Partial oxidation of an iron-tetrazolate metal-organic framework (MOF) upon exposure to ambient atmosphere yields a mixed-valence material with single-crystal conductivities tunable over 5 orders of magnitude and exceeding 1 S/cm, the highest for a three-dimensionally connected MOF. Variable-temperature conductivity measurements reveal a small activation energy of 160 meV. Electronic spectroscopy indicates the population of midgap states upon air exposure and corroborates intervalence charge transfer between Fe and Fe centers. These findings are consistent with low-lying Fe defect states predicted by electronic band structure calculations and demonstrate that inducing metal-based mixed valency is a powerful strategy toward realizing high and systematically tunable electrical conductivity in MOFs.

A Cu-azolate metal-organic framework uptakes stoichiometric loadings of Group 1 and 2 metal halides, demonstrating efficient reversible release and reincorporation of immobilized anions within the framework. Ion pairing interactions lead to anion-dependent Li + and Mg 2+ transport in Cu 4 (ttpm) 2 •0.6CuCl 2 , whose high surface area affords a high density of uniformly distributed mobile metal cations and halide binding sites. The ability to systematically tune the ionic conductivity yields a solid electrolyte with a Mg 2+ ion conductivity rivaling the best materials reported to date. This MOF is one of the first in a promising class of frameworks that introduces the opportunity to control the identity, geometry, and distribution of the cation hopping sites, offering a versatile template for application-directed design of solid electrolytes. ASSOCIATED CONTENT Supporting Information. Materials and Methods. Weight percentages of M n+ ions in the electrolytes. 1 H NMR spectra of MOF-MX n /PC. [110] reflection of Cu[(Cu 4 Cl)(ttpm) 2 ] 2 •CuCl 2. Electrolyte potential windows of MOF-LiX. SEM-EDS. I-V curve of Cu 4 (ttpm) 2 •0.6CuCl 2. Variable temperature EIS spectra of MOF-MX n. Li + transference number data of MOF-LiX. Li redox CVs with MOF-LiX. Arrhenius data of MOF-AlCl 3. The Supporting Information is available free of charge on the ACS Publications website.

Photocontrolled self-assembly of molecules has been utilized to change the physical properties of organic materials for various applications, while photon energy storage materials that incorporate photochromic molecules such as azobenzenes have been recognized as another highly attractive class of materials that convert and store photon energy in the strained chemical bonds. Herein, we demonstrate the photocontrolled self-assembly and disassembly of photon energy storage materials based on new diacetylene derivatives with azobenzene moieties and with varied alkyl spacers and linkers. We

Under an applied magnetic field, superparamagnetic Fe 3 O 4 nanoparticles with complementary DNA strands assemble into crystalline, pseudo-1D elongated superlattice structures. The assembly process is driven through a combination of DNA hybridization and particle dipolar coupling, a property dependent on particle composition, size, and inter-particle distance. The DNA controls inter-particle distance and crystal symmetry, while the magnetic field leads to anisotropic crystal growth. Increasing the dipole interaction between particles by increasing particle size or external field strength leads to a preference for a particular crystal morphology (e.g., rhombic dodecahedra, stacked clusters, and smooth rods). Molecular dynamics (MD) simulations show that an understanding of both DNA hybridization energetic and magnetic interactions are required to predict the resulting crystal morphology. Taken together, the data show that applied magnetic fields with magnetic nanoparticles can be deliberately used to access nanostructures beyond what is possible with DNA hybridization alone.