RESUMEN
The dimensional reduction of solids into smaller fragments provides a route to achieve new physical properties and gain deeper insight into the extended parent structures. Here, we report the synthesis of CuTOTP-OR (TOTPn- = 2,3,6,7-tetraoxidotriphenylene), a family of copper-based macrocycles that resemble truncated fragments of the conductive two-dimensional (2D) metal-organic framework Cu3(HHTP)2 (HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene). The planar metal-organic macrocycles self-assemble into ordered nanotubes with internal diameters of â¼2 nm and short interlayer distances of â¼3.20 Å. Strong π-π stacking interactions between macrocycles facilitate out-of-plane charge transport, and pressed pellet conductivities as high as 2(1) × 10-3 S cm-1 are observed. Peripheral alkyl functionalization enhances solution processability and enables the fabrication of thin-film field-effect transistor devices. Ambipolar charge transport is observed, suggesting that similar behavior may be operative in Cu3(HHTP)2. By coupling the attractive features of metal-organic frameworks with greater processability, these macrocycles enable facile device integration and a more nuanced understanding of out-of-plane charge transport in 2D conductive metal-organic frameworks.
RESUMEN
The percyanated dodecaborate anion [B12(CN)12]2- was prepared by reacting [B12I12]2- with CuCN in the presence of a palladium catalyst at elevated pressure and temperature in a microwave reactor. The fully cyanated cluster was isolated as a tetraethylammonium salt in yields of up to 39% and characterized by NMR and IR spectroscopy and mass spectrometry. The crystal structure of a copper complex of the percyanated anion, (CH3CN)3Cu[µ-B12(CN)12]Cu(NCCH3)3, was determined by single-crystal X-ray diffraction.
RESUMEN
Redox-active tetraoxolene ligands such as 1,4-dihydroxybenzoquinone provide access to a diversity of metal-organic architectures, many of which display interesting magnetic behavior and high electrical conductivity. Here, we take a closer look at how structure dictates physical properties in a series of 1D iron-tetraoxolene chains. Using a diphenyl-derivatized tetraoxolene ligand (H2Ph2dhbq), we show that the steric profile of the coordinating solvent controls whether linear or helical chains are exclusively formed. Despite similar ligand environments, only the helical chain displays temperature-dependent valence tautomerism, switching from (FeII)(Ph2dhbq2-) to (FeIII)(Ph2dhbq3Ë-) at temperatures below 203 K. The stabilization of ligand radicals leads to exceptionally strong magnetic exchange coupling (J = -230 ± 4 cm-1). Meanwhile, the linear chains are more amenable to oxidative doping, leading to Robin-Day class II/III mixed-valency and an increase in electrical conductivity by nearly three orders of magnitude. While previous studies have focused on the effects of changing metal and ligand identity, this work highlights how altering the metal-ligand connectivity can be a similarly powerful tool for tuning materials properties.
RESUMEN
Due to their unique topology and distinct physical properties, cycloparaphenylenes (CPPs) are attractive building blocks for new materials synthesis. While both noncovalent interactions and irreversible covalent bonds have been used to link CPP monomers into extended materials, a coordination chemistry approach remains less explored. Here we show that nucleophilic aromatic substitution reactions can be leveraged to rapidly introduce donor groups (-OR, -SR) onto polyfluorinated CPP rings. Demethylation of methoxide-substituted CPPs produces polycatechol nanohoop ligands that are readily metalated to produce well-defined, multimetallic CPP complexes. As catechols are recurring motifs throughout coordination chemistry and dynamic covalent chemistry, the polycatechol nanohoops reported here open the door to new strategies for the bottom-up synthesis of atomically precise CPP-based materials.