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Four new ferrocenylsubphthalocyanines Y-BSubPc, with ferrocenylcarboxylic acid YH = Fc-CH2–CH2–COOH (1) or Fc-CH═CH–COOH (2) in the axial Y position, were synthesized with a 40% yield. The axial fe...

Three different classes of ferrocenyl-containing β-keto compounds Fc-CO-CH2-CO-R were synthesised to obtain two β-diketones with R = CH3, 3, and R = Fc (ferrocenyl = FeII(C5H5)(C5H4)), 4, a β-ketoester, 5, with R = OEt and a β-ketoamide, 6, with R = NH2. The β-diketones exhibited keto ⇌ enol tautomerization with the enol form Fc-CO-CH=C(OH)-R as the dominant isomer. Both the β-ketoester and β-ketoamide primarily existed in the keto form. FTIR and 1H NMR measurements could distinguish between keto and enol isomers. Dilute CHCl3 solutions of 3 and 4 exhibited FTIR ѵC=O keto vibrations between 1627 and 1712 cm−1 and ѵC=O enol vibrations between 1590 and 1660 cm−1. X-ray photoelectron spectroscopic (XPS) measurements showed keto isomer Fe 2p3/2 photoelectron lines at smaller binding energies than enol isomers. Significantly lower calculated molecular energies of the keto form of the β-ketoester 5 and β-ketoamide 6 utilising the Gaussian09 suite of programs at the B3LYP (uB3LYP for open-shell species), confirmed that 5 and 6 almost exclusively exists in the keto conformation. Cyclic voltammetry also distinguished between keto and enol isomers, and it was found that the electrochemical reversible ferrocenyl formal oxidation potential, E°ꞌ, of keto isomers of compounds can be estimated with the equation E°ꞌketo = 170.99χR–57.57 where χR is the group electronegativities of R in FcCOCH2COR. This result complements earlier research that enables calculation of the ferrocenyl formal oxidation potentials of enol isomers of β-diketones. Computational studies further showed that the HOMO orbitals of 3–6 is exclusively on the Fe centre and computed Mulliken spin densities on the dxy orbital of the oxidised iron species approached 1 e−.

A range of ferrocenyl aryl ethers of type Fc–O–Ar (Fc = Fe(η5-C5H5)(η5-C5HnX4–n); n = 2–4; X = H, P(O)(OEt)2, SO2CF3; Ar = 2,4-(NO2)2-C6H3, 4-NO2-C6H4) have been successfully prepared by using the nucleophilic aromatic substitution reaction (SNAr) of Fc–OLi (1a–Li) and electron-deficient aryl fluorides, enabling a new pathway to this rarely described family of organometallic compounds. Initial studies of 1a–Li and o-phosphonato-substituted hydroxyferrocenes (1b–Li) have also been performed, indicating a low nucleophilicity of the oxygen atom. The SNAr reaction protocol tolerates ortho substituents, e.g. phosphonato and sulfonyl groups, resulting in 1,2-X,O (X = S, P) ferrocenyl ethers that can be obtained in a one-pot synthesis procedure including 1,3-O → C anionic phospho- and thia-Fries rearrangements. Within these studies, the first 1,3-diortho-functionalized ferrocenyl aryl ether could be synthesized. An electrochemical study of the redox potentials of the obtained compounds allows conclusions on the ...

Tris-(8-hydroxyquinolinato)aluminium (Alq3) was used as both the emission and electron transporting layer in organic light emitting diodes. One way to tune the emissive color of Alq3 is to introduce substituents onto the hydroxyquinoline ligands. These substituents will have an effect on the energy gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital. In this study, Alq3 powders were synthesized with –CH3 substituted at position 5 and 7 (tris-(5,7-dimethyl-8-hydroxyquinolinato)aluminium) and –Cl at position 5 (tris-(5-chloro-8-hydroxyquinolinato) aluminium). Optical absorption and cyclic voltammetry measurements were performed on the samples. The optical band gap was determined from these measurements. The band gap did not vary with more than 0.2 eV from the theoretical value of Alq3.

