M(H2O)(PO3C10H6OH)·(H2O)0.5 (M = Co, Mn, Zn, Cu): a new series of layered metallophosphonate compounds obtained from 6-hydroxy-2-naphthylphosphonic acid

Four new metallophosphonates M(H₂O)(PO₃C₁₀H₆OH)·(H₂O)_0.5 (M = Mn, Co, Cu, Zn) were obtained as single crystal and polycrystalline powders by hydrothermal synthesis from the precursors 6-hydroxy-2-naphthylphosphonic acid and the corresponding metal salts. These analogous hybrids crystalized in the space group P12₁/c1 in a lamellar structure. Their layered structures consisted of inorganic [M(H₂O)(PO₃C)] layers stacked with organic bilayers of 6-hydroxy-2-naphthyl moieties "HO-C₁₀H₆" and free water molecules. Their structures were determined by single crystal X-ray diffraction and confirmed by powder X-ray diffraction and Le Bail refinement for the powder sample. The removal of water upon heating at 250 °C was studied by thermogravimetric analysis and temperature-dependent powder X-ray diffraction. Their magnetic properties were studied by SQUID magnetometry and show antiferromagnetic behavior for the Co analogue and the occurrence of a canted antiferromagnetic order at T_N = 12.2 K for the Mn analogue. The Cu compound displayed an unprecedented ferromagnetic behavior. Their absorption and luminescence properties were investigated and revealed that the ligand and the compounds displayed a common behavior below a wavelength of 400 nm. Specific absorption bands were found in the compounds with Co²⁺ and Cu²⁺ at 539 nm and 849 nm, respectively. Moreover, particular luminescence bands were found for the compounds with Mn²⁺, Co²⁺ and Zn²⁺ at 598 nm, 551 nm and 530 and 611 nm, respectively.

Flexible bifunctional monoethylphosphonate/carboxylates of Zn(ii) and Co(ii) reinforced with DABCO co-ligand: paradigmatic structural organization with topology

The prototypal [M₂(EtBCP)₂(DABCO)_0.5] MOFs, compliant with isoreticular expansion in two-dimensions, show flexibility manifested by a two-step CO₂ adsorption isotherm, which might be associated to the “lever-action” of the metal-phosphonate moieties.

One-Dimensional Fluorene-Based Co(II) Phosphonate Co(H2O)2PO3C–C12H9·H2O: Structure and Magnetism

A new Co(II) phosphonate, Co(H2O)2PO3C–C12H9·H2O, has been synthesized under hydrothermal conditions. The monoclinic P21/c structure of this organic–inorganic hybrid consists of isolated perovskite-type chains of corner-shared CoO4(H2O)2 octahedra interconnected via phosphonate groups. The unique one-dimensional structure of this phase is closely related to the single-chain magnet (SCM) phosphonate Co(H2L)(H2O), with L = 4-Me-C6H4-CH2N(CPO3H2)2, that contains isolated chains of CoO5N octahedra. Like the latter, this hybrid exhibits 1D antiferromagnetic interactions and the possibility of an effective pseudo spin contribution due to spin canting at low temperature, but, in contrast, is not an SCM. This different magnetic behavior is explained by the different geometry of the octahedral chains and by the possible existence of weak antiferromagnetic interactions between the chains. This opens the route to the investigation of a large series of compounds by tuning the chemical composition and structure of the phosphonic acid used as organic precursor of hybrid materials.

Manganese Fluorene Phosphonates: Formation of Isolated Chains

9,9-dimethylfluorenyl-2-phosphonic acid 1 was reacted with manganese nitrate tetrahydrate to produce under hydrothermal conditions the crystalline manganese phosphonate Mn(H2O)2[O2(OH)PC15H13]2·2H2O which crystallize in the P21/c space group. This compound is a rare example of Mn-phosphonate material featuring isolated chains. The interactions between these chains containing the 9,9-dimethylfluorenyl moieties, result from Van der Waals interactions involving the fluorene ligands and C···H–C hydrogen bonds as revealed by Hirshfeld Surfaces. This material features antiferromagnetic exchange interactions as revealed by the magnetic susceptibility as a function of the temperature.

