Syntheses and reactivity of the apically functionalized (pseudo)macrobicyclic iron(II) tris-dioximates and their hybrid phthalocyaninatoclathrochelate derivatives comprising reactive and vector terminal groupстатья
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Аннотация:Binuclear FeII, ZrIV(HfIV)-containing phthalocyaninatoclathrochelates with terminal reactive formyl group were prepared using three synthetic approaches, (i) the direct template condensation of appropriate chelating and capping ligand synthons on the iron(II) ion as a matrix, (ii) a transmetallation of the initially obtained macrobicyclic precursors with labile capping fragment(s), and (iii) a macrobicyclization of the suitable semiclathrochelate intermediates. The latter pathway was found to be a most favorable synthetic approach, typically giving the target hybrid compound in its highest yield. Reactivity of the single terminal formyl group of thus obtained iron(II) phthalocyaninatoclathrochelates were functionalized using post-synthetic strategy via a hydrazonate condensation with isoniazid, giving the corresponding cage complex with biorelevant pharmacophoric fragment. These binuclear compounds and their semiclathrochelate precursors were characterized using elemental analysis, MALDI-TOF mass spectrometry, UV-vis, 1H and 13C {1H} NMR spectroscopy, and by the single crystal X-ray diffraction experiments. The ditopic hybrid molecules contain two relatively independent chromophoric centers (i.e., a metallo(IV)phthalocyaninate core and a semiclathrochelate iron(II)-centered tris-α-dioximate fragment). As follows from XRD data, the geometry of their FeN6-polyhedra is close to intermediate between a trigonal prism (the distortion angle φ = 0°) and a trigonal antiprism (φ = 60°). The capping heptacoordinate metal(IV) ions form their MIVN4O3-coordination polyhedra and are shifted from the mean plane of a phthalocyanine macrocycle at a distance from 0.9 to 1.2 Å. The developed multistep synthetic approach is proposed as a general convenient and straightforward strategy for obtaining of a wide range of binuclear hybrid cage complexes of this type, functionalized for their target delivery to various biosystems (biotargets).