A Three-Dimensional Framework Structure Constructed from 2-(2-Pyridyl-N-oxide) Ethylphosphonic Acid and Nd(III)

Abstract

A multistep synthesis for 2-(2-pyridyl-N-oxide) ethylphosphonic acid 6-H2 is described along with its spectroscopic (IR, NMR) data and a single-crystal X-ray diffraction structure analysis. Combination of the ligand with Nd(OH)3 results in the formation of a complex Nd(6-H)3. Single-crystal X-ray diffraction analysis reveals a three-dimensional crystal network generated by hydrogen-bonded chains along the crystallographic c axis. The hydrogen bonds are formed between phosphonic acid anion (6-H)(-1) protons on one chain and pyridyl N-oxide oxygen atoms in neighboring chains. The asymmetric unit contains 1/3[Nd(6-H)3] and there are two unique Nd(III) atoms, each with point symmetry. As a result, each Nd(III) ion is bound to six (6-H)(-1) ligands and the symmetry about the Nd(III) ion is octahedral with each vertex occupied by a phosphonate oxygen atom. The Nd-O bond lengths are essentially identical: Nd(1)-O(3), 2.336 (1) A; Nd(2)-O(4), 2.340 (1) A. The monoanionic ligand (6-H)(-1), therefore, serves to bridge the unique Nd(III) centers.

Phosphonic acid: preparation and applications

“…This two-step sequence: 1. bromotrimethylsilane; 2. methanolysis or hydrolysis was used for the synthesis of numerus phosphonic acids including heterocyclic compounds that are too sensitive to be prepared by the transformation of phosphonates under acidic conditions. As an illustration, the thiophene diphosphonic acid 49 [ 173 ], the pyridine oxide 50 [ 179 ], the furane phosphonic acid 51 [ 174 ], the bipyridine bis thiophene phosphonic acid 52 [ 180 ] or the α-aminophosphonic acid 53 that was assessed as inhibitor of the human farnesyl pyrophosphate synthase (hFPPS) [ 181 ] were prepared from their corresponding diethylphosphonates ( Fig. 18 ).…”

Structures and luminescent properties of lanthanide phosphonates

“…These molecular units of Er(HL) 3 (H 2 L)·8H 2 O (L = L 4 or L 5 ) are further interconnected by extensive hydrogen bonds into a 3D structure. When 2-(2-pyridyl-N-oxide) ethylphosphonic acid (H 2 L 6 ) was used, the non-hydrated Nd(HL 6 ) 3 was isolated [40]. Each ligand is bidentate bridging by using two phosphonate oxygen atoms, the third one is protonated and is only involved in hydrogen bonding.…”

Syntheses, Crystal Structures, Thermal Stabilities, and Magnetic and Luminescent Properties of 3D Heterometal Phosphonates: NaM[O3PCH(OH)CO2] (M = Mn, Fe, Co, Zn)

“…These emissions cannot be attributed to MLCT (metal-to-ligand charge transfer) and LMCT (ligand-to-metal charge transfer) in nature, and may probably be assigned to the intraligand n-π* transition for two reasons: (1) a bright blue-green emission with λ max = 460 nm can also be observed from a solution of (H 2 O 3 P)-CH(OH)(CO 2 H) and (2) all maximum bands of corresponding excitation spectra for solids 1a-4a and (H 2 O 3 P)-CH(OH)(CO 2 H) solution fall in the range of 360-377 nm (Supporting Information, Figure S9, S10). [5] The lifetimes for λ ex,em = 380,450 nm of 1a and λ ex,em = 368,460 nm of 2a are 1.67 (2) Figure S10). This phenomenon is also observed for 1b.…”

“…[1] During the past two years, phosphonic acids containing a second functional group such as hydroxy, amine, carboxyl, and pyridyl, were successfully introduced as bridging ligands for the isolation of new metal phosphonates with intriguing structures and properties. [2][3][4][5] This is mainly due to the additional functional groups that can improve the solubility and crystallinity of metal phosphonates, which results in the growth of suitable single crystals for X-ray structural analysis. Then, an instinctive strategy of attaching two additional functional groups to the phosphonic acid was performed to obtain several novel solids, such as M x [Fe(O 2 CCH 2 ) 2 NCH 2 PO 3 ] 6 ·nH 2 O (M = Na, K, Rb), with a maple leaf lattice and lanthanide phosphonates possessing homochiral porous frameworks as well as blue, red, or near IR luminescence.…”