Rare earth metal-organic complexes constructed from hydroxyl and carboxyl modified arenesulfonate: syntheses, structure evolutions, and ultraviolet, visible and near-infrared luminescence

The reaction of 2-hydroxyl-4-carboxylbenzenesulfonic acid (H₃L) and rare earth (RE) metal nitrates together with two N-heterocyclic ligands gives rise to the formation of 38 complexes, namely, [La(H₂L)₂(ox)_0.5(H₂O)₄]_n·2nH₂O (1-La) (ox = oxalate), [RE₂(H₂L)₂ (ox)(H₂O)₁₂]·2(H₂L)·8H₂O (2-RE) (RE = Nd, Sm, Eu, Gd, Tb, Dy), [RE(SO₄)(H₂O)₇]·(H₂L)·3H₂O (3-RE) (RE = Ho, Er, Tm, Yb, Lu and Y), [RE(L)(H₂O)₃]_n·nH₂O (4-RE) (RE = Er, Tm, Yb and Lu), [RE(L)(2,2'-bipy)(H₂O)]_n (5-RE) (RE = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho and Y, 2,2'-bipy = 2,2'-bipyridine), [RE(L)(1,10-phen)(H₂O)]_n (6-RE) (RE = La, Pr, Nd, Sm, Eu, 1,10-phen = 1,10-phenanthroline), and [RE(L')(1,10-phen)₂(H₂O)]_n (7-RE) (RE = Gd, Tb, Ho, Er, Yb and Lu, H₃L' = 2-hydroxy-3-nitro-4-carboxybenzenesulfonic acid), which have been characterized by elemental analysis, IR, TG, PL, powder and single-crystal X-ray diffraction. Complexes 1-La, 2-RE and 3-RE present zigzag chain, di- and mono-nuclear structures, in which H₂L^- acts as a counterion and monodentate and μ₂-bridging monoanions. For the three species, light RE metal cations tend to induce the formation of oxalate while heavy RE metal cations tend to induce the formation of sulfate. Complexes 4-RE and 5-RE exhibit layer structures incorporating helical chains, in which the L^3- trianion presents μ₃ and μ₄ coordination modes. Complexes 6-RE containing light RE metal cations show layer structures incorporating helical chains, while complexes 7-RE containing heavy RE metal cations have helical chain structures supported by the bridging of in situ generated L'^3-. Remarkably, the in situ generated oxalates in 1-La and 2-RE, as well as the in situ generated L'^3- in 7-RE, also play a crucial role in determining the structures of these complexes. Structure evolutions make these complexes present various luminescent emissions. Complexes 3-Tm, 3-Yb, 3-Lu, 3-Y and 4-Lu exhibit ultraviolet emissions from 354 to 370 nm. Complexes 1-La and 6-La present blue emissions at 442 and 463 nm. Complexes 2-Eu, 2-Tb, 5-Tb and 7-Tb exhibit characteristic red and green emissions while the complex 5-Y presents a green emission at 501 nm. Meanwhile, complexes 2-Nd, 3-Yb, 4-Yb, 5-Nd, 6-Nd, and 7-Yb show near-infrared (NIR) emissions. Moreover, 2-Eu, 2-Tb, 5-Tb, 7-Tb and 5-Y show longer luminescence lifetimes from 390.47 to 1211.57 μs.

