Date of Award

Summer 2012

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Chemistry & Biochemistry

Program/Concentration

Chemistry

Committee Director

lasubramanian Ramjee

Committee Member

Kenneth G. Brown

Committee Member

John B. Cooper

Committee Member

Jennifer Poutsma

Call Number for Print

Special Collections LD4331.C45 S42 2012

Abstract

One main objective of the present work is to functionalize cuboctahedral platinum nanoparticles with various multidentate resorcinarene surfactants and study their influence in determining their catalytic activity. We hypothesized that catalytically active and recyclable catalysts can be achieved by incomplete yet strong passivation of the nanoparticle surfaces by using multidentate resorcinarene surfactants. We have developed phase transfer protocols for functionalizing cuboctahedral platinum nanoparticles with resorcinarene thiol or amine. Fluorescence assay confirmed that both these nanoparticles contained almost comparable unpassivated metal area. The activity of such phase transferred nanoparticles was tested in the catalytic hydrogenation of allyl alcohol. The conversion of ally! alcohol to propanol depended on both the nature and concentration of the stabilizing resorcmarene surfactant. While nanoparticles passivated with resorcinarene amine led to almost quantitative conversion under certain conditions, up to 58% conversion could be obtained even with resorcinarene thiol stabilized Pt nanoparticles. In the presence of excess surfactants, no changes in the size and shape of the nanoparticles were observed after catalysis. On the other hand, TEM analysis after catalysis showed that in the absence of excess surfactant, resorcinarene thiol stabilized nanoparticles were stable, while resorcinarene amine stabilized nanoparticles were substantially aggregated. Overall, these results indicate that resorcinarene thiol can substantially increase the stability and hence the reusability of the nanoparticles without compromising on their catalytic activity.

Nanodiamonds have attracted lot of attention in recent years. However, their dispersion stabilization, or lack thereof, poses major limitations on their applications. Though covalent functionalization approaches have been developed to disperse nanodiamonds in non-polar organic solvents, there are certain inherent disadvantages. This work shows that resorcinarene amine surfactant can extract nanodiamonds of different sizes and shapes from aqueous to organic layer. Control experiments showed that both resorcinarene skeleton and amine groups are necessary for the extraction. Based on infrared spectroscopic analysis, we believe that these nanodiamonds are electrostatically stabilized by the resorcinarene amine surfactant. We in collaboration with Dr. Albin's group have showed that such resorcinarene surfactant stabilized nanodiamond dispersions can act as superior nucleation seeds for diamond film growth by chemical vapor deposition method.

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DOI

10.25777/g5v0-d993

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