Science & Mathematics

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    Observations on a Population of Heath Wrinklewort 'Rutidosis Heterogama' Philipson 1937 (Magnoliopsida: Asteraceae) in Cooranbong, New South Wales
    (Field Naturalists Club of Victoria, 2023-10-01) Annable, Terence
    The Heath Wrinklewort 'Rutidosis heterogama' is one of 9 Rutidosis spp. endemic to Australia (Atlas of Living Australia [ALA] 2023). This species is a small perennial herb with a ca- pitulum (flower head) (Fig. 1) of bright yellow, polygamous (mainly bisexual), monocarpous florets. Its distribution includes 3 disjunct locations: two in north-eastern New South Wales (NSW) and 1 in the Lower Hunter-Central Coast region of NSW. One of the north-east- ern locations is on the coast, with populations occurring between Wooli and Evans Head in Yuraygir and Bundjalung National Parks (NSW Office of Environment and Heritage [NSW OEH] 2017); the other site occurs on the New England Tablelands, with populations found from Torrington and Ashford south to Wands- worth, south-west of Glen Innes (NSW OEH 2017). On the Lower Hunter-Central Coast, the species occurs from Wyong to Newcastle (NSW OEH 2017). The 2 north-eastern populations are separated by about 150 km and each is separated from the Lower Hunter-Central Coast population by about 350 km. There are very few occurrences of 'R. heterogama' between these respective populations (ALA 2023). Most of the other 8 species of Rutidosis also have re- stricted distributions in eastern Australia, but Grey Wrinklewort 'R. helichrysoides' is widespread across Australia (ALA 2023), and Button Wrinklewort 'R. leptorhynchoides' is known from southern NSW, through eastern Victoria and into western Victoria (ALA 2023).
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    Heterobimetallic N‑Heterocyclic Carbene Complexes: A Synthetic, Spectroscopic, and Theoretical Study
    (2016-07-18) Barnard, Peter J.; Dutton, Jason L.; Skelton, Brian W.; Wilson, David J.; Pell, Thomas P.

    A new synthetic methodology has been developed for the preparation of heterobimetallic group 11 and group 12 complexes of a symmetrical bis-NHC “pincer” ligand. The synthetic route involved the initial preparation of a mononuclear [Au(NHC)2]+ complex with pendent imidazole moieties on the NHC ligands. Subsequent alkylation of the imidazole groups with Et3OBF4 and metalation with a second metal ion (Ag(I) or Hg(II)) provided two heterobimetallic complexes. Four homobimetallic (Cu(I)2, Ag(I)2, Au(I)2, and Hg(II)2) complexes of the same bis-NHC “pincer” ligand were also prepared. The homobimetallic Cu(I)2, Au(I)2, and Hg(II)2 complexes and heterobimetallic Au(I)−Ag(I) and Au(I)−Hg(II) complexes and the synthetic intermediates for the heterobimetallic complexes were characterized by X-ray crystallography. These X-ray structures show that the bimetallic complexes adopt “twisted” conformations in the solid state, supporting short M···M interactions. Crystalline samples of the homobimetallic Ag(I)2 and Au(I)2 and heterobimetallic Au(I)−Ag(I) and Au(I)−Hg(II) complexes were emissive at room temperature and at 77 K. The geometries of the synthesized complexes were optimized at the M06-L/def2-SVP level of theory, and the electronic nature of the M···M interactions for all synthesized complexes was investigated using natural bond orbital (NBO) calculations.

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    Reactions of [PhI(pyridine)2]2+ with Model Pd and Pt II/IV Redox Couples
    (2014-02-03) Dutton, Jason L.; Wilson, David J.; Georgiou, Dayne C.; Corbo, Robert

    The results of the reactions of the dicationic iodine(III) family of oxidants [PhI(pyridine)2]2+ with model Pd(II) and Pt(II) complexes are described. Depending on the specific reaction pairs, a variety of outcomes are observed. For palladium, Pd(IV) complexes cannot be observed but are implicated in C−C and C−N bond formation for Pd(II) starting materials based on phenylpyridine and 2,2-bipyridine, respectively. Theoretical comparisons with similar processes for −Cl and −OAc rather than pyridine indicate that these provide greater thermodynamic stability, and our results here show that they also give greater kinetic stability (the failure of MP2 methods for these systems is quite dramatic). In contrast, oxidation and delivery of the pyridine ligands gives dicationic Pt(IV) complexes that may be isolated and structurally characterized.

