Mössbauer, vibrational and electronic spectroscopy of trinuclear μ-oxo iron(III) acetate clusters with pyridine and derivatives as ligands

Fernandes, Christiane; Stadler, Eduardo; Drago, Valderes; Cunha, Carlos Jorge da; Kuwabara, Izaura Hiroko

doi:10.1016/s0584-8539(96)01753-9

Cited by 11 publications

(8 citation statements)

References 11 publications

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“…As thermal treatment is reported to reduce Fe 3+ to Fe 2+ in MIL-126(Fe), 14 (Figure 8g). The isomer shifts and quadrupolar splittings are consistent with homovalent [Fe III 3 O(RCO 2 ) 6 ] SBUs for both samples when compared to data from discrete complexes [73][74][75][76] and analogous MOFs, 77 confirming complete oxidation of Fe 2+…”

Section: L-prolinesupporting

confidence: 67%

Kinetic Control of Interpenetration in Fe–Biphenyl-4,4′-dicarboxylate Metal–Organic Frameworks by Coordination and Oxidation Modulation

et al. 2019

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Phase control in the self-assembly of metal-organic frameworks (MOFs) is often a case of trial and error; judicious control over a number of synthetic variables is required to select the desired topology and control features such as interpenetration and defectivity. Herein, we present a comprehensive investigation of self-assembly in the Fe-biphenyl-4,4′-dicarboxylate system, demonstrating that coordination modulation can reliably tune between the kinetic product, non-interpenetrated MIL-88D(Fe), and the thermodynamic product, twofold interpenetrated MIL-126(Fe). Density functional theory simulations reveal that correlated disorder of the terminal anions on the metal clusters results in hydrogen-bonding between adjacent nets in the interpenetrated phase and is the thermodynamic driving force for its formation. Coordination modulation slows self-assembly and therefore selects the thermodynamic product MIL-126(Fe), while offering fine control over defectivity, inducing mesoporosity, but electron microscopy shows MIL-88D(Fe) persists in many samples despite not being evident by diffraction. Interpenetration control is also demonstrated using the 2,2′bipyridine-5,5′-dicarboxylate linker; it is energetically prohibitive for it to adopt the twisted conformation required to form the interpenetrated phase, although multiple alternative phases are identified due to additional coordination of Fe cations to its N-donors. Finally, we introduce oxidation modulation-the use of metal precursors in different oxidation states to that found in the final MOF-to kinetically control self-assembly. Combining coordination and oxidation modulation allows the synthesis of pristine MIL-126(Fe) with BET surface areas close to the predicted maximum for the first time, suggesting that combining the two may be a powerful methodology for the controlled self-assembly of high-valent MOFs. linkers used in this study. b) Packing structure of the twofold interpenetrated MIL-126(Fe), with the distinct nets coloured red and blue. Redrawn from CCDC deposition MIBMER. 14 c) Packing structures, viewed down the c axis, of open and closed MIL-88D(Fe), generated from simulated structures (not to scale), C: grey; O: red; Fe: orange spheres; H atoms removed for clarity.

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Section: L-prolinesupporting

confidence: 67%

Kinetic Control of Interpenetration in Fe–Biphenyl-4,4′-dicarboxylate Metal–Organic Frameworks by Coordination and Oxidation Modulation

et al. 2019

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“…The spectra of 1-HCl (1 eq), prepared from FeCl 3 , and 1′-HCl (1 eq), prepared from FeCl 2 , have single quadrupolar doublets and show no discernible differences. The isomer shifts and quadrupolar splittings are consistent with homovalent [Fe III 3 O(RCO 2 ) 6 ] SBUs for both samples when compared to data from discrete complexes [71][72][73][74] and analogous MOFs, 75 confirming complete oxidation of Fe 2+ to Fe 3+ in the synthesis of 1′-HCl (1 eq).…”

Section: Synthesis Of 1 Using Fe 2+ (1′)supporting

confidence: 69%

Kinetic Control of Interpenetration in Fe-Biphenyl-4,4′-dicarboxylate MOFs by Coordination and Oxidation Modulation

Bara¹,

Wilson²,

Mörtel³

et al. 2018

Preprint

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Phase control in the self-assembly of metal-organic frameworks (MOFs) – materials wherein organic ligands connect metal ions or clusters into network solids with potential porosity – is often a case of trial and error. Judicious control over a number of synthetic variables is required to select for the desired topology and control features such as interpenetration and defectivity, which have significant impact on physical properties and application. Herein, we present a comprehensive investigation of self-assembly in the Fe-biphenyl-4,4'-dicarboxylate system, demonstrating that coordination modulation, the addition of competing ligands into solvothermal syntheses, can reliably tune between the kinetic product, non-interpenetrated MIL-88D(Fe), and the thermodynamic product, two-fold interpenetrated MIL-126(Fe). DFT simulations reveal that correlated disorder of the terminal anions on the metal clusters in the interpentrated phase results in H-bonding between adjacent nets and is the thermodynamic driving force for its formation. Coordination modulation slows self-assembly and therefore selects the thermodynamic product MIL-126(Fe), while offering fine control over defectivity, inducing mesoporosity, but electron microscopy shows the MIL-88D(Fe) phase persists in many samples despite not being evident in diffraction experiments, suggesting its presence accounts for the lower than predicted surface areas reported for samples to date. Interpenetration control is also demonstrated by utilizing the 2,2'-bipyridine-5,5'-dicarboxylate linker; DFT simulations show that it is energetically prohibitive for it to adopt the twisted conformation required to form the interpenetrated phase, and are confirmed by experimental data, although multiple alternative phases are identified due to additional coordination of the Fe cations to the N-donors of the ligand. Finally, we introduce oxidation modulation – the concept of using metal precursors in a different oxidation state to that found in the final MOF – as a further protocol to kinetically control self-assembly. Combining coordination and oxidation modulation allows the synthesis of pristine MIL-126(Fe) with BET surface areas close to the predicted maximum capacity for the first time, suggesting that combining the two may be a powerful methodology for the controlled self-assembly of high-valent MOFs.<br><br>

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“…1, with main bands at cm À1 : 1590 (m asym COO À ), 1423 (m sym COO), 1350 (sym bend CH 3 ), 1034 (rock CH 3 ), 662 and 618 (in plane and out-of-plane bend COO À , respectively) and at 563 (m as M 3 O). The frequency difference between the antisymmetric and symmetric stretching modes of the carboxylate group is typical of acetate ligand bridging two metal ions [10][11][12]. The redox behavior of the most soluble clusters Scheme 1.…”

mentioning

confidence: 99%

A new facile high yield preparative route for mixed-trinuclear acetate clusters

Vrubel

Hasegawa

Oliveira

et al. 2006

Inorganic Chemistry Communications

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Mössbauer, vibrational and electronic spectroscopy of trinuclear μ-oxo iron(III) acetate clusters with pyridine and derivatives as ligands

Cited by 11 publications

References 11 publications

Kinetic Control of Interpenetration in Fe–Biphenyl-4,4′-dicarboxylate Metal–Organic Frameworks by Coordination and Oxidation Modulation

Kinetic Control of Interpenetration in Fe–Biphenyl-4,4′-dicarboxylate Metal–Organic Frameworks by Coordination and Oxidation Modulation

Kinetic Control of Interpenetration in Fe-Biphenyl-4,4′-dicarboxylate MOFs by Coordination and Oxidation Modulation

A new facile high yield preparative route for mixed-trinuclear acetate clusters

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