Imperial College London

PROFESSOR NICHOLAS LONG

Faculty of Natural SciencesDepartment of Chemistry

Sir Edward Frankland BP Chair -Inorganic Chemistry
 
 
 
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Contact

 

+44 (0)20 7594 5781n.long Website CV

 
 
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Location

 

501jMolecular Sciences Research HubWhite City Campus

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Summary

 

Publications

Publication Type
Year
to

306 results found

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

Conference paper

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.

Journal article

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

Conference paper

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.

Journal article

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

Conference paper

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.

Journal article

Vilar Compte R, Wilson N, Mak LH, cilibrizzi A, gee AD, long NJ, woscholski Ret al., 2016, A lipophilic copper(II) complex as an optical probe for intracellular detection of NO, Dalton Transactions, Vol: 45, Pages: 18177-18182, ISSN: 1477-9226

A 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 article

Wilson LE, Hassenrueck C, Winter RF, White AJP, Albrecht T, Long NJet al., 2016, Functionalised Biferrocene Systems towards Molecular Electronics, European Journal of Inorganic Chemistry, Vol: 2017, Pages: 496-504, ISSN: 1434-1948

Biferrocene 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 article

Lemmer M, Inkpen MS, Kornysheva K, Long NJ, Albrecht Tet al., 2016, Unsupervised vector-based classification of single-molecule charge transport data, Nature Communications, Vol: 7, Pages: 1-10, ISSN: 2041-1723

The 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.

Journal article

Pan J, Harriss BI, Chan CF, Jiang L, Tsoi TH, Long NJ, Wong WT, Wong WK, Wong KLet al., 2016, Gallium and Functionalized-Porphyrins Combine to Form Potential Lysosome-Specific Multimodal Bioprobes, Inorganic Chemistry, Vol: 55, Pages: 6839-6841, ISSN: 1520-510X

A water-soluble bimetallic normal ("cold") and radiochemical ("hot") gallium-porphyrin-ruthenium-bipyridine complex (GaporRu-1) has been synthesized by microwave methodology in short reaction times with good (>85%) yields. (68)GaporRu-1 is demonstrated to be a potential multimodal and functional bioprobe for positron emission tomography (PET), lysosome specific optical imaging, and photodynamic therapy.

Journal article

Inkpen MS, Scheerer S, Linseis M, White AJP, Winter RF, Albrecht T, Long NJet al., 2016, Oligomeric ferrocene rings, Nature Chemistry, Vol: 8, Pages: 825-830, ISSN: 1755-4330

Cyclic oligomers comprising strongly interacting redox-active monomer units represent an unknown, yet highly desirable class of nanoscale materials. Here we describe the synthesis and properties of the first family of molecules belonging to this compound category—differently sized rings comprising only 1,1′-disubstituted ferrocene units (cyclo[n], n = 5–7, 9). Due to the close proximity and connectivity of centres (covalent Cp–Cp linkages; Cp = cyclopentadienyl) solution voltammograms exhibit well-resolved, separated 1e– waves. Theoretical interrogations into correlations based on ring size and charge state are facilitated using values of the equilibrium potentials of these transitions, as well as their relative spacing. As the interaction free energies between the redox centres scale linearly with overall ring charge and in conjunction with fast intramolecular electron transfer (∼107 s−1), these molecules can be considered as uniformly charged nanorings (diameter ∼1–2 nm).

Journal article

McCluskey S, Plisson C, Wells L, Long N, Tate Eet al., 2016, Evaluation of phosphonium cations as imaging agents for cardiac energetics and dysfunction, Publisher: SOC NUCLEAR MEDICINE INC, ISSN: 0161-5505

Conference paper

Farnaby J, Hickson J, Long N, 2016, Synthetic routes to multi-metallic f-element complexes with redox-active ligands, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727

Conference paper

Phanopoulos A, Long NJ, Miller PW, 2016, Triphosphine ligands: coordination chemistry and recent catalytic applications, The Chemical Bond III, Editors: Mingos, Publisher: Springer, Pages: 31-61

Phosphines are a long established class of ligand that are known to form a vast array of transition metal complexes. They behave as neutral electron pair donors, or Lewis bases, that alter the solubility and stereoelectronic properties of the metal centre. A key motivation for their continued development is for homogeneous catalysis. For over five decades, transition metal–phosphine complexes have been used for catalytic reactions, mainly exploiting monodentate or bidentate phosphine ligands. Multidentate phosphines by comparison have received much less attention in part because they tend to form more stable complexes with a saturated coordination environment around the metal centre. Recent developments in the areas of catalytic reduction of carboxylic acid derivatives using molecular hydrogen and in the field of biomass up-conversion have exploited catalysts based on tridentate phosphines. This chapter highlights the use of these multidentate phosphines for synthesis of coordination complexes and discusses some of their recent applications in homogeneous catalysis.

