Andrew J. P. White

Imperial College London, Londinium, England, United Kingdom

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Publications (708)2483.83 Total impact

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    ABSTRACT: Full experimental details on the synthesis of angular building blocks based on dipyrromethenes and the 1,10-phenanthroline nucleus are described.
    Tetrahedron. 10/2014; 70(40):7358–7362.
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    ABSTRACT: Platinum(II) and palladium(II) complexes [M(CH3)(L)]SbF6 with substituted terpyridine ligands L undergo light-driven oxygen insertion reactions into metal methyl bonds resulting in methylperoxo complexes [M(OOCH3)(L)]SbF6. The oxygen insertion reactions occur readily for complexes with methyl ligands that are activated due to steric interaction with substituents (NH2, NHMe or CH3) at the 6,6"-positions on the terpyridine ligand. All complexes exhibit attractive intramolecular π···π or M···M interactions in the solid state and in solution, which lead to excited triplet dinuclear M-M complexes upon irradiation. A mechanism is proposed whereby a dinuclear intermediate is generated upon irradiation that has a weakened M-C bond in the excited state, resulting in the observed oxygen insertion reactions.
    Journal of the American Chemical Society 09/2014; · 10.68 Impact Factor
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    ABSTRACT: We describe the synthesis and characterisation of two new polymers consisting of an electron-rich backbone containing indacenodithiophene (IDT) and dithiophene (DT) with the electron-poor units benzothiadiazole (BT) and benzopyrazolothiadiazole (BPT) fused on top of DT. The effect of this substitution has been studied and discussed by optical, electrochemical and computational means. Despite having very similar molecular distribution as well as thermal and electrochemical properties, the addition of the stronger electron-withdrawing BPT unit leads to a substantial change on the absorption properties by promoting the intramolecular charge transfer (ICT) band alongside the π-π*. Furthermore, we also reporte organic field effect transistors and solar cells device results, giving hole mobilities of 0.07 cm2/Vs with low threshold voltage (<10 V) and power conversion efficiencies of up to 2.2%.
    J. Mater. Chem. C. 08/2014;
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    ABSTRACT: A much improved route to 1,1’-bis(arylethynyl)ferrocenes comprising accessible thiolates on the aryl ring is reported. Unanticipated reactions between AcCl, TBAF/BBr3 and ferrocenyl-alkynes are also discussed, offering a rationale for previous synthetic difficulties.
    Dalton Transactions 08/2014; · 3.81 Impact Factor
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    ABSTRACT: Arylazopyrazoles, a novel class of 5-membered azo photoswitches, offer quantitative photoswitching and high thermal stability of the Z-isomer (half-lives of 10 and ~1000 days). The conformation of the Z-isomers of these compounds, and also the arylazopyrroles, is highly dependent on the substitution pattern on the heteroarene, allowing a twisted or planar geometry, which in turn has a significant impact on the electronic spectral properties of the compounds.
    Journal of the American Chemical Society 08/2014; · 10.68 Impact Factor
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    ABSTRACT: The chromo-fluorogenic detection of carbon monoxide in air has been achieved using a simple, inexpensive system based on ruthenium(II). This probe shows exceptional sensitivity and selectivity in its sensing behavior in the solid state. A color response visible to the naked eye is observed at 5 ppb of CO and a remarkably clear color change occurs from orange to yellow at the onset of toxic CO con-centrations (100 ppm) in air. Even greater sensitivity (1 ppb) can be achieved through a substantial increase in turn-on emission fluorescence in the presence of carbon monoxide, both in air and in solution. No response is observed with other gases including water vapor. Immobilization of the probe on a cellulose strip allows the system to be applied in its current form in a simple optoelectronic device to give a numerical reading and/or alarm.
    Journal of the American Chemical Society 08/2014; · 10.68 Impact Factor
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    ABSTRACT: We report [Y{N(SiMe3)2}3] as a precatalyst for the dehydrocoupling of sterically demanding amines with β-diketiminate stabilised aluminium dihydrides. While simple fluorinated anilines readily undergo Al-H/N-H dehydrocoupling under thermal conditions, catalytic methods are required to achieve reasonable rates of reaction for ortho-substituted anilines or hindered aliphatic amines.
