13428-22-3

Strongly luminescent tricarbonylrhenium(i) complexes are promising candidates in the field of optical materials. In this study, three new complexes bearing a 3-(2-pyridyl)-1,2,4-triazole (pyta) bidentate ligand with an appended phenyl group were obtained in very good yields owing to an optimized synthetic procedure. The first member of this series,i.e.complex1, was compared with the previously studied complexRePBOto understand the influence of the fluorescent benzoxazole unit grafted on the phenyl ring. Then, to gauge the effect of steric hindrance on the luminescence properties, the phenyl group of complex1was substituted in theparaposition by a bulkytert-butyl group or an adamantyl moiety, affording complexes2and3, respectively. The results of theoretical calculations indicated that these complexes were quite similar from an electronic point of view, as evidenced by the electrochemical study. In dichloromethane solution, under excitation in the UV range, all the complexes emitted weak phosphorescence in the red region. In the solid state, they could be excited in the blue region of the visible spectrum and they emitted strong yellow light. The photoluminescence quantum yield was markedly increased with raising the size of the substituent, passing from 0.42 for1to 0.59 for3. The latter complex also exhibited clear waveguiding properties, unprecedented for rhenium complexes. From this point of view, these easy-synthesized and spectroscopically attractive complexes constitute a new generation of emitters for use in imaging applications and functional materials. However, the comparison withRePBOshowed that the presence of the benzoxazole group leads to unsurpassed mechanoresponsive luminescence (MRL) properties, due to the involvement of a unique photophysical mechanism that takes place only in this type of complex.

The invention relates to an aliphatic-aromatic heterocyclic compound A which comprises at least two heterocyclic rings B and C, to a metal extractant composition E comprising this aliphatic-aromatic heterocyclic compound A and an organic acid D having at least one carboxylic, sulfonic, sulfuric, phosphinic, phosphonic, or phosphoric acid group, and to a process to extract one or more metals M selected from the group consisting of Ni and Co from an aqueous acidic leach solution PL comprising ions of at least one of the metals M, and further, at least one kind of further ions selected from the group consisting of Fe ions, Al ions, Cu ions, Mg ions, Mn ions, and also silicate anions, by mixing the solution PL with an extractant composition E, separating the organic and aqueous phases, and recovering the metal M from the separated organic phase.