XAFS study of copper(II) complexes with square planar and square pyramidal coordination geometries

Gaur, Abhijeet; Klysubun, Wantana; Nair, N. Nitin; Shrivastava, B. D.; Prasad, Jagdish; Srivastava, Krishna

doi:10.1016/j.molstruc.2016.04.008

Cited by 42 publications

(27 citation statements)

References 25 publications

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“…For the Mt-CuPhen sat the XANES signal features are similar to the ones present in the references CuO and CuPhen crystals, nevertheless, closer to that of the CuPhen crystals, even if with a slight increase in the intensity of the pre-edge feature corresponding to the 1 s → 3d transition. These line-shape differences, although small, for a same metallic atom are indicative of different coordination geometries (Gaur et al, 2016). Therefore, considering the DR UV-Vis and X-ray diffraction results, not only the distorted octahedral coordination of the Mt-CuPhen sat , but also a larger distorted character than the crystals can be confirmed.…”

Section: Xas Spectroscopymentioning

confidence: 72%

“…These variations can be explained by the different nature of ligand and the coordination geometry of the photo-absorber atom (Cu) (Palladino et al, 1993;Kim and Lee, 2003). For example, the reference CuO and CuSO 4 × 5H 2 O are in same divalent form, but CuO has a square planar geometry, while the reference CuSO 4 × 5H 2 O is in an octahedral geometry (Gaur et al, 2016), which induces those differences in the XANES response. For the case of CuPhen crystals, the XANES profile is quite close to that of reference CuSO 4 × 5H 2 O, but with a lower intensity of edge shoulder related to a decrease of the 4p density of states.…”

Section: Xas Spectroscopymentioning

confidence: 99%

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A new material based on montmorillonite and Cu(II)-phenanthroline complex for effective capture of ammonia from gas phase

Castellini

Malferrari

Bernini

et al. 2020

Applied Clay Science

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The intercalation of [Cu(Phen)(H 2 O) 2 ] 2+ (CuPhen) in montmorillonite (Mt) produces a stable hybrid material that is very efficient in removing NH 3 from gas phase even at extremely low pressures.The process was studied by elemental analysis, X-ray powder diffraction, thermal analysis coupled with evolved gas mass spectrometry and DR UV-Vis, NMR and X-ray absorption spectroscopy. The adsorption of CuPhen on Mt consists of two consecutive steps. During the first one, CuPhen intercalates alone into Mt through a cation exchange process, afterwards CuPhen and SO 4 2− ions entry jointly into the mineral interlayer. The two-steps adsorption process is described by a VI-type isotherm, successfully fitted by two independent Frumkin isotherms. NH 3 trapping is long-lasting, easy, fast even at extremely low gas pressure and reversible under mild conditions. Mt containing CuPhen always results well performant in removing ammonia from gas phase, but an appreciably higher adsorption capacity of NH 3 is obtained when SO 4 2− ion is absent from the interlayer. This hybrid montmorillonite is thus a promising material to be used in industrial or environmental contexts, as an efficient air-cleaner.

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Section: Xas Spectroscopymentioning

confidence: 72%

Section: Xas Spectroscopymentioning

confidence: 99%

A new material based on montmorillonite and Cu(II)-phenanthroline complex for effective capture of ammonia from gas phase

Castellini

Malferrari

Bernini

et al. 2020

Applied Clay Science

View full text Add to dashboard Cite

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“…These features indicate that a certain distortion of the octahedral coordination of Cu(II) center occurs [11,18]. The XANES signal of Mt-CuPhen is still similar to that for Cu(II)Phen crystals, but show clear intermediate characteristics between CuO and Cu(II)Phen, probably due to an even more pronounced distortion of the octahedral coordination of Cu(II) or even a decrease in its coordination number (possibly from six to five, thus assuming a square pyramidal geometry) [26]. Figure S2 shows the evolution of Mt-CuPhen XANES spectrum at different H 2 S exposure times.…”

