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doi: 10.1039/b702341cpmid: 17534483
Since the description of efficient electroluminescence from aluminium tris(hydroxyquinoline) in the mid 1980s, interest in new complexes and polymers with luminescence properties as emitting layers in light-emitting diodes has steadily increased. Recently, Ln() ion complexes have gained in importance for this type of application. Here we review some of the seminal work in the area, along with new developments in the field. The photophysical characterization of complexes of lanthanide ions both in solution and in the solid state allows the determination of which of the complexes might be successfully utilized as emitting layers in light-emitting diodes for display applications. However, the architecture of the device is also of major importance, to allow for good charge transport and recombination and thus obtain pure colors and high emission quantum efficiency.
Biernat, Anne; Schwalbe, Matthias; Wallace, Dawn; Reglinski, John; Spicer, Mark D.
doi: 10.1039/b705161cpmid: 17534484
The synthesis and structure of two related sodium complexes are reported which demonstrate that sulfur can preferentially complex to sodium irrespective of the presence of more apposite donor species such as DMF.
Charbonnière, Loïc J.; Mameri, Samir; Flot, David; Waltz, Fanny; Zandanel, Christelle; Ziessel, Raymond F.
doi: 10.1039/b700837fpmid: 17534485
The synthesis of ligand H based on a disymmetrically substituted terpyridine core functionalised by a carboxylic acid in the 6-position and a bis(carboxymethyl)aminomethyl function in the 6″-position is described. The coordination behaviour of this heptadentate (4N/3O) ligand with lanthanide cations (Ln = Eu, Gd and Tb) was studied in solution showing the formation of complexes with [Ln] stoichiometry. Complexes with general formula [Ln(HO)] were isolated from neutral water solutions containing equimolar amounts of cations and ligands, and the complexes were characterized in the solid state (elemental analysis, IR) and in solution (mass spectrometry). The photo-physical properties of the luminescent complexes of Eu and Tb were studied in water solution by means of absorption, steady state and time-resolved emission spectroscopies. Evolution of the luminescence lifetimes of the Eu and Tb complexes in HO and DO reveals the presence of two water molecules coordinated in the first coordination sphere of the cations. Despite this important hydration number, the overall luminescence quantum yields of the complexes remained elevated, especially in the case of Tb ( = 22.0 and 6.5% respectively for Tb and Eu). Upon crystallisation the Gd complex formed dimeric species in which two gadolinium atoms are each heptacoordinated by one ligand, the coordination sphere being completed by a single water molecule and a bridging carboxylate function, pointing to different behaviours in the solid and liquid states.
Franken, Andreas; Hodson, Bruce E.; McGrath, Thomas D.; Stone, F. Gordon A.
doi: 10.1039/b701219epmid: 17534486
The ferracarborane [N(PPh)][6,6,6,10,10,10-(CO)--6,10,1-FeCBH] () reacts in CHCl with 3 molar equivalents of Ag[PF] to yield the trifluoro-substituted species [N(PPh)][7,8,9-F-6,6,6,10,10,10-(CO)--6,10,1-FeCBH] (). Compound undergoes structural rearrangement in toluene at reflux temperatures, forming [N(PPh)][8,9,10-F-6,6,6,7,7,7-(CO)--6,7,1-FeCBH] (). Alternatively, reaction of either or with a 10-fold excess of Ag[PF] in CHCl forms two species: namely, [N(PPh)][2,7,9,10-F-6,6,6,8,8,8-(CO)--6,8,1-FeCBH] (), in which one further B–F substitution has occurred and the {FeCB} cluster core has rearranged, plus a mono-iron co-product, [N(PPh)][3,8,9-F-7,7,7-(CO)--7,1-FeCBH] () that is formed by polyhedral contraction. Treatment of with [NO][BF] in CHCl results in CO substitution at the 4-connected iron vertex [Fe(10)], producing the zwitterionic complex [7,8,9-F-6,6,6,10,10-(CO)-10-NO--6,10,1-FeCBH] (). Addition of MeNO to a mixture of and PEt in CHCl also results in CO substitution, forming the isomeric species [N(PPh)][7,8,9-F-6,6,,10,10-(CO)--PEt--6,10,1-FeCBH] [ = 6, = 10 (); = 10, = 6 ()] in a 5 : 1 ratio. Treatment of with [NO][BF] and then CNBu in CHCl allows further, successive CO substitution at Fe(10) to yield first a neutral, zwitterionic complex [7,8,9-F-6,6,6,10-(CO)-10-NO-10-PEt--6,10,1-FeCBH] () and then [7,8,9-F-6,6,6-(CO)-10-CNBu-10-NO-10-PEt--6,10,1-FeCBH] (). The molecular structures of compounds , , , , and have been established by X-ray diffraction.
Jeß, Inke; Taborsky, Petr; Pospíšil, Jiří; Näther, Christian
doi: 10.1039/b701905jpmid: 17534487
Three new coordination polymers based on CuI and 2,3-dimethylpyrazine (2,3-dmpyz) were prepared, structurally characterized and investigated for their thermal and luminescence properties. In the ligand rich 2 : 3 compound [(CuI)(2,3-dmpyz)] (CuI) dimers are found, which are connected by the N-donor ligands into chains, whereas in the structure of the 1 : 1 intermediate [(CuI)(2,3-dmpyz)] (CuI) tetramers are found, which are also connected into chains. The crystal structure of the ligand deficient 2 : 1 compound [(CuI)(2,3-dmpyz)] is built up of CuI double chains, which are connected by the 2,3-dmpyz ligands into layers. Thermal decomposition of results in its direct transformation into the ligand deficient compound , without the formation of the 1 : 1 compound as an intermediate. A similar thermal reactivity is found for compound , which transforms into on heating. Stirring of a crystalline suspension of pure or in acetonitrile, always leads to a transformation into the ligand deficient compound indicating that compound is the most stable of all the coordination polymers, whereas compounds and are metastable. The luminescence properties of the CuCl and CuI coordination polymers were investigated at 298 and 77K. It was observed that the emission maxima strongly depends on the nature of the halide atom and the composition and structure of the coordination polymers. In addition, several of these compounds show luminescence thermochromism. These results are compared with those obtained for the previously reported CuCl and CuBr(2,3-dimethylpyrazine) coordination polymers.
Aldous, David W.; Stephens, Nicholas F.; Lightfoot, Philip
doi: 10.1039/b702146apmid: 17534488
Nine new vanadium oxyfluorides, containing ten different oligomeric vanadium (oxy)fluoride anions have been prepared by solvothermal synthesis in water–ethylene glycol and using organic cations as co-crystallising agents. Crystal structures are reported for each. Amongst the ten structure types, five represent previously unobserved moieties, including one monomeric unit (-[VOF(HO)]), two dimers ([VOF(HO)] and [VOF]) and two tetramers (both isomers of composition [VOF]). Structural relationships between the various units are discussed, together with some rationalisation of their occurrence as a function of synthetic variables.
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