    Chemical Communications 07/2014; · 6.38 Impact Factor
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    ABSTRACT: Iso-selective initiators for the ring-opening polymerization (ROP) of rac-lactide are rare outside of Group 13. We describe the first examples of highly iso-selective lutetium initiators. The phosphasalen lutetium ethoxide complex shows excellent iso-selectivity, with a Pi value of 0.81-0.84 at 298 K, excellent rates, and high degrees of polymerization control. Conversely, the corresponding La derivative exhibits moderate heteroselectivity (Ps =0.74, 298 K). Thus, the choice of metal center is shown to be crucial in determining the level and mode of stereocontrol. The relative order of rates for the series of complexes is inversely related to metallic covalent radius: that is, La>Y>Lu.
    Angewandte Chemie International Edition in English 07/2014; · 13.45 Impact Factor
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    ABSTRACT: A catalyst- and by-product-free protocol for the synthesis of σ–π conjugated organosilicon polymers is reported. The regiospecific [2+2] cycloaddition of CC triple bonds to SiSi double bonds allowed the preparation of air-stable ethynyl-terminated extended monomers from 1,4-bis(ethynyl)benzene and the para-phenylene bridged tetrasiladiene, Tip2SiSiTip-pC6H4-SiTipSiTip2 (Tip=2,4,6-iPr3C6H2). The polymer obtained from the extended monomer and further tetrasiladiene exhibits pronounced σ–π conjugation, as was evident from the red-shift in the absorption spectrum compared to model systems. We show that the thermal stability of the employed bis(alkyne) co-monomer is translated into this polymer.
    Chemistry 06/2014; · 5.93 Impact Factor
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    ABSTRACT: Lithium organoamidocuprates of the general stoichiometry LiCuR(NR) are an important class of organocopper reagents and have found widespread application in conjugate addition and other bond-forming reactions. The dependence of the structures and equilibrium of these species on the steric and electronic properties of the amido group is reported in both the solid state and in solution. Three different cuprate complexes have been crystallographically characterized: the organoamidocuprate [Cu2Li2Mes2TMP2] () (TMP = 2,2,6,6-tetramethylpiperidide) which is shown to adopt a head-to-tail conformation; [Cu2Li2(N(CH2Ph)CH2CH2NMe2)4] () which is a homoamidocuprate and contains additional coordination of the lithium centres from intra-molecular tertiary amine groups; and the diastereomeric organoamidocuprate [Cu2Li2Mes2(N(R-CH(Ph)Me)(CH2CF3))2] () which adopts a head-to-head conformation. Complex is unique in being the first crystallographically characterised example of a head-to-head isomer of a heterocuprate, and its structure also has implications for the use of scalemic amidocuprates in asymmetrically induced conjugate addition. The solution equilibria of all new complexes have also been studied using (7)Li NMR spectroscopy, and in each case the species observed in the crystal structure was shown to also be the predominant isomer in solution.
    Dalton Transactions 06/2014; · 3.81 Impact Factor
  • Adi E. Nako, Qian Wen Tan, Andrew J. P. White, Mark R. Crimmin
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    ABSTRACT: We report the synthesis and isolation of three new σ-complexes of Cu(I) in which E–H (E = Al, Zn) σ-bonds are coordinated to copper. The addition of the main group hydride to a toluene-solvated Cu(I) complex results in reversible ligand exchange, and the Cu(I) σ-complexes have been crystallized. Experimental and computational data provide a wealth of evidence for weak binding of the E–H bond to Cu(I), which can be ascribed to σ-donation from the E–H bond into the 4s orbital of copper and back-donation from copper into the E–H σ* orbital.
    Organometallics 05/2014; 33(11):2685–2688. · 4.15 Impact Factor
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    ABSTRACT: http://www.readcube.com/articles/10.1002/chin.201416232
    ChemInform 04/2014; 45(16).
