Metal-containing organic compounds for memory and data storage applications.

With the upcoming trend of Big Data era, some new types of memory technologies have emerged as substitutes for the traditional Si-based semiconductor memory devices, which are encountering severe scaling down technical obstacles. In particular, the resistance random access memory (RRAM) and magnetic random access memory (MRAM) hold great promise for the in-memory computing, which are regarded as the optimal strategy and pathway to solve the von Neumann bottleneck by high-throughput in situ data processing. As far as the active materials in RRAM and MRAM are concerned, organic semiconducting materials have shown increasing application perspectives in memory devices due to their rich structural diversity and solution processability. With the introduction of metal elements into the backbone of molecules, some new properties and phenomena will emerge accordingly. Consequently, the RRAM and MRAM devices based on metal-containing organic compounds (including the small molecular metal complexes, metallopolymers, metal-organic frameworks (MOFs) and organic-inorganic-hybrid perovskites (OIHPs)) have been widely explored and attracted intense attention. In this review, we highlight the fundamentals of RRAM and MRAM, as well as the research progress of the applications of metal-containing organic compounds in both RRAM and MRAM. Finally, we discuss the challenges and future directions for the research of organic RRAM and MRAM.

Recent Advances in the Optimization of Organic Light-Emitting Diodes with Metal-Containing Nanomaterials.

Metal-containing nanomaterials have attracted widespread attention in recent years due to their physicochemical, light-scattering and plasmonic properties. By introducing different kinds and different structures of metal-containing nanomaterials into organic light-emitting diodes (OLEDs), the optical properties of the devices can be tailored, which can effectively improve the luminous efficiency of OLEDs. In this review, the fundamental knowledge of OLEDs and metallic nanomaterials were firstly introduced. Then we overviewed the recent development of the optimization of OLEDs through introducing different kinds of metal-containing nanomaterials.

A molecular approach to magnetic metallic nanostructures from metallopolymer precursors.

In recent years, metallopolymers have attracted much attention as precursors to generate magnetic metal/metal alloy nanoparticles (NPs) through pyrolysis or photolysis because they offer the advantages of ease of solution processability, atomic level mixing and stoichiometric control over composition. The as-generated NPs usually possess narrow size distributions with precise control of composition and density per unit area. Moreover, patterned NPs can be achieved on various substrates in this way owing to the good film-forming property of metallopolymers and such work is important for many applications based on metal nanostructures. By combining the merits of both the solution processability of metallopolymers and nanoimprint lithography (NIL), a new platform can be created for fabricating bit-patterned media (BPM) and the next-generation of nanoscale ultra-high-density magnetic data storage devices. Furthermore, most of these metallopolymers can be used directly as a negative-tone resist to generate magnetic metallic nanostructures by electron-beam lithography and UV photolithography. Self-assembly and subsequent pyrolysis of metalloblock copolymers can also afford well-patterned magnetic metal or metal alloy NPs in situ with periodicity down to dozens of nanometers. In this review, we highlight the use of metallopolymer precursors for the synthesis of magnetic metal/metal alloy NPs and their nanostructures and the related applications.

From lithium bis(trimethylsilyl)amide with cyanoamine into triazine compounds: synthesis and structures of lithium 6-((trimethylsilyl)amido)-2,4-bis(dimethylamino)[1,3,5]triazines and their manganese and cobalt complexes.

Addition reactions of lithium bis(trimethylsilyl)amide with dimethylcyanamide lead to novel lithium salts of 6-((trimethylsilyl)amido)-2,4-bis(dimethylamino)[1,3,5]triazines [LLi(D)](2) (L = NC(NMe(2))NC(NMe(2))NC(NSiMe(3)); D = Me(2)NCN (1), Et(2)O (2)) and to the Mn and Co complexes [LL'M] (L' = N{N(SiMe(3))C(NMe(2))}(2); M = Mn (3), Co (4)); the structures of crystalline 1, 3, and 4 are reported. Their formation involves trimethylsilyl shifts, ring formation, and unusual Me(2)NSiMe(3) elimination.

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.

An inorganic magnetic fluorescent nanoprobe with favorable biocompatibility for dual-modality bioimaging and drug delivery.

