Co-reporter:David J. Lewis, Zoe Pikramenou
Coordination Chemistry Reviews 2014 Volumes 273–274() pp:213-225
Publication Date(Web):15 August 2014
DOI:10.1016/j.ccr.2014.03.019
•The route to the development of water-soluble gold nanoparticles for functionalisation.•Advantages of metal complexes as biological imaging agents.•Approaches to coating nanoparticles with luminescent metal complexes.•Gadolinium coated gold nanoparticles for magnetic resonance imaging.The use of gold nanoparticles as a scaffold on which to assemble molecular architectures presents a versatile approach to produce nanoprobes with modalities defined by the properties of the capping architectures at the molecular level. Lanthanide ions, with their characteristic magnetic and luminescent properties, are ideal probes for imaging applications. Gold nanoparticles represent an inert, biocompatible and rigid scaffold on which to assemble molecular complexes using clean, facile chemistries. The size of the gold nanoparticles can be easily tuned using robust and established chemistry. The combination of the stable, long-lived luminescence signal or characteristic magnetic properties afforded by the trivalent lanthanide ions with the size-tuneable inert gold core allows the formation of tailored nanoprobes ideally suited to the investigation of biological systems and biomedical applications. In this review the different methods for attachment of lanthanide complexes onto gold nanoparticles are presented for the production of nanoprobes with luminescence and magnetic resonance signal outputs. A short introduction outlining the development of the preparation methods for water-soluble gold nanoparticles is presented, followed by the approaches to the functionalisation of gold nanoparticles with metal-complexes which set the scene for the lanthanide studies. Two approaches of introducing lanthanides onto gold nanoparticles are identified and the systems are grouped in the discussion under the attachment of pre-assembled lanthanide complexes and the employment of ligands on nanoparticles that bind lanthanides. The preparation and properties of lanthanide-coated nanoparticles are then discussed in detail as luminescent visible and near infrared probes. Finally, the development of gold nanoparticles as a platform on which to assemble Gd(III) complexes for magnetic resonance imaging applications is discussed.
Co-reporter:Samuel J. Adams, David J. Lewis, Jon A. Preece, and Zoe Pikramenou
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 14) pp:11598
Publication Date(Web):June 16, 2014
DOI:10.1021/am502347c
Luminescent transition metal complexes are introduced for the microcontact printing of optoelectronic devices. Novel ruthenium(II), RubpySS, osmium(II), OsbpySS, and cyclometalated iridium(III), IrbpySS, bipyridyl complexes with long spacers between the surface-active groups and the metal were developed to reduce the distance-dependent, nonradiative quenching pathways by the gold surface. Indeed, surface-immobilized RubpySS and IrbpySS display strong red and green luminescence, respectively, on planar gold surfaces with luminescence lifetimes of 210 ns (RubpySS·Au) and 130 and 12 ns (83%, 17%) (IrbpySS·Au). The modified surfaces show enhancement of their luminescence lifetime in comparison with solutions of the respective metal complexes, supporting the strong luminescence signal observed and introducing them as ideal inorganic probes for imaging applications. Through the technique of microcontact printing, complexes were assembled in patterns defined by the stamp. Images of the red and green patterns rendered by the RubpySS·Au and IrbpySS·Au monolayers were revealed by luminescence microscopy studies. The potential of the luminescent surfaces to respond to biomolecular recognition events is demonstrated by addition of the dominant blood-pool protein, bovine serum albumin (BSA). Upon treatment of the surface with a BSA solution, the RubpySS·Au and IrbpySS·Au monolayers display a large luminescence signal increase, which can be quantified by time-resolved measurements. The interaction of BSA was also demonstrated by surface plasmon resonance (SPR) studies of the surfaces and in solution by circular dichroism spectroscopy (CD). Overall, the assembly of arrays of designed coordination complexes using a simple and direct μ-contact printing method is demonstrated in this study and represents a general route toward the manufacture of micropatterned optoelectronic devices designed for sensing applications.Keywords: imaging; luminescence; optical active surfaces; printing; recognition
Co-reporter:Nicola J. Rogers, Sunil Claire, Robert M. Harris, Shiva Farabi, Gerald Zikeli, Iain B. Styles, Nikolas J. Hodges and Zoe Pikramenou
Chemical Communications 2014 vol. 50(Issue 5) pp:617-619
Publication Date(Web):05 Nov 2013
DOI:10.1039/C3CC47606E
Gold nanoparticles are efficiently labelled with a luminescent ruthenium complex, producing 13 and 100 nm diameter, monodisperse red-emissive imaging probes with luminescence lifetimes prolonged over the molecular unit. Single, 100 nm particles are observed in whole cell luminescence imaging which reveals their biomolecular association with chromatin in the nucleus of cancer cells.
