Electronic and atomic structure of subchondral femoral bone in intact and osteoarthritic knee compartments

In the work we suggest an answer to the question: how is the local electronic and atomic structure as well as molecular architecture of bone tissue distorted in case of skeletal pathology? X-ray diffraction and photoelectron spectroscopy techniques are applied to medial and lateral condyles of the femoral bone resected during total knee arthroplasty in patients with medial compartmental knee osteoarthritis (OA). The measured data are examined and discussed. It is shown that the skeletal pathology affects local electronic and atomic structure of mineral matrix in bone. For the first time the site-dependent changes in cristallinity, binding energies and chemical composition of the intact and OA damaged areas of femur-saw-cuts are investigated. Specifically, in the sclerotic area crystallinity of the subchondral bone tissue increases, the binding energies of the Ca and P 2p core levels demonstrate opposite shifts and the widths of the core−1 photoelectron lines are maximal. The results show perspectives for development of novel approaches to medical imaging and diagnosis of bone tissue at the subcellular level

Electronic structure of the [Ni(Salen)] complex studied by core-level spectroscopies

The nature and structure of occupied and empty valence electronic states (molecular orbitals, MOs) of the [Ni(Salen)] molecular complex (NiO2N2C16H14) have been studied by X-ray photoemission and absorption spectroscopy combined with density functional theory (DFT) calculations. As a result, the composition of the high-lying occupied and low-lying unoccupied electronic states has been identified. In particular, the highest occupied molecular orbital (HOMO) of the complex is found to be predominantly located on the phenyl rings of the salen ligand, while the states associated with the occupied Ni 3d-derived molecular orbitals (MOs) are at higher binding energies. The lowest unoccupied molecular orbital (LUMO) is also located on the salen ligand and is formed by the 2pπ orbitals of carbon atoms in phenyl groups of the salen macrocycle. The unoccupied MOs above the LUMO reflect σ- and π-bonding between Ni and its nearest neighbours. All valence states have highly mixed character. The specific nature of the unoccupied Ni 3d-derived σ-MO is a consequence of donor-acceptor chemical bonding in [Ni(Salen)]. This journal i