New isoreticular phosphonate MOFs based on a tetratopic linker

Abstract

The tetratopic linker 1,1,2,2-tetrakis(4-phosphonophenyl)ethylene (H8TPPE) was used to synthesize the three new porous metal-organic frameworks of composition [M2(H2O)2(H2TPPE)] ∙ xH2O (M= Al3+, Ga3+, Fe3+), denoted as M-CAU-53 under hydrothermal reaction...

Mechanochemical Synthesis of Phosphonate-Based Proton Conducting Metal–Organic Frameworks

“…Recent efforts have identified crystalline porous metal–organic frameworks (MOFs) as a promising class of materials for use as PEMs due to their diverse and tunable framework structures, high porosity, and physicochemical properties. ,− Furthermore, the high crystallinity of MOFs offers an excellent opportunity to understand the proton-conducting mechanism by investigating the proton transfer pathway and the structure–property relationships by using diffraction techniques − and theoretical calculation. , Two main approaches exist for improving the performance of MOF-based proton-conductive electrolytes. The first approach is based on including proton carrier guest molecules (ammonium-based cations, N-heterocycle-based molecules) into the MOF pores. , In the second approach, organic linkers with acidic functionalities (sulfono- or phosphono-groups) are included in the MOF structure. ,, In this regard, phosphonate-based MOFs are gaining interest for designing potential proton conductors. − Aryl phosphonic acid linkers provide extremely rich and robust metal-binding modes, resulting in a great variety of possible structures with unique thermal and chemical stability. − Moreover, the uncoordinated oxygen atoms of phosphonic acid participate in the formation of hydrogen bond networks with the lattice water (solvent) molecules, which facilitates the proton conduction …”

The role of sulfonate groups and hydrogen bonding in the proton conductivity of two coordination networks

“…Impedance measurements were carried out using a Novocontrol broadband dielectric spectrometer (Alpha-A High Performance Frequency Analyzer). The samples were mounted between two Novocontrol BDS1200 based blocking gold-plated electrodes, and two-wire mode measurements were made, as described in earlier studies [ 21 , 29 ]. The impedance data was recorded in the frequency range from 1 Hz to 4.61 MHz at an applied voltage of 0.1 V. Temperature and humidity were controlled by an Espec SH-242 climate chamber.…”

A robust eco-compatible microporous iron coordination polymer for CO2 capture

“…[24][25][26] The Fe(III)-phosphonate MOFs such as Fe-CAU-53 were also recently reported. 27 However, not all of these MOFs exhibit a high hydrolytic stability that is not only driven by the type of SBUs but also the connectivity as well as the size and hydrophobic character of the organic linker. [14][15][16][17][18][19][20][21][22][23][24][25][26][27] As an example, the good hydrothermal stability of MIL-53(Fe) is certainly due to its 1D micropore channel structure based on [Fe(OH)(COO) 2 ] n chains while the mesoporous MIL-101(Fe) and PCN-333(Fe) based on the oxo-trimer SBU present a limited water stability.…”

“…27 However, not all of these MOFs exhibit a high hydrolytic stability that is not only driven by the type of SBUs but also the connectivity as well as the size and hydrophobic character of the organic linker. [14][15][16][17][18][19][20][21][22][23][24][25][26][27] As an example, the good hydrothermal stability of MIL-53(Fe) is certainly due to its 1D micropore channel structure based on [Fe(OH)(COO) 2 ] n chains while the mesoporous MIL-101(Fe) and PCN-333(Fe) based on the oxo-trimer SBU present a limited water stability. Due to the presence of CO 2 adsorption sites such as Lewis acid Fe 3+ sites or polar functions (OH and F) and a high pore volume, a few Fe-MOFs such as MIL-100(Fe), MIL-88A(Fe), soc MOF(Fe), Fe-BTB and Fe-BTC have been considered for CO 2 capture, and some of them have shown attractive CO 2 uptake at low pressure (>2 mmol g À1 at 1 bar, 298 K).…”