Herein, we report a semiconductive, proton-conductive, microporous hydrogen-bonded organic framework (HOF) derived from phenylphosphonic acid and 5,10,15,20‐tetrakis[p‐phenylphosphonic acid] porphyrin (GTUB5). The structure of GTUB5 was characterized using single crystal X-ray diffraction. A narrow band gap of 1.56 eV was extracted from a UV-Vis spectrum of pure GTUB5 crystals, in excellent agreement with the 1.65 eV band gap obtained from DFT calculations. The same band gap was also measured for GTUB5 in DMSO. The proton conductivity of GTUB5 was measured to be 3.00 × 10⁻⁶ S cm⁻¹at 75 °C and 75% relative humidity. The surface area was estimated to be 422 m² g⁻¹from grand canonical Monte Carlo simulations. XRD showed that GTUB5 is thermally stable under relative humidities of up to 90% at 90 °C. These findings pave the way for a new family of organic, microporous, and semiconducting materials with high surface areas and high thermal stabilities.

We report a novel metal organic framework (MOF) based on a cobalt arylphosphonate, namely, [Co₂(H₄-MTPPA)]·3NMP·H₂O (1·3NMP·H₂O), which was prepared solvothermically from the tetrahedral linker tetraphenylmethane tetrakis-4-phosphonic acid (H₈-MTPPA) and CoSO₄·7H₂O in N-methyl-2-pyrrolidone (NMP).

Herein, the first semiconducting and magnetic phosphonate metal–organic framework (MOF), TUB75, is reported, which contains a 1D inorganic building unit composed of a zigzag chain of corner‐sharing copper dimers. The solid‐state UV–vis spectrum of TUB75 reveals the existence of a narrow bandgap of 1.4 eV, which agrees well with the density functional theory (DFT)‐calculated bandgap of 1.77 eV. Single‐crystal conductivity measurements for different orientations of the individual crystals yield a range of conductances from 10⁻³ to 10³ S m⁻¹ at room temperature, pointing to the directional nature of the electrical conductivity in TUB75. Magnetization measurements show that TUB75 is composed of antiferromagnetically coupled copper dimer chains. Due to their rich structural chemistry and exceptionally high thermal/chemical stabilities, phosphonate MOFs like TUB75 may open new vistas in engineerable electrodes for supercapacitors.

This review is divided into three different parts. In the introduction, the current applications of metal‐organic frameworks (MOFs) are shown. Furthermore, the overall stability, a comparison of phosphonate MOFs with carboxylate MOFs, the structural richness of phosphonate MOFs with the challenge in synthesis and different linker geometries is discussed. In the second part, several phosphonate MOFs with Y‐shaped planar, X‐shaped planar, and X‐shaped tetrahedral linker systems are described. The final part discusses different structures of inorganic building units (IBUs) with different metal atoms and a comparison of the formed MOF structures.

A conductive phosphonate metal–organic framework (MOF), [{Cu(H₂O)}(2,6‐NDPA)_0.5] (NDPA = naphthalenediphosphonic acid), which contains a 2D inorganic building unit (IBU) comprised of a continuous edge‐sharing sheet of copper phosphonate polyhedra is reported. The 2D IBUs are connected to each other via polyaromatic 2,6‐NDPA's, forming a 3D pillared‐layered MOF structure. This MOF, known as TUB40, has a narrow band gap of 1.42 eV, a record high average electrical conductance of 2 × 10² S m⁻¹ at room temperature based on single‐crystal conductivity measurements, and an electrical conductance of 142 S m⁻¹ based on a pellet measurement. Density functional theory (DFT) calculations reveal that the conductivity is due to an excitation from the highest occupied molecular orbital on the naphthalene‐building unit to the lowest unoccupied molecular orbital on the copper atoms. Temperature‐dependent magnetization measurements show that the copper atoms are antiferromagnetically coupled at very low temperatures, which is also confirmed by the DFT calculations. Due to its high conductance and thermal/chemical stability, TUB40 may prove useful as an electrode material in supercapacitors.