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

Hybrid Materials: A Metareview

The field of hybrid materials has grown so wildly in the last 30 years that writing a comprehensive review has turned into an impossible mission. Yet, the need for a general view of the field remains, and it would be certainly useful to draw a scientific and technological map connecting the dots of the very different subfields of hybrid materials, a map which could relate the essential common characteristics of these fascinating materials while providing an overview of the very different combinations, synthetic approaches, and final applications formulated in this field, which has become a whole world. That is why we decided to write this metareview, that is, a review of reviews that could provide an eagle's eye view of a complex and varied landscape of materials which nevertheless share a common driving force: the power of hybridization.

Persistent luminescence nanoparticles functionalized by polymers bearing phosphonic acid anchors: synthesis, characterization, and in vivo behaviour

Optical in vivo imaging has become a widely used technique and is still under development for clinical diagnostics and treatment applications. For further development of the field, researchers have put much effort into the development of inorganic nanoparticles (NPs) as imaging probes. In this trend, our laboratory developed ZnGa_1.995O₄Cr_0.005 (ZGO) nanoparticles, which can emit a bright persistent luminescence signal through the tissue transparency window for dozens of minutes and can be activated in vivo with visible irradiation. These properties endow them with unique features, allowing us to recover information over a long-time study with in vivo imaging without any background. To target tissues of interest, ZGO must circulate long enough in the blood stream, a phenomenon which is limited by the mononuclear phagocyte system (MPS). Depending on their size, charge and coating, the NPs are sooner or later opsonized and stored into the main organs of the MPS (liver, spleen, and lungs). The NPs therefore have to be coated with a hydrophilic polymer to avoid this limitation. To this end, a new functionalization method using two different polyethylene glycol phosphonic acid polymers (a linear one, later named lpPEG and a branched one, later named pPEG) has been studied in this article. The coating has been optimized and characterized in various aqueous media. The behaviour of the newly functionalized NPs has been investigated in the presence of plasmatic proteins, and an in vivo biodistribution study has been performed. Among them ZGOpPEG exhibits a long circulation time, corresponding to low protein adsorption, while presenting an effective one-step process in aqueous medium with a low hydrodynamic diameter increase. This new method is much more advantageous than another strategy we reported previously that used a two-step PEG silane coating performed in an organic solvent (dimethylformamide) for which the final hydrodynamic diameter was twice the initial diameter.

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.

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.

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.

Hydrothermal synthesis of bacterial cellulose-copper oxide nanocomposites and evaluation of their antimicrobial activity

In this work, for the first time bacterial cellulose (BC) hydrogel membranes were used for the fabrication of antimicrobial cellulosic nanocomposites by hydrothermal deposition of Cu derivative nanoparticles (i.e.Cu(0) and CuxOy species). BC-Cu nanocomposites were characterized by FTIR, SEM, AFM, XRD and TGA, to study the effect of hydrothermal processing time on the final physicochemical properties of final products. XRD result show that depending on heating time (3-48h), different CuxOy phases were achieved. SEM and AFM analyses unveil the presence of the Cu(0) and copper CuxOy nanoparticles over BC fibrils while the surface of 3D network became more compact and smother for longer heating times. Furthermore, the increase of heating time placed deleterious effect on the structure of BC network leading to decrease of BC crystallinity as well as of the on-set degradation temperature. Notwithstanding, BC-Cu nanocomposites showed excellent antimicrobial activity against E. coli, S. aureus and Salmonella bacteria suggesting potential applications as bactericidal films.

On the complexation of metal cations with “pure” diethylenetriamine-N,N,N′,N′′,N′′-pentakis(methylenephosphonic) acid

Complexation of various metal cations by DTPMA obtained by an efficient synthetic procedure has been investigated, assessing its sequestering ability and speciation in real systems.