Chromophore-labelled, luminescent platinum complexes: syntheses, structures, and spectroscopic properties

Ligands based upon 4-carboxamide-2-phenylquinoline derivatives have been synthesised with solubilising octyl hydrocarbon chains and tethered aromatic chromophores to give naphthyl (HL2), anthracenyl (HL3) and pyrenyl (HL4) ligand variants, together with a non-chromophoric analogue (HL1) for comparison. 1H NMR spectroscopic studies of the ligands showed that two non-interchangeable isomers exist for HL2 and HL4 while only one isomer exists for HL1 and HL3. Supporting DFT calculations on HL4 suggest that the two isomers may be closely isoenergetic with a relatively high barrier to exchange of ca. 100 kJ mol−1. These new ligands were cyclometalated with Pt(II) to give complexes [Pt(L1–4)(acac)] (acac = acetylacetonate). The spectroscopically characterised complexes were studied using multinuclear NMR spectroscopy including 195Pt{1H} NMR studies which revealed δPt ca. −2785 ppm for [Pt(L1–4)(acac)]. X-ray crystallographic studies were undertaken on [Pt(L3)(acac)] and [Pt(L4)(acac)], each showing the weakly distorted square planar geometry at Pt(II); the structure of [Pt(L3)(acac)] showed evidence for intermolecular Pt–Pt interactions. The UV-vis. absorption studies show that the spectral profiles for [Pt(L2–4)(acac)] are a composite of the organic chromophore centred bands and a broad 1MLCT (5d → π*) band (ca. 440 nm) associated with the complex. Luminescence studies showed that complexes [Pt(L2–4)(acac)] are dual emissive with fluorescence characteristic of the tethered fluorophore and long-lived phosphorescence attributed to 3MLCT emission. In the case of the pyrenyl derivative, [Pt(L4)(acac)], the close energetic matching of the 3MLCT and 3LCpyr excited states led to an elongation of the 3MLCT emission lifetime (τ = 42 μs) under degassed solvent conditions, suggestive of energy transfer processes between the two states

Luminescent 1,8-Naphthalimide-Derived ReI Complexes: syntheses, spectroscopy, X-ray structure and preliminary bioimaging in fission yeast cells

A series of picolyl-functionalised, fluorescent 1,8-naphthalimide ligands (L) have been synthesised and coordi-nated to ReI to form luminescent cationic complexes of the general form fac-[Re(phen)(CO)3(L)]BF4. The complexes were characterised by using a range of spectroscopic and analytical techniques. One example of a complex was also characterised in the solid-state by using single-crystal X-ray diffraction, reveal-ing a distorted octahedral coordination sphere at ReI and Re– C/Re–N bond lengths within the expected ranges. All ligands were shown to be fluorescent, with the 4-amino derivatives showing intramolecular charge transfer in the visible region (511–534 nm). The complexes generally showed a mixture of ligand-centred and/or 3MLCT emission depending upon the na-ture of the coordinated 1,8-naphthalimide ligand. For selected complexes, confocal fluorescence microscopy was undertaken by using fission yeast cells (Schizosaccharomyces pombe) and showed that the structure of the 1,8-naphthalimide ligand influ-ences the uptake and localisation of the rhenium complex

Synthesis and characterisation of phosphorescent rhenium(I) complexes of hydroxy- and methoxy-substituted imidazo[4,5- f ]-1,10-phenanthroline ligands

Eight new fluorescent ligands (L1-L8) derived from the fused imidazo[4,5-f]-1,10-phenanthroline core, have been synthesised utilising a one-pot methodology. The ligands include two points of structural variety, allowing multiply-substituted aryl groups (including hydroxy and methoxy moieties) to be attached to the ligand core. The ligands L1-L8 are fluorescent (λem = 399–426 nm) and react with pentacarbonylbromorhenium to give coordination complexes of the form fac-[ReBr(CO)3(NˆN)] (where NˆN = L1-L8). The complexes were characterised using a variety of spectroscopic and analytical techniques, including single crystal X-ray diffraction studies on two examples. The rhenium complexes were all found to be luminescent, revealing classical 3MLCT emission at 579–587 nm in aerated solution with corresponding lifetimes in the range 149–166 ns

Assessing fishery and ecological consequences of alternate management options for multispecies fisheries

Demands for management advice on mixed and multispecies fisheries pose many challenges, further complicated by corresponding requests for advice on the environmental impacts of alternate management options. Here, we develop, and apply to North Sea fisheries, a method for collectively assessing the effects of, and interplay between, technical interactions, multispecies interactions, and the environmental effects of fishing. Ecological interactions involving 21 species are characterized with an ensemble of 188 plausible parameterizations of size-based multispecies models, and four fleets (beam trawl, otter trawl, industrial, and pelagic) characterized with catch composition data. We use the method to evaluate biomass and economic yields, alongside the risk of stock depletion and changes in the value of community indicators, for 10 000 alternate fishing scenarios (combinations of rates of fishing mortality F and fleet configuration) and present the risk vs. reward trade-offs. Technical and multispecies interactions linked to the beam and otter trawl fleets were predicted to have the strongest effects on fisheries yield and value, risk of stock collapse and fish community indicators. Increasing beam trawl effort led to greater increases in beam trawl yield when otter trawl effort was low. If otter trawl effort was high, increases in beam trawl effort led to reduced overall yield. Given the high value of demersal species, permutations of fleet effort leading to high total yield (generated primarily by pelagic species) were not the same as permutations leading to high catch values. A transition from F for 1990 to 2010 to FMSY, but without changes in fleet configuration, reduced risk of stock collapse without affecting long-term weight or value of yield. Our approach directly addresses the need for assessment methods that treat mixed and multispecies issues collectively, address uncertainty, and take account of trade-offs between weight and value of yield, state of stocks and state of the environment

