Lanthanoid β-triketonates: a new class of highly efficient NIR emitters for bright NIR-OLEDs

The reaction of hydrated YbCl3 with potassium tribenzoylmethanide yields a new bimetallic tetranuclear Yb3+/K+ assembly. This species not only possesses the longest excited state lifetime and quantum yield reported for the Yb3+ diketonate family but is also suitable to be incorporated in NIR-OLEDs, whose performance outclasses any other reported lanthanoid-based device with NIR emission

Investigation of the structure and magnetism in lanthanide ß-triketonate tetranuclear assemblies

The preparation of discrete tetranuclear lanthanide/alkali metal (Ae) assemblies bearing a tribenzoylmethane ligand (LH) is discussed. These assemblies have the general formula [Ln(Ae·HOEt)(L)4]2, where Ln3+ = Gd3+, Tb3+, Dy3+, Ho3+ and Ae+ = Na+, K+, Rb+. The coordination geometries of the lanthanide species were analyzed and compared, revealing a trend between an eight-coordinate square antiprism and triangular dodecahedron dependent on the nature of lanthanide, alkali metal, and lattice solvent. The potassium-containing analogs were also analyzed for their magnetic susceptibility

Recyclable calix[4]arene–lanthanoid luminescent hybrid materials with color-tuning and color-switching properties

Inorganic–organic hybrid materials combine the properties of both components providing functionality with a wide range of potential applications. Phase segregation of the inorganic and organic components is a common challenge in these systems, which is overcome here by copolymerizing a metal-free calixarene ionophore and methyl methacrylate. A lanthanoid ion is then added using a swelling–deswelling procedure. The resulting luminescent hybrid materials can be made to emit any required color, including white light, by loading with an appropriate mixture of lanthanoids. The gradation of the emitted color can also be finely adjusted by changing the excitation wavelength. The polymer monolith can be recycled to emit a different color by swelling with a solution containing a different lanthanoid ion. This methodology is flexible and has the potential to be extended to many different ionophores and polymer matrices

The photochemistry of rhenium(I) tricarbonyl N-heterocyclic carbene complexes

The photophysical and photochemical properties of the new tricarbonyl rhenium(I) complexes bound to N-heterocyclic carbene ligands (NHC), fac-[Re(CO)3(N^C)X] (N^C = 1-phenyl-3-(2-pyridyl)imidazole or 1-quinolinyl-3-(2-pyridyl)imidazole; X = Cl or Br), are reported. The photophysics of these complexes highlight phosphorescent emission from triplet metal-to-ligand (3MLCT) excited states, typical of tricarbonyl rhenium(I) complexes, with the pyridyl-bound species displaying a ten-fold shorter excited state lifetime. On the other hand, these pyridyl-bound species display solvent-dependent photochemical CO dissociation following what appear to be two different mechanisms, with a key step being the formation of cationic tricarbonyl solvato-complexes, being themselves photochemically active. The photochemical mechanisms are illustrated with a combination of NMR, IR, UV-Vis, emission and X-ray structural characterization techniques, clearly demonstrating that the presence of the NHC ligand is responsible for the previously unobserved photochemical behavior in other photoactive tricarbonyl rhenium(I) species. The complexes bound to the quinolinyl-NHC ligand (which possess a lower-energy 3MLCT) are photostable, suggesting that the photoreactive excited state is not any longer thermally accessible. The photochemistry of the pyridyl complexes was investigated in acetonitrile solutions and also in the presence of triethylphosphite, showing a competing and bifurcated photoreactivity promoted by the trans effect of both the NHC and phosphite ligands

Heteronuclear bimetallic complexes with 3d and 4f elements

Three heteronuclear bimetallic complexes [Cu(MeOH)(L)Ln(NO3)3] ( 1-Ce ; Ln = Ce, 1-Pr ; Ln = Pr, and 1-Nd ; Ln = Nd) were prepared using H2L (1,3-bis[(3-methoxysalicylidene)amino]-2,2-dimethylpropane) in methanol, affording the complexes as green crystalline materials. These can be prepared in a one-pot synthesis from 2,2-dimethylpropan-1,3-diamine, o-vanillin, copper(II) nitrate, and Ln(III) nitrate (Ln = Ce, Pr, Nd). X-ray crystallography, high-resolution mass spectrometry, and UV-vis spectroscopy were used to characterize the bimetallic complexes. All three complexes showed the copper center adopting a five-coordinate square pyramidal geometry and the lanthanoid cation adopting a ten-coordinate geometry.Publisher PDFPeer reviewe

Globular cluster systems in low-luminosity early-type galaxies near the Fornax Cluster centre

