Guido D. Batema

Utrecht University, Utrecht, Utrecht, Netherlands

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Publications (10)27.97 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: A series of organometallic 4,4'-substituted benzylidene aniline complexes 4-ClPt-3,5-(CH2NMe2)2C6H2CH[double bond, length as m-dash]NC6H4R'-4', abbreviated as PtCl[NCN(CH[double bond, length as m-dash]NC6H4R'-4')-4], with R' = NMe2, Me, H, Cl, CN (, respectively), was synthesized via a Schiff-base condensation reaction involving reaction of PtCl[NCN(CH[double bond, length as m-dash]O)-4] () with the appropriate 4-R'-substituted aniline derivative () in toluene. The resulting arylplatinum(ii) products were obtained in 75-88% yield. Notably, product was also obtained in 68% yield from a reaction in the solid state by grinding solid with aniline . The structures of , , and in the solid state (single crystal X-ray diffraction) showed a non-planar geometry, in particular for compound . The electronic interaction between the donor benzylidene fragment PtCl(NCN-CH) and the para-R' aniline substituent through the azomethine bridge was studied with NMR and UV/Vis spectroscopy. Linear correlations were found between the azomethine (1)H, the (195)Pt NMR and various (13)C NMR chemical shifts, and the substituent parameters σF and σR of R' at the aniline site. In common with organic benzylidene anilines, the azomethine (1)H NMR chemical shift showed anomalous substituent behavior. The (195)Pt NMR chemical shift of the platinum center can be used as a probe for the electronic properties of the delocalized π-system of the benzylidene aniline framework, to which it is connected. The dual substituent parameter treatment of the azomethine (13)C NMR shift gave important insight into the unique behaviour of the Pt-pincer group as a substituent. Inductively, it is a very strong electron-withdrawing group, whereas mesomerically it behaves like a very strong electron donating group.
    Dalton Transactions 07/2014; · 3.81 Impact Factor
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    ABSTRACT: We report a field effect transistor (FET) based on a network of single-walled carbon nanotubes (SWCNTs) that for the first time can selectively detect a single gaseous molecule in air by chemically functionalizing the SWCNTs with a selective molecular receptor. As a target model we used SO2. The molecular synthetic receptor is a square-planar NCN-pincer platinum (II) complex (NCN is the N,C,N′-terdentate-coordinating monoanionic [C6H3(CH2NMe2)3-2,6]− ligand) to which SO2 selectively binds. Because of the strong electronwithdrawing character of SO2, it withdraws negative charge from the synthetic receptor thus affecting the electronic properties of the functionalized SWCNTs. The minimum concentration detected is 0.05% SO2 in air at room temperature. Interferences like CH4 and CO2 need to be present in a higher concentration than SO2 to give a significant response.
    Sensors and Actuators B: Chemical. 01/2009;
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    ABSTRACT: A series of 4,4′-disubstituted organic−organometallic stilbenes, i.e., the 4′-substituted stilbenoid-NCN-pincer platinum(II) complexes [PtCl(NCN-R-4)] (NCN-R-4 = [C6H2(CH2NMe2)2-2,6-R-4]− in which R = C2H2C6H4-R′-4′ with R′ = NPh2, NMe2, OMe, SiMe3 H, I, CN, NO2) (1−8), were studied for their electronic, electrochemical, and NLO properties. Complex 7 was also chemically oxidized using Cu(II)Cl2, yielding the [Pt(IV)Cl3(NCN(C2H2C6H4-CN-4′)-4)] complex 11. In contrast to 1 and 7, 11 did not show luminescent properties in solution at room temperature. In the solid state (X-ray crystallography) 11 has an overall bent structure, with the pincer moiety and the cyano group beneath the plane of the central double bond. Stilbenoid pincer complex 1 (R′ = NPh2) was also studied with UV/vis spectroscopy in a series of different solvents. The compound shows an intense low-energy transition band, appearing at a lower energy (λmax = 374–379 nm) than 2 (R′ = NMe2), which contains a stronger donor group. The UV/vis absorption data of a selected series of stilbenoid pincer platinum complexes were interpreted in terms of a qualitative orbital model based on DFT and TD-DFT calculations. The trends observed in the transition energies correlate well with the donor/acceptor properties of the substituents. It was shown that the HOMO–LUMO gap of the stilbenoid pincer platinum compounds decreases when going from an electron-neutral group (R′ = H) toward an electron-donating (R′ = NMe2) or -accepting (R′ = NO2) group. The fluorescence properties of 1 were also investigated using fluorescence and laser spectroscopy, showing that the metal center favors nonradiative decay from the excited state to the ground state. For 7 (R′ = CN), solid-state 13C CP/MAS NMR measurements were performed, and a value of 1J(13C,195Pt) = 1003 ± 15 Hz was obtained for the Cipso carbon, reflecting π-contributions in the carbon−metal bond. The cyclic voltammetry study on the complexes revealed an irreversible oxidation from Pt(II) to Pt(IV). In general the oxidation potential is influenced by the electronic character of the R′ substituent. The influence of the para R′ substituent on the hyperpolarizability of the compound was investigated using the femtosecond (frequency-resolved) HRS technique. For 1−7 good βzzz values were measured (βzzz ranging from (164–1324) × 10−30 esu) with the highest value for 6 (R′ = I). The higher βzzz values were found for the compounds that contain a low-energy UV/vis absorption band and/or a large absorption coefficient. Donor–acceptor complexes 7 and 8 were successfully applied in an organic light-emitting diode (OLED). In the electroluminescence spectrum of 7 (R′ = CN) a low-energy emission band was observed at 643 nm. This band also appeared in the solid-state luminescence spectra of 7, however, only at low temperatures (298–15 K). The emission band was assigned to result from a triplet excited state. The present study shows that the introduction of a NCN-pincer platinum fragment in a donor–acceptor stilbenoid molecule leads to complexes that have promising NLO properties. These compounds can now successfully be applied in OLED devices, although the performances of the devices have to be improved to become interesting for practical applications.
