Structures, Bonding and Sensor Properties of Some Alkaline o-Phthalatocuprates

Comprehensive study of the structure and bonding of disodium, dipotassium and diammonium di-o-phthalatocuprates(II) dihydrates has been undertaken. The crystal structure of ammonium o-phthalatocuprate has been determined. The identity of structures of phthalatocuprate chains in potassium and ammonium salts has been revealed. Vibrational spectra of all three compounds have been recorded, and the assignment of vibrational bands has been made. Force field calculations have shown a minor effect of outer-sphere cations (Na+, K+, NH4+) on both intraligand (C-O) and metal–ligand bond strengths. Synthesized compounds have been tested as electrochemical sensors on D-glucose, dopamine and paracetamol. Their sensitivity to analytes varied in the order of Na+ > K+ > NH4+. This effect has been explained by the more pronounced steric hindrance of copper ions in potassium and ammonium salts.

Using molecular docking and molecular dynamics to investigate protein-ligand interactions

Molecular docking and molecular dynamics (MD) are powerful tools used to investigate protein-ligand interactions. Molecular docking programs predict the binding pose and affinity of a protein-ligand complex, while MD can be used to incorporate flexibility into docking calculations and gain further information on the kinetics and stability of the protein-ligand bond. This review covers state-of-the-art methods of using molecular docking and MD to explore protein-ligand interactions, with emphasis on application to drug discovery. We also call for further research on combining common molecular docking and MD methods.

Metrical Oxidation States of 1,4-Diazadiene (DAD) Derived Ligands

The conventional method of assigning formal oxidation states (FOS) to metals and ligands is an important tool for understanding and predicting chemical reactivity, in particular in catalysis research. For complexes containing redox-noninnocent ligands, the oxidation state of the ligand can be ambiguous (i.e. their spectroscopic oxidation state can differ from the formal oxidation state), and thus frustrates the assignment of the oxidation state of the metal. A quantitative correlation between empirical metric data of redox active ligands and their oxidation states using a metrical oxidation state (MOS) model has been developed for catecholate and aminophenolate derived ligands by Brown. In the present work, we present a MOS model for 1,4-diazabutadiene (DADⁿ) ligands. The model is based on a similar approach as reported by Brown, correlating the intra-ligand bond lengths of the DADⁿ moiety in a quantitative manner to the MOS using geometrical information from X-ray structures in the Cambridge Crystallographic Data Center (CCDC) database. However, accurate determination of the MOS of these ligands turned-out to be dependent the coordination mode of the DAD^2- moiety, which can adopt both a planar <i>κ²</i>-<i>N₂</i>-geometry and a <i>η⁴</i>-<i>N₂</i>-<i>C₂</i> π-coordination mode in (transition) metal complexes in its doubly reduced, dianionic enediamide oxidation state. A reliable MOS model was developed taking the intrinsic differences in intra-ligand bond distances between these coordination modes of the DAD^2‒ ligand into account. Three different models were defined and tested using different geometric parameters (C=C→M distance, M-N-C angle, M-N-C-C torsion angle) to describe the C=C backbone coordination to the metal in the <i>η⁴</i>-<i>N₂</i>-<i>C₂</i> π-coordination mode of the DAD^2‒ ligand. Statistical analysis revealed that the C=C→M distance best describes the <i>η⁴</i>-<i>N₂</i>-<i>C₂</i> coordination mode, using a cut-off value of 2.46 Å for π-coordination. The developed MOS model was used to validate the oxidation state assignment of elements not contained within the training set (Sr, Yb and Ho), thus demonstrating the applicability of the MOS model to a wide range of complexes. Chromium complexes with complex electronic structures were also shown to be accurately described by MOS analysis. Furthermore, it is shown that a combination of MOS analysis and FOD calculations provide an inexpensive method to gain insight into the electronic structure of singlet spin state (S = 0) [M(trop₂dad)] transition metal complexes showing multireference character.<br>

Metrical Oxidation States of 1,4-Diazadiene (DAD) Derived Ligands

The conventional method of assigning formal oxidation states (FOS) to metals and ligands is an important tool for understanding and predicting chemical reactivity, in particular in catalysis research. For complexes containing redox-noninnocent ligands, the oxidation state of the ligand can be ambiguous (i.e. their spectroscopic oxidation state can differ from the formal oxidation state), and thus frustrates the assignment of the oxidation state of the metal. A quantitative correlation between empirical metric data of redox active ligands and their oxidation states using a metrical oxidation state (MOS) model has been developed for catecholate and aminophenolate derived ligands by Brown. In the present work, we present a MOS model for 1,4-diazabutadiene (DADⁿ) ligands. The model is based on a similar approach as reported by Brown, correlating the intra-ligand bond lengths of the DADⁿ moiety in a quantitative manner to the MOS using geometrical information from X-ray structures in the Cambridge Crystallographic Data Center (CCDC) database. However, accurate determination of the MOS of these ligands turned-out to be dependent the coordination mode of the DAD^2- moiety, which can adopt both a planar <i>κ²</i>-<i>N₂</i>-geometry and a <i>η⁴</i>-<i>N₂</i>-<i>C₂</i> π-coordination mode in (transition) metal complexes in its doubly reduced, dianionic enediamide oxidation state. A reliable MOS model was developed taking the intrinsic differences in intra-ligand bond distances between these coordination modes of the DAD^2‒ ligand into account. Three different models were defined and tested using different geometric parameters (C=C→M distance, M-N-C angle, M-N-C-C torsion angle) to describe the C=C backbone coordination to the metal in the <i>η⁴</i>-<i>N₂</i>-<i>C₂</i> π-coordination mode of the DAD^2‒ ligand. Statistical analysis revealed that the C=C→M distance best describes the <i>η⁴</i>-<i>N₂</i>-<i>C₂</i> coordination mode, using a cut-off value of 2.46 Å for π-coordination. The developed MOS model was used to validate the oxidation state assignment of elements not contained within the training set (Sr, Yb and Ho), thus demonstrating the applicability of the MOS model to a wide range of complexes. Chromium complexes with complex electronic structures were also shown to be accurately described by MOS analysis. Furthermore, it is shown that a combination of MOS analysis and FOD calculations provide an inexpensive method to gain insight into the electronic structure of singlet spin state (S = 0) [M(trop₂dad)] transition metal complexes showing multireference character.<br>

Basic Approaches to the Design of Intrinsic Self-Healing Polymers for Triboelectric Nanogenerators

Triboelectric nanogenerators (TENGs) as a revolutionary system for harvesting mechanical energy have demonstrated high vitality and great advantage, which open up great prospects for their application in various areas of the society of the future. The past few years have seen exponential growth in many new classes of self-healing polymers (SHPs) for TENGs. This review presents and evaluates the SHP range for TENGs, and also attempts to assess the impact of modern polymer chemistry on the development of advanced materials for TENGs. Among the most widely used SHPs for TENGs, the analysis of non-covalent (hydrogen bond, metal–ligand bond), covalent (imine bond, disulfide bond, borate bond) and multiple bond-based SHPs in TENGs has been performed. Particular attention is paid to the use of SHPs with shape memory as components of TENGs. Finally, the problems and prospects for the development of SHPs for TENGs are outlined.