engleski

New Mn(II) Azomethine Complex Dyes

The chromium azo complexes or unsymmetrical chromium complexes containing an azo or an azomethine group were widely used in the dyeing of textile fabrics or as dyes in the photographic industry [1-4] in the last decades. Determination of their toxicity has indicated the high values which were reason for searching their substitution with other metals, which could gave new metal complex compounds with satisfactory dyeing properties. As manganese is important and necessary element in nature and not been listed as toxic (according to the Eco-Text Standard 100), this paper was focussed on the researching on its azomethine complexes. The dyeing properties of the Mn(II) complexes with 2-[(2-quinolylmethilene)amino]-phenol (QMAP), 2-[(2-pyridylmethilene) amino]-phenol (PMAP), 2-[(2-pyridylmethilene)amino]-napthol (PMAN) and 2-[(2-pyrroryl methilene)amino]-phenol (PYPAP) were compared. The influence of size of the ligands on type, size and stability of the Mn(II) chelate molecules and further on their application properties were examined and discussed. PMAN PYMAP A comparison of the results of spectrometric methods gave an insight into the metal chelates structures, the ligand donors sets, different stechiometry and character of metal chelates molecules. Owning to the structure of the ligands, different types of manganese complexes are formed. It has been found that manganese is coordinated to QMAP through the nitrogens from the azomethine and quinoline groups and through the oxygen of hydroxyl group, forming 1:1 (M:L) complex with an acetate in the coordination sphere5. Although Mn-PMAP is isolated as perchlorate (because of better yield), it also showed 1:1, metal to ligand ratio, type of complex6. For the Mn-PYMAP was found that two metal atoms, both coordinated to each ligand, were bridged by the oxygen from acetate, forming stable binuclear complex. PYMAP was coordinated to manganese through two hetero and two azomethine nitrogens and to only one oxygen, behaving therefore as tridentate bianion and bidentate monoanion at the same time7. Characterization of the new solid Mn-PMAN complex showed that Mn-PMAN forms unexpected cationic chelate of the M2L3 type with perchlorate as anion. The experimental studies of dying kinetics have been directed towards determining the relative K/S values from Kubelka-Munk's equation and some of the results (for dyeing wool fibres, at T=80°C and pH=6.0) are presented in Table 1. WOOL K/S t/min 10 20 30 60 90 120 Mn-KMAP 1.11 3.85 5.30 7.10 8.10 8.64 Mn-PMAP 0.61 1.51 5.00 8.15 10.05 10.50 Mn-PMAN 0.95 2.54 3.11 4.93 5.11 5.20 This table confirms that the size of formed complexes is responsible for dyeing kinetics and also indicates that time is very important factor because it is connected first with a decrease of dye aggregates in dyebath, which depend on first 30 minutes of dyeing process, and second with a increase of their adsorption on fibres. From this aspect, the Mn-PMAP dye showed that dye exhaustion was lowest, comparing with others, which indicates that smaller molecules form greater aggregates and therefore reduce dyeing kinetics. At the end of the process, the affinity of the Mn-complex dyes for wool has been determined and it has been shown that it is closely connected with the size of chelate molecules and their arrangement in space. Although the lowest K/S value are obtained for very big Mn-PMAN complex dye, it can be accepted as dye. However, higher K/S values of another two dyes give the advantage to their application as dyes. Also, the experimental studies of the dyeing kinetics showed that Mn-PYMAP complex had not affinity either for wool or polyamide fibres.

manganese; azomethine dye

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