Lanthanum Complex with Neridronic Acid: Synthesis and Properties

Abstract

Currently, various amino bisphosphonates are widely used in the treatment of many bone diseases. One of the most well-known complex compounds of neridronic acid (6-amino-1-hydroxyhexylidene-1,1- bisphosphonic acid) is sodium neridronate – a bisphosphonate, which is used to treat osteogenesis and Paget's disease. However, there is no data on compounds of neridronic acid with rare earth elements. A new complex of lanthanum with 6-amino-1-hydroxyhexylidene-1,1-bisphosphonic acid (I) was obtained and characterized by various physicochemical methods (chemical analysis, IR spectroscopy, solid-phase 31P NMR spectroscopy, optical microscopy, PCA, DTA). According to the research data the complex I has the composition {La[(H3N-(CH2)5-C(OH)(PO2(OH))2]2(H2O)2}[OH]·H2O and represents the coordination 1D-polymer due to two bridged phosphonic groups with lanthanum atoms in a tetragonal-antiprismatic environment. In a crystal, polymer chains form a 3D-frame porous structure by means of strong hydrogen bonds O─H ··· O and N─H ··· O with endless channels, available to include a variety of inorganic anions or small organic molecules. A study under the microscope showed that the sample is needle crystals (thin rods) of different lengths. The particle size distribution was obtained by laser diffraction, and the average particle size was determined: 50 µm in length and 2.5 µm in thickness.

Structural characterization of hydrogen bonding for antipyrine derivatives: Single-crystal X-ray diffraction and theoretical studies

“…It should be underlined that the compound properties are determined mainly by the specific features of chemical bonding, including hydrogen bonding and intermolecular interactions, between structural units. These distinguishing features are responsible for the self-organization of ions and molecules in crystal packing with the formation of channels opened to the intercalation of small species, for example, complexes with neridronic acid (6-amino-1-hydroxyhexylidene-1,1-bisphosphonic acid) showing promise for treating osteogenesis and the Paget's disease [11]. In the case of solvation (e.g., styryl dyes of the benzoselenazole series), the system of hydrogen bonding makes the structure more rigid compared with the non-solvation one owing to the solvate molecules participation in the hydrogen bond formation [12].…”