National Research Foundation, South Africa, (DIB, Grant number 76226; JCS, Grant number 81829), and by the Spanish MICINN and CAM (IF, Grants CTQ2010-20714-CO2-01/BQU, Consolider-Ingenio 2010, CSD2007-00006, S2009/PPQ-1634).

The series [(CO)5W═C(XR)Fc] (1, XR = OEt; 3, XR = NHBu) as well as [(CO)5W═C(XR)–Fc′–(XR)C═W(CO)5] (2, XR = OEt; 4, XR = NHBu) of mono- and biscarbene tungsten(0) complexes with Fc = FeII(C5H5)(C5H4) for monosubstituted derivatives and Fc′ = FeII(C5H4)2 for disubstituted derivatives were synthesized and characterized spectroscopically. The oxidized ferrocenium complex [1+]·PF6 was also synthesized and characterized. Electrochemical and computational studies were mutually consistent in confirming the sequence of redox events for the carbene derivatives 1–4 as first a carbene double-bond reduction to a radical anion, –W–C•, at peak cathodic potentials less than −2 V, then a ferrocenyl group oxidation in the range 0.206 0.540 V vs FcH/FcH+ in CH2Cl2/[(nBu4)N][PF6]. This is in contrast with the sequence of oxidation events in ferrocenylcarbene complexes of chromium, where Cr(0) is first oxidized in a one-elec...

A series of ten ferrocenyl, furyl, and thienyl mono- and biscarbene chromium(0) complexes were synthesized and characterized spectroscopically and electrochemically. The single crystal structure of the biscarbene complex [(CO)5Cr═C(OEt)-Fu'-(OEt)C═Cr(CO)5] (4a) was determined: C20H12Cr2O13; triclinic; P1; a = 6.2838(5), b = 12.6526(9), c = 29.1888(19) Å, α = 89.575(2), β = 88.030(2), γ = 87.423(2)°; Z = 4. Results from an electrochemical study in CH2Cl2 were mutually consistent with a computational study in showing that the carbene double bond of 1-6 is reduced to an anion radical, (-)Cr-C• at formal reduction potentials-1.7 V vs FcH/FcH(+). The Cr centers are oxidized in two successive one electron transfer steps to Cr(II) via the Cr(I) intermediate. Only Cr(I) oxidation is electrochemically irreversible. Dicationic Cr(II) species formed upon two consecutive one-electron oxidation processes are characterized by a peculiar bonding situation as they are stabilized by genuine CH···Cr agostic interactions. With respect to aryl substituents, carbene redox processes occurred at the lowest potentials for ferrocene derivatives followed by furan complexes. Redox process in the thiophene derivatives occurred at the highest potentials. This result is mutually consistent with a (13)C NMR study that showed the Cr═C functionality of furyl complexes were more shielded than thienyl complexes. The NHBu carbene substituent resulted in carbene complexes showing redox processes at substantially lower redox potentials than carbenes having OEt substituents.

The interaction of Fe(III) and Cu(II) with Aspergillus awamori-derived recombinant human lactoferrin was studied by means of UV–Vis and electron paramagnetic resonance spectroscopy. Results are interpreted as to indicate that non-specific metal binding occurs after a 2:1 stoichiometric metal uptake at the two specific binding sites of lactoferrin has taken place. Like wild-type lactoferrin from human milk, the expressed protein also coordinates the metal at the two specific binding sites to two deprotonated tyrosil and one histidine side chain, one aspartate and a bidentate sinergistic anion, here carbonate. Results of the cobalt(III), manganese(III), cerium(III) and cerium(IV) lactoferrin complexes are also presented and differences induced by the medium (Tris–HCl, phosphate and Hepes buffers) are explained.