Book chapter

Phanopoulos A, White AJP, Long NJ, Miller PWet al., 2016, Insight into the stereoelectronic parameters of N-triphos ligands via coordination to tungsten(0), Dalton Transactions, Vol: 45, Pages: 5536-5548, ISSN: 1477-9226

A series of new N-triphos tungsten complexes have been synthesised and structurally characterised. The coordination behaviour of a range of N-triphos (N(CH2PR2)3, NP3R) ligands, and a mixed-arm diphosphine-pyridyl (PPNCyh) ligand were explored. The steric and electronic parameters of five N-triphos ligands: NP3Ph, NP3iPr, NP3Cyp, NP3Cyh and NP3PhF2, and the carbon-centred triphos ligand, CH3C(CH2PPh2)3 (MeCP3Ph), were established. Steric parameters were evaluated by analysing the cone angles calculated from X-ray crystal structures, whilst the electron-donating ability of the ligands was determined from 31P–77Se NMR coupling constants of selenium derivatives and the IR carbonyl stretching frequencies across a series of tungsten–carbonyl complexes. In general, electron-rich phosphines formed bidentate complexes while less electron-rich ligands coordinated in a tridentate mode, regardless of steric bulk. An indirect interaction between the apical nitrogen of the ligand and metal centre is implicated for tridentate complexes and is supported through DFT calculations and analysis of N-protonated complexes. Complexes 1, 3, 4, 6–8 and 10 were characterised by single-crystal X-ray crystallography.

Journal article

Kumar S, Johnson TW, Wood CK, Qu T, Wittenberg NJ, Otto L, Shaver J, Long NJ, Victoria RH, Edel JB, Oh SHet al., 2016, Template-Stripped Multifunctional Wedge and Pyramid Arrays for Magnetic Nanofocusing and Optical Sensing, Acs Applied Materials & Interfaces, Vol: 8, Pages: 9319-9326, ISSN: 1944-8252

We present large-scale reproducible fabrication of multifunctional ultrasharp metallic structures on planar substrates with capabilities including magnetic field nanofocusing and plasmonic sensing. Objects with sharp tips such as wedges and pyramids made with noble metals have been extensively used for enhancing local electric fields via the lightning-rod effect or plasmonic nanofocusing. However, analogous nanofocusing of magnetic fields using sharp tips made with magnetic materials has not been widely realized. Reproducible fabrication of sharp tips with magnetic as well as noble metal layers on planar substrates can enable straightforward application of their material and shape-derived functionalities. We use a template-stripping method to produce plasmonic-shell-coated nickel wedge and pyramid arrays at the wafer-scale with tip radius of curvature close to 10 nm. Further we explore the magnetic nanofocusing capabilities of these ultra-sharp substrates deriving analytical formulas and comparing the results with computer simulations. These structures exhibit nanoscale spatial control over the trapping of magnetic microbeads and nanoparticles in solution. Additionally, enhanced optical sensing of analytes by these plasmonic-shell-coated substrates is demonstrated using surface-enhanced Raman spectroscopy. These methods can guide the design and fabrication of novel devices with applications including nanoparticle manipulation, biosensing, and magnetoplasmonics.

Journal article

Inkpen MS, White AJP, Albrecht T, Long NJet al., 2016, Complexes comprising ‘dangling’ phosphorus arms and tri(hetero)metallic butenynyl moieties, Journal of Organometallic Chemistry, Vol: 812, Pages: 145-150, ISSN: 1872-8561

Trans-RuCl2(PP3)2 (1a) (PP3 = tris[2-(diphenylphosphino)ethyl]phosphine) was prepared by reaction of RuCl2(PPh3)3 with 2 eq. PP3. Through coordination of two potentially tetradentate ligands in a bidentate arrangement, four uncoordinated phosphine moieties remain readily available for subsequent reaction. This is demonstrated through their facile oxidation with hydrogen peroxide, providing trans-RuCl2(PP[Pdouble bond; length as m-dashO]2)2 (1b) (PP[Pdouble bond; length as m-dashO]2 = bis[2-(diphenylphosphine oxide)ethyl][2-(diphenylphosphino)ethyl]phosphine). Whilst chloride abstraction reactions from 1a appear slow (typical for trans dichlorides), cis-RuCl2(PP3) is shown to react rapidly with ethynylferrocene under ‘Dixneuf’ conditions (CH2Cl2, NaPF6, NEt3), providing the tri(hetero)metallic butenynyl complex [(PP3)Ru(η3–FcC3CHFc)]PF6 (2, Fc = ferrocenyl). The pendant groups of 1a-b offer great potential for future coordination studies (for example, to prepare mixed transition metal/lanthanide materials), whereby the facile synthetic route to 2 suggests a path towards examination of complex mixed-valence systems comprising multiple redox-active centres.