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    The Dalton Quantum Chemistry Program System
    (2014-05-01) Agren, Hans; Ziolkowski, Marcin; Wilson, David J.; Watson, Mark A.; Vahtras, Olav; Thogersen, Lea; Thorvaldsen, Andreas J.; Tew, David P.; Tellgren, Erik I.; Teale, Andrew M.; Taylor, Peter R.; Sylvester-Hvid, Kristian O.; Steindal, Arnfinn H.; Sneskov, Kristian; Schimmelpfennig, Bernd; Sauer, Stephan; Saue, Trond; Sanchez de Meras, Alfredo; Samson, Claire; Salek, Pawel; Rybkin, Vladimir V.; Ruud, Kenneth; Ruden, Torgeir A.; Rinkevicius, Zilvinas; Reine, Simen; Provasi, Patricio F.; Pedersen, Thomas B.; Pawlowski, Filip; Packer, Martin J.; Osted, Anders; Olsen, Jogvan Magnus H.; Olsen, Jeppe; Norman, Patrick; Nielsen, Christian B.; Neiss, Christian; Myhre, Rolf H.; Mikkelsen, Kurt V.; Melo, Juan I.; Lutnaes, Ola B.; Ligabue, Andrea; Kristensen, Kasper; Krapp, Andreas; Kongsted, Jacob; Koch, Henrik; Kobayashi, Rika; Knecht, Stefan; Klopper, Wim; Kjaergaard, Thomas; Kirpekar, Sheela; Kauczor, Joanna; Jorgensen, Poul; Jonsson, Dan; Jensen, Hans Jorgen A.; Jansik, Branislav; Iozzi, Maria F.; Hoyvik, Ida-Marie; Host, Stinne; Hjertenaes, Eirik; Hetema, Hinne; Hennum, Alf Christian; Helgaker, Trygve; Heiberg, Hanne; Hattig, Christof; Halkier, Alsger; Hald, Kasper; Frediani, Luca; Fliegl, Heike; Ferrighi, Lara; Fernandez, Berta; Ettenhuber, Patrick; Eriksen, Janus J.; Enevoldsen, Thomas; Ekstrom, Ulf; Dalskov, Erik K.; Dahle, Pal; Coriani, Sonia; Cimiraglia, Renzo; Christiansen, Ove; Boman, Linus; Bast, Radovan; Bakken, Vebjorn; Bak, Keld L.; Angeli, Celestino; Aidas, Kestutis

    Dalton is a powerful general‐purpose program system for the study of molecular electronic structure at the Hartree–Fock, Kohn–Sham, multiconfigurational self‐consistent‐field, Møller–Plesset, configuration‐interaction, and coupled‐cluster levels of theory. Apart from the total energy, a wide variety of molecular properties may be calculated using these electronic‐structure models. Molecular gradients and Hessians are available for geometry optimizations, molecular dynamics, and vibrational studies, whereas magnetic resonance and optical activity can be studied in a gauge‐origin‐invariant manner. Frequency‐dependent molecular properties can be calculated using linear, quadratic, and cubic response theory. A large number of singlet and triplet perturbation operators are available for the study of one‐, two‐, and three‐photon processes. Environmental effects may be included using various dielectric‐medium and quantum‐mechanics/molecular‐mechanics models. Large molecules may be studied using linear‐scaling and massively parallel algorithms. Dalton is distributed at no cost from http://www.daltonprogram.org for a number of UNIX platforms.

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    The First Bismuth–NHC Complexes
    (2014-01-14) Dutton, Jason L.; Wilson, David J.; Vin Tan, Kel; Corbo, Robert; Aprile, Antonio

    The synthesis, isolation and crystallographic characterization of the first N-heterocyclic carbene adducts of bismuth is reported, by direct reaction of the Dipp2NHC (Dipp = 2,6-diisopropylphenyl) or iPr2(Me2)- NHC with BiCl3. This represents the last non-radioactive element from groups 13–17 for which an NHC– element fragment remained unreported.

