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  • Journal article
    Leber R, Wilson LE, Robaschik P, Inkpen MS, Payne DJ, Long NJ, Albrecht T, Hirjibehedin CF, Heutz Set al., 2017,

    High Vacuum Deposition of Biferrocene Thin Films on Room Temperature Substrates

    , Chemistry of Materials, Vol: 29, Pages: 8663-8669, ISSN: 0897-4756

    Metallocenes are a promising candidate for future spintronic devices due to their versatile and tunable magnetic properties. However, single metallocenes, e.g., ferrocene, sublimate below room temperature, and therefore the implementation for future applications is challenging. Here, a method to prepare biferrocene thin films using organic molecular beam deposition (OMBD) is presented, and the effect of substrate and deposition rate on the film structure and morphology as well as its chemical and magnetic properties is investigated. On Kapton and Si substrates, biferrocene interacts only weakly with the substrate, and distinct grains scattered over the surface are observed. By incorporating a 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) seeding layer and depositing biferrocene at high deposition rates of 1.0 Å s–1, it is possible to achieve a well-ordered densely packed film. With spintronic applications in mind, the magnetic properties of the thin films are characterized using superconducting quantum interference device (SQUID) magnetometry. Whereas initial SQUID measurements show weak ferromagnetic behavior up to room temperature due to oxidized molecule fragments, measurements of biferrocene on PTCDA capped with LiF show the diamagnetic behavior expected of biferrocene. Through the successful deposition of biferrocene thin films and the ability to control the spin state, these results demonstrate a first step toward metallocene-based spintronics.

  • Conference paper
    Zhang G, Lin S, Leow CH, Pang K, Hernandez-Gil J, Chee M, Long NJ, Matsunaga TO, Tang M-Xet al., 2017,

    Acoustic Response of Targeted Nanodroplets Post-Activation using High Frame Rate Imaging

    , IEEE International Ultrasonics Symposium (IUS), Publisher: IEEE, ISSN: 1948-5719
  • Journal article
    Gallo J, Harriss BI, Hernandez-Gil J, Banobre-Lopez M, Long NJet al., 2017,

    Probing T-1-T-2 interactions and their imaging implications through a thermally responsive nanoprobe

    , Nanoscale, Vol: 9, Pages: 11318-11326, ISSN: 2040-3364

    The complex and specialised diagnostic process through magnetic resonance imaging (MRI) could be simplified with the implementation of dual T1–T2 contrast agents. T1- and T2-weighted MR are compatible modalities, and co-acquisition of contrast enhanced images in both T1 and T2 will drastically reduce artefacts and provide double-checked results. To date, efforts in the development of dual MRI probes have provided inconsistent results. Here we present the preparation and relaxometric study of a dual T1–T2 MRI probe based on superparamagnetic nanoparticles, paramagnetic Gd3+ chelates and pNIPAM (poly(N-isopropylacrylamide)), in which the distance between paramagnetic and superparamagnetic species can be modulated externally via temperature variations. Such a probe alleviates traditional nanotechnology limitations (e.g. batch to batch variability) as comparisons can be established within a single probe.

  • Journal article
    Al-Owaedi OA, Bock S, Milan DC, Oerthel M-C, Inkpen MS, Yufit DS, Sobolev AN, Long NJ, Albrecht T, Higgins SJ, Bryce MR, Nichols RJ, Lambert CJ, Low PJet al., 2017,

    Insulated molecular wires: inhibiting orthogonal contacts in metal complex based molecular junctions

    , Nanoscale, Vol: 9, Pages: 9902-9912, ISSN: 2040-3364

    Metal complexes are receiving increased attention as molecular wires in fundamental studies of the transport properties of metal|molecule|metal junctions. In this context we report the single-molecule conductance of a systematic series of d8 square-planar platinum(II) trans-bis(alkynyl) complexes with terminal trimethylsilylethynyl (C[triple bond, length as m-dash]CSiMe3) contacting groups, e.g. trans-Pt{C[triple bond, length as m-dash]CC6H4C[triple bond, length as m-dash]CSiMe3}2(PR3)2 (R = Ph or Et), using a combination of scanning tunneling microscopy (STM) experiments in solution and theoretical calculations using density functional theory and non-equilibrium Green's function formalism. The measured conductance values of the complexes (ca. 3–5 × 10−5G0) are commensurate with similarly structured all-organic oligo(phenylene ethynylene) and oligo(yne) compounds. Based on conductance and break-off distance data, we demonstrate that a PPh3 supporting ligand in the platinum complexes can provide an alternative contact point for the STM tip in the molecular junctions, orthogonal to the terminal C[triple bond, length as m-dash]CSiMe3 group. The attachment of hexyloxy side chains to the diethynylbenzene ligands, e.g. trans-Pt{C[triple bond, length as m-dash]CC6H2(Ohex)2C[triple bond, length as m-dash]CSiMe3}2(PPh3)2 (Ohex = OC6H13), hinders contact of the STM tip to the PPh3 groups and effectively insulates the molecule, allowing the conductance through the full length of the backbone to be reliably measured. The use of trialkylphosphine (PEt3), rather than triarylphosphine (PPh3), ancillary ligands at platinum also eliminates these orthogonal contacts. These results have significant implications for the future design of organometallic complexes for studies in molecular junctions.

