Semiconductor Behavior of a Three-Dimensional Strontium-Based Metal–Organic Framework

The self-assembly of a three-dimensional strontium-based metal–organic framework [Sr­(Hbtc)­(H₂O)]_<i>n</i> (<b>1</b>) was achieved through the reaction of Sr­(NO₃)₂ with a 1,2,4-benzenetricarboxylic acid (1,2,4-H₃btc) ligand under hydrothermal conditions. This Sr-based metal–organic framework exhibits remarkable semiconducting behavior, as evidenced by theoretical calculations and experimental measurements. Temperature-dependent DC conductivity, near-room-temperature AC conductivity, diffuse reflection spectra, and photoluminescence spectra provide strong proof that compound <b>1</b> shows a band gap of 2.3 eV, which is comparable to that for other commonly available semiconducting materials (e.g., CdSe, CdTe, ZnTe, GaP, etc.). The optimized molecular structure and electronic properties (density of states and band gap energy) of <b>1</b> were calculated using density functional theory, and the results are consistent with experimental findings. This is the first report on the semiconducting properties of a strontium-based MOF, which will pave the way for further studies in semiconducting MOFs with interesting potential applications in optoelectronic devices

High‑κ Samarium-Based Metal–Organic Framework for Gate Dielectric Applications

The self-assembly of a samarium-based metal–organic framework [Sm₂(bhc)­(H₂O)₆]_<i>n</i> (<b>1</b>) in good yield was achieved by reacting Sm­(NO₃)₃·6H₂O with benzenehexacarboxylic acid (bhc) in a mixture of H₂O–EtOH under hydrothermal conditions. A structural analysis showed that compound <b>1</b> crystallized in a space group of <i>Pnmn</i> and adopted a 3D structure with (4,8) connected nets. Temperature dependent dielectric measurements showed that compound <b>1</b> behaves as a high dielectric material with a high dielectric constant (κ = 45.1) at 5 kHz and 310 K, which is comparable to the values for some of the most commonly available dielectric inorganic metal oxides such as Sm₂O₃, Ta₂O₅, HfO₂, and ZrO₂. In addition, electrical measurements of <b>1</b> revealed an electrical conductivity of about 2.15 × 10^–7 S/cm at a frequency of 5 kHz with a low leakage current (<i>I</i>_leakage = 8.13 × 10^–12 Amm^–2). Dielectric investigations of the Sm-based MOF provide an effective path for the development of high dielectric materials in the future