Development and optimisation of a sex pheromone lure for monitoring populations of saddle gall midge, Haplodiplosis marginata

Saddle gall midge, Haplodiplosis marginata (von Roser) (Diptera: Cecidomyiidae), is a sporadic pest of cereals in Northern and Central Europe and is of increasing importance in the UK. Recently the major component of the sex pheromone produced by adult female H. marginata was reported to be 2-nonyl butyrate. The importance of absolute configuration on attractiveness, the effects on trap catches of the addition of minor pheromone components, dispenser type, and pheromone loading are described in the development of an optimised pheromone lure with which to trap H. marginata males. In analyses of volatiles collected from virgin female H. marginata by gas chromatography (GC) coupled to electroantennographic recording (EAG) from the antenna of a male H. marginata, two EAG responses were observed. Analyses by coupled GC-mass spectrometry (MS) indicated these were due to 2-nonyl butyrate and a trace amount (1%) of 2-heptyl butyrate. A similar trace amount of 2-nonanol was detected in GC-MS analyses but this compound did not elicit an EAG response when the synthetic compound was tested, whereas while the other two compounds did. These three compounds were not observed in collections of volatiles made from male H. marginata. The 2-nonyl butyrate was shown to be the (R)-enantiomer, and i. In field trapping tests (R)-2-nonyl butyrate was at least ten times10× more attractive to male H. marginata than the racemic compound, and while the (S)-enantiomer was unattractive. Addition of the potential minor components individually or together at the naturally -occurring ratios did not increase or reduce the attractiveness of the lure. Polyethylene vials and rubber septa were equally effective as pheromone dispensers, lasting for at least five 5 weeks in the field in the UK, although laboratory tests indicated release from the former was more uniform and more likely to last longer in the field. Increasing loading of pheromone in the dispenser increased attractiveness. Traps baited with polyethylene vials containing 0.5 mg of (R)-2-nonyl butyrate are recommended for monitoring H. marginata and these are far more sensitive than water or sticky traps currently used for monitoring this pest

Lanthanide tetrazolate complexes combining single-molecule magnet and luminescence properties: the effect of the replacement of tetrazolate n3 by β-diketonate ligands on the anisotropy energy barrier

Three new sets of mononuclear LnIII complexes of general formulas [LnL3]⋅CH3OH [LnIII=Yb (1), Er (2), Dy (3), Gd (4), and Eu (5)], [LnL2(tmh)(CH3OH)]⋅n H2O⋅m CH3OH [LnIII=Yb (1 b), Er (2 b), Dy (3 b), Gd (4 b)], and [LnL2(tta)(CH3OH)]⋅CH3OH [LnIII=Yb (1 c), Er (2 c), Dy (3 c), Gd (4 c)] were prepared by the reaction of Ln(CF3SO3)⋅n H2O salts with the tridentate ligand 2-(tetrazol-5-yl)-1,10-phenanthroline (HL) and, for the last two sets, additionally with the β-diketonate ligands 2,2,6,6-tetramethylheptanoate (tmh) and 2-thenoyltrifluoroacetonate (tta), respectively. In the [LnL3]⋅CH3OH complexes the LnIII ions are coordinated to three phenanthroline tetrazolate ligands with an LnN9 coordination sphere. Dynamic ac magnetic measurements on 1–3 reveal that these complexes only exhibit single-molecule magnet (SMM) behavior when an external dc magnetic field is applied, with Ueff values of 11.7 K (1), 16.0 K (2), and 20.2 K (3). When the tridentate phenanthroline tetrazolate ligand is replaced by one molecule of methanol and the β-diketonate ligand tmh (1 b–3 b) or tta (1 c–3 c), a significant increase in Ueff occurs and, in the case of the DyIII complexes 3 b and 3 c, out-of-phase χ′′ signals below 15 and 10 K, respectively, are observed in zero dc magnetic field. CASSCF+RASSI ab initio calculations performed on the DyIII complexes support the experimental results. Thus, for 3 the ground Kramers’ doublet is far from being axial and the first excited state is found to be very close in energy to the ground state, so the relaxation barrier in this case is almost negligible. Conversely, for 3 b and 3 c, the ground Kramers’ doublet is axial with a small quantum tunneling of the magnetization, and the energy difference between the ground and first Kramers’ doublets is much higher, which allows these compounds to behave as SMMs at zero field. Moreover, these calculations support the larger Ueff observed for 3 b compared to 3 c. Additionally, the solid-state photophysical properties of 1, 2, 4, and 5 show that the phenanthroline tetrazolate ligand can act as an effective antenna to sensitize the characteristic YbIII, ErIII, and EuIII emissions through an energy-transfer process