The synthesis and characterization of three propynyloxycoumarins are reported in this work together with the formation of three different series of gold(i) organometallic complexes. Neutral complexes are constituted by water soluble phosphines (PTA and DAPTA) which confer water solubility to them. The X-ray crystal structure of 7-(prop-2-in-1-yloxy)-1-benzopyran-2-one and its corresponding dialkynyl complex is also shown and the formation of rectangular dimers for the gold derivative in the solid state can be observed. A detailed analysis of the absorption and emission spectra of both ligands and complexes allows us to attribute the luminescent behaviour to the coumarin organic ligand. Moreover, the presence of the gold(i) metal atom seems to be responsible for an increase of coumarin phosphorescence emission. The biological activity of the complexes showed that the anionic complexes triggered strong cytotoxic effects in two different cell lines whereas the neutral gold alkynyl complexes led to lower effects against tumor cell growth. Thioredoxin reductase (TrxR) inhibition was very strong in the case of the neutral complexes (IC50 values below 0.1 μM) but moderate for the anionic complexes (IC50 values above 0.8 μM).
A phosphine-gold(i)-alkynyl-coumarin complex, [Au{7-(prop-2-ine-1-yloxy)-1-benzopyran-2-one}(DAPTA)] (), was synthesized and the formation of long luminescent fibers in solution was characterized via fluorescence microscopy and dynamic light scattering. The fibers presented strong blue and green luminescence, suggesting that the gold(i) in the complex increased intersystem crossing due to the heavy atom effect, resulting in a significant increase in triplet emission. The X-ray structure of the fibers indicates that both aurophilic, π-π interactions and hydrogen bonding contribute to their formation in aqueous solvents.
Seven imidazolium salts have been synthesized from octadecylimidazole (Im18). These salts differ in the length of the alkyl chain length bound to the second nitrogen atom of the imidazolium ring [R = Me, Et, iPr, Pr, Bu, decyl (Dec), octadecyl] and were used as synthetic precursors to obtain two series of gold(I) carbene complexes (AuNHC). The first series contains one labile ligand at the second coordinative position [a] 6120 show [M -Cl] + and [M -Cl + MeCN] + peaks in all cases, as exemplified in Figure 4 for MC4.
Three series of rhodium organometallic complexes, mono-(1c, 2c, 5c, 6c), di-(1a-6a) and tetranuclear (1b, 5b, 6b), containing six different diphosphines (1,1'bis(diphenylphosphino)methane or dppm (1), 1,2-bis(diphenylphosphino)ethane or dppe (2), 1,4-bis(diphenylphosphino)butane or dppb (3), bis(diphenylphosphino)acetylene or dppa (4), 1,2-bis(diphenylphosphino)benzene or dppbz (5) and 4,5-bis(diphenylphosphino)-9,9'-dimethylxanthene or xantphos (6) were successfully synthesised. These Rh(I) complexes were characterised by conventional techniques. The influence of the flexibility/rigidity of these P-donor ligands was carefully analysed, including their effect on both synthesis and catalysis. The luminescent properties of the dinuclear and tetranuclear complexes were investigated and only those containing dppa, dppbz and xantphos displayed luminescence. Structures of dinuclear complexes were modelled by using DFT methods in order to elucidate the most possible conformation. The different types of complexes were applied in the catalytic hydrogenation of (E)-4phenylbut-3-en-2-one, showing high activity and similar catalytic behaviour. No cooperative effect could be inferred.
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