Title page for ETD etd-060105-145235

Document Type thesis

Author Name Purohit, Nipa S

URN etd-060105-145235

Title Non-covalent Assembly of Reversible Photoswitchable Surfaces

Degree MS

Department Chemistry & Biochemistry

Advisors
Dr. W. Grant Mcgimpsey, Advisor

Keywords
multilayers
mixed monolayers

Date of Presentation/Defense 2005-05-11

Availability unrestricted

Abstract
Previous studies carried out in our laboratory resulted in the development of noncovalently
assembled multilayered thin films incorporating metal ions such as Cu(II) and
organic ligands including dicarboxypyridine. In one study, a SAM consisting of 4-[(10-
mercaptodecyl)oxy]pyridine-2,6-dicarboxylic acid was deposited on gold. The pyridine
group was then used to complex a layer of Cu(II) ions which in turn were capped by cis-
2,2’-dipyridylethylene. This stilbene analog undergoes photoinduced cis-trans
isomerization on the surface resulting in a substantial increase in the hydrophilicity of the
surface leading to the possibility of creating virtual microfluidic valves and pumps.
However, the photoswitchable wettability was irreversible. Stilbene-4,4-dicarboxylic acid
was the ligand selected for generating a reversible system. The decision to use this
stilbene moiety was based on molecular modeling and the commercial availability of both
cis and trans forms. When 4-[(10-mercaptodecyl)oxy]pyridine-2,6-dicarboxylic acid was
used as SAM, the stilbene-4,4’-dicarboxylic acid did not undergo photoisomerization.
Prolonged irradiation leads to photodegradation of film. A mixed SAM of dodecanethiol
and mercaptoundecanoic acid was used to create space on the surface and facilitate
isomerization. But cis-trans isomerization of the stilbene moiety was not achieved by this
system. When a mixed SAM of 4-[(10-mercaptodecyl)oxy]pyridine-2,6-dicarboxylic acid
and 4-tert butylbenzenethiol was used, stilbene-4,4-dicarboxylic acid showed reversible
photoinduced cis-trans isomerization for one complete cycle leading to a reversible
change in wettability. After one cycle of isomerization the film photodegrades.

Files
npurohit.pdf

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Document Type	thesis
Author Name	Purohit, Nipa S
URN	etd-060105-145235
Title	Non-covalent Assembly of Reversible Photoswitchable Surfaces
Degree	MS
Department	Chemistry & Biochemistry
Advisors	Dr. W. Grant Mcgimpsey, Advisor
Keywords	multilayers mixed monolayers
Date of Presentation/Defense	2005-05-11
Availability	unrestricted
Abstract Previous studies carried out in our laboratory resulted in the development of noncovalently assembled multilayered thin films incorporating metal ions such as Cu(II) and organic ligands including dicarboxypyridine. In one study, a SAM consisting of 4-[(10- mercaptodecyl)oxy]pyridine-2,6-dicarboxylic acid was deposited on gold. The pyridine group was then used to complex a layer of Cu(II) ions which in turn were capped by cis- 2,2’-dipyridylethylene. This stilbene analog undergoes photoinduced cis-trans isomerization on the surface resulting in a substantial increase in the hydrophilicity of the surface leading to the possibility of creating virtual microfluidic valves and pumps. However, the photoswitchable wettability was irreversible. Stilbene-4,4-dicarboxylic acid was the ligand selected for generating a reversible system. The decision to use this stilbene moiety was based on molecular modeling and the commercial availability of both cis and trans forms. When 4-[(10-mercaptodecyl)oxy]pyridine-2,6-dicarboxylic acid was used as SAM, the stilbene-4,4’-dicarboxylic acid did not undergo photoisomerization. Prolonged irradiation leads to photodegradation of film. A mixed SAM of dodecanethiol and mercaptoundecanoic acid was used to create space on the surface and facilitate isomerization. But cis-trans isomerization of the stilbene moiety was not achieved by this system. When a mixed SAM of 4-[(10-mercaptodecyl)oxy]pyridine-2,6-dicarboxylic acid and 4-tert butylbenzenethiol was used, stilbene-4,4-dicarboxylic acid showed reversible photoinduced cis-trans isomerization for one complete cycle leading to a reversible change in wettability. After one cycle of isomerization the film photodegrades.
Files	npurohit.pdf