Silver-Based Hybrid Materials from meta- or para-Phosphonobenzoic Acid: Influence of the Topology on Silver Release in Water

Abstract

(Word Style "BD_Abstract").Three novel silver-based Metal Organic Frameworks materials which were synthesized from either 3-phosphono or 4-phosphonobenzoic acid and silver nitrate are reported. The novel hybrids were synthesized under hydrothermal conditions; the pH of the reaction media was controlled by adding different quantities of urea thereby producing different topologies.Compound 1 (Ag3(4-PO3-C6H4-COO)), synthesised in presence of urea, exhibits a compact 3D structure in which both phosphonic acid and carboxylic acid functional groups are linked to the silver-based inorganic network. Compound 2 (Ag(4-PO3H-C6H4-COOH)), which was synthesized at lower pH (without urea), has a layered structure in which only the phosphonic acid functional groups from 4-phosphonobenzoic acid moieties are linked to the silver inorganic network; the carboxylic acid groups being engaged in hydrogen bonds. Finally, material 3 (Ag(3-PO3H-C6H4-COOH)) was synthesised from 3-phosphonobenzoic acid and silver nitrate without urea. This material 3 features a layered structure exhibiting carboxylic acid functional groups linked via hydrogen bonds in the interlayer space. After the full characterization of these materials (single X-ray structure, IR, TGA), their ability to release silver salts in aqueous environment was measured. Silver release, determined in aqueous solution by cathodic stripping voltammetry, shows that the silver release capacity of these materials is dependent on the topology of the hybrids. The more compact structure 1 is extremely stable in water with only trace levels of silver ions being detected. On the other hand, compounds 2 and 3, in which only the phosphonic acid functional groups were bonded to the inorganic network, released larger quantities of silver ions into aqueous solution. These results which were compared with the silver release of the previously described compound 4 (Ag6(3-PO3-C6H4-COO)2). The results clearly show that the release capacity of silver-based metal organic framework can be tuned by 3 modifying their topology which, in the present study, is governed by the regio-isomer of the organic precursor and the synthetic conditions under which the hybrids are prepared.4

Hydrothermal synthesis for new multifunctional materials: A few examples of phosphates and phosphonate-based hybrid materials

“…The study of silver release was achieved by determining the concentration of silver salt in water after having added a determined volume of water to a sample of each hybrid. It indicated, as expected, that material B releases easily and rapidly silver salts, while compound A releases roughly half of the quantities in similar conditions [35]. These results illustrate the possibility of controlling the quantity of silver released from a silver-based hybrid, by focusing on two research approaches: the nature of the regio-isomer of the phosphonatebased anion (meta versus para-phosphonobenzoic not developed here) [35] and the participation (or not) of the two functional groups in the formation of ionocovalent bonds which is, in turn, governed by the conditions of synthesis (with urea versus without urea).…”

“…Others similar 2D lamellar structures containing supramolecular dimeric units are observed in Ag(m-PO 2 OH-C 6 H 4 -COOH) and Pb(m-PO 3 C 6 H 4 COOH) obtained from silver nitrate salt at 140°C or from lead(II) acetate at 180°C, the main difference lies in the structure of their inorganic layer. In the silver material, it is composed of silver oxide chains [AgO 2 ] 1 connected by PO 3 C tetrahedra [35] whereas the lead material described by Fang et al [36] is built of PbO 5 polyhedra connected by oxygen corners. The use of urea, ammonia, potassium or sodium hydroxide, or solvent initially added with the initial precursors allows to modify the pH of the media before or during the heating cycle (i.e.…”

“…Two materials were synthesised from meta-phosphonobenzoic acid (m-PO(OH) 2 -C 6 H 4 -COOH) at 140°C under hydrothermal treatment by reaction of silver nitrate with meta-phosphonobenzoic acid [35]. During the hydrothermal syntheses the addition of urea resulted in the production of Ag 6 (m-PO 3 -C 6 H 4 -COO) 2 in which both phosphonic acid and carboxylic acid functional groups were involved in iono-covalent bonds with silver salt (Fig.…”

Charge-Assisted Hydrogen-Bonded Networks of NH4+ and [Co(NH3)6]3+ with the New Linker Anion of 4-Phosphono-Biphenyl-4′-Carboxylic Acid

“…Various metal complexes have been synthesized with a ligand from deprotonated 4-phosphono-benzoic acid, including the metals barium [22], cobalt [23], copper [23], europium [24], lead [20], lithium [25], silver [26], strontium [27], thorium [28], titanium [29], uranium [28] and zinc [30,31]. However, the extended biphenyl-based variant 4-phosphono-biphenyl-4'-carboxylic acid (H 3 BPPA) was unknown so far (Scheme 1).…”

Layered Simple Hydroxides Functionalized by Fluorene‐Phosphonic Acids: Synthesis, Interface Theoretical Insights, and Magnetoelectric Effect

“…The X n− anion located in the interlayer space may be substituted by a large variety of molecules via anionic exchange reaction. [45] The rigidity results from a direct connection of the phosphonic acid on an aromatic [46] or heteroaromatic ring [47] acting as a rigid molecular platform. As for the related compounds layered double hydroxides, [M 1-x 2+ M' x 3+ (OH) 2 ] x+ (X n− ) x/n .mH 2 O without anchoring of X − anions onto the layers, only a few works on the intercalation of molecules bearing phosphonic acids have been reported.…”