    03/2008;
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    ABSTRACT: A series of novel 4,4'-disubstituted organic-organometallic stilbenes were synthesized, that is, the 4'-substituted stilbenoid- NCN-pincer platinum(II) complexes [PtCl(NCN-R-4)] (NCN-R-4 = [C6H2(CH2NMe2)2-2,6-R-4]- in which R = C2H2C6H4-R'-4' with R' = NMe2, OMe, SiMe3, H, I, CN, NO2) (1-7). In these compounds the PtCl grouping can be considered to be present as a donor substituent. Their synthesis involved a Horner-Wadsworth-Emmons reaction of [PtCl(NCN-CHO-4)] (9) with the appropriate phosphonate ester derivatives (8a-g). Under these reaction conditions, the C-Pt bond in aldehyde 9 was not affected, and the platinated stilbene products were obtained in 53-90% yield. The solidstate structures of complexes 1, 2 and 5-7 were determined by single-crystal X-ray diffraction, which revealed interesting bent conformations for 2, 5 and 7. Linear correlations were found between both the 13C{1H} (C ipso to Pt) and the 195Pt{1H} NMR chemical shift and the Hammett σp value of the R' substituent; therefore, these NMR shifts can be used as a qualitative probe for the electronic properties of the delocalized π-system to which it is connected. The platinum-stilbene complexes were investigated for charge-transfer properties in solvents of different polarity. The luminescent properties, shown by donor-acceptor complexes 1, 6 and 7, were investigated by fluorescence spectroscopy, and the complexes showed positive solvatochromism, which indicates dipolar character of the excited state. The excited state lifetimes, which were in the picosecond range, and the quantum yields (ranging from 0.002 to 0.2) were also determined for these complexes. It was established that the presence of the transition metal favours nonradiative decay from the excited state to the ground state.
    Berichte der deutschen chemischen Gesellschaft 02/2007; 2007(10):1422 - 1435. · 2.94 Impact Factor
  • Eur.J.Inorg.Chem. 01/2007;
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    ABSTRACT: The synthesis of the two novel diphosphine compounds 1,2-bis(3-(diphenylphosphino)-4-methoxyphenyl)benzene (1; Terphos), and 1,2-bis(2-diphenylphosphino)benzene (2), both derived from a terphenyl backbone structure, are described. Straightforward synthetic routes have been employed to obtain these ligands in good yields from cheap starting materials. The coordination of ligands 1 and 2 with PtCl2(cod) has been studied by NMR spectroscopy, and the X-ray crystal structures of the resulting complexes 4 and 5 were determined. The 31P NMR spectra of the mononuclear products demonstrate solely cis coordination for both bidentate ligands, with corresponding coupling constants JPt-P of 3810 Hz (cis-[PtCl2(1)], complex 4) and 3712 Hz (cis-[PtCl2(2)], 5). The bite angles P1−Pt−P2 were 98.74 and 105.89°, respectively, in the distorted square-planar complexes. The new diphosphines have been applied in the platinum/tin-catalyzed hydroformylation of 1-octene, and both ligands give active and selective platinum catalysts.
    Organometallics. 09/2005; 24(22).
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    ABSTRACT: The relatively insensitive surface plasmon resonance (SPR) signal detection of low-molecular-mass analytes that bind with weak affinity to a protein--for example, carbohydrate-lectin binding--is hampering the use of biosensors in interaction studies. In this investigation, low-molecular-mass carbohydrates have been labeled with an organoplatinum(II) complex of the type [PtCl(NCN-R)]. The attachment of this complex increased the SPR response tremendously and allowed the detection of binding events between monosaccharides and lectins at very low analyte concentrations. The platinum atom inside the organoplatinum(II) complex was shown to be essential for the SPR-signal enhancement. The organoplatinum(II) complex did not influence the specificity of the biological interaction, but both the signal enhancement and the different binding character of labeled compounds when compared with unlabeled ones makes the method unsuitable for the direct calculation of biologically relevant kinetic parameters. However, the labeling procedure is expected to be of high relevance for qualitative binding studies and relative affinity ranking of small molecules (not restricted only to carbohydrates) to receptors, a process of immense interest in pharmaceutical research.
    ChemBioChem 08/2005; 6(7):1196-203. · 3.74 Impact Factor
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    ABSTRACT: [reaction: see text] A novel organoplatinum(II) biomarker is introduced to facilitate the solid-phase screening of combinatorial libraries for substrates and inhibitors of enzymes and receptors. The robust organoplatinum(II) biomarker can be incorporated, on amine functions, in peptides using standard peptide coupling techniques. The chemistry, stability, and (reversible) coloration process with KI(3) of the organoplatinum(II) biomarker was investigated.
    Organic Letters 07/2003; 5(12):2021-4. · 6.14 Impact Factor
  • Angewandte Chemie International Edition 04/2003; 42(11):1284-7. · 11.34 Impact Factor
  • G.D. Batema

Publication Stats

48 Citations
27.97 Total Impact Points

Institutions

  • 2007–2014
    • Utrecht University
      • • Division of Organic Chemistry and Catalysis
      • • Faculty of Science
      • • Division of Inorganic Chemistry and Catalysis
      Utrecht, Utrecht, Netherlands
  • 2009
    • Universitat Rovira i Virgili
      • Department of Analytical Chemistry and Organic Chemistry (DQAQO)
      Tarragona, Catalonia, Spain