WoS İndeksli Yayınlar Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/394

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Start date: 2020Institution Author: search.filters.institutionAuthor.Erkartal, Mustafa

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Now showing 1 - 3 of 3
  • Article
    Citation - WoS: 7
    Citation - Scopus: 7
    Unveiling the Multifaceted Properties of a 3D Covalent-Organic Framework: Pressure-Induced Phase Transition, Negative Linear Compressibility and Auxeticity
    (Elsevier, 2023-08) Erkartal, Mustafa
    High-pressure behavior and mechanical properties of a three-dimensional covalent-organic framework (NPN-1) were investigated by using different types of first principles molecular simulations. An irreversible pressureinduced first-order isosymmetric phase transition was predicted at 0.14 GPa. The subunit of NPN-1 retains its rigidity under pressure thanks to the strong covalent bonds. However, compression leads to significant tilting of the nitrophenyl groups. The mechanical properties of frameworks are highly anisotropic. Remarkably, both phases exhibit not only negative linear compressibility along the c-axis but also negative Poisson's ratio in certain directions. Detailed structural analysis revealed that the origin of the phase transition and anomalous mechanical properties of both phases are the wine-rack motif and strut-hinge mechanism. To the best of our knowledge, this study is the first report of such behavior in COFs, opening up new avenues for the exploration of COFs as materials for many promising applications.
  • Article
    Citation - WoS: 7
    Citation - Scopus: 7
    Giant Negative Linear Compressibility, Isosymmetric Phase Transition, and Breathing Effect in a 3D Covalent Organic Framework
    (Amer Chemical Soc, 2023-12-26) Erkartal, Mustafa
    A set of remarkable piezo-mechanical properties, including isosymmetric phase transition, negative linear compressibility (NLC), and a breathing effect in a three-dimensional covalent organic framework (NPN-3), was uncovered using density functional theory. The pressure-induced first-order phase transition observed between 0.9 and 1 GPa is isosymmetric and irreversible. NPN-3 shows giant NLC along the c-axis (K-c = 42.04 TPa-1) prior to the phase transition. The high-density NPN-3-hd obtained as a result of the phase transition shows an exciting phase transition from a closed pore to an open pore under hydrostatic tensile pressure, similar to the breathing effect. These extraordinary piezo-mechanical attributes within NPN-3 can be attributed to the diamondoid (dia) topology, which is commonly found within flexible MOFs and COFs. Additionally, the remarkable adaptability of the tetraphenyl adamantane monomer to distinct conformations under pressure can be seen in these properties. These findings underscore the potential utility of COFs as materials for piezo-mechanical sensors and serve as a source of inspiration for further exploration into the intricate mechanical behaviors of COFs.
  • Article
    Citation - WoS: 6
    Citation - Scopus: 7
    Extreme Flexibility and Unusual Piezomechanical Properties of Zinc-Alkyl Metal-Organic Frameworks: A First Principles Study
    (Elsevier, 2023-06) Erkartal, Mustafa
    The behavior of three Zn-alkyl-based MOFs, ZnGA (Zn-Glutarate), ZnAA (Zn-Adipate), and ZAG-4 (Zinc Alky Gate), under hydrostatic compression has been investigated using first-principles DFT simulation, which has proven its reliability in previous studies. Due to the lack of the high pressure experimental data for ZnGA and ZnAA, the reliability of the simulation parameters was tested by taking ZAG-4, whose structural flexibility has been previously reported experimentally and computationally, as a benchmark. All three structures were found to exhibit elastic deformation under pressure up to 15 GPa, due to the flexibility of the alkyl chains that allow the structures to move without disrupting the metal-ligand coordination. Interestingly, the structures exhibit different mechanical properties, with ZAG-4 showing negative linear compressibility (NLC), ZnGA showing positive linear compressibility (PLC), and ZnAA showing zero linear compressibility (ZLC). The NLC in ZAG-4 is attributed to the proton transfer between phosphonate oxygen and water in the structure as previously reported, while the ZLC in ZnAA is due to a dumbbell-like structural motif formed by substructures displaying both NLC and PLC.