Novel mesoporous organosilicas containing size-selective micropores from covalently bound calixcrowns

Liu, Chunqing; Lambert, Joseph B.; Fu, Lei

doi:10.1039/b315943d

Cited by 12 publications

(6 citation statements)

References 27 publications

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“…Elemental analysis for carbon and nitrogen as indicators for the implemented organic functionality revealed ca. 1.1 mmol of urea groups per 1 g of UreaMS, which is in the same order of magnitude as for other functionalized materials designed for metal-ion adsorption. ,,,, The experimental C/N ratio (3.0) is virtually the same as theoretically expected for the bis-urea residue (2.6).…”

Section: Resultssupporting

confidence: 64%

Urea-Containing Mesoporous Silica for the Adsorption of Fe(III) Cations

et al. 2006

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A urea-containing mesoporous silica with intraframework urea groups (UreaMS) was synthesized via a surfactant-templated route by co-condensation of an organosilane precursor and tetraethoxysilane. The material possesses hexagonal pores with a high degree of uniformity and shows long-range order as confirmed by the measurement of powder X-ray diffraction and N2 adsorption isotherms. A detailed characterization by chemical analysis, 29Si MAS NMR, X-ray photoelectron spectroscopy, thermogravimetric analysis, and FT-IR spectroscopy confirmed the integrity of urea groups inside the walls of the material. The results revealed a density of one urea group per ca. 13−16 silicon atoms. The efficiency of UreaMS for the adsorption of Fe(III) cations was tested. A distribution coefficient of K d = 700 mL g-1 and an adsorption capacity of 0.19 mmol g-1 were determined. X-ray photoelectron spectroscopy confirmed the conservation of the oxidation state +3 for the iron within the mesoporous silica material.

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Section: Resultssupporting

confidence: 64%

Urea-Containing Mesoporous Silica for the Adsorption of Fe(III) Cations

et al. 2006

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“…72). 291 With these materials, high uptake extraction of Cs + ions from water with high selectivity could be performed. These synthetic materials are potentially useful for a wide variety of applications, which require the selective binding of Cs + ions, e.g.…”

Section: Molecular Recognition With Nanostructured Materialsmentioning

confidence: 99%

Molecular recognition: from solution science to nano/materials technology

Ariga¹,

Itô²,

Hill³

et al. 2012

Chem. Soc. Rev.

401

188

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In the 25 years since its Nobel Prize in chemistry, supramolecular chemistry based on molecular recognition has been paid much attention in scientific and technological fields. Nanotechnology and the related areas seek breakthrough methods of nanofabrication based on rational organization through assembly of constituent molecules. Advanced biochemistry, medical applications, and environmental and energy technologies also depend on the importance of specific interactions between molecules. In those current fields, molecular recognition is now being re-evaluated. In this review, we re-examine current trends in molecular recognition from the viewpoint of the surrounding media, that is (i) the solution phase for development of basic science and molecular design advances; (ii) at nano/materials interfaces for emerging technologies and applications. The first section of this review includes molecular recognition frontiers, receptor design based on combinatorial approaches, organic capsule receptors, metallo-capsule receptors, helical receptors, dendrimer receptors, and the future design of receptor architectures. The following section summarizes topics related to molecular recognition at interfaces including fundamentals of molecular recognition, sensing and detection, structure formation, molecular machines, molecular recognition involving polymers and related materials, and molecular recognition processes in nanostructured materials.

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“…Solvent extraction using complexing agents such as crown ethers and calixarenes have been tested; however, their resistance to ionizing radiation is suspect. 3,4 Natural clays, micas, and zeolites like clinoptilolite have been shown to possess ionexchange capabilities and can be highly selective and thermally stable but can deteriorate due to dissolution of silicon and aluminum in highly alkaline or acidic solutions. [5][6][7] Crystalline antimonic acids, microporous tungstates, and mixed metal antimonates have also received attention for their ion-exchange capabilities and potential uses in waste remediation.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of Protonated Zirconium Trisilicate and Its Exchange Phases with Strontium

Fewox

Clearfield

2008

J. Phys. Chem. A

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A partially protonated form of the mineral umbite has been prepared by ion exchange of K2ZrSi3O9 x H2O with acetic acid. The protonated phase, compound 1, is assigned the formula H1.45K0.55ZrSi3O9 x 2 H2O and crystallizes in the space group P2(1)/c with unit cell dimensions of a = 7.1002(2), b = 10.1163(3), c = 13.1742(5), and beta = 91.181(1) degrees. The characteristic building blocks of the acid phase are almost identical to those of the parent compound. The framework is composed of polymeric chains of trisilicate groups linked by zirconium atoms, resulting in zeolite-type channels. When viewed down the a axis, two unique ion-exchange channels can be seen. Site 1 is marked by a 12-membered ring and contains 2 cations. Site 2, a 16-membered ring, contains 4 water molecules. Compound 2, consists of a mixed Sr2+ and K+ phase synthesized from 1 by ion exchange with Sr(NO3)2. Compound 2 has the formula K0.34Sr0.83ZrSi3O9 x 1.8 H2O and crystallizes in the same space group P2(1)/c. It has cell dimensions of a = 7.1386(3), b = 10.2304(4), c = 13.1522(4), and beta = 90.222(1) degrees. The Sr2+ cations are distributed evenly among the two exchange sites, showing no preference for either cavity. Compound 3 is the fully substituted Sr phase, SrZrSi3O9 x 2 H2O, and retains the same space group as that of the previous two compounds having unit cell dimensions of a = 7.1425(5), b = 10.2108(8), c = 13.0693(6), and beta = 90.283(1) degrees. The strontium cations show a slight affinity for ion-exchange site 2, having a higher occupancy of 0.535, while site 1 is occupied by the remainder of the Sr2+ cations with an occupancy of 0.465. Batch uptake studies demonstrate a selectivity series among alkaline earth cations of Ba2+ > Sr2+ > Ca2+ > Mg2+.

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Novel mesoporous organosilicas containing size-selective micropores from covalently bound calixcrowns

Cited by 12 publications

References 27 publications

Urea-Containing Mesoporous Silica for the Adsorption of Fe(III) Cations

Urea-Containing Mesoporous Silica for the Adsorption of Fe(III) Cations

Molecular recognition: from solution science to nano/materials technology

Synthesis and Characterization of Protonated Zirconium Trisilicate and Its Exchange Phases with Strontium

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