Role of the Alkali-Metal Cation Size in the Self-Assembly of Polyoxometalate-Monolayer Shells on Gold Nanoparticles

2012 ◽  
Vol 51 (14) ◽  
pp. 7436-7438 ◽  
Author(s):  
Yifeng Wang ◽  
Offer Zeiri ◽  
Shelly Sharet ◽  
Ira A. Weinstock
Keyword(s):  
Gold Nanoparticles ◽  
Alkali Metal ◽  
Metal Cation ◽  
Self Assembly ◽  
Alkali Metal Cation ◽  
The Self ◽  
Cation Size

The self-assembly of some novel [2]rotaxanes and their alkali metal cation complexation

1996 ◽  
pp. 483 ◽  
Author(s):  
Masumi Asakawa ◽  
Peter R. Ashton ◽  
Sayeedha Iqbal ◽  
J. Fraser Stoddart ◽  
Nigel D. Tinker ◽  
...  
Keyword(s):  
Alkali Metal ◽  
Metal Cation ◽  
Self Assembly ◽  
Alkali Metal Cation ◽  
The Self ◽  
Cation Complexation ◽  
Alkali Metal Cation Complexation ◽  
Metal Cation Complexation

The Influence of Alkali Metal Cation Size on the Formation and Dissociation of Crown Ether Fullerene Dimers in Electrospray Mass Spectrometry

2015 ◽  
Vol 120 (1) ◽  
pp. 786-792 ◽  
Author(s):  
Ina D. Kellner ◽  
Marc S. von Gernler ◽  
Manolis D. Tzirakis ◽  
Michael Orfanopoulos ◽  
Thomas Drewello
Keyword(s):  
Mass Spectrometry ◽  
Crown Ether ◽  
Alkali Metal ◽  
Metal Cation ◽  
Electrospray Mass Spectrometry ◽  
Alkali Metal Cation ◽  
Fullerene Dimers ◽  
Cation Size

Influence of alkali metal cations on the photoheterolysis of 9-cyclopropyl-9-fluorenol and the reactivity of the 9-cyclopropyl-9-fluorenyl cation in non-acidic zeolites

2003 ◽  
Vol 81 (6) ◽  
pp. 647-659 ◽  
Author(s):  
Melanie A O'Neill ◽  
Frances L Cozens
Keyword(s):  
Alkali Metal ◽  
Metal Cation ◽  
Diffuse Reflectance ◽  
Bond Cleavage ◽  
Alkali Metal Cation ◽  
Zeolite Framework ◽  
Time Resolved ◽  
Highly Sensitive ◽  
Cation Size ◽  
Acidic Zeolites

Alkali metal cation regulation of carbocation formation and reactivity in non-acidic zeolites is probed using the photoheterolysis reaction of 9-cyclopropyl-9-fluorenol. Nanosecond time-resolved diffuse reflectance is employed to directly observe the 9-cyclopropyl-9-fluorenyl cation as a transient species within the non-acidic zeolites. The efficiency of carbocation formation via photoheterolysis and the dynamics of other reaction pathways available to photoexcited 9-cyclopropyl-9-fluorenol are found to be strongly dependent on the zeolite alkali metal counterion. In particular, the yield of carbocation decreases with increasing counterion size in a manner consistent with the zeolite assisting the excited state C—O bond cleavage via Lewis acid catalysis involving the metal cation. Zeolite encapsulation is also found to modulate the ability of water and methanol to assist photoheterolysis. For instance, the influence of coadsorbed water on the photoheterolysis reaction within zeolites is found to be highly sensitive to the alkali metal cation. The rate constant for intrazeolite decay of the 9-cyclopropyl-9-fluorenyl cation increases significantly as the alkali metal cation size increases and as the Si–Al ratio decreases. These reactivity trends suggest that the intrazeolite decay of the 9-cyclopropyl-9-fluorenyl cation involves nucleophilic addition at the active site [Si-O-Al]– bridges of the zeolite framework. In addition, the reactivity of the 9-cyclopropyl-9-fluorenyl cation within alkali metal zeolites can be regulated by the co-inclusion of reagents such as methanol, water, and 1,1,1,3,3,3-hexafluoro-2-propanol.Key words: cation-exchanged zeolites, 9-cyclopropyl-9-fluorenyl cation, laser photolysis, reactivity.

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