyne functionality of 1 gave another new heterotrimetallic cluster complex [Os3(CO)10(μ-H){μ-NC5H3{C2Co2(CO)6}(η5-C5H4)Fe(η5-C5H5)}] 2 in which the molecule possesses a Co2C2 core adopting the pseudo-tetrahedral geometry having the alkyne bond lying perpendicular to the Co–Co vector. Characterization of 1 and 2 by IR and 1H NMR spectroscopies indicated that these complexes consist of an orthometalated trinuclear carbonyl cluster unit rigidly connected to a ferrocenyl unit. Electrochemical studies on 1 and 2 revealed that both of them undergo a reversible one-electron oxidation at iron followed by an irreversible oxidation of the Os3 cluster core. Another simple mononuclear zinc(II) complex [ZnCl2{(NC5H4C≡C(η5-C5H4)Fe(η5-C5H5)}2] 3 was also prepared for comparison of the electrochemical data with those of 1 and 2.