Spherical octanuclear clusters in a Na–Ln–dipic system – encapsulation of a nitrate ion and incorporation of water nonamers and dodecamers

Elahi, Syed Meheboob; Rajasekharan, Melath V.

doi:10.1039/c5ce00843c

Cited by 3 publications

(4 citation statements)

References 63 publications

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“…The chemistry of Na + in this context differs significantly from the other alkali ions. Crystallisation at ambient temperature under careful control of pH leads to the hexagonal form containing a Ce 2 Na 6 12+ spherical cluster, while below 10 ° C a triclinic modification ( 2 ) is obtained. In the case of Na/Nd as well as Na/Gd ( 7 ) only the triclinic form is obtained irrespective of the temperature of crystallisation.…”

Section: Resultsmentioning

confidence: 99%

“…Na/(Ce−Dy) formed an isomorphous triclinic series. In addition, an hexagonal form was also detected depending on crystallization conditions which form was fully characterized only very recently . During the intervening period, a few more studies on Na 3 Ln (dipic) 3 ⋅ x H 2 O,– Cs 3 Ln (dipic) 3 ⋅ x H 2 O– and Na Ln (dipic) 2 (H 2 O) 3 ⋅ x H 2 O have been reported.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, an hexagonal form was also detected depending on crystallization conditions which form was fully characterized only very recently. [9] During the intervening period, a few more studies on Na 3 Ln(dipic) 3 ·xH 2 O, [10a-e] Cs 3 Ln(dipic) 3 ·xH 2 O [10a, f-g] and NaLn(dipic) 2 (H 2 O) 3 ·xH 2 O [11] have been reported. The present work deals with the whole series from Li to Cs and presents the following s-4 f network compounds: […”

Section: Introductionmentioning

confidence: 99%

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Alkali Ion - Ce³⁺- DipicH₂System : Coordination Networks and Water Clusters.

Elahi

Rajasekharan

2016

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Heterometallic coordination polymers having the general formula [A3(H2O)nCe(dipic)3]⋅mH2O, where A denotes an alkali metal ion (Li–Cs), have been obtained by reacting an aqueous solution of Ce(NO3)3⋅6H2O with alkali hydroxides in presence of dipicH2. Ce(dipic)33– ion functions as a metallo‐ligand by linking the alkali ions. While the lightest alkali ion forms a 2D coordination network (1, n=6, m=3), all others form 3D networks (Na: 2, n=8, m=7; K: 3, n=9, m=3; Rb: 4 and 5, n=6, m=2; Cs: 6, n=6, m=3). The structure of compound 2 was inferred from the isomorphous Na−Gd compound (7) which formed better quality crystals. Remarkably, both Na and K networks are built around alkali ion‐water chains. In the case of the three lighter alkali ions, the lattice water molecules are assembled into water clusters: tetramer (Li); acyclic heptamer (Na); water tape (K). X‐ray powder diffraction studies show that the hydrated structures could be regenerated by exposure of the dehydrated samples to moisture in the case of Li, Na and K, but not for Rb and Cs.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Alkali Ion - Ce³⁺- DipicH₂System : Coordination Networks and Water Clusters.

Elahi

Rajasekharan

2016

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“…We have recently demonstrated examples of catalysis using an octanuclear, approximately cubic, M 8 L 12 coordination cage host denoted H or H w , depending on external substituents ( Figure 1) [10,[28][29][30], which in water binds a wide range of hydrophobic guests in the central cavity, driven principally by the hydrophobic effect [31][32][33]. We note that a diverse range of octanuclear cages with the capacity to bind guests in the cavity is known [34][35][36][37]. The basis of guest binding in our hosts H/H w in solution is well understood to the extent that we have developed a reliable predictive model for quantifying the guest binding free energies [38,39].…”

Section: Introductionmentioning

confidence: 99%

Catalysis of an Aldol Condensation Using a Coordination Cage

et al. 2020

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The aldol condensation of indane-1,3-dione (ID) to give 'bindone' in water is catalysed by an M 8 L 12 cubic coordination cage (H w ). The absolute rate of reaction is slow under weakly acidic conditions (pH 3-4), but in the absence of a catalyst it is undetectable. In water, the binding constant of ID in the cavity of H w is ca. 2.4 (±1.2) × 10 3 M −1 , giving a ∆G for the binding of −19.3 (±1.2) kJ mol −1 . The crystal structure of the complex revealed the presence of two molecules of the guest ID stacked inside the cavity, giving a packing coefficient of 74% as well as another molecule hydrogen-bonded to the cage's exterior surface. We suggest that the catalysis occurs due to the stabilisation of the enolate anion of ID by the 16+ surface of the cage, which also attracts molecules of neutral ID to the surface because of its hydrophobicity. The cage, therefore, brings together neutral ID and its enolate anion via two different interactions to catalyse the reaction, which-as the control experiments show-occurs at the exterior surface of the cage and not inside the cage cavity.

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