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    ABSTRACT: The reactivity of the novel tridentate phosphine ligand N(CH2PCyp2)3 (N-triphos(Cyp), 2; Cyp = cyclopentyl) with various ruthenium complexes was investigated and compared that of to the less sterically bulky and less electron donating phenyl derivative N(CH2PPh2)3 (N-triphos(Ph), 1). One of these complexes was subsequently investigated for reactivity toward levulinic acid, a potentially important biorenewable feedstock. Reaction of ligands 1 and 2 with the precursors [Ru(COD)(methylallyl)2] (COD = 1,5-cycloocatadiene) and [RuH2(PPh3)4] gave the tridentate coordination complexes [Ru(tmm){N(CH2PR2)3-κ(3)P}] (R = Ph (3), Cyp (4); tmm = trimethylenemethane) and [RuH2(PPh3){N(CH2PR2)3-κ(3)P}] (R = Ph (5), Cyp (6)), respectively. Ligands 1 and 2 displayed different reactivities with [Ru3(CO)12]. Ligand 1 gave the tridentate dicarbonyl complex [Ru(CO)2{N(CH2PPh2)3-κ(3)P}] (7), while 2 gave the bidentate, tricarbonyl [Ru(CO)3{N(CH2PCyp2)3-κ(2)P}] (8). This was attributed to the greater electron-donating characteristics of 2, requiring further stabilization on coordination to the electron-rich Ru(0) center by more CO ligands. Complex 7 was activated via oxidation using AgOTf and O2, giving the Ru(II) complexes [Ru(CO)2(OTf){N(CH2PPh2)3-κ(3)P}](OTf) (9) and [Ru(CO3)(CO){N(CH2PPh2)3-κ(3)P}] (11), respectively. Hydrogenation of these complexes under hydrogen pressures of 3-15 bar gave the monohydride and dihydride complexes [RuH(CO)2{N(CH2PPh2)3-κ(3)P}] (10) and [RuH2(CO){N(CH2PPh2)3-κ(3)P}] (12), respectively. Complex 12 was found to be unreactive toward levulinic acid (LA) unless activated by reaction with NH4PF6 in acetonitrile, forming [RuH(CO)(MeCN){N(CH2PPh2)3-κ(3)P}](PF6) (13), which reacted cleanly with LA to form [Ru(CO){N(CH2PPh2)3-κ(3)P}{CH3CO(CH2)2CO2H-κ(2)O}](PF6) (14). Complexes 3, 5, 7, 8, 11, and 12 were characterized by single-crystal X-ray crystallography.
    Inorganic Chemistry 03/2014; · 4.59 Impact Factor
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    ABSTRACT: A bio-inspired manganese(ii) complex with a linear pentadentate ligand framework containing soft sulfur donors and an alternating NSNSN binding motif displays excellent dual CAT/SOD-like antioxidant activity with high turnover efficiency and good operation stability in an aqueous environment.
    Chemical Communications 03/2014; · 6.38 Impact Factor
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    ABSTRACT: Square-planar palladium(II) and platinum(II) methyl complexes with terpyridine and 6,6″-diamino terpyridine ligands undergo methyl exchange reactions upon exposure to light. The half-life of the methyl exchange reactions correlates with the relative Pd–C and Pt–C bond strengths. No exchange between methyl and phenyl groups is observed, probably due to the stronger Pt–C bond in the platinum phenyl complex. A mechanism is proposed whereby a dinuclear intermediate is generated upon irradiation that has a weakened M–C bond in the excited state, resulting in the observed methyl exchange reactions.
    Organometallics 03/2014; 33(6):1453–1461. · 4.15 Impact Factor
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    ABSTRACT: The synthesis, characterization, and zinc coordination chemistry of the three proligands 2-tert-butyl-4-[tert-butyl (1)/methoxy (2)/nitro (3)]-6-{[(2'-dimethylaminoethyl)methylamino]methyl}phenol are described. Each of the ligands was reacted with diethylzinc to yield zinc ethyl complexes 4-6; these complexes were subsequently reacted with phenylsilanol to yield zinc siloxide complexes 7-9. Finally, the zinc siloxide complexes were reacted with phenylsilane to produce the three new zinc hydride complexes 10-12. The new complexes 4-12 have been fully characterized by NMR spectroscopy, mass spectrometry, and elemental analyses. The structures of the zinc hydride complexes have been probed using VT-NMR spectroscopy and X-ray diffraction experiments. These data indicate that the complexes exhibit mononuclear structures at 298 K, both in the solid state and in solution (d 8-toluene). At 203 K, the NMR signals broaden, consistent with an equilibrium between the mononuclear and dinuclear bis(μ-hydrido) complexes. All three zinc hydride complexes react rapidly and quantitatively with carbon dioxide, at 298 K and 1 bar of pressure over 20 min, to form the new zinc formate complexes 13-15. The zinc formate complexes have been analyzed by NMR spectroscopy and VT-NMR studies, which reveal a temperature-dependent monomer-dimer equilibrium that is dominated by the mononuclear species at 298 K.
    Organometallics 03/2014; 33(5):1112-1119. · 4.15 Impact Factor
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    ABSTRACT: Two novel [2+2] metallo-assemblies based on a guanosine-substituted terpyridine ligand (1) coordinated to palladium(II) (2 a) and platinum(II) (2 b) are reported. These supramolecular assemblies have been fully characterized by NMR spectroscopy, ESI mass spectrometry and elemental analyses. The palladium(II) complex (2 a) has also been characterized by single crystal X-ray diffraction studies confirming that the system is a [2+2] metallo-rectangle in the solid state. The stabilities of these [2+2] assemblies in solution have been confirmed by DOSY studies as well as by variable temperature (1) H NMR spectroscopy. The ability of these dinuclear complexes to interact with quadruplex and duplex DNA was investigated by fluorescent intercalator displacement (FID) assays, fluorescence resonance energy transfer (FRET) melting studies, and electrospray mass spectrometry (ESI-MS). These studies have shown that both these assemblies interact selectively with quadruplex DNA (human telomeric DNA and the G-rich promoter region of c-myc oncogene) over duplex DNA, and are able to induce dimerization of parallel G-quadruplex structures.
