ABSTRACT
Under suitable conditions, C-alkylpyrogallol[4]arenes (PgCs) arrange into spherical metal-organic nanocapsules (MONCs) upon coordination to appropriate metal ions. Herein we present the synthesis and structural characterization of a novel FeII/FeIII-seamed MONC, as well as studies related to its electrochemical and magnetic behaviors. Unlike other MONCs that are assembled through 24 metal ions, this nanocapsule comprises 32 Fe ions, uncovering 8 additional coordination sites situated between the constituent PgC subunits. The FeII ions are likely formed by the reducing ability of DMF used in the synthesis, representing a novel synthetic route toward polynuclear mixed-valence MONCs.
ABSTRACT
Two structurally analogous Mn-seamed C-alkylpyrogallol[4]arene (PgC n)-based metal-organic nanocapsules (MONCs) have been synthesized under similar reaction conditions and characterized by crystallographic, electrochemical, and magnetic susceptibility techniques. Both MONCs contain 24 Mn centers, but, somewhat surprisingly, marked differences in oxidation state distribution are observed upon analysis. One MONC contains exclusively MnII ions, while the other is a mixed-valence MnII/ MnIII assembly. We propose that these disparate oxidation state distributions arise from slight differences in pH achieved during synthesis, a factor that may lead to many spectacular new MONCs (and associated host-guest chemistries).
ABSTRACT
C-alkylpyrogallol[4]arenes (PgCs) have been studied for their ability to form metal-organic nanocapsules (MONCs) through coordination to appropriate metal ions. Here we present the synthesis and characterization of an MnII/MnIII-seamed MONC in addition to its electrochemical and magnetic behavior. This MONC assembles from 24 manganese ions and 6 PgCs, while an additional metal ion is located on the capsule interior, anchored through the introduction of bridging nitrite ions. The latter originate from an in situ redox reaction that occurs during the self-assembly process, thus representing a new route to otherwise unobtainable nanocapsules.
ABSTRACT
The synthesis and single-crystal X-ray diffraction structure of a dimeric zinc-seamed nanocapsule using a mixed pyrogallol/resorcinol[4]arene are presented. The use of "mixed" macrocycles results in an incomplete seam of coordination bonds around the nanocapsule's typically octa-metalated belt. The self-assembly of the nanocapsule occurs such that the single resorcinol moiety of each macrocycle aligns transversely. This yields a hepta-metalated capsule where the defect occurs in such a way as to provide minimal disruption to the overall structure of the nanocapsule.