Results
- Showing results for:
- Reset all filters
Search results
-
Journal articleAl-Owaedi OA, Bock S, Milan DC, et al., 2017,
Insulated molecular wires: inhibiting orthogonal contacts in metal complex based molecular junctions
, Nanoscale, Vol: 9, Pages: 9902-9912, ISSN: 2040-3364Metal 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 articleWilson LE, Hassenrück C, Winter RF, et 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 articleLong NJ, albrecht T, wilson L, et al., 2017,
Ferrocene- and biferrocene-containing macrocycles towards single molecule electronics
, Angewandte Chemie-International Edition, Vol: 56, Pages: 6838-6824, ISSN: 1521-3773Cyclic 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 articleLi H, Harriss BI, Phinikaridou A, et 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: 2206-7418A 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 paperMcCluskey S, Plisson C, Long N, et 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 paperMccluskey S, Plisson C, Tate E, et 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 articleLin S, Shah A, Hernández-Gil J, et 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: 2213-5979We 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 paperWilson 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 paperCoakley 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 paperColeman 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 articleAnders D, Bongarzone S, Gee AD, et al., 2017,
Electrochemical [11C]CO2 to [11C]CO conversion for PET imaging
, Chemical Communications (London), Vol: 53, Pages: 2982-2985, ISSN: 0009-241XThe 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 articleBock S, Al-Owaedi OA, Eaves SG, et al., 2017,
Single-molecule conductance studies of organometallic complexes bearing 3-thienyl contacting groups
, Chemistry - A European Journal, Vol: 23, Pages: 2133-2143, ISSN: 0947-6539The 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.
-
Journal articleVilar Compte R, Wilson N, Mak LH, et al., 2016,
A lipophilic copper(II) complex as an optical probe for intracellular detection of NO
, Dalton Transactions, Vol: 45, Pages: 18177-18182, ISSN: 1477-9226A new chemical sensor for cellular imaging of NO is presented. This cell-permeable probe is based on a complex where copper(II) is coordinated to a tridentate ligand substituted with a fluorophore (NBD) and an octyl group. The fluorescent response of this complex towards a range of reactive species (namely NO, NO2-, NO3-, H2O2, ClO-, O2-and ONOO-) has been studied in vitroshowing that the probe is highly selective for NO. The probe is readily taken up by cells and is able to image the cellular concentrations of NO
-
Journal articleWilson LE, Hassenrueck C, Winter RF, et al., 2016,
Functionalised Biferrocene Systems towards Molecular Electronics
, European Journal of Inorganic Chemistry, Vol: 2017, Pages: 496-504, ISSN: 1434-1948Biferrocene systems offer a motif that incorporates multiple redox-active centres, enabling redox control, high levels of stability and near perfect conductance levels, and thus is an ideal participant within future molecular electronic systems. However, the incorporation of biferrocene can be restricted by current synthetic routes. Herein, we discuss a new method for the synthesis and incorporation of biferrocenyl motifs within extended conjugated systems. We have synthesised a family of compounds featuring biferrocenyl–ethynyl units with various pendant heteroaromatic linkages. The new compounds are probed with use of cyclic voltammetry, UV/Vis/near-infrared (NIR) spectroelectrochemistry and X-ray crystallography to gain further understanding of their structural and electronic properties.
-
Journal articleLemmer M, Inkpen MS, Kornysheva K, et al., 2016,
Unsupervised vector-based classification of single-molecule charge transport data
, Nature Communications, Vol: 7, Pages: 1-10, ISSN: 2041-1723The stochastic nature of single-molecule charge transport measurements requires collection of large data sets to capture the full complexity of a molecular system. Data analysis is then guided by certain expectations, for example, a plateau feature in the tunnelling current distance trace, and the molecular conductance extracted from suitable histogram analysis. However, differences in molecular conformation or electrode contact geometry, the number of molecules in the junction or dynamic effects may lead to very different molecular signatures. Since their manifestation is a priori unknown, an unsupervised classification algorithm, making no prior assumptions regarding the data is clearly desirable. Here we present such an approach based on multivariate pattern analysis and apply it to simulated and experimental single-molecule charge transport data. We demonstrate how different event shapes are clearly separated using this algorithm and how statistics about different event classes can be extracted, when conventional methods of analysis fail.
This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.
Contact
Professor Nick Long
Email: n.long@imperial.ac.uk
Telephone: +44 (0)20 7594 5781
Location
501J
Molecular Sciences Research Hub
White City Campus