Section: Xas Analysis Of Mt-cuphen Before and After H 2 S Exposurementioning

confidence: 73%

“…In Figure S1a, Cu reference compounds with formal 2+ oxidation state display different position, intensity, and shape of the absorption edge, which can be attributed to the different nature of the ligand and to Cu local geometry [23][24][25][26][27]. Changes also occur for the Cu(II)Phen crystals and Mt-CuPhen material ( Figure S1b).…”

Section: Xas Analysis Of Mt-cuphen Before and After H 2 S Exposurementioning

confidence: 99%

“…Changes also occur for the Cu(II)Phen crystals and Mt-CuPhen material ( Figure S1b). The reference compounds CuO and CuSO 4 •5H 2 O, both containing Cu(II), show differences in the XANES region that can be attributed to the different Cu coordination (i.e., square planar geometry for CuO and octahedral geometry for CuSO 4 •5H 2 O) [26]. The XANES profile of Cu(II)Phen crystals ( Figure S1b) is closer to that of CuSO 4 •5H 2 O; however, it shows a pre-edge of low intensity, an absorption edge moved to higher energy with respect to CuSO 4 •5H 2 O, and a whiteline of high intensity.…”

Section: Xas Analysis Of Mt-cuphen Before and After H 2 S Exposurementioning

confidence: 99%

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Interlayer-Confined Cu(II) Complex as an Efficient and Long-Lasting Catalyst for Oxidation of H2S on Montmorillonite

et al. 2020

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Removal of highly toxic H2S for pollution control and operational safety is a pressing need. For this purpose, a montmorillonite intercalated with Cu(II)-phenanthroline complex [Cu[(Phen)(H2O)2]2+ (Mt-CuPhen) was prepared to capture gaseous H2S under mild conditions. This hybrid material was simple to obtain and demonstrated an outstanding ability to entrap H2S at room temperature, retaining high efficiency for a very long time (up to 36.8 g of S/100 g Mt-CuPhen after 3 months of exposure). Sorbent and H2S uptake were investigated by elemental analysis, X-ray powder diffraction measurements, diffuse reflectance (DR) UV–Vis and infrared spectroscopy, thermal analysis and evolved gas mass spectrometry, scanning electron microscopy equipped with energy-dispersive X-ray spectrometer, and X-ray absorption spectroscopy. The H2S capture was studied over time and a mechanism of action was proposed. The entrapping involves a catalytic mechanism in which [Cu[(Phen)(H2O)2]2+ acts as catalyst for H2S oxidation to S0 by atmospheric oxygen. The low cost and the long-lasting performance for H2S removal render Mt-CuPhen an extremely appealing trap for H2S removal and a promising material for many technological applications.

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Copper‐Functionalized Metal–Organic Framework as Catalyst for Oxidant‐Controlled Partial Oxidation of Cyclohexene

et al. 2018

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Microwave irradiation is exploited for the facile, onestep functionalization of Cu(acac) 2 to -NH 2 pendant groups of MIL-53(Al)-NH 2 , a metal-organic framework material, under mild reaction conditions and a short reaction time. PXRD, XPS, XAS, and EPR spectroscopy are used to investigate the structure and chemical nature of the copper species on the framework. The copper center exists in the +2 oxidation state with a square-planar geometry and NO 3 coordination environment. The copper complex is anchored to the framework by imine bond formation. This copper-functionalized MIL-53(Al)-NH 2 or [a

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XAFS study of copper(II) complexes with square planar and square pyramidal coordination geometries

Cited by 42 publications

References 25 publications

A new material based on montmorillonite and Cu(II)-phenanthroline complex for effective capture of ammonia from gas phase

A new material based on montmorillonite and Cu(II)-phenanthroline complex for effective capture of ammonia from gas phase

Interlayer-Confined Cu(II) Complex as an Efficient and Long-Lasting Catalyst for Oxidation of H2S on Montmorillonite

Copper‐Functionalized Metal–Organic Framework as Catalyst for Oxidant‐Controlled Partial Oxidation of Cyclohexene

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