25983-13-5Relevant articles and documents
A novel quinoxalinedione-bicapped tri-ruthenium carbonyl cluster [Ru3(μ-H)2(CO)6(μ3-HDCQX)2]: synthesis, characterization, anticancer activity and theoretical investigation of Ru–Ru and Ru–Ligand bonding interactions
Alfallous, Khalifa A.,Attia, Attia S.,El-Shahat, M. F.
, (2021)
A new tri-ruthenium dihydrido cluster, [Ru3(μ-H)2(CO)6(HDCQX)2] (1), in which two HDCQX (H2DCQX = 6,7-dichloroquinoxaline-2,3-dione) ligands cap both faces of the tri-ruthenium triangle similarly through oxygen atoms, has been synthesized and characterized by mass, IR, NMR (1H and 13C) and electronic spectroscopy. DFT calculations, in both gas and solution (CPCM/DMSO) phases, were performed to analyze the electronic structure of the cluster and interpret its vibrational and NMR spectra. The presence of non-equivalent bridging hydrides was assigned by 1H NMR as two singlet resonances at δ ?16.85 and ?17.67 ppm and confirmed by theoretical DFT-GIAO calculations at δ ?12.92 and ?14.48 ppm. Time-dependent density functional theory (TD-DFT) calculations, performed to characterize the frontier orbitals and interpret the electronic spectrum, indicated that the lowest-energy transition of 1 originates from a highly delocalized HOMO with Ru–Ru (σ), Ru–CO (π) and Ru–CO (σ*) contributions and ends in the LUMO with Ru1–Ru2–Ru3 (σ*) and QX/QX′ (π*) anti-bonding character. The natural transition orbital (NTO) corresponding to this transition revealed a decrease of the electron density on the Ru1Ru2(CO)4 fragment and an increase of the electron density on the Ru1–Ru2–Ru3 unit and the HDCQX ligands. The Ru–Ru and Ru–ligand bonding was studied by the quantum theory of atoms in molecules (QTAIM) and electron localization function (ELF) methods. Both confirmed the presence of unique bonding between the Ru1 and Ru2 atoms and not between Ru3 and the other Ru atoms. While the QTAIM assigned the Ru1–Ru2 bonding as a transit between pure closed-shell and pure shared-shell interactions, the ELF analysis suggested that this bond is dominated by a fluctuation of electron density. The covariance analysis indicated that the core basin populations C(Ru1) and C(Ru2) account for 76% of the V(Ru1, Ru2) variance. Natural bond orbital (NBO) analysis of the Ru3(μ-H)2O4(CO)6 unit indicated a 2c–2e bonding type for the Ru–O, Ru–C and Ru–Ru bonds with orbital occupations of 1.88–1.95, 1.95–1.96, and 1.57 e, respectively, and a 3c–2e bonding for the Ru–H–Ru bonds with an orbital occupation of ca. 1.7 e. NBO second-order perturbative energy analysis was performed to estimate the strength of the Ru–CO π-back-donation and to establish a correlation between the stabilization energy (E(2)) and the spectroscopic data. Although the calculated stabilization energy (E(2)total) follows the expected trend of decreasing the CO stretching frequency (νCO) and increasing the 13CO chemical shift with the extent of the Ru–CO π-back-donation, the latter parameter was more consistent in estimating the strength of such interactions. The in vitro anticancer activities of the title compound and cisplatin were determined against three common types of human cancer cell lines, HCT-116 (colon), HELA (cervix) and MCF-7 (breast). The IC50 values of 3.18 ± 0.40, 4.21 ± 0.29 and 5.39 ± 0.52 μM, respectively, represent 4- and 2-times improvement in potency relative to cisplatin (12.06 ± 1.28, 10.34 ± 2.08 and 6.29 ± 1.68 μM, respectively) against the HCT-116 and HeLa cancer cell lines.
Synthesis of novel halogenated heterocycles based on o‐phenylenediamine and their interactions with the catalytic subunit of protein kinase ck2
Maciejewska, Agnieszka Monika,Paprocki, Daniel,Poznański, Jaros?aw,Speina, El?bieta,Winiewska‐szajewska, Maria
supporting information, (2021/06/09)
Protein kinase CK2 is a highly pleiotropic protein kinase capable of phosphorylating hundreds of protein substrates. It is involved in numerous cellular functions, including cell viability, apoptosis, cell proliferation and survival, angiogenesis, or ER‐stress response. As CK2 activity is found perturbed in many pathological states, including cancers, it becomes an attractive target for the pharma. A large number of low‐mass ATP‐competitive inhibitors have already been developed, the majority of them halogenated. We tested the binding of six series of halogenated heterocyclic ligands derived from the commercially available 4,5‐dihalo‐benzene‐1,2‐diamines. These ligand series were selected to enable the separation of the scaffold effect from the hydrophobic interactions attributed directly to the presence of halogen atoms. In silico molecular docking was initially applied to test the capability of each ligand for binding at the ATP‐binding site of CK2. HPLC‐derived ligand hydrophobicity data are compared with the binding affinity assessed by low‐volume differential scanning fluorimetry (nanoDSF). We identified three promising ligand scaffolds, two of which have not yet been described as CK2 inhibitors but may lead to potent CK2 kinase inhibitors. The inhibitory activity against CK2α and toxicity against four reference cell lines have been determined for eight compounds identified as the most promising in nanoDSF assay.
A One-pot Facile Synthesis of 2,3-Dihydroxyquinoxaline and 2,3-Dichloroquinoxaline Derivatives Using Silica Gel as an Efficient Catalyst
Zhang, Pei-Ming,Li, Yao-Wei,Zhou, Jing,Gan, Lin-Ling,Chen, Yong-Jie,Gan, Zong-Jie,Yu, Yu
, p. 1809 - 1814 (2018/07/25)
An efficient one-pot reaction has been developed for the synthesis of 2,3-dichloroquinoxaline derivatives 3a–n. The reaction was performed in two steps via a silica gel catalyzed tandem process from o-phenylenediamine and oxalic acid, followed by addition of phosphorus oxychloride (POCl3). A variety of 2,3-dichloroquinoxalines have been obtained in good to excellent overall yields. Eight known compounds 3a–3h were characterized by IR, 1H-NMR, and mass spectroscopies. Compounds 3i–3n without spectroscopic data were characterized by IR, 1H-NMR, 13C-NMR, and mass spectroscopies.
