Grafted metallocalixarenes as single-site surface organometallic catalysts

Justin M Notestein, Enrique Iglesia, Alexander Katz

Research output: Contribution to journalArticle

81 Citations (Scopus)

Abstract

Metallocalixarenes were grafted onto silica using a surface organometallic approach and shown to be active and selective catalysts for epoxidation of alkenes using organic hydroperoxides. Calixarene-TiIV precursors were anchored at surface densities from 0.1 to near-monolayer coverages (0.025-0.25 calixarene nm-2). Several spectroscopic methods independently detected calixarene-TiIV connectivity before and after epoxidation catalysis. Kinetic analyses of cyclohexene epoxidation confirmed that the active sites were anchored on the silica surface and were significantly more active than their homogeneous analogues. The steric bulk and multidentate binding of the calixarenes led to structural stability and to single-site behavior during epoxidation catalysis. Rate constants were independent of surface density for cyclohexene epoxidation with tert-butyl hydroperoxide (11.1 ± 0.3 M -2 s-1) or cumene hydroperoxide (25 ± 2 M -2 s-1). The materials and methods reported here allow the assembly of robust surface organometallic structures in which the active sites behave as isolated species, even near saturation monolayer coverages. In turn, this makes possible the rational design and synthesis of a class of heterogeneous oxide catalysts with atomic-scale precision at the active site.

Original languageEnglish
Pages (from-to)16478-16486
Number of pages9
JournalJournal of the American Chemical Society
Volume126
Issue number50
DOIs
Publication statusPublished - Dec 22 2004

Fingerprint

Calixarenes
Epoxidation
Organometallics
Catalytic Domain
Catalysts
Catalysis
Silicon Dioxide
Monolayers
tert-Butylhydroperoxide
Silica
Alkenes
Oxides
Hydrogen Peroxide
Olefins
Rate constants
Kinetics

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Grafted metallocalixarenes as single-site surface organometallic catalysts. / Notestein, Justin M; Iglesia, Enrique; Katz, Alexander.

In: Journal of the American Chemical Society, Vol. 126, No. 50, 22.12.2004, p. 16478-16486.

Research output: Contribution to journalArticle

Notestein, Justin M ; Iglesia, Enrique ; Katz, Alexander. / Grafted metallocalixarenes as single-site surface organometallic catalysts. In: Journal of the American Chemical Society. 2004 ; Vol. 126, No. 50. pp. 16478-16486.
@article{e4ae093b6ac44e19a4b482cdbe14b5be,
title = "Grafted metallocalixarenes as single-site surface organometallic catalysts",
abstract = "Metallocalixarenes were grafted onto silica using a surface organometallic approach and shown to be active and selective catalysts for epoxidation of alkenes using organic hydroperoxides. Calixarene-TiIV precursors were anchored at surface densities from 0.1 to near-monolayer coverages (0.025-0.25 calixarene nm-2). Several spectroscopic methods independently detected calixarene-TiIV connectivity before and after epoxidation catalysis. Kinetic analyses of cyclohexene epoxidation confirmed that the active sites were anchored on the silica surface and were significantly more active than their homogeneous analogues. The steric bulk and multidentate binding of the calixarenes led to structural stability and to single-site behavior during epoxidation catalysis. Rate constants were independent of surface density for cyclohexene epoxidation with tert-butyl hydroperoxide (11.1 ± 0.3 M -2 s-1) or cumene hydroperoxide (25 ± 2 M -2 s-1). The materials and methods reported here allow the assembly of robust surface organometallic structures in which the active sites behave as isolated species, even near saturation monolayer coverages. In turn, this makes possible the rational design and synthesis of a class of heterogeneous oxide catalysts with atomic-scale precision at the active site.",
author = "Notestein, {Justin M} and Enrique Iglesia and Alexander Katz",
year = "2004",
month = "12",
day = "22",
doi = "10.1021/ja0470259",
language = "English",
volume = "126",
pages = "16478--16486",
journal = "Journal of the American Chemical Society",
issn = "0002-7863",
publisher = "American Chemical Society",
number = "50",

}

TY - JOUR

T1 - Grafted metallocalixarenes as single-site surface organometallic catalysts

AU - Notestein, Justin M

AU - Iglesia, Enrique

AU - Katz, Alexander

PY - 2004/12/22

Y1 - 2004/12/22

N2 - Metallocalixarenes were grafted onto silica using a surface organometallic approach and shown to be active and selective catalysts for epoxidation of alkenes using organic hydroperoxides. Calixarene-TiIV precursors were anchored at surface densities from 0.1 to near-monolayer coverages (0.025-0.25 calixarene nm-2). Several spectroscopic methods independently detected calixarene-TiIV connectivity before and after epoxidation catalysis. Kinetic analyses of cyclohexene epoxidation confirmed that the active sites were anchored on the silica surface and were significantly more active than their homogeneous analogues. The steric bulk and multidentate binding of the calixarenes led to structural stability and to single-site behavior during epoxidation catalysis. Rate constants were independent of surface density for cyclohexene epoxidation with tert-butyl hydroperoxide (11.1 ± 0.3 M -2 s-1) or cumene hydroperoxide (25 ± 2 M -2 s-1). The materials and methods reported here allow the assembly of robust surface organometallic structures in which the active sites behave as isolated species, even near saturation monolayer coverages. In turn, this makes possible the rational design and synthesis of a class of heterogeneous oxide catalysts with atomic-scale precision at the active site.

AB - Metallocalixarenes were grafted onto silica using a surface organometallic approach and shown to be active and selective catalysts for epoxidation of alkenes using organic hydroperoxides. Calixarene-TiIV precursors were anchored at surface densities from 0.1 to near-monolayer coverages (0.025-0.25 calixarene nm-2). Several spectroscopic methods independently detected calixarene-TiIV connectivity before and after epoxidation catalysis. Kinetic analyses of cyclohexene epoxidation confirmed that the active sites were anchored on the silica surface and were significantly more active than their homogeneous analogues. The steric bulk and multidentate binding of the calixarenes led to structural stability and to single-site behavior during epoxidation catalysis. Rate constants were independent of surface density for cyclohexene epoxidation with tert-butyl hydroperoxide (11.1 ± 0.3 M -2 s-1) or cumene hydroperoxide (25 ± 2 M -2 s-1). The materials and methods reported here allow the assembly of robust surface organometallic structures in which the active sites behave as isolated species, even near saturation monolayer coverages. In turn, this makes possible the rational design and synthesis of a class of heterogeneous oxide catalysts with atomic-scale precision at the active site.

UR - http://www.scopus.com/inward/record.url?scp=11444269129&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=11444269129&partnerID=8YFLogxK

U2 - 10.1021/ja0470259

DO - 10.1021/ja0470259

M3 - Article

VL - 126

SP - 16478

EP - 16486

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

SN - 0002-7863

IS - 50

ER -