Co-reporter:David J. Lewis, Valentina Dore, Nicola J. Rogers, Thomas K. Mole, Gerard B. Nash, Panagiota Angeli, and Zoe Pikramenou
Langmuir 2013 Volume 29(Issue 47) pp:14701-14708
Publication Date(Web):October 28, 2013
DOI:10.1021/la403172m
To establish highly luminescent nanoparticles for monitoring fluid flows, we examined the preparation of silica nanoparticles based on immobilization of a cyclometalated iridium(III) complex and an examination of the photophysical studies provided a good insight into the Ir(III) microenvironment in order to reveal the most suitable silica nanoparticles for micro particle imaging velocimetry (μ-PIV) studies. Iridium complexes covalently incorporated at the surface of preformed silica nanoparticles, [Ir-4]@Si500-Z, using a fluorinated polymer during their preparation, demonstrated better stability than those without the polymer, [Ir-4]@Si500, as well as an increase in steady state photoluminescence intensity (and therefore particle brightness) and lifetimes which are increased by 7-fold compared with nanoparticles with the same metal complex attached covalently throughout their core, [Ir-4]⊂Si500. Screening of the nanoparticles in fluid flows using epi-luminescence microscopy also confirm that the brightest, and therefore most suitable particles for microparticle imaging velocimetry (μ-PIV) measurements are those with the Ir(III) complex immobilized at the surface with fluorosurfactant, that is [Ir-4]@Si500-Z. μ-PIV studies demonstrate the suitability of these nanoparticles as nanotracers in microchannels.
Co-reporter:David J. Lewis, Federica Moretta, Alexander T. Holloway and Zoe Pikramenou
Dalton Transactions 2012 vol. 41(Issue 42) pp:13138-13146
Publication Date(Web):24 Sep 2012
DOI:10.1039/C2DT31106B
In order to evaluate quinoline as a remote sensitiser, we have prepared a DTPA based ligand, H33L, bearing quinoline bisamide arms for the complexation of a range of lanthanide(III) ions to give the neutral complexes LnL where Ln3+ = Y3+, Eu3+, Sm3+, Tb3+, Er3+, Yb3+, Nd3+, Gd3+. Detection of the phosphorescence signal exhibited by the GdL complex at 77 K confirmed that the triplet energy level of the sensitiser at 21190 cm−1 was suitable for the indirect population of a range of lanthanide luminescent states. A full photophysical analysis of the complexes reveals that SmL and EuL display red emission when excited through the ligand-based absorption band centred at 330 nm, extending the excitation to violet light around 370 nm. We demonstrate that quinoline sensitizes near-infrared emission in the YbL, ErL and NdL complexes, in powder form as well as in solution. Most importantly, the luminescence for YbL and NdL was sufficiently efficient to be detected in non-deuterated solvent.
Co-reporter:Amy Davies;David J. Lewis;Steven G. Thomas;Stephen P. Watson
PNAS 2012 Volume 109 (Issue 6 ) pp:
Publication Date(Web):2012-02-07
DOI:10.1073/pnas.1112132109
Water soluble, luminescent gold nanoparticles are delivered into human platelets via a rapid, pH-controlled mechanism using
a pH low insertion peptide, pHLIP. The approach introduces cocoating of gold nanoparticles with a europium luminescent complex, EuL and the pHLIP peptide to give pHLIP•EuL•Au. The 13-nm diameter gold nanoparticles act as a scaffold for the attachment of both the luminescent probe and the peptide
to target delivery. Their size allows delivery of approximately 640 lanthanide probes per nanoparticle to be internalized
in human platelets, which are not susceptible to transfection or microinjection. The internalization of pHLIP•EuL•Au in platelets, which takes just minutes, was studied with a variety of imaging modalities including luminescence, confocal
reflection, and transmission electron microscopy. The results show that pHLIP•EuL•Au only enters the platelets in low pH conditions, pH 6.5, mediated by the pHLIP translocation across the membrane, and not at pH 7.4. Luminescence microscopy images of the treated platelets show clearly
the red luminescence signal from the europium probe and confocal reflection microscopy confirms the presence of the gold particles.
