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Poly(alkylidenamines) dendrimers as scaffolds for the preparation of low-generation ruthenium based metallodendrimers

Publication . Rodrigues, João; Jardim, Manuel G.; Figueira, João; Gouveia, Marisol; Tomás, Helena; Rissanen, Kari

The aim of this article is to highlight the use of nitrile-functionalized poly(alkylidenamines) dendrimers as building blocks for the preparation of low-generation ruthenium based cationic metallodendrimers having in view potential biomedical applications. Air-stable poly(alkylidenamines) nitrile dendrimers, peripherally functionalized with the ruthenium moieties [Ru(Z5-C5H5)(PPh3)2]+ or [RuCl(dppe)2]+, have been prepared, characterized and are being studied for their anticancer activity. The followed strategy is based on the biological advantages associated with low-generation dendrimers, the known activity of ruthenium compounds as anticancer drugs and the stability of these dendrimers at the physiological temperature.

2011Journal article

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A convenient route for the preparation of the monohydride catalyst trans-[RuCl(H)(dppe)2] (dppe=Ph2PCH2CH2PPh2): improved synthesis and crystal structure

Publication . Figueira, João; Jardim, Manuel G.; Rodrigues, João; Valkonen, Arto; Rissanen, Kari

A novel and improved room temperature synthesis of the monohydride catalyst trans-[RuCl(H)(dppe)2] complex (1, dppe (1,2-bis(diphenylphosphino)ethane) = Ph2PCH2CH2PPh2) proceeds through oxidation of methanol (the solvent) by the pentacoordinated cis-[RuCl(dppe)2][PF6] complex and t-BuOK as the base is described. Compound 1 was fully characterized by NMR (1H, 13C, 31P), ESI-MS(TOF +), FTIR and elemental analysis. The X-ray structure of 1 was reported for the first time and unambiguously confirms the trans-configuration of the complex.

2013Journal article

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Electrodeposition of polyaniline on self-assembled monolayers on graphite for the voltammetric detection of iron(II)

Publication . Camacho, Cláudia S.; Mesquita, José C.; Rodrigues, João

Conducting polyaniline (PANI) prepared by potentiodynamic electropolymerization on unmodified graphite, and on graphite modified by self-assembled monolayers (SAMs) of 3-mercapto-1-propanesulfonic acid sodium salt (MPS) or 4-aminothiophenol (4-ATP), has been studied by cyclic voltammetry and electrochemical impedance. For the various PANI-modified electrodes, the electropolymerization behaviour of aniline is not significantly different, as well as the polyaniline redox behaviour. Despite that, the films electrodeposited on self-assembled seem to be thinner than those directly obtained on graphite. The 4-aminothiophenol self-assembled exerts more influence on polyaniline, particularly through a relative enhancement of the redox couple benzoquinone/hydroquinone. It was verified by cyclic voltammetry that Fe(II) is detected with the several PANI-modified electrodes. The comparison of the Fe(II) redox voltammetry on the different PANI-modified electrodes shows that does not significantly depend on of the modified electrode used. Complementarily, there is a relative increase in current of the redox couple Fe(II)/Fe(III) on polyaniline compared to that observed in graphite, suggesting an electrocatalytic process. However, that effect may be explained by an increase in surface area. Nevertheless, our results have shown clearly, with polyaniline, an increase in the reversible nature of the voltammetry of the redox couple Fe(II)/Fe(III).

2016Journal article

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Synthesis, characterization and solid-state photoluminescence studies of six alkoxy phenylene ethynylene dinuclear palladium(II) rods

Publication . Figueira, João; Czardybon, Wojciech; Mesquita, José Carlos; Rodrigues, João; Lahoz, Fernando; Russo, Luca; Valkonen, Arto; Rissanen, Kari

A rare family of six discrete binuclear [PdCl(PEt3)2] phenylene ethynylene rods with alkoxy side chains (methoxy, ethoxy and heptoxy) have been developed, and their solid-state photoluminescence results have been presented and discussed. The shorter bridging ligands are of the general formula H–CuC– C6H2(R)2–CuC–H, where R = H, OCH3, OC 2H5, and OC7H15, whereas the longer ones are based on H– CuC–C6H4–CuC–C6H2(R)2–CuC–C6H4–CuC–H, where R = OCH3, OC 2H5. These ligands display increasing length in both the main dimension (backbone length) as well as the number of carbons in the side chains (R, alkoxide side chain) that stem from the central phenylene moiety. The X-ray crystal structures of two of the prepared complexes are reported: one corresponds to a shorter rod, 1,4-bis[trans(PEt3)2ClPd-CuC]-2,5-diethoxybenzene (6c), while the second one is associated with a longer rod, the binuclear complex 1,4-bis[trans-(PEt3)2ClPd-4-(–CuC–C6H4–CuC)]-2,5-diethoxybenzene (7c). All new compounds were characterized by NMR spectroscopy (1H, 13C{1H} and 31P{1H}) as well as ESI-MS(TOF), EA, FTIR, UV-Vis, cyclic voltammetry and solid-state photoluminescence. Our work shows the inﬂuence of the alkoxy side chains on the electronic structure of the family of binuclear Pd rods by lowering its oxidation potential. In addition to this, the increase of the length of the bridge results in a higher oxidation potential. Solid state photoluminescence results indicate that Pd complexes are characterized by a marked decrease in both the emission intensity and the ﬂuorescence lifetime values as compared to their ligands. This behaviour could be due to some degree of ligand-to-metal charge transfer.

2015Journal article

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