[Show abstract][Hide abstract] ABSTRACT: An iron(II)bis-terpyridine complex bearing 4′ pendant pyrenyl groups on each ligand (Fe(tpySCH2-pyr)22+) was synthesized, characterized electrochemically and was shown to form a novel redox polymer via anodic electropolymerization. Immersion of glassy carbon electrodes into dilute acetonitrile solutions of the complex and then into clean electrolyte established that the complex will physisorb onto glassy carbon at 0.1 monolayer coverage from 500 μM solution. Anodic cyclic voltammetry of the pyrenyl iron compound revealed well-resolved Fe(II/III) centered redox waves near 0.9 V and an irreversible, pyrene centered oxidation at ca. 1.1 V. The Fe(II/III) waves grew in magnitude over time and persisted in fresh complex-free electrolyte indicating a surface electropolymerization reaction most likely mediated via the pyrene pendant groups, and exhibiting facile charge transport through a ca. 100 nm polymer film. Spectroelectrochemical analysis of Fe(tpySCH2-pyr)2(OTf)2 films grown on indium–tin oxide transparent electrodes confirmed the presence of a Fe(II/III) redox-active film that has a nearly Nernstian response, but with a small Fe(II) component that does not oxidize interfacially.
Full-text · Article · Feb 2012 · Electrochimica Acta
[Show abstract][Hide abstract] ABSTRACT: The enantiomers of N,N'-bis(1-phenylethyl)-2,6-pyridinedicarboxamide (L), namely, (R,R)-1, and (S,S)-1, react with Ln(III) ions to give stable [LnL(3)](3+) complexes in an anhydrous acetonitrile solution and in the solid state, as evidenced by electrospray ionization mass spectrometry, NMR, luminescence titrations, and their X-ray crystal structures, respectively. All [LnL(3)](3+) complexes [Ln(III) = Eu, Gd, Tb, and Yb; L = (R,R)-1 and (S,S)-1] are isostructural and crystallize in the cubic space group I23. Although the small quantum yields of the Ln(III)-centered luminescence clearly point to the poor efficiency of the luminescence sensitization by the ligand and the intersystem crossing and ligand-to-metal energy transfers, the ligand triplet-excited-state energy seems relatively well suited to sensitize many Ln(III) ion's emission for instance, in the visible (Eu and Tb), near-IR (Nd and Yb), or both regions (Pr, Sm, Dy, Er, and Tm).
Preview · Article · Dec 2011 · Inorganic Chemistry
[Show abstract][Hide abstract] ABSTRACT: The synthesis of two optical isomers of N,N'-bis(1-phenylethyl)-2,6-pyridinedicarboxamide and the constant circularly polarized luminescence (CPL) activity of their acetonitrile trivalent europium complex solutions over a long period of time open new perspectives for performing accurate routine CPL calibration tests at low cost.
Preview · Article · Oct 2007 · Chemical Communications
[Show abstract][Hide abstract] ABSTRACT: We studied the influence of three bis(terpyridine)-Fe(II) molecules-(X-tpy)2FeCl2 (X = H (1), SAc (2), and 4-phenyl-SAc (3)-on charge storage of a nanowire transistor. The molecules were assembled on the surface of an indium oxide nanowire that forms the conduction channel of the transistor. We found that the charge storage characteristics of such a device strongly depends on the structure of the terpyridine ligand: both retention time (tau) and threshold voltage shift (DeltaVth) increased in the order of 1 < 2 < 3, with tau of 200 s, 12 h, and 287 h and DeltaVth at 4.8, 12, and 28 V, respectively. Furthermore, when we placed the devices with molecules 1 and 3 in a vacuum and recorded the I-Vg curves in a two-day period, we observed higher hysteresis stability for device with molecule 3. For example, DeltaVth was reduced from 4.8 to 1.7 V for the device with molecule 1, while there was no reduction in DeltaVth for the device with molecule 2. These results suggest that thiolate headgroup and/or longer ligand length raises the charge tunneling barrier and results in longer charge retention and wider, more stable memory window. This work demonstrates the potential of chemical synthesis toward tailored device characteristics.
Preview · Article · Jun 2004 · Journal of the American Chemical Society
[Show abstract][Hide abstract] ABSTRACT: An equimolar mixture of TiF4 and Ti(NMe2)4 in CH3CN gave orange crystals of [TiF2(NMe2)2]4 in good yield. This complex is a cyclic tetramer of TiF2(NMe2)2, where each titanium atom is bonded to one terminal fluoride and terminal amide ligands and to two pairs of bridging fluoride and bridging amide ligands. This complex was employed as a catalyst for polymerizations of ethylene, propylene, and styrene in the presence of methylaluminoxane (MAO); the activity was relatively low for these olefin polymerizations.
Preview · Article · Jun 2003 · Inorganica Chimica Acta
[Show abstract][Hide abstract] ABSTRACT: The half-open chromocene complex (η5-C5Me5)(η5-2,4-C7H11)Cr (1) has been characterized by X-ray diffraction. It crystallizes in space group P with a = 7.592(2), b = 8.665(6), c = 12.452(14) Å, α = 78.50(8), β = 79.41(6) and γ = 86.72(4)°, Z = 2, V = 787(15) Å3 and Dcalc = 1.19 g/cm3. The structure of this paramagnetic complex reveals a normal U-shaped pentadienyl moiety. Complex 1 is carbonylated in hexane solution under 40 psi CO at room temperature to yield the diamagnetic monocarbonyl adduct (η5-C5Me5)(η5-2,4-C7H11)CrCO (2). The X-ray structure of 2 has also been determined; the complex crystallizes in space group P with a = 8.2810(14), b = 8.8096(17), c = 12.0825(24) Å, α = 97.147(15), β = 91.712(15) and γ = 116.128(14)°, Z = 2, V = 781.7(3) Å3 and Dcalc = 1.319 g/ cm3. The structure of 2 reveals an unusual S-pentadienyl ligand geometry.
No preview · Article · Jan 1993 · Inorganica Chimica Acta
[Show abstract][Hide abstract] ABSTRACT: Potassium t-butoxide promotes alkylation of non-enolizable ketones and aldehydes by zirconocene dialkyls. The reaction proceeds with loss of cyclopentadienide ion from the metal center.
No preview · Article · Oct 1991 · Tetrahedron Letters