Furthermore, transmission electron microscopy gives a detailed insight of the internalization and spatial localization of
the gold nanoparticles in the platelets. Thus, we demonstrate the potential of the design to translocate multimodal nanoparticle
probes into cells in a pH dependent manner.
Co-reporter:Alison C. Savage and Zoe Pikramenou
Chemical Communications 2011 vol. 47(Issue 22) pp:6431-6433
Publication Date(Web):09 May 2011
DOI:10.1039/C1CC11477H
Water soluble gold nanoparticles are coated with peptides bearing a dithiol surface active group for studies of lanthanide binding; characteristic red luminescence is observed upon europium binding to the nanoparticles.
Co-reporter:LinetteL. Ruston;GraemeM. Robertson Dr.
Chemistry – An Asian Journal 2010 Volume 5( Issue 3) pp:571-580
Publication Date(Web):
DOI:10.1002/asia.200900367
Abstract
The formation of ternary complexes of lanthanide–diethylenetriamine pentaacetic acid (DTPA)–bisamide complexes with different aromatic acids and their application in luminescent screening assays are presented. The europium complexes of DTPA–bisethylamide (BEA), DTPA–bisbutylamide (BUA), DTPA–bis(2-norbornyl) (NBA), and DTPA–bis(1-adamantyl) (ADA) have been isolated and the sensitization of emission upon 1:1 formation with aromatic acids has been studied by luminescence spectroscopy. The ternary complexes show stronger luminescence with picolinate (PCA) rather than phthalate (PTA) or benzoate (BZA), with the latter forming 1:2 complexes. Isophthalate and dipicolinate sensitizers do not show a 1:1 formation of the ternary complexes. Electrospray mass spectra show characteristic peaks that confirm the formation of the ternary complexes, and NMR spectroscopic studies demonstrated a conformational locking effect upon formation of the ternary complex. It is shown that europium complexes with bulkier amide arms provide complexes with stronger luminescence enhancement that is clearly attributable to the bulkiness of the amide arms. In a luminescence screening experiment, different substitutions on BZA and PCA were examined. Sensitizers with a long alkyl chain show greater luminescent enhancements than the nonsubstituted acids, which can be attributed to an “umbrella” effect of the alkyl chain that protects the europium luminescent center from the quenching of secondary high-energy vibrations, in particular OH from water molecules. The same effect is presented for the quinoline derivatives as sensitizers. Quinoline derivatives with salicylate binding units were identified as the best sensitizers when combined with EuADA, which is even bulkier than EuNBA, with HQ-3COO showing a 50-fold enhancement of emission upon formation of 1:1 complexes.
Co-reporter:J. Faiz;A. I. Philippopoulos;A. G. Kontos;P. Falaras;Z. Pikramenou
Advanced Functional Materials 2007 Volume 17(Issue 1) pp:
Publication Date(Web):15 NOV 2006
DOI:10.1002/adfm.200600188
A supramolecular complex [Ru(dcb)2(α-CD-5-bpy)]Cl2 (1-α-CD) (dcb = 4,4′-dicarboxyl-2,2′-bipyridine, α-CD-5-bpy = 6-mono[5-methyl(5′-methyl-2,2′-bipyridyl)]-permethylated α-CD) (CD: cyclodextrin) based on a ruthenium tris-bipyridyl core with an appended α-CD cavity is designed and synthesised, in order to facilitate dye/redox couple interaction and dye regeneration in nanocrystalline TiO2 solar cells. The luminescent complex is fully characterized and anchored on mesoporous titania electrodes showing increased power-conversion efficiency in solid-state dye-sensitized solar cells using a composite polymer electrolyte. Direct comparison of the properties of the CD complex with an analogous ruthenium complex [Ru(dcb)2(5,5′-dmbpy)]Cl2 (2) (5,5′-dmbpy = 5,5′-dimethylbipyridine) without the CD cavity reveals that the photovoltaic performance of 1-α-CD is enhanced by about 40 % compared to 2. Independent studies have shown complexation of the iodide redox couple to the CD in 1-α-CD. These results indicate that the CD moiety is able to act as a mediator and fine tune the photoelectrode/electrolyte interface.
Co-reporter:Peter B. Glover;Andrew P. Bassett;Peter Nockemann Dr.;Benson M. Kariuki Dr.;Rik Van Deun Dr. Dr.
