Metal-organic frameworks (MOFs) containing redox active linkers have led to hybrid compounds exhibiting high electrical conductivity, which enables their use in applications in electronics and electrocatalysis. While many computational studies predict two-dimensional (2D) MOFs to be metallic, the majority of experiments show decreasing conductivity on cooling, indicative of a gap in the electronic band structure. To date, only a handful of MOFs have been reported that exhibit increased electrical conductivity upon cooling indicative of a metallic character, which highlights the need for better understanding the origin of the conductivity. A 2D MOF containing iron bis(dithiolene) motifs was recently reported to exhibit semiconducting behavior with record carrier mobility. Herein, we report that high crystallinity and the elimination of guest species results in an iron 2,3,6,7,10,11-tripheylenehexathiolate (THT) MOF, FeTHT, exhibiting a complex transition from semiconducting to metallic upon cooling, similar to what was shown for the analogous CoTHT. Remarkably, exposing the FeTHT to air significantly influences the semiconducting-to-metallic transition temperature (100 to 300 K), and ultimately results in a material showing metallic-like character at, and above, room temperature. This study indicates these materials can tolerate a substantial degree of doping that ultimately results in charge delocalization and metallic-like conductivity, an important step towards enabling their use in chemiresistive sensing and optoelectronics. carriers, preventing fast charge transport through the framework. This leads to materials with insulating or large gap semiconducting behavior. 5,14,15 Efforts to reduce the barriers to charge transport have included the addition of guest species, [16][17][18] doping, [19][20][21] and variation of the metal center and its oxidation state. [22][23][24][25][26] These modifications can encourage through-space 27,28 or throughbond 29 electronic transport and have led to MOFs with improved conductivities, with one example reporting tunable conductivity over six orders of magnitude. 17 Recently, the development of MOFs with redox active linkers has led to a breakthrough in the field of electrically conductive MOFs. 11,12,15,[30][31][32][33][34] Several two-and three-dimensional (2D/3D) frameworks with planar, π-conjugated, and redox-active linkers, like semiquinones/cathecolates, [35][36][37][38][39][40][41][42][43] diimines, [44][45][46][47][48] and dithiolenes, 19,21,[48][49][50][51][52][53][54][55][56][57][58][59][60][61] have been reported to display high electrical conductivity. Yet, while computational studies often predict these 2D MOFs to be metallic, 50,[62][63][64][65] the majority of the frameworks reported display a decrease in conductivity on cooling as thermally-populated carriers are lost. In contrast, the primary mechanism for carrier scattering in metals is due to lattice vibrations that are significantly dampened at lower temperatures, resulting in more efficient transport o...

A new Os-based B-site ordered double perovskite with the chemical composition of Ca2ScOsO6 was successfully synthesized. The crystal structure of the title compound was determined by employing the powder X-ray diffraction method and was found to crystallize in the monoclinic P21/n space group with the cell constants of a = 5.4716(1) Å, b = 5.6165(1) Å, c = 7.8168 (1) Å, and β = 89.889 (2)°. The temperature-dependent magnetic susceptibility data suggest that this novel S = (3)/2 compound undergoes an antiferromagnetic transition at ∼ 69 K. Fitting the high-temperature susceptibility data (100-300 K) to Currie-Weisse behavior showed C = 1.734 emu·K/mol (μeff = 3.72 bohr magnetons) and θ = -341 K, which is indicative of dominant antiferromagnetic interactions. Temperature-dependent specific heat measurements exhibit a λ shape anomaly at 69 K, which is consistent with a long-range ordering of the spins. Because of a triangular arrangement of antiferromagnetically ordered magnetic ions, the system exhibits some degree of geometric magnetic frustration (GMF), but not strongly. Spin-dimer analysis, employing extended Hückel theory, reveals that a dominant exchange interaction exists (along the a crystallographic axis in perovskite layer), which violates the perfect condition for GMF.

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Single crystals of Ln2Fe4–x Co x Sb5–y Bi y (Ln = La, Ce; 0 ≤ x < 0.5; 0 ≤ y ≤ 0.2) were grown using Bi flux and self-flux methods. The compounds adopt the La2Fe4Sb5 structure type with tetragonal space group I4/mmm. The La2Fe4Sb5 structure type is comprised of rare earth atoms capping square Sb nets in a square antiprismatic fashion and two transition-metal networks forming a PbO-type layer with Sb and transition-metal isosceles triangles. Substituting Co into the transition-metal sublattice results in a decrease in the transition temperature and reduced frustration, indicative of a transition from localized to itinerant behavior. In this manuscript, we demonstrated that Bi can be used as an alternate flux to grow single crystals of antimonides. Even with the incorporation of Bi into the Sb square net, the magnetic properties are not significantly affected. In addition, we have shown that the incorporation of Co into the Fe triangular sublattice leads to an itinerant magnetic system.