Novos complexos de níquel(II) com fosfinas e N-alquilsulfonilditiocarbimatos: Síntese, caracterização e atividade antifúngica contra Botrytis cinerea e Colletotrichum acutatum

• Autor(a) principal: Vidigal, Antonio Eustáquio Carneiro
• Data de Publicação: 2013
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/2146
• topic: Ditiocarbimato; Fosfina; Atividade anti-fúngica; Dithiocarbimates; Phosphine; Anti-fungal activity; CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA INORGANICA

This work describes the syntheses, characterization and study of the antifungal activity of eight nickel(II) complexes with phosphines (triphenylphosphine and 1,2-bis(diphenylphosphine)ethane) (dppe) and N-alkylsulfonyldithiocarbimates. The complexes were obtained by the reaction of nickel(II) chloride hexahydrate with potassium N-alkylsulfonyldithiocarbimates and the appropriate phosphine (PPh3 or dppe), using ethanol/water as solvents. The complexes, with the general formulae [Ni(RSO2N=CS2)(PPh3)2] and [Ni(RSO2N=CS2)dppe] (R= CH3-, CH3CH2-, CH3CH2CH2CH2- and CH3CH2CH2CH2CH2CH2CH2CH2-), were characterized by melting points, elemental analyses of C, H, N, and Ni, HR-ESI-MS, IR, UV-Vis and 1H, 13C and 31P NMR spectroscopies. The results of the elemental analyses and the HR-ESI-MS spectra confirmed the proposed formulae. The observation of new bands (νNi-S) in their vibrational spectra and the shifts of characteristic bands (νCN, νassSO2, νsimSO2, νCS2) when compared to the spectra of the free ligands confirmed the formation of the complexes. The ultraviolet-visible spectra showed the expected bands for all complexes. The observation of d-d transitions pointed to a quadratic geometry arround the nickel atom. The NMR spectra of the complexes were typical for diamagnetic species, supporting the hypothesis of a square planar environment around the nickel atom. All the expected signals were observed in their 1H, 13C and 31P NMR spectra. Three complexes used in this study have been described in the literature ([Ni(CH3SO2N=CS2)(PPh3)2], [Ni(CH3SO2N=CS2)dppe] e [Ni(CH3 CH2SO2N=CS2)dppe]) (OLIVEIRA, 1997 and OLIVEIRA et al, 2008). They were resynthesized to be included in the biological testing. The activity of the complexes was tested against Botrytis cinerea and Colletotrichum acutatum. The complexes containing triphenylphosphine were active against both fungi, while the complexes with dppe showed little activity. These results indicated that the mode of action of the complexes might involve the intracellular release of the phosphines. The minimum doses required to inhibit 50% of the fungal growth (IC50) were determined from dose-inhibition curves obtained under the treatments with triphenylphosphine and with the nickel(II) complexes with triphenylphosphine and the dithiocarbimates. A greater activity of the more lipophilic compounds containing longer aliphatic chain groups (R with 4 and 8 carbon atoms), suggested that the stronger interaction with the cell membrane is also important for the activity of these complexes.