Chemistry - A European Journal 2007 Volume 13(Issue 22) pp:
Publication Date(Web):15 JUN 2007
DOI:10.1002/chem.200700087
In this paper we demonstrate that the effect of aromatic CF substitution in ligands does not always abide by conventional wisdom for ligand design to enhance sensitisation for visible lanthanide emission, in contrast with NIR emission for which the same effect coupled with shell formation leads to unprecedented long luminescence lifetimes. We have chosen an imidodiphosphinate ligand, N-{P,P-di(pentafluorophinoyl)}-P,P-dipentafluorophenylphosphinimidic acid (HF20tpip), to form ideal fluorinated shells about all visible- and NIR-emitting lanthanides. The shell, formed by three ligands, comprises twelve fully fluorinated aryl sensitiser groups, yet no-high energy XH vibrations that quench lanthanide emission. The synthesis, full characterisation including X-ray and NMR analysis as well as the photophysical properties of the emissive complexes [Ln(F20tpip)3], in which Ln=Nd, Sm, Eu, Gd, Tb, Dy, Er, Yb, Y, Gd, are reported. The photophysical results contrast previous studies, in which fluorination of alkyl chains tends to lead to more emissive lanthanide complexes for both visible and NIR emission. Analysis of the fluorescence properties of the HF20tpip and [Gd(F20tpip)3] reveals that there is a low-lying state at around 715 nm that is responsible for partially quenching of the signal of the visible emitting lanthanides and we attribute it to a π–σ* state. However, all visible emitting lanthanides have long lifetimes and unexpectedly the [Dy(F20tpip)3] complex shows a lifetime of 0.3 ms, indicating that the elimination of high-energy vibrations from the ligand framework is particularly favourable for Dy. The NIR emitting lanthanides show strong emission signals in powder and solution with unprecedented lifetimes. The luminescence lifetimes of [Nd(F20tpip)3], [Er(F20tpip)3] and [Yb(F20tpip)3] in deuteurated acetonitrile are 44, 741 and 1111 μs. The highest value observed for the [Yb(F20tpip)3] complex is more than half the value of the Yb ion radiative lifetime.
Co-reporter:Peter B. Glover;Andrew P. Bassett;Peter Nockemann Dr.;Benson M. Kariuki Dr.;Rik Van Deun Dr. Dr.
Chemistry - A European Journal 2007 Volume 13(Issue 22) pp:
Publication Date(Web):17 JUL 2007
DOI:10.1002/chem.200790080
Co-reporter:David J. Lewis, Thomas M. Day, Julie V. MacPherson and Zoe Pikramenou
Chemical Communications 2006 (Issue 13) pp:1433-1435
Publication Date(Web):22 Feb 2006
DOI:10.1039/B518091K
Gold nanoparticles were used as a scaffold to assemble multiple tailor-made europium(III) complexes yielding water-soluble gold nanoparticles that display red, EuIII, luminescence.
Co-reporter:Anna C. G. Hotze, Jonathan A. Faiz, Nikolaos Mourtzis, Gabriel I. Pascu, Philip R. A. Webber, Guy J. Clarkson, Konstantina Yannakopoulou, Zoe Pikramenou and Michael J. Hannon
Dalton Transactions 2006 (Issue 24) pp:3025-3034
Publication Date(Web):13 Apr 2006
DOI:10.1039/B518027A
Ruthenium(II) pyridylimine complexes are explored for their potential as units that might be incorporated into electronic or photonic arrays. The complexes [Ru(bipy)2(L)][PF6]2 (1) and [Ru(tpy)(L)Cl][BF4] (2) with L = phenylpyridin-2-ylmethylene-amine are synthesized and fully characterised using X-ray diffraction analysis and (2D) NMR spectroscopy. 1 displays emission in the far-red area of the spectrum at room temperature. The emission is significantly shifted to longer wavelength with respect to [Ru(bpy)3]2+ indicating that the lowest MLCT state is localised on the pyridylimine ligand. 2 is non-emissive at room temperature and at 77 K.
