Amorphous coordination polymers and metal-organic frameworks (MOFs) have attracted much attention owing to their various functionalities. Here, we demonstrate the tunable water adsorption behavior of a series of amorphous cyanide-bridged MOFs with different metals (M[Ni(CN)]: ; M = Mn, Fe, and Co). All three compounds adsorb up to six water molecules at a certain vapor pressure () and undergo conversion to crystalline Hofmann-type MOFs, M(HO)[Ni(CN)]·4HO (; M = Mn, Fe, and Co). The of , , and for water adsorption is / = 0.4, 0.6, and 0.9, respectively. Although the amorphous nature of these materials prevented structural elucidation using X-ray crystallography techniques, the local-scale structure around the N-coordinated M centers was analyzed using L-, K-edge X-ray absorption fine structure, and magnetic measurements. Upon hydration, the coordination geometry of these metal centers changed from tetrahedral to octahedral, resulting in significant reorganization of the MOF local structure. On the other hand, Ni[Ni(CN)] () containing square-planar Ni centers did not undergo significant structural transformation and therefore abruptly adsorbed HO in the low-pressure region. We could thus define how changes in the bond lengths and coordination geometry are related to the adsorption properties of amorphous MOF systems.
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http://dx.doi.org/10.1021/acs.inorgchem.0c03742 | DOI Listing |
J Chem Theory Comput
January 2025
Preferred Networks, Inc., Tokyo 100-0004, Japan.
Mapping the chemical reaction pathways and their corresponding activation barriers is a significant challenge in molecular simulation. Given the inherent complexities of 3D atomic geometries, even generating an initial guess of these paths can be difficult for humans. This paper presents an innovative approach that utilizes neural networks to generate initial guesses for reaction pathways based on the initial state and learning from a database of low-energy transition paths.
View Article and Find Full Text PDFJ Phys Chem A
January 2025
Novosibirsk State University, Pirogov str. 1, Novosibirsk 630090, Russian Federation.
Nine metal complexes formed by three symmetric β-diketonates (, acetylacetonate (), 1,1,1,3,3,3-hexafluoro-acetylacetonate (), and 2,2,6,6-tetramethylheptane-3,5-dionate ()) and three metal ions (with three different coordination geometries, , Be - tetrahedral, Cu - square planar, and Pb - "swing" square pyramidal) were investigated. The study combines structural analyses, vibrational spectroscopic techniques, and quantum chemical calculations with the aim of bridging crystal structure, electronic structure, molecular topology, and far-infrared (FIR) spectroscopic characteristics. The effect of intramolecular interactions on the structural, electronic, and spectroscopic features is the center of this study.
View Article and Find Full Text PDFDalton Trans
January 2025
Czech Academy of Sciences, J. Heyrovsky Institute of Physical Chemistry, Dolejškova 2155/3, 182 23 Prague 8, Czech Republic.
Copper isotopes and their complexes are intensively studied due to their high potential for applications in radiodiagnosis and radiotherapy. Here, we study the Cu complex of 1,8-bis(2-hydroxybenzyl)-cyclam (HL), which forms an unexpected variety of isomers differing in the mutual orientation of the substituents on the cyclam nitrogen atoms, the protonation of the phenolate pendant, and the ligand denticity. The interconversion of the isomers is rather slow, which made the isolation, identification and investigation of some of the individual species possible.
View Article and Find Full Text PDFDalton Trans
January 2025
Department of Applied Chemistry, Cochin University of Science and Technology, Kochi 22, Kerala, India.
The rise of various diseases demands the development of new agents with antioxidant, antimicrobial, anti-inflammatory, enzyme-inhibiting, and cytotoxic properties. In this study, heterocyclic Schiff base complexes of Cu(II) featuring a benzo[]thiophene moiety were synthesized and their biological activities evaluated. The complexes were characterized using FT-IR, UV-Vis, and EPR spectroscopy, TG-DTG analysis, magnetic moment measurements, molar conductivity measurements, and elemental analyses.
View Article and Find Full Text PDFDalton Trans
January 2025
Department of Materials Science and Engineering, School of Molecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Wangchan, Rayong 21210, Thailand.
Dinuclear aluminum complexes bearing a constrained 'indanimine' ligand based on a short hydrazine bridge were synthesized. Single-crystal X-ray crystallography reveals bimetallic penta-coordinated aluminum centers having a distorted trigonal bipyramidal geometry. A short Al-Al distance of 4.
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