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The thermodynamics of the binding of a series of structurally related Ru(II) antitumor complexes, that is, alpha-[Ru(azpy)2Cl2] 1, beta-[Ru(azpy)2Cl2] 2, alpha-[Ru(azpy)(bpy)Cl2] 3, and cis-[Ru(bpy)2Cl2] 4 to DNA purine bases (gunine, adenine at N7 site) has been studied by using the DFT method. The binding of imine form of 9-methyladenine (9-MeAde) to the Ru(II) moiety in a didentate fashion via its N6 and N7 atoms was also considered. The geometrical structures of the DNA model base adducts were obtained at the B3LYP/(LanL2DZ + 6-31G(d)) level in vacuo. The following exact single-point energy calculations were performed at the B3LYP/(LanL2DZ(f)+6-311+G(2d, 2p)) level both in vacuo and in aqueous solution using the COSMO model. The bond dissociation enthalpies and free energies, reaction enthalpies and free energies both in the gas phase and in aqueous solution for all considered Ru(II)-DNA model base adducts were obtained from the computations. The calculated bond dissociation enthalpies and free energies allow us to build a binding affinity order for the considered Ru(II)-DNA model base adducts. The theoretical results show that the guanine N7 is a preferred site for this series of complexes and support such an experimental fact that alpha-[Ru(azpy)(bpy)(9-EtGua)H2O](2+) (3-(9-EtGua)) is isomerized to alpha'-[Ru(azpy)(bpy)(9-EtGua)H2O](2+) (3'-(9-EtGua)). On the basis of structural and thermodynamical characteristics, the possible structure-activity relationship was obtained, and the distinct difference in cytotoxicities of this series of structurally related antitumor complexes was explained theoretically.
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http://dx.doi.org/10.1021/jp711799g | DOI Listing |
J Phys Chem A
September 2025
Department of Chemistry, Tsinghua University, Beijing 100084, China.
A series of Cu-based single-atom catalysts (SACs) with asymmetric coordination were designed to accelerate lithium-sulfur (Li-S) chemistry. The electronegativity contrast from the dopant induces a localized electronic asymmetry that amplifies Jahn-Teller distortion at the Cu center. This distortion profoundly modulates the Cu 3d electronic structure and its interaction with Li-S intermediates.
View Article and Find Full Text PDFChaos
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School of Computational Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.
Although many real-world time series are complex, developing methods that can learn from their behavior effectively enough to enable reliable forecasting remains challenging. Recently, several machine-learning approaches have shown promise in addressing this problem. In particular, the echo state network (ESN) architecture, a type of recurrent neural network where neurons are randomly connected and only the read-out layer is trained, has been proposed as suitable for many-step-ahead forecasting tasks.
View Article and Find Full Text PDFChaos
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The Key Laboratory of Intelligent Computing and Signal Processing of Ministry of Education, School of Internet, Anhui University, Hefei 230601, China.
A captivating challenge in network research is the reconstruction of complex network structures from limited binary-state time series data. Although some reconstruction approaches based on dynamical rules or sparse system of linear equations have been proposed, these approaches either rely on known dynamical rules, limiting their generality, or the system of linear equations is often empirically determined, with weak interpretability and the performance being sensitive to parameter settings. To address these limitations, we propose a network reconstruction method based on linearization grounded in mean-field approximation.
View Article and Find Full Text PDFRSC Med Chem
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Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, TX 76798-7348, United States of America.
A strategy for targeting tumor-associated hypoxia utilizes reductase enzyme-mediated cleavage to convert biologically inert prodrugs to their corresponding biologically active parent therapeutic agents selectively in areas of pronounced hypoxia. Small-molecule inhibitors of tubulin polymerization represent unique therapeutic agents for this approach, with the most promising functioning as both antiproliferative agents (cytotoxins) and as vascular disrupting agents (VDAs). VDAs selectively and effectively disrupt tumor-associated microvessels, which are typically fragile and chaotic in nature.
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Institute of Inorganic Chemistry of the Czech Academy of Sciences, Husinec-Řež 1001, 250 68 Řež, Czech Republic.
Coordination polymers (CPs) are versatile materials formed by metal ions and organic ligands, offering a broad range of structural and functional possibilities. Phosphonates and phosphinates are particularly attractive ligands for CPs due to their multiple binding sites, varied coordination geometries, and ability to form robust network structures. Phosphonates, considered harder ligands, form strong bonds with hard metals such as Fe, while phosphinates offer additional versatility due to the varied pendant groups on phosphorus.
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