Co-reporter:Johanna M. Haider and Zoe Pikramenou
Chemical Society Reviews 2005 vol. 34(Issue 2) pp:120-132
Publication Date(Web):2005/01/25
DOI:10.1039/B203904B
The introduction of photoactive metal centres onto cyclodextrin receptors opens up new possibilities for the design of sensors, wires and energy conversion systems. This tutorial review focuses on strategies involving such metallocyclodextrins for the construction of supramolecular arrays with light-activated functions. The assembly procedures for building such arrays are presented, together with the features required for their functions both as sensors for ion or small molecule detection and as wires for photoinduced long-range energy or electron transport. Systems for metal ion sensing are described where the cyclodextrin plays a mediating role in influencing the luminescence properties of an organic probe, responsive to metal binding. Small molecule sensing by the cyclodextrin cavity is realised using luminescent lanthanide or transition metal functionalised cyclodextrins. The light signal of the photoactive metal is switched on or off upon binding an analyte in the cyclodextrin cavity. The metallocyclodextrin systems that function as wires are distinguished by the controlled assembly of transition metal polypyridine and metalloporphyrin units. These units have inherent photoactivity that defines the vectorial direction of energy or electron transfer processes through the wire.
Co-reporter:Jonathan A. Faiz, Neil Spencer and Zoe Pikramenou
Organic & Biomolecular Chemistry 2005 vol. 3(Issue 23) pp:4239-4245
Publication Date(Web):25 Oct 2005
DOI:10.1039/B508607H
A mono-6-O-propargyl permethylated β-cyclodextrin, 3, has been prepared by two synthetic routes as a versatile building block for the construction of cyclodextrin dimers and trimers with a core junction which is potentially electron conducting. Glaser–Hay coupling of 3 gave β-cyclodextrin dimer 6, and Pd(0)-catalysed coupling allowed the preparation of a cyclodextrin dimer with a 1,4-phenylene bridge, 7, and a cyclodextrin trimer based on a 1,3,5-trisubstituted benzene, 8. All compounds have been fully characterised, and in particular, detailed analysis by 2D NMR spectroscopic techniques has provided useful insight into the identities of the compounds. The detailed full characterisation of mono-3,6-anhydro-heptakis(2,3-O-methyl)-hexakis(6-O-methyl)-β-cyclodextrin, 5, is also described. Product 5 is formed during the methylation of compound 3, and its formation was found to be sensitive to the reaction conditions. The absorption and fluorescence spectra of the phenylene-bridged dimer 7 and trimer 8 are also reported. They show different properties of the excited state based on the different electronic coupling imposed by the phenylene core.
Co-reporter:M. Margarita Castaño-Briones, Andrew P. Bassett, Linette L. Meason, Peter R. Ashton and Zoe Pikramenou
Chemical Communications 2004 (Issue 24) pp:2832-2833
Publication Date(Web):26 Oct 2004
DOI:10.1039/B412999G
Luminescent lanthanide racks are formed in solution through supramolecular assembly of lanthanide ions with a rigid bis-didentate sensitiser ligand and octadentate aminopolycarboxylate ligands.
Co-reporter:Johanna M. Haider Dr.;René M. Williams Dr.;Luisa De Cola Dr. Dr.
Angewandte Chemie 2003 Volume 115(Issue 16) pp:
Publication Date(Web):23 APR 2003
DOI:10.1002/ange.200250164
Licht auf Wasserräder: Photoinduzierten Energietransfer zwischen Metallzentren ermöglicht ein Ruthenium(II)-Cyclodextrin-„Rad“, das in Wasser gebildet wird. Osmium- und Iridiumkomplex-Gäste mit hydrophoben Schwänzen können nichtkovalent in den Cyclodextrinhohlräumen gebunden werden. In derartigen Systemen ist eine Zwei-Wege-Kommunikation möglich, da ein Energietransfer sowohl vom Rutheniumkern zu den äußeren Metallzentren möglich ist (violette Pfeile) als auch umgekehrt (weißer Pfeil).
Co-reporter:Johanna M. Haider Dr.;René M. Williams Dr.;Luisa De Cola Dr. Dr.
Angewandte Chemie International Edition 2003 Volume 42(Issue 16) pp:
Publication Date(Web):23 APR 2003
DOI:10.1002/anie.200250164
Shedding light on water wheels: Photoinduced energy transfer is demonstrated between metal centers by a RuII) cyclodextrin “wheel” assembled in water. Os- and Ir-complex guests with hydrophobic tails can be bound noncovalently in the cyclodextrin cavities. In such systems two-way communication is possible as energy transfer can occur from the Ru core to the outer metal centers (purple arrows) or from the outer metal units to the Ru core (white arrow).