    Chemistry 03/2014; · 5.93 Impact Factor
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    ABSTRACT: The gold(I) complexes [Au{S2CN(CH2CH═CH2)2}(L)] [L = PPh3, PCy3, PMe3, CN(t)Bu, IDip] are prepared from KS2CN(CH2CH═CH2)2 and [(L)AuCl]. The compounds [L2(AuCl)2] (L2 = dppa, dppf) yield [(L2){AuS2CN(CH2CH═CH2)2}2], while the cyclic complex [(dppm){Au2S2CN(CH2CH═CH2)2}]OTf is obtained from [dppm(AuCl)2] and AgOTf followed by KS2CN(CH2CH═CH2)2. The compound [Au2{S2CN(CH2CH═CH2)2}2] is prepared from [(tht)AuCl] (tht = tetrahydrothiophene) and the diallyldithiocarbamate ligand. This product ring-closes with [Ru(═CHPh)Cl2(SIMes)(PCy3)] to yield [Au2(S2CNC4H6)2], whereas ring-closing of [Au{S2CN(CH2CH═CH2)2}(PR3)] fails. Warming [Au2{S2CN(CH2CH═CH2)2}2] results in formation of gold nanoparticles with diallydithiocarbamate surface units, while heating [Au2(S2CNC4H6)2] with NaBH4 results in nanoparticles with 3-pyrroline dithiocarbamate surface units. Larger nanoparticles with the same surface units are prepared by citrate reduction of HAuCl4 followed by addition of the dithiocarbamate. The diallydithiocarbamate-functionalized nanoparticles undergo ring-closing metathesis using [Ru(═CHC6H4O(i)Pr-2)Cl2(SIMes)]. The interaction between the dithiocarbamate units and the gold surface is explored using computational methods to reveal no need for a countercation. Preliminary calculations indicate that the Au-S interactions are substantially different from those established in theoretical and experimental studies on thiolate-coated nanoparticles. Structural studies are reported for [Au{S2CN(CH2CH═CH2)2}(PPh3)] and [Au2{S2CN(CH2CH═CH2)2}2]. In the latter, exceptionally short intermolecular aurophilic interactions are observed.
    Inorganic Chemistry 02/2014; · 4.59 Impact Factor
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    ABSTRACT: The new DO3A-derived dithiocarbamate ligand, DO3A-(t)Bu-CS2K, is formed by treatment of the ammonium salt [DO3A-(t)Bu]HBr with K2CO3 and carbon disulfide. DO3A-(t)Bu-CS2K reacts with the ruthenium complexes cis-[RuCl2(dppm)2] and [Ru(CH═CHC6H4Me-4)Cl(CO)(BTD)(PPh3)2] (BTD = 2,1,3-benzothiadiazole) to yield [Ru(S2C-DO3A-(t)Bu)(dppm)2](+) and [Ru(CH═CHC6H4Me-4)(S2C-DO3A-(t)Bu)(CO)(PPh3)2], respectively. Similarly, the group 10 metal complexes [Pd(C,N-C6H4CH2NMe2)Cl]2 and [PtCl2(PPh3)2] form the dithiocarbamate compounds, [Pd(C,N-C6H4CH2NMe2)(S2C-DO3A-(t)Bu)] and [Pt(S2C-DO3A-(t)Bu)(PPh3)2](+), under the same conditions. The linear gold complexes [Au(S2C-DO3A-(t)Bu)(PR3)] are formed by reaction of [AuCl(PR3)] (R = Ph, Cy) with DO3A-(t)Bu-CS2K. However, on reaction with [AuCl(tht)] (tht = tetrahydrothiophene), the homoleptic digold complex [Au(S2C-DO3A-(t)Bu)]2 is formed. Further homoleptic examples, [M(S2C-DO3A-(t)Bu)2] (M = Ni, Cu) and [Co(S2C-DO3A-(t)Bu)3], are formed from treatment of NiCl2·6H2O, Cu(OAc)2, or Co(OAc)2, respectively, with DO3A-(t)Bu-CS2K. The molecular structure of [Ni(S2C-DO3A-(t)Bu)2] was determined crystallographically. The tert-butyl ester protecting groups of [M(S2C-DO3A-(t)Bu)2] (M = Ni, Cu) and [Co(S2C-DO3A-(t)Bu)3] are cleaved by trifluoroacetic acid to afford the carboxylic acid products, [M(S2C-DO3A)2] (M = Ni, Cu) and [Co(S2C-DO3A)3]. Complexation with Gd(III) salts yields trimetallic [M(S2C-DO3A-Gd)2] (M = Ni, Cu) and tetrametallic [Co(S2C-DO3A-Gd)3], with r(1) values of 11.5 (Co) and 11.0 (Cu) mM(-1) s(-1) per Gd center. DO3A-(t)Bu-CS2K can also be used to prepare gold nanoparticles, Au@S2C-DO3A-(t)Bu, by displacement of the surface units from citrate-stabilized nanoparticles. This material can be transformed into the carboxylic acid derivative Au@S2C-DO3A by treatment with trifluoroacetic acid. Complexation with Gd(OTf)3 or GdCl3 affords Au@S2C-DO3A-Gd with an r(1) value of 4.7 mM(-1) s(-1) per chelate and 1500 mM(-1) s(-1) per object.