We present a photometric study of the globular cluster systems of the Fornax cluster galaxies NGC 1374, NGC 1379, and NGC 1387. The data consists of images from the wide-field MOSAIC Imager of the CTIO 4-m telescope, obtained with Washington C and Kron-Cousins R filters. The images cover a field of 36 x 36 arcmin, corresponding to 200 x 200 kpc at the Fornax distance. Two of the galaxies, NGC 1374 and NGC 1379, are low-luminosity ellipticals while NGC 1387 is a low-luminosity lenticular. Their cluster systems are still embedded in the cluster system of NGC 1399. Therefore the use of a large field is crucial and some differences to previous work can be explained by this. The colour distributions of all globular cluster systems are bimodal. NGC 1387 presents a particularly distinct separation between red and blue clusters and an overproportionally large population of red clusters. The radial distribution is different for blue and red clusters, red clusters being more concentrated towards the respective galaxies. The different colour and radial distributions point to the existence of two globular cluster subpopulations in these galaxies. Specific frequencies are in the range S_N= 1.4-2.4, smaller than the typical values for elliptical galaxies. These galaxies might have suffered tidal stripping of blue globular clusters by NGC 1399.Comment: 14 pages, 12 figures. Accepted for publication in MNRA

Development of a tomographic myelin scan

The principle that myelin can be imaged nonivnvasiely using the emission tomographic distribution of a lipophilic radioactive tracer was investigated. Properties of agents suitable for noninvasive myelin scanning are discussed with specific reference to blood-brain barrier permeability, metabolism, and tracer lipophilicity. The brain distributions of inert tracers are correlated with their partitioning between octanol and saline. A test probe, iodobenzene, was labeled with iodine 125 for preliminary invasive studies in the rabbit. The equilibrium brain distribution, determined either autoradiographically of by regional dissection, corresponded closely to that of myelin. 123 I-labeled iodobenzene, a gamma-emitting analog, was then administered to a monkey, and tomographic reconstruction revealed a pattern of brain uptake corresponding to white matter.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/50299/1/410100303_ftp.pd

The STEM Ecosystem: building cross-disciplinary leadership capacity in science, technology, engineering and mathematics.

The disciplines of Science, Technology, Engineering and Mathematics (STEM) are critical for national productivity and global competitiveness. Demand for tertiary graduates with cross-disciplinary STEM skills will continue to exponentially exceed supply in Australia in the next 25 years (McLaughlin & Reid, 2012). Leadership in the promotion of STEM cross-disciplinary learning and teaching is critical to the development of future graduates. With these identified skills shortages across the STEM professions, there is a growing need for academic staff to impart knowledge from their own disciplines across new STEM learning boundaries and build skills in providing cross-disciplinary STEM opportunities for future graduates. This project, through the connection of industry, STEM academics and students created these opportunities and demonstrated the emerging potential in cross-disciplinary learning and teaching. The project also forged new patterns of learning opportunities in STEM tertiary education across Australia and crossed discipline and Australian Qualifications Framework (AQF) boundaries

Investigation of the Photophysical Properties of a Eu3+ Coordination Polymer Bearing an α-Nitrile Substituted β-Diketonate Ligand via Emission and Ultrafast Transient Absorption Spectroscopy

Reaction of the β-diketone ligand, 2-cyano-1,3-phenyl-1,3-propandione (LH), with hydrated EuCl3 in the presence of 1,10-phenanthroline (Phen), results in the crystallisation of a one-dimensional Eu3+ coordination polymer of formulation [Eu(Phen)(L)3]∞, formed by coordination of the nitrile group of an O,O′-bound ligand to a neighbouring metal centre. An investigation of the metal-centred emission of the polymer, both in the solid state and solution, revealed red emission characterised by relatively long-lived excited state lifetimes and high intrinsic quantum yields. However, analysis of the overall quantum yield and sensitisation efficiency reveals that ultrafast processes in the ligand potentially inhibit Eu3+ sensitisation. Further investigations into these processes using transient absorption spectroscopy suggest that substitution at the α-C position may significantly decrease sensitisation via the antenna effect

Probing the effect of ß-triketonates in visible and NIR emitting lanthanoid complexes

An isomorphous series of lanthanoid complexes containing tribenzoylmethanide (tbm) and 1,10-phenanthroline (phen) ligands has been synthesised and structurally characterised. These complexes, formulated as [Ln(phen)(tbm)3] (Ln = Eu3+, Er3+ and Yb3+), were compared with analogous dibenzoylmethanide (dbm) [Ln(phen)(dbm)3] complexes to investigate the effect of changing ß-diketonate to ß-triketonate ligands on the photophysical properties of the complex. The photophysical properties for the Eu3+ complexes were similar for both systems, whereas a modest enhancement was observed for Yb3+ and Er3+ moving from the dbm to the tbm complexes. A detailed study of the NIR photophysical properties was achieved by adapting the integrating sphere method for the calculation of overall quantum yields in the solid state