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    Is the Perfluorinated Trityl Cation Worth a Revisit? A Theoretical Study on the Lewis Acidities and Stabilities of Highly Halogenated Trityl Derivatives
    (2014-06-10) Dutton, Jason L.; Wilson, David J.; Couchman, Shannon A.

    The relative Lewis acidities of a series of known, unknown and observed but unstable halogenated derivatives of the trityl cation have been probed in a computational study. The Lewis acidity was investigated from hydride, fluoride and methide affinities. The results indicate that the perhalogen-ated trityl cation [C(C6F5)3]+ is a desirable synthetic target, especially in the modern age of weakly coordinating anions. Our results also indicate that the stable [C(C6Cl5)3]+ cation may be an equally interesting Lewis acid.

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    Synthesis and Biological Evaluation of Substituted 2-anilino-7H-pyrrolopyrimidines as PDK1 Inhibitors
    (2014-05-21) Abbott, Belinda M.; Deady, Leslie W.; Wilson, David J.; Brzozowski, Martin; O'Brien, Nathan J.

    An efficient and scalable route for a series of novel substituted 2-anilino-7H-pyrrolopyrimidine compounds as potential inhibitors of PDK1, an important regulator of the PI3K/Akt pathway that is dysregulated in many cancers, was developed and is described. The synthetic strategy was designed around Suzuki and BuchwaldeHartwig cross-couplings of a boronate fragment and various customised anilines sequentially with 2,4-dichloro-7-tosyl-7H-pyrrolopyrimidine. All fragments were constructed separately and cross-coupled to provide access to a range of novel compounds. Biological evaluation of these was undertaken, with modest inhibition observed.

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    Activation of the C–N Bond of N-heterocyclic Carbenes by Inorganic Elements
    (2014-09-14) Dutton, Jason L.; Wilson, David J.; Iversen, Kalon J.

    N-heterocyclic carbenes (NHCs) are generally considered to be extremely robust, ideal spectator ligands. However, in the past two years there have been several reports of the activation of the endocyclic C–N bond with subsequent insertion into element–hydrogen and element–carbon bonds. The new reaction pathway casts the reactivity of the NHC heterocyclic ring into a new light, especially in the context of potential catalyst decomposition. The synthetic reports and theoretical studies in this rapidly developing area are summarized here.

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    Iridium Complexes of N-Heterocyclic Carbene Ligands: Investigation into the Energetic Requirements for Efficient Electrogenerated Chemiluminescence
    (2014-09-22) Hogan, Conor F.; Wilson, David J.; Barnard, Peter J.; Quan, Linh M.; Stringer, Bradley D.

    A series of five heteroleptic Ir(III) complexes of the general form Ir(ppy)2(C∧C:) have been prepared (C∧C represents a bidentate cyclometalated phenyl-substituted imidazolylidene ligand). The five complexes arise from the cyclometalated phenyl ring of the NHC ligand being unsubstituted or having electron-donating (OMe and Me) or electron-withdrawing (Cl and F) groups at the 2- and 4- positions of the ring. The synthesized phenyl-substituted imidazole precursors, imidazolium salts, and Ir(III) complexes have been characterized by elemental analysis, NMR spectroscopy, cyclic voltammetry, and electronic absorption and emission spectroscopy. The molecular structures for two imidazolium salts and two Ir(III) complexes were determined by single-crystal X-ray diffraction. Each of the Ir(III) complexes exhibited intense photoluminescence in acetonitrile solution at

    room temperature with quantum yields (ϕp) ranging from 42% to 68% and excited-state lifetimes on the order of 2 μs. Voltammetric experiments revealed one formal metal-based oxidation process and two ligand-based reductions for each complex.

    All complexes gave moderate to intense annihilation electrochemiluminescence (ECL); however, only the fluorinated complex produced significant coreactant ECL. The combined electrochemical, spectroscopic, and theoretical investigations offer insights into the reasons for this behavior and suggest useful strategies for the design of ECL emitters. A plot of oxidation potential versus emission color is proposed as a convenient reference guide to aid in the prediction of energy sufficiency in ECL reactions.