Co-reporter:Steven W. Magennis;Simon Parsons Dr.
Chemistry - A European Journal 2002 Volume 8(Issue 24) pp:
Publication Date(Web):13 DEC 2002
DOI:10.1002/1521-3765(20021216)8:24<5761::AID-CHEM5761>3.0.CO;2-H
Luminescent lanthanide complexes have been developed, based on the assembly of bulky ligands around the lanthanide ion, to provide shell-type protection of the ion from coordinated solvent molecules. Aryl-functionalised imidodiphosphinate ligands (tpip and Metpip) provide a bidentate anionic site that leads to hexa-coordinate lanthanide complexes in which the aryl groups surround the ion. There are twelve phenyl groups around the lanthanide that act as “remote” (from the binding site) sensitisers for the metal ion. It is shown that these ligands are suitable for sensitising luminescence for all the lanthanides that emit in the visible range, namely, SmIII, EuIII, TbIII, DyIII. A “built-in” shield on the ligand is designed to provide a complete block of the approach of water to the lanthanide ion. The synthesis of the ligands and their lanthanides complexes as well as detailed photophysical studies of the complexes in solution and in the solid-state are presented.
Co-reporter:Johanna M. Haider
European Journal of Inorganic Chemistry 2001 Volume 2001(Issue 1) pp:
Publication Date(Web):27 NOV 2000
DOI:10.1002/1099-0682(20011)2001:1<189::AID-EJIC189>3.0.CO;2-N
Cyclodextrin recognition sites are assembled in macromolecular structures by using metal assembly principles. Methylated cyclodextrins are functionalised with bidentate bipyridine and tridentate terpyridine units to give versatile receptor ligands, β-CD−mbpy and β-CD−ttp, respectively, for metal complexation. Tris-cyclodextrin complexes are prepared by reaction of the β-CD−mbpy receptor with iron(II) and by reaction of β-CD−ttp with europium(III). The latter leads to a luminescent complex with three recognition sites around the luminescent metal core. Bis-cyclodextrin complexes are prepared by addition of iron(II) to β-CD−ttp. The characterisation of the compounds and their luminescent properties are reported.
Co-reporter:Henning Krass Dipl.-Chem.;Edward A. Plummer;Johanna M. Haider Dr.;Philip R. Barker;Nathaniel W. Alcock Dr. Dr.;Michael J. Hannon Dr.;Dirk G. Kurth Dr.
Angewandte Chemie International Edition 2001 Volume 40(Issue 20) pp:
Publication Date(Web):10 OCT 2001
DOI:10.1002/1521-3773(20011015)40:20<3862::AID-ANIE3862>3.0.CO;2-N
Layer-by-layer deposition of π-assembled arrays of discrete metallo units with aryl tails and polystyrenesulfonate gives structurally well-defined thin films (see schematic representation). The formation of these films, which is controlled by π–π interactions, metal–ion coordination, and electrostatic interactions, bridges the gap between supramolecular crystal engineering and design of layered materials.
Co-reporter:Henning Krass Dipl.-Chem.;Edward A. Plummer;Johanna M. Haider Dr.;Philip R. Barker;Nathaniel W. Alcock Dr. Dr.;Michael J. Hannon Dr.;Dirk G. Kurth Dr.
Angewandte Chemie 2001 Volume 113(Issue 20) pp:
Publication Date(Web):10 OCT 2001
DOI:10.1002/1521-3757(20011015)113:20<3980::AID-ANGE3980>3.0.CO;2-8
Die Schicht-für-Schicht-Abscheidung von π-π-verbrückten Verbänden aus diskreten Metallkomplexen, die an den Liganden über Arylsubstituenten verfügen, mit Polystyrolsulfonat liefert strukturierte Filme (siehe schematische Darstellung). Die Bildung dieser strukturierten Schichtanordnung, die außer durch π-Wechselwirkungen noch durch Metallionen-Koordination und elektrostatische Wechselwirkungen beeinflusst wird, schließt die Lücke zwischen supramolekularem Kristall-Engineering und dem Design von Schichtmaterialien.