Phosphonic acid: preparation and applications

The phosphonic acid functional group, which is characterized by a phosphorus atom bonded to three oxygen atoms (two hydroxy groups and one P=O double bond) and one carbon atom, is employed for many applications due to its structural analogy with the phosphate moiety or to its coordination or supramolecular properties. Phosphonic acids were used for their bioactive properties (drug, pro-drug), for bone targeting, for the design of supramolecular or hybrid materials, for the functionalization of surfaces, for analytical purposes, for medical imaging or as phosphoantigen. These applications are covering a large panel of research fields including chemistry, biology and physics thus making the synthesis of phosphonic acids a determinant question for numerous research projects. This review gives, first, an overview of the different fields of application of phosphonic acids that are illustrated with studies mainly selected over the last 20 years. Further, this review reports the different methods that can be used for the synthesis of phosphonic acids from dialkyl or diaryl phosphonate, from dichlorophosphine or dichlorophosphine oxide, from phosphonodiamide, or by oxidation of phosphinic acid. Direct methods that make use of phosphorous acid (H3PO3) and that produce a phosphonic acid functional group simultaneously to the formation of the P-C bond, are also surveyed. Among all these methods, the dealkylation of dialkyl phosphonates under either acidic conditions (HCl) or using the McKenna procedure (a two-step reaction that makes use of bromotrimethylsilane followed by methanolysis) constitute the best methods to prepare phosphonic acids.

Silver-based hybrid materials from meta- or para-phosphonobenzoic acid: influence of the topology on silver release in water

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)), synthesized in the 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 synthesized 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 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.

Heterodinuclear (Sm, Tb) lanthanide pivalates with heterocyclic N-donors: synthesis, structure, thermal behavior, and magnetic and photoluminescence properties

The PL color evidently changes from red at 300 K to bright green at 77 K.

A distorted honeycomb motif in divalent transition metal compounds based on 4-phosphonbenzoic acid and exchange coupled Co(II) and Cu(II): synthesis, structural description and magnetic properties

The first example of a two-dimensional inorganic hybrid material with cobalt as an open-shell transition metal ion and 4-phosphonbenzoic acid as a linker is presented together with its copper analogue. For both metal ions the inorganic part consists of edge-sharing metal-oxygen octahedra leading to a metal honeycomb motif. The magnetic properties of the cobalt compound are reported together with those of the corresponding copper compound based on the remarkably six-coordinated copper(II) ions.

Structural study of hydrated/dehydrated manganese thiophene-2,5-diphosphonate metal organic frameworks, Mn2(O3P-C4H2S-PO3)·2H2O

Synthesis of thiophene-2,5-diphosphonic acid 2 is reported, and its use for synthesis of the original pristine materials Mn(2)(O(3)P-C(4)H(2)S-PO(3))·2H(2)O 3 is reported. The structure of material 3 has been fully resolved from single-crystal X-ray diffraction. Mn(2)(O(3)P-C(4)H(2)S-PO(3))·2H(2)O 3 crystallizes in a monoclinic cell (space group P2) with the following parameters: a = 11.60(1) Å, b = 4.943(5) Å, c = 19.614(13) Å, β = 107.22°. A noticeable feature of the structure of compound 3 is the orientation of the thiophene heterocycles that adopt two different orientations in two successive layers (along c). Thermal analysis of compound 3 indicates that the water molecules are easily removed from 160 to 230 °C while the dehydrated structure is stable up to 500 °C. The dehydrated compound obtained from 3 can be rehydrated to give the polymorphic compound Mn(2)(O(3)P-C(4)H(2)S-PO(3))·2H(2)O 4, which crystallizes in an orthorhombic cell (space group Pnam) with the following parameters: a = 7.5359(3) Å, b = 7.5524(3) Å, c = 18.3050(9) Å. The main difference between the structures of 3 and 4 arises from both the orientation of the thiophene rings (herringbone-type organization in 4) and the structure of the inorganic layers. The thiophene-2,5-diphosphonic acid moieties engaged in materials 3 and 4 adopt a different orientation likely due to rotation around the P-C bonds and via the dehydrated state 5, which is likely more flexible than the hydrated states. Study of the magnetic properties performed on compound 3 and 4 and on the dehydrated compounds Mn(2)(O(3)P-C(4)H(2)S-PO(3)) 5 complemented by the structural study has permitted us to characterize the antiferromagnetic ground state of sample 3, a weak ferromagnetic component in sample 4, and complete paramagnetic behavior in sample 5.