In this work, we present the development of a high water soluble biological nanoprobe through the covalent bonding of ß-CD onto the surface of iron oxide­gold nanoclusters (Fe3O4@Au@ß-CD). Fe3O4@Au@SiO2 NPs were also prepared for comparison. The maximum emission peak of magnetic fluorescent NPs red-shifted by 30 nm and the lifetime was also elongated to 5.21 µs after surface modified with ß-CD. The relaxivities and in vitro magnetic resonance imaging ability of the resultant magnetic fluorescent NPs were also studied, indicating that Fe3O4@Au@ß-CD NPs have the lowest r2/r1 ratio and could be a potential T2 contrast agent for MR imaging. The MTT assay proved that, Fe3O4@Au@ß-CD NPs are of excellent water solubility and biocompatibility. In vitro confocal fluorescence imaging was also performed, manifesting that Fe3O4@Au@ß-CD NPs can be selectively uptaken by gastric cancer cells (MGC-803) and exhibit red fluorescence in the cells. The preliminary drug loading and releasing measurements demonstrate that it can also act as targeted drug delivery nanosystem. All these experimental results indicate that, Fe3O4@Au@ß-CD NPs hold great application perspective in the diagnosis and therapy of gastric cancer cells as biological nanoprobes.

Realization of efficient light out-coupling in organic light-emitting diodes with surface carbon-coated magnetic alloy nanoparticles.

A significant enhancement in light extraction in organic light-emitting diodes (OLEDs) is realized by using composite hole transport layers (HTLs) with surface carbon-coated magnetic alloy nanoparticles (NPs). Compared to the control device with a standard architecture, the current efficiencies of fluorescent green OLEDs can be enhanced by 47.1% and 48.5% by mixing the surface carbon-coated magnetic FePt (0.5 wt‰) and CoPt (0.5 wt‰) alloy NPs into poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), yielding the maximum values of 5.40 cd A-1 and 5.45 cd A-1, respectively. The presence of an alloy NP-incorporated PEDOT:PSS HTL also acts as an optical out-coupling layer contributing to the efficiency enhancement, accomplished through the collective effects of light-scattering, localized surface plasmon resonance and increased electron trap density induced by magnetic alloy NPs.

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.

Metallopolymer precursors to L10-CoPt nanoparticles: synthesis, characterization, nanopatterning and potential application.

Ferromagnetic (L10 phase) CoPt alloy nanoparticles (NPs) with extremely high magnetocrystalline anisotropy are promising candidates for the next generation of ultrahigh-density data storage systems. It is a challenge to generate L10 CoPt NPs with high coercivity, controllable size, and a narrow size distribution. We report here the fabrication of L10 CoPt NPs by employing a heterobimetallic CoPt-containing polymer as a single-source precursor. The average size of the resulting L10 CoPt NPs is 3.4 nm with a reasonably narrow size standard deviation of 0.58 nm. The coercivity of L10 CoPt NPs is 0.54 T which is suitable for practical application. We also fabricated the L10 CoPt NP-based nanoline and nanodot arrays through nanoimprinting the polymer blend of CoPt-containing metallopolymer and polystyrene followed by pyrolysis. The successful transfer of the pre-defined patterns of the stamps onto the surface of the polymer blend implies that this material holds great application potential as a data storage medium.

Conjugated Oligothiophene Derivatives Based on Bithiophene with Unsaturated Bonds as Building Blocks for Solution-Processed Bulk Heterojunction Organic Solar Cells.

A new building block ATVTA that uses stiff carbon-carbon triple bonds (A) on 1,2-di(2-thienyl)-ethene (TVT) has been developed. Oligothiophene derivatives S-01 with a TVT unit, S-02 with a 5,5'-diethynyl-2,2'-dithienyl (AT2) unit and S-03 with ATVTA were synthesized to compare their effects in a systematic study. Due to the better π-conjugation extension of the TVT unit, S-01 exhibits the most red-shifted absorption profile among them, whereas S-02 possesses the deepest HOMO level. While the HOMO level of S-03 is down-shifted by 0.02 eV relative to that of S-01, the alkyne linkages can effectively down-shift the HOMO level. By replacing the terminal units of S-03 with stronger electron acceptors, S-04 and S-05 exhibited broader absorption profiles and lower HOMO levels than those of S-03. Organic solar cells based on these molecules were fabricated and an S-03:PC60 BM (1:1, w/w) based device afforded the highest Voc value of 0.96 V and a power conversion efficiency (PCE) of 2.19 %.

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.