Co-reporter:David J. Lewis ; Peter B. Glover ; Melissa C. Solomons
Journal of the American Chemical Society () pp:
Publication Date(Web):December 23, 2010
DOI:10.1021/ja109157g
Lanthanide complexes based on bis(amides) of diethylenetriaminepentaacetic acid with thiol functionalities are modified with 2,2′-dipyridyl disulfide to give activated complexes that can selectively react with thiol-functionalized complexes to form heterometallic lanthanide macrocycles. The preparation and full characterization of the polyaminocarboxylate ligands N,N′′-bis[p-thiophenyl(aminocarbonyl)]diethylenetriamine-N,N′,N′′-triacetic acid (H3Lx) and the activated N,N′′-bis[p-(pyridyldithio)[phenyl(aminocarbonyl)]]diethylenetriamine-N,N′,N′′-triacetic acid (H3Ly) and the complexes LaLx, NdLx, SmLx, EuLx, GdLx, DyLx, TbLx, ErLx, and YbLx are reported. The luminescence properties of the LnLx complexes emitting in the visible (where Ln = Dy3+, Tb3+, Eu3+, and Sm3+) are examined by steady-state and time-resolved photoluminescence, and the triplet state energy level of GdLx was estimated to be 24 100 cm−1 from the 0−0 band of the 77 K phosphorescence spectrum. Near-infrared emission was detected for the NdLx, YbLx, and ErLx complexes, demonstrating the versatility of the thiophenol chromophore. The assembly of purely heterometallic EuTbLx2 macrocycles by reaction of EuLx with TbLy was followed by UV−vis absorption spectroscopy, monitoring the characteristic absorption peak of pyridyl-2-thione at 353 nm. Analysis of the solution by mass spectrometry reveals the formation of purely heterometallic macrocycle EuTbLx2. This is in contrast with the results obtained by dynamic self-assembly under oxidative conditions, where we observe a statistical mixture of macrocyclic complexes of Eu2Lx2, Tb2Lx2, and EuTbLx2. The EuTbLx2 macrocycle displays dual color emission, incorporating the characteristic f−f transitions of Eu3+ and Tb3+. Investigation into the time-resolved photophysical properties of EuTbLx2 reveals energy transfer from Tb3+ to Eu3+, facilitated by the different conformations of the macrocycle in solution.
Co-reporter:Alison C. Savage and Zoe Pikramenou
Chemical Communications 2011 - vol. 47(Issue 22) pp:NaN6433-6433
Publication Date(Web):2011/05/09
DOI:10.1039/C1CC11477H
Water soluble gold nanoparticles are coated with peptides bearing a dithiol surface active group for studies of lanthanide binding; characteristic red luminescence is observed upon europium binding to the nanoparticles.
Co-reporter:Nicola J. Rogers, Sunil Claire, Robert M. Harris, Shiva Farabi, Gerald Zikeli, Iain B. Styles, Nikolas J. Hodges and Zoe Pikramenou
Chemical Communications 2014 - vol. 50(Issue 5) pp:NaN619-619
Publication Date(Web):2013/11/05
DOI:10.1039/C3CC47606E
Gold nanoparticles are efficiently labelled with a luminescent ruthenium complex, producing 13 and 100 nm diameter, monodisperse red-emissive imaging probes with luminescence lifetimes prolonged over the molecular unit. Single, 100 nm particles are observed in whole cell luminescence imaging which reveals their biomolecular association with chromatin in the nucleus of cancer cells.
Co-reporter:David J. Lewis, Federica Moretta, Alexander T. Holloway and Zoe Pikramenou
Dalton Transactions 2012 - vol. 41(Issue 42) pp:NaN13146-13146
Publication Date(Web):2012/09/24
DOI:10.1039/C2DT31106B
In order to evaluate quinoline as a remote sensitiser, we have prepared a DTPA based ligand, H33L, bearing quinoline bisamide arms for the complexation of a range of lanthanide(III) ions to give the neutral complexes LnL where Ln3+ = Y3+, Eu3+, Sm3+, Tb3+, Er3+, Yb3+, Nd3+, Gd3+. Detection of the phosphorescence signal exhibited by the GdL complex at 77 K confirmed that the triplet energy level of the sensitiser at 21190 cm−1 was suitable for the indirect population of a range of lanthanide luminescent states. A full photophysical analysis of the complexes reveals that SmL and EuL display red emission when excited through the ligand-based absorption band centred at 330 nm, extending the excitation to violet light around 370 nm. We demonstrate that quinoline sensitizes near-infrared emission in the YbL, ErL and NdL complexes, in powder form as well as in solution. Most importantly, the luminescence for YbL and NdL was sufficiently efficient to be detected in non-deuterated solvent.
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