EPR and magnetic studies of a novel copper metal organic framework (STAM-I)

Mkami, Hassane El; Mohideen, M. Infas H.; Pal, Chanchal Kumar; McKinlay, Alistair C.; Scheimann, O.; Morris, Russell E.

doi:10.1016/j.cplett.2012.06.012

Cited by 43 publications

(53 citation statements)

References 27 publications

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“…(i) a main resonance centered at B 0 =325 mT and peak-to-peak line width of about ΔB pp =24 mT, on which traces of an hyperfine structure are barely evident, and (ii) two smaller contributions at about B 0 =12 mT and B 0 =470 mT. In accordance with literature, 20,[43][44][45] we assign the central resonance peaked at B 0 =325 mT to the complex [Cu(OH 2 ) 6 ] 2+ , which involves a Cu 2+ ion, with electron spin S=1/2, coordinated with six water molecules and not connected with the framework of HKUST-1. It presumably is a defect formed during the material synthesis.…”

Section: Sample Asupporting

confidence: 89%

Decomposition Process of Carboxylate MOF HKUST-1 Unveiled at the Atomic Scale Level

et al. 2016

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HKUST-1 is a metal–organic framework (MOF) which plays a significant role in both applicative and basic fields of research, thanks to its outstanding properties of adsorption and catalysis but also because it is a reference material for the study of many general properties of MOFs. Its metallic group comprises a pair of Cu2+ ions chelated by four carboxylate bridges, forming a structure known as paddle-wheel unit, which is the heart of the material. However, previous studies have well established that the paddle-wheel is incline to hydrolysis. In fact, the prolonged exposure of the material to moisture promotes the hydrolysis of Cu–O bonds in the paddle-wheels, so breaking the crystalline network. The main objective of the present experimental investigation is the determination of the details of the structural defects induced by this process in the crystal, and it has been successfully pursued by coupling the electron paramagnetic resonance spectroscopy with other more commonly considered techniques, such as X-ray diffraction, surface area estimation, and scanning electron microscopy. Thanks to this original approach we have recognized three stages of the process of decomposition of HKUST-1, and we have unveiled the details of the corresponding equilibrium structures of the paddle-wheels at the atomic scale level

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Section: Sample Asupporting

confidence: 89%

Decomposition Process of Carboxylate MOF HKUST-1 Unveiled at the Atomic Scale Level

et al. 2016

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“…This broadening is due to the strong interconnection between paddlewheel units, where the broadening is so much that the individual signals merge with each other and there is a single broad signal. The observed broad signal is typical of polymeric complexes, and supports polymeric paddlewheel structure of the synthesized complex. It has been pointed out that well resolved and separate ESR lines indicate weak exchange interactions among the individual ESR active molecules of the lattice as observed in case of discrete mononuclear and dinuclear copper complexes , …”

Section: Resultssupporting

confidence: 70%

“…In a recent analogue of this type, hexanuclear complexes have been designed, where a copper and two oxygen atoms of the central paddlewheel unit are coordinated from both sides in a similar fashion . There are complexes where copper ions are coordinated by trans‐dicarboxylate ligands resulting in MOF based on paddlewheel units having interesting magnetic properties , . We have synthesized a complex belonging to the uncommon stepped type of polymeric paddlewheel carboxylates.…”

Section: Introductionmentioning

confidence: 99%

Polymeric Copper(II) Paddlewheel Carboxylate: Structural Description, Electrochemistry, and DNA‐binding Studies

Iqbal

Ali

Tahir

2018

Zeitschrift anorg allge chemie

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A polymeric complex of copper(II) was isolated and purified from the self‐assembly of CuSO4 and 2‐phenyl acetate in aqueous medium. It was characterized through FT‐IR, UV/Vis, electron spin resonance, electrochemical solution studies, and powder and single crystal XRD techniques. The structure was revealed to consist of directly interconnected dimeric paddlewheel building units without any intervening ligand. This type of polymeric paddlewheel structures are found very rarely. Each copper is lying in a CuO5 square pyramid coordinated by four oxygen atoms in the square base while the axial oxygen belongs to the neighboring paddlewheel. Purity and uniform crystalline nature of the complex was assessed from matching theoretical and experimental powder XRD spectra. ESR spectrum consisted of a broad signal with g value = 2.2427, whereas electrochemical studies revealed diffusion controlled electron transfer processes with diffusion co‐efficient = 1.628 × 10–7 cm2·s–1. The results of spectroscopic techniques support each other. The complex afforded mixed binding mode with DNA yielding DNA‐binding constant values of 1.384 × 104 m–1 and 8.845 × 104 m–1 using absorption spectroscopy and cyclic voltammetry, respectively. The complex also exhibited significant activity against anti‐fungal strain Helminthosporium solani by inhibiting its 75 % ± 2.5 growth. The preliminary studies heralded excellent biological potential of the synthesized complex.

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“…6b). [56][57][58] The EPR signal of the triplet center obtained at 77 K has a signicantly smaller amplitude than the one obtained at 300 K. This feature is expected since the population of the excited S ¼ 1 magnetic state decreases exponentially with the decrease of temperature. The main central resonance observed in the spectrum of the bulk HKUST-1 in Fig.…”

Section: Structural Property Investigationsmentioning

confidence: 82%

Confined crystallization of a HKUST-1 metal–organic framework within mesostructured silica with enhanced structural resistance towards water

et al. 2017

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EPR and magnetic studies of a novel copper metal organic framework (STAM-I)

Cited by 43 publications

References 27 publications

Decomposition Process of Carboxylate MOF HKUST-1 Unveiled at the Atomic Scale Level

Decomposition Process of Carboxylate MOF HKUST-1 Unveiled at the Atomic Scale Level

Polymeric Copper(II) Paddlewheel Carboxylate: Structural Description, Electrochemistry, and DNA‐binding Studies

Confined crystallization of a HKUST-1 metal–organic framework within mesostructured silica with enhanced structural resistance towards water

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