  • Journal article
    Wilson LE, Hassenrück C, Winter RF, White AJP, Albrecht T, Long NJet al., 2017,

    Ferrocene‐ and Biferrocene‐Containing Macrocycles towards Single‐Molecule Electronics

    , Angewandte Chemie, Vol: 129, Pages: 6942-6946, ISSN: 0044-8249

    <jats:title>Abstract</jats:title><jats:p>Cyclic multiredox centered systems are currently of great interest, with new compounds being reported and developments made in understanding their behavior. Efficient, elegant, and high‐yielding (for macrocyclic species) synthetic routes to two novel alkynyl‐conjugated multiple ferrocene‐ and biferrocene‐containing cyclic compounds are presented. The electronic interactions between the individual ferrocene units have been investigated through electrochemistry, spectroelectrochemistry, density functional theory (DFT), and crystallography to understand the effect of cyclization on the electronic properties and structure.</jats:p>

  • Journal article
    Long NJ, albrecht T, wilson L, white A, winter R, hassenruck Cet al., 2017,

    Ferrocene- and biferrocene-containing macrocycles towards single molecule electronics

    , Angewandte Chemie-International Edition, Vol: 56, Pages: 6838-6824, ISSN: 1521-3773

    Cyclic multiredox centered systems are currently of great interest, with new compounds being reported and developments made in understanding their behavior. Efficient, elegant, and high-yielding (for macrocyclic species) synthetic routes to two novel alkynyl-conjugated multiple ferrocene- and biferrocene-containing cyclic compounds are presented. The electronic interactions between the individual ferrocene units have been investigated through electrochemistry, spectroelectrochemistry, density functional theory (DFT), and crystallography to understand the effect of cyclization on the electronic properties and structure.

  • Journal article
    Li H, Harriss BI, Phinikaridou A, Lacerda S, Ramniceanu G, Doan B-T, Ho K-L, Chan C-F, Lo W-S, Botnar RM, Lan R, Richard C, Law G-L, Long NJ, Wong K-Let al., 2017,

    Gadolinium and Platinum in Tandem: Real-time Multi-Modal Monitoring of Drug Delivery by MRI and Fluorescence Imaging.

    , Nanotheranostics, Vol: 1, Pages: 186-195, ISSN: 2206-7418

    A novel dual-imaging cisplatin-carrying molecular cargo capable of performing simultaneous optical and MR imaging is reported herein. This long-lasting MRI contrast agent (r1 relaxivity of 23.4 mM(-1)s(-1) at 3T, 25 (o)C) is a photo-activated cisplatin prodrug (PtGdL) which enables real-time monitoring of anti-cancer efficacy. PtGdL is a model for monitoring the drug delivery and anti-cancer efficacy by MRI with a much longer retention time (24 hours) in several organs such as renal cortex and spleen than GdDOTA and its motif control GdL. Upon complete release of cisplatin, all PtGdL is converted to GdL enabling subsequent MRI analyses of therapy efficacy within its reasonably short clearance time of 4 hours. There is also responsive fluorescence enhancement for monitoring by photon-excitation.

  • Conference paper
    McCluskey S, Plisson C, Long N, Wells Let al., 2017,

    Preclinical evaluation of [<SUP>18</SUP>F]Mitophos_07 as an imaging agent for doxorubicin induced cardiotoxicity

    , Annual Meeting of the Society-of-Nuclear-Medicine-and-Molecular-Imaging (SNMMI), Publisher: SOC NUCLEAR MEDICINE INC, ISSN: 0161-5505
  • Conference paper
    Mccluskey S, Plisson C, Tate E, Wells L, Long Net al., 2017,

    Preclinical evaluation of [<SUP>18</SUP>F]Mitophos_07 as an imaging agent for doxorubicin-induced cardiotoxicity

    , Publisher: WILEY, Pages: S72-S72, ISSN: 0362-4803
  • Journal article
    Lin S, Shah A, Hernández-Gil J, Stanziola A, Harriss BI, Matsunaga TO, Long N, Bamber J, Tang M-Xet al., 2017,