Journal article

Laurent D, Vinet L, Lamprianou S, Daval M, Filhoulaud G, Ktorza A, Wang H, Sewing S, Juretschke H-P, Glombik H, Meda P, Boisgard R, Nguyen DL, Stasiuk GJ, Long NJ, Montet X, Hecht P, Kramer W, Rutter GA, Hecksher-Sorensen Jet al., 2016, Pancreatic β-cell imaging in humans: fiction or option?, Diabetes Obesity & Metabolism, Vol: 18, Pages: 6-15, ISSN: 1462-8902

Diabetes mellitus is a growing worldwide epidemic disease, currently affecting 1 in 12 adults. Treatment of disease complications typically consumes ∼10% of healthcare budgets in developed societies. Whilst immune-mediated destruction of insulin-secreting pancreatic β cells is responsible for Type 1 diabetes, both the loss and dysfunction of these cells underly the more prevalent Type 2 diabetes. The establishment of robust drug development programmes aimed at β-cell restoration is still hampered by the absence of means to measure β-cell mass prospectively in vivo, an approach which would provide new opportunities for understanding disease mechanisms and ultimately assigning personalized treatments. In the present review, we describe the progress towards this goal achieved by the Innovative Medicines Initiative in Diabetes, a collaborative public–private consortium supported by the European Commission and by dedicated resources of pharmaceutical companies. We compare several of the available imaging methods and molecular targets and provide suggestions as to the likeliest to lead to tractable approaches. Furthermore, we discuss the simultaneous development of animal models that can be used to measure subtle changes in β-cell mass, a prerequisite for validating the clinical potential of the different imaging tracers.

Journal article

Inkpen MS, Du S, Hildebrand M, White AJP, Harrison NM, Albrecht T, Long NJet al., 2015, The unusual redox properties of fluoroferrocenes revealed through a comprehensive study of the haloferrocenes, Organometallics, Vol: 34, Pages: 5461-5469, ISSN: 1520-6041

We report the synthesis and full characterization of the entire haloferrocene (FcX) and 1,1′-dihaloferrocene (fcX2) series (X = I, Br, Cl, F; Fc = ferrocenyl, fc = ferrocene-1,1′-diyl). Finalization of this simple, yet intriguing set of compounds has been delayed by synthetic challenges associated with the incorporation of fluorine substituents. Successful preparation of fluoroferrocene (FcF) and 1,1′-difluoroferrocene (fcF2) were ultimately achieved using reactions between the appropriate lithiated ferrocene species and N-fluorobenzenesulfonimide (NFSI). The crude reaction products, in addition to those resulting from analogous preparations of chloroferrocene (FcCl) and 1,1′-dichloroferrocene (fcCl2), were utilized as model systems to probe the limits of a previously reported “oxidative purification” methodology. From this investigation and careful solution voltammetry studies, we find that the fluorinated derivatives exhibit the lowest redox potentials of each of the FcX and fcX2 series. This counterintuitive result is discussed with reference to the spectroscopic, structural, and first-principles calculations of these and related materials.

Journal article

Long NJ, Stasiuk G, Gallo J, Bañobre-López2 M, Keasberry N, Wood Cet al., 2015, Tuning the relaxation rates of dual mode T1/T2 nanoparticle contrast agents: a study into the ideal system, Nanoscale, Vol: 7, Pages: 16119-16128, ISSN: 2040-3372

Magnetic resonance imaging (MRI) is an excellent imaging modality. However the low sensitivity of the technique poses a challenge to achieving an accurate image of function at the molecular level. To overcome this, contrast agents are used; typically gadolinium based agents for T1 weighted imaging, or iron oxide based agents for T2 imaging. Traditionally, only one imaging mode is used per diagnosis although several physiological situations are known to interfere with the signal induced by the contrast agents in each individual imaging mode acquisition. Recently, the combination of both T1 and T2 imaging capabilities into a single platform has emerged as a tool to reduce uncertainties in MR image analysis. To date, contradicting reports on the effect on the contrast of the coupling of a T1 and T2 agent have hampered the application of these specialised probes. Herein, we present a systematic experimental study on a range of gadolinium-labelled magnetite nanoparticles envisioned to bring some light into the mechanism of interaction between T1 and T2 components, and advance towards the design of efficient (dual) T1 and T2 MRI probes. Unexpected behaviours observed in some of the constructs will be discussed. In this study, we demonstrate that the relaxivity of such multimodal probes can be rationally tuned to obtain unmatched potentials in MR imaging, exemplified by preparation of the magnetite-based nanoparticle with the highest T2 relaxivity described to date.

Journal article

Duerrbeck A, Hor A, Long N, 2015, New highly-emissive soluble dynamic Eu(III) coordination polymers for Ln(III) and transition metal sensing applications, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727

Conference paper

Miller P, Phanopoulos A, Long N, 2015, Direct conversion of levulinic acid to 2-methyltetrahydrofuran using discrete Ru and Rh N-triphos catalysts, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727

Conference paper

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