    Inorganic Chemistry 02/2014; · 4.59 Impact Factor

Publication Stats

3k Citations
2,483.83 Total Impact Points

Institutions

  • 1992–2014
    • Imperial College London
      • Department of Chemistry
      Londinium, England, United Kingdom
  • 2012
    • Universität des Saarlandes
      Saarbrücken, Saarland, Germany
  • 2002–2012
    • University College London
      • Department of Chemistry
      London, ENG, United Kingdom
    • Imperial Valley College
      South Kensington, Maryland, United States
  • 2011
    • Universitat Jaume I
      • Departament de Química Inorgànica i Orgànica
      Castelló de la Plana, Valencia, Spain
    • Bayer HealthCare
      Leverkusen, North Rhine-Westphalia, Germany
  • 2010
    • Ivanovo State University of Chemistry and Technology
      Iwanowo, Ivanovo, Russia
    • Karlsruhe Institute of Technology
      Carlsruhe, Baden-Württemberg, Germany
  • 2002–2010
    • Università degli Studi di Messina
      • Dipartimento di Scienze Chimiche
      Messina, Sicily, Italy
    • University of Sunderland
      Sunderland, England, United Kingdom
  • 1999–2010
    • Universidad de Extremadura
      • Faculty of Veterinary
      Ara Pacis Augustalis, Extremadura, Spain
  • 2009
    • The University of Manchester
      • School of Chemistry
      Manchester, ENG, United Kingdom
  • 2007
    • The University of Warwick
      • Department of Chemistry
      Warwick, ENG, United Kingdom
    • University of Barcelona
      • Department of Organic Chemistry
      Barcino, Catalonia, Spain
  • 2006
    • Medical University of Łódź
      Łódź, Łódź Voivodeship, Poland
  • 2004–2006
    • University of Wuerzburg
      • Institute of Inorganic Chemistry
      Würzburg, Bavaria, Germany
    • University of East Anglia
      • Wolfson Materials and Catalysis Centre
      Norwich, ENG, United Kingdom
    • University of Bath
      • Department of Chemistry
      Bath, ENG, United Kingdom
  • 2003–2006
    • University of Miami
      • Department of Chemistry
      Coral Gables, FL, United States
  • 2000–2006
    • University of California, Los Angeles
      • Department of Chemistry and Biochemistry
      Los Angeles, CA, United States
    • University of Bologna
      • "Giacomo Ciamician" Department of Chemistry CHIM
      Bologna, Emilia-Romagna, Italy
  • 2005
    • King's College London
      • Department of Chemistry
      London, ENG, United Kingdom
    • Australian National University
      • Research School of Chemistry
      Canberra, Australian Capital Territory, Australia
    • ICIQ Institute of Chemical Research of Catalonia
      Tarraco, Catalonia, Spain
  • 1998
    • University of Ljubljana
      • Faculty of Chemistry and Chemical Technology
      Ljubljana, Ljubljana, Slovenia
    • Northwestern University
      • Department of Chemistry
      Evanston, IL, United States
  • 1997
    • Newcastle University
      • School of Chemistry
      Newcastle-on-Tyne, England, United Kingdom
  • 1996–1997
    • University of Birmingham
      • School of Chemistry
      Birmingham, ENG, United Kingdom