    Optically and acoustically triggerable sub-micron phase-change contrast agents for enhanced photoacoustic and ultrasound imaging

    , Photoacoustics, Vol: 6, Pages: 26-36, ISSN: 2213-5979

    We demonstrate a versatile phase-change sub-micron contrast agent providing three modes of contrast enhancement: 1) photoacoustic imaging contrast, 2) ultrasound contrast with optical activation, and 3) ultrasound contrast with acoustic activation. This agent, which we name 'Cy-droplet', has the following novel features. It comprises a highly volatile perfluorocarbon for easy versatile activation, and a near-infrared optically absorbing dye chosen to absorb light at a wavelength with good tissue penetration. It is manufactured via a 'microbubble condensation' method. The phase-transition of Cy-droplets can be optically triggered by pulsed-laser illumination, inducing photoacoustic signal and forming stable gas bubbles that are visible with echo-ultrasound in situ. Alternatively, Cy-droplets can be converted to microbubble contrast agents upon acoustic activation with clinical ultrasound. Potentially all modes offer extravascular contrast enhancement because of the sub-micron initial size. Such versatility of acoustic and optical 'triggerability' can potentially improve multi-modality imaging, molecularly targeted imaging and controlled drug release.

  • Conference paper
    Wilson L, Albrecht T, Long N, 2017,

    Delocalised chains and rings of ferrocenes

    , 253rd National Meeting of the American-Chemical-Society (ACS) on Advanced Materials, Technologies, Systems, and Processes, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
  • Conference paper
    Coakley E, Long N, 2017,

    Dual-modal MR/NIR fluorescent probes for zinc sensing applications

    , 253rd National Meeting of the American-Chemical-Society (ACS) on Advanced Materials, Technologies, Systems, and Processes, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
  • Conference paper
    Coleman C, Williams C, Long N, 2017,

    Asymmetric hybrid salen/phosphasalen initiators for the iso-selective ring-opening polymerisation of rac-lactide

    , 253rd National Meeting of the American-Chemical-Society (ACS) on Advanced Materials, Technologies, Systems, and Processes, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
  • Journal article
    Anders D, Bongarzone S, Gee AD, Long NJet al., 2017,

    Electrochemical [11C]CO2 to [11C]CO conversion for PET imaging

    , Chemical Communications (London), Vol: 53, Pages: 2982-2985, ISSN: 0009-241X

    The development of a novel electrochemical methodology to generate carbon-11 carbon monoxide ([11C]CO) from cyclotron-produced carbon-11 carbon dioxide ([11C]CO2) using Ni(cyclam) and Zn(cyclen) complexes is described. This methodology allows up to 10% yields of [11C]CO from [11C]CO2. Produced [11C]CO was subsequently converted to [11C]N-benzylbenzamide under mild conditions with a radiochemical purity (RCP) of >98%.

  • Journal article
    Bock S, Al-Owaedi OA, Eaves SG, Milan DC, Lemmer M, Skelton BW, Osorio HM, Nichols RJ, Higgins SJ, Cea P, Long NJ, Albrecht T, Martin S, Lambert CJ, Low PJet al., 2017,

    Single-molecule conductance studies of organometallic complexes bearing 3-thienyl contacting groups

    , Chemistry - A European Journal, Vol: 23, Pages: 2133-2143, ISSN: 0947-6539

    The compounds and complexes 1,4-C6H4(C≡C-cyclo-3-C4H3S)2 (2), trans-[Pt(C≡C-cyclo-3-C4H3S)2(PEt3)2] (3), trans-[Ru(C≡C-cyclo-3-C4H3S)2(dppe)2] (4; dppe=1,2-bis(diphenylphosphino)ethane) and trans-[Ru(C≡C-cyclo-3-C4H3S)2{P(OEt)3}4] (5) featuring the 3-thienyl moiety as a surface contacting group for gold electrodes have been prepared, crystallographically characterised in the case of 3–5 and studied in metal|molecule|metal junctions by using both scanning tunnelling microscope break-junction (STM-BJ) and STM-I(s) methods (measuring the tunnelling current (I) as a function of distance (s)). The compounds exhibit similar conductance profiles, with a low conductance feature being more readily identified by STM-I(s) methods, and a higher feature by the STM-BJ method. The lower conductance feature was further characterised by analysis using an unsupervised, automated multi-parameter vector classification (MPVC) of the conductance traces. The combination of similarly structured HOMOs and non-resonant tunnelling mechanism accounts for the remarkably similar conductance values across the chemically distinct members of the family 2–5.

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