Metal-center exchange of tetrahedral cages: single crystal to single crystal and spin-crossover properties

Zhang, Fengli; Chen, Jiaqian; Qin, Long-Fang; Tian, Lei; Li, Zaijun; Ren, Xiaofeng; Gu, Zhi‐Guo

doi:10.1039/c6cc00711b

Cited by 33 publications

(25 citation statements)

References 41 publications

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“…With highly ordered cellular-like porous structure, MOFs have been applied in catalalysis, drug delivery, environmental fields, and so on. It has been reported that there are three types of crystal transformation for MOFs, namely, rotation of bond angles, transformation through vapor sorption/desorption, and substitution of metal ions . These transformations caused alterations reflecting in extensiveness like coordination number, space group, color, and magnetism .…”

Section: Introductionmentioning

confidence: 99%

“…It has been reported that there are three types of crystal transformation for MOFs, namely, rotation of bond angles, 8 transformation through vapor sorption/desorption, 9 and substitution of metal ions. 10 These transformations caused alterations reflecting in extensiveness like coordination number, space group, color, and magnetism. 9 Different combinations based on the same metal ions and organic struts brought varied structures and functions.…”

Section: ■ Introductionmentioning

confidence: 99%

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CD-MOFs Crystal Transformation from Dense to Highly Porous Form for Efficient Drug Loading

Ding

Guo

et al. 2019

Crystal Growth & Design

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Transformation of a dense metal–organic framework (MOF) to a highly porous form can radically improve its applications in drug loading. In this study, an environmentally friendly synthesis of potassium acetate γ-cyclodextrin metal–organic framework (γ-CD-MOF) in water was identified as a dense crystal form. Importantly, the molecular arrangement of the dense γ-CD-MOF was confirmed by single crystal X-ray diffraction and other characterizations. If the dense γ-CD-MOF was directly dried after separation from the mother solution, it is incapable of loading a model drug. However, the fresh dense crystal could be transformed into a highly porous form by introducing ethanol. The crystal transformation was demonstrated by enhanced drug loading capability and characterizations of powder X-ray diffraction (PXRD), small-angle X-ray scattering (SAXS), and the N2 adsorption isotherm. In all, the crystal transformation from dense to highly porous form could significantly facilitate the applications of γ-CD-MOFs in drug loading and other potential fields.

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Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

CD-MOFs Crystal Transformation from Dense to Highly Porous Form for Efficient Drug Loading

Ding

Guo

et al. 2019

Crystal Growth & Design

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“…These reversibly formed systems display multiple different mechanisms of ligand exchange, including transimination as well as M–L bond cleavage, which suggests they have potential as stimuli-responsive magnets. However, there are far fewer examples of room temperature, high spin Fe(II) helicates, − and especially the larger cage complexes − than their low spin counterparts. Fe-iminopyridyl cages are commonly (if not always) diamagnetic, − in contrast to Fe(II) complexes with other N and O bidentate ligands. − , The strong N–Fe–N coordination that allows the formation of highly complex yet stable cage assemblies also favors low spin Fe(II).…”

Section: Introductionmentioning

confidence: 99%

Small Structural Variations Have Large Effects on the Assembly Properties and Spin State of Room Temperature High Spin Fe(II) Iminopyridine Cages

et al. 2018

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Small changes in steric bulk at the terminus of bis-iminopyridine ligands can effect large changes in the spin state of self-assembled Fe(II)-iminopyridine cage complexes. If the added bulk is properly matched with ligands that are either sufficiently flexible to allow twisted octahedral geometries at the Fe centers or can assemble with unusual mer configurations at the metals, room temperature high spin Fe(II) cages can be synthesized. These complexes maintain their high spin state in solution at low temperatures and have been characterized by X-ray crystallographic and computational methods. The high spin M2L3 meso-helicate and M4L6 cage complexes display longer N–Fe bond distances and larger interligand N–Fe–N bond angles than their diamagnetic counterparts, and these structural changes invert the ligand selectivity in narcissistic self-sorting and accelerate subcomponent exchange rates. The paramagnetic cages can be easily converted to diamagnetic cages by subcomponent exchange under mild conditions, and the intermediates of the exchange process can be visualized in situ by NMR analysis.

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“…Aus der Literatur ist bekannt, dass der Austausch von Azin‐Bausteinen im letzten Teilschritt der Selbstorganisation durch geeignete Azol‐Bausteine eine effektive Möglichkeit darstellt, die Ligandenfeldstärke zu verringern. Eine solche Verringerung der Ligandenfeldstärke kann letztlich zur Stabilisierung des paramagnetischen high‐spin ‐Zustandes in Eisen(II)‐Kationen führen und bei geschickter Feinabstimmung sogar einen Spin‐Crossover‐Prozess ermöglichen [10d,e, 16, 17a,b, 18, 19] …”

Section: Introductionunclassified

Eine Familie von Heterobimetallischen Würfeln zeigt Spin‐Crossover‐Verhalten nahe Raumtemperatur

et al. 2021

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Durch die Verwendung von 4‐(4′‐Pyridyl)anilin als einfachen organischen Baustein in Kombination mit drei verschiedenen Aldehydkomponenten und Metall(II)salzen wurden drei verschiedene Fe8Pt6‐Würfel und ihre entsprechenden Zn8Pt6‐Analoga mit Hilfe des Subkomponenten Selbstorganisationsansatzes hergestellt. Während die Verwendung von Zink(II)‐Salzen zu diamagnetischen Käfigen führte, ergaben Eisen(II)‐Salze metallosupramolekulare Käfige, die in Lösung Spin‐Crossover‐Verhalten zeigen. Die Spin‐Übergangstemperatur T1/2 hängt von der verwendeten Aldehydkomponente ab, wodurch sich ein Baukasten für die gezielte Synthese von Spin‐Crossover‐Verbindungen mit maßgeschneiderten Übergangseigenschaften ergibt. Der Einbau von 4‐Thiazolcarbaldehyd oder N‐Methyl‐2‐Imidazolcarbaldehyd führte zu Käfigen, die bei Raumtemperatur einen Spin‐Crossover durchlaufen, während der mit 1H‐4‐Imidazolcarbaldehyd erhaltene Käfig einen Spin‐Übergang bei niedrigen Temperaturen zeigt. Drei der neuen Aggregate wurden durch Synchrotron‐Röntgenbeugung strukturell charakterisiert und alle Strukturen wurden mittels Massenspektrometrie, NMR und UV/Vis‐Spektroskopie untersucht.

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Metal-center exchange of tetrahedral cages: single crystal to single crystal and spin-crossover properties

Cited by 33 publications

References 41 publications

CD-MOFs Crystal Transformation from Dense to Highly Porous Form for Efficient Drug Loading

CD-MOFs Crystal Transformation from Dense to Highly Porous Form for Efficient Drug Loading

Small Structural Variations Have Large Effects on the Assembly Properties and Spin State of Room Temperature High Spin Fe(II) Iminopyridine Cages

Eine Familie von Heterobimetallischen Würfeln zeigt Spin‐Crossover‐Verhalten nahe Raumtemperatur

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