Lactide polymerization using a sterically encumbered, flexible zinc complex

4-(tert-Butyl)-2-trityl-6-(di-(2-picolyl)amine)phenol, LH, was prepared from paraformaldehyde, 4-(tert-butyl)-2-tritylphenol and di-(2-picolyl)amine. Reaction with Zn(N(SiMe3)2)2 gave LZnN(SiMe3)2. The complex was shown by X-ray diffraction study, variable temperature NMR and DFT calculations to coordinate only one pyridine ligand, which allows for fast and facile complex isomerisation. LZnN(SiMe3)2 was active in rac-lactide polymerization, but in contrast to previous complexes of this type did not show any evidence for isotactic monomer enchainment via a catalytic-site mediated chain-end control mechanism. Addition of alcohol led to increased activity, but the complex was unstable in the presence of free alcohol.

Synthesis, Crystallographic Structure, Hirshfeld Surface Analysis, Drug-likeness Properties and Molecular Docking Studies of New Oxime-pyridine Compounds

A detailed description of the two new pyridine ligands, (2E,3Z)-3-[2-(3-chloropyridin-2-yl)hydrazinylidene]-N-hydroxybutan-2-imine and 3-chloro-2-{(2Z)-2-[1-(4 nitrophenyl)ethylidene]hydrazinyl}, is reported. The synthesized compounds were characterized by spectroscopic studies, spectral features were performed by TD-DFT calculations. New-generation pyridine ligand of HL2 was also determinate by single-crystal X-ray diffraction and Hirshfeld surface analysis with two-dimensional fingerprint plots was used to analyze intermolecular interactions in crystals. Molecular-docking was performed to investigate the binding areas of chemical compounds, and the results showed the inhibitory activity of the studied HL1 and HL2 against E. coli. The results of the current study revealed the drug-likeness and bioactive properties of the ligands.

Dichlorido(pyridine-κN)[2,3,5,6-tetrakis(pyridin-2-yl)pyrazine-κ3 N 2,N 1,N 6]nickel(II)

In the title complex, [NiCl2(C5H5N)(C24H16N6)], the NiII ion is six-coordinated in a distorted octahedral coordination environment defined by three N atoms of the tridentate 2,3,5,6-tetra-2-pyridylpyrazine ligand, one N atom of the pyridine ligand and two Cl− anions, with the latter being mutually trans. The complex is disposed about a twofold rotation axis along the a axis. The complex molecules are connected in the crystal via C—H...Cl, C—H...N and π–π [closest inter-centroid separation = 3.7446 (14) Å between pyridyl rings].

Two-photon excitable boron complex based on tridentate imidazo[1,5-a]pyridine ligand for heavy-atom-free mitochondria-targeted photodynamic therapy

We have synthesized a cyan fluorescent boron complex based on a tridentate imidazo[1,5-a]pyridine ligand.

Stepwise synthesis of Zr-based metal-organic frameworks: Incorporating trinuclear zirconocene-based metallo-pyridine ligand

Two isostructural heterometallic ZrMOFs (denoted as ZrMOF-Co/Ni) were obtained by stepwise sysnthesis approach. Single-crystal X-ray structural analyses indicate that two ZrMOFs are both built from trinuclear zirconocene-based metallo-pyridine buliding blocks,...

In Cellulo Evaluation of the Therapeutic Potential of NHC Platinum Compounds in Metastatic Cutaneous Melanoma

We describe here the evaluation of the cytotoxic efficacy of two platinum (II) complexes bearing an N-heterocyclic carbene (NHC) ligand, a pyridine ligand and bromide or iodide ligands on a panel of human metastatic cutaneous melanoma cell lines representing different genetic subsets including BRAF-inhibitor-resistant cell lines, namely A375, SK-MEL-28, MeWo, HMCB, A375-R, SK-MEL-5-R and 501MEL-R. Cisplatin and dacarbazine were also studied for comparison purposes. Remarkably, the iodine-labelled Pt-NHC complex strongly inhibited proliferation of all tested melanoma cells after 1-h exposure, likely due to its rapid uptake by melanoma cells. The mechanism of this inhibitory activity involves the formation of DNA double-strand breaks and apoptosis. Considering the intrinsic chemoresistance of metastatic melanoma cells of current systemic treatments, these findings are promising and could give research opportunities in the future to improve the prognosis of patients suffering from unresectable metastatic melanoma that are not eligible or that do not respond to the most effective drugs available to date, namely BRAF inhibitors and the anti-PD-1 monoclonal antibody (mAb).