Self-assembled monolayers on gold and glass substrates are employed as templates to direct the crystal growth and polymorphism of active pharmaceutical ingredients. Orthogonal approaches are used to control polymorphism either through complementary hydrogen-bonding interactions or through repulsive interactions.

"Retinal prostheses are becoming a viable therapy for inner retinal degeneration caused by age related macular degeneration (AMD) and retinitis pigmentosa (RP). The majority of ocular and periocular prosthetic devices employ photodiodes and a microelectrode interface to convert light into a nerve impulse within the retina. Problems with this design include the need of an external power source, the lack of biocompatibility of the microelectrode array, and the need for complicated surgical procedures. Self-assembled monolayer (SAM) technology offers an alternative strategy, where neurons can be stimulated by light activation of a single layer of a photovoltaic SAM. We have developed a SAM structure where the photoexcitable dye 2-[2-[4-(dibutylamino)phenyl]ethenyl]-3-caboxymethylbenzothiazolium bromide (NK5962) was covalently immobilized to an indium tin oxide (ITO) and 3-(aminopropyl) trimethoxysilane (APTMS) surface. The NK562 derivatized surface was characterized through contact angle goniometry, electrochemical impedance spectroscopy, grazing angle infrared spectroscopy, and ultraviolet-visible absorption spectrophotometry. NG108-15 neurons were differentiated onto the surface and neural responses from electrical stimulation and photostimulation of the system were measured using whole-cell current and voltage clamp methodologies. We found an average 2.9 mV decrease in NG108-15 threshold potential for every 10 mV increase in ITO surface potential. Following photostimulation, there was a 1.8±0.2 fold increase (p < 0.05) in the sodium channel current amplitude and a 2.00 ± 0.22 fold increase (p < 0.05 ) in voltage amplitude of NG108-15 neurons on the ITO-APTMS-NK5962 surface due to transfer of energy from the excited dye surface to the attached neurons. The degree of photostimulation decreased upon using 344, 430, and 603 nm optical filters to block increasing amounts of the wavelengths of incident light capable of being absorbed by NK5962. The sodium current amplitude slightly increased at 50% transmittance of incident light relative to 100% transmittance, then sharply decreased at 12.5%, 6.25%, 3.13% transmittance. Upon addition of tetrodotoxin (TTX), sodium channel blockage was observed and portrayed by decreased sodium current and voltage response amplitudes, validating the voltage and current clamp results described above. Our findings indicate that the NK5962 photoelectric film shows promise as an implant for restoring light sensitivity to the retina. "

The purpose of this thesis is to study the InAs self-organized quantum dots and InAs/GaAsN digital alloys. We have studied the optical properties of these structures after rapid thermal annealing. The measured samples are InGaAs/InAs¡BInGaAs/InAlAs/InAs¡BInGaAs/AlAs/InAs quantum dots and InAs/GaAsN short-period superlattice quantum well structures. We have investigated the effect of different strain-reducing layer (SRL) on the photoluminescence (PL) of self-assembled InAs/GaAs quantum dots. From experiments, the coverage layers of Al composition can increase the energy splitting between the ground and first excited states of the quantum dots. It is related to the thickness and composition of the cap layers. Using thick InAlAs and InGaAs together as a SRL results in the energy splitting up to 123meV. However the PL intensity decreases three times. After rapid thermal annealing up to 800¢XC, the QDs with Al-composed cap layer show no shift of peak wavelength. For InAs/GaAsN digital alloys, through temperature dependent PL spectrum, we can observe PL peak has a blue shift form room temperature to 100K, and a red shift from 100K to 10K. It is similar to the InGaAsN quantum well. However, one of the samples shows temperature insensitive for the PL peaks.

The reaction of hydroquinone and 1,12-dibromododecane affords 4-(12-bromo-dodecyloxy)phenol (4, 7% yield). The alkyl bromide (4) was converted to the corresponding thiol with thiourea to afford 4-(12-mercaptododecyloxy)phenol (1) in 52% yield. The reaction of t-butyllithium with 4-bromoanisole followed by reaction with 1-12-dibromododecane affords a mixture of 4-bromoanisole, 1,12-dibromododecane ,and 4-(12-bromododecyl)-anisole (6). Silica gel chromatography resulted in an inseperable mixture of 4-bromoanisole and (6). Reaction of the mixture with BBr3 afforded 4-(12-bromododecyl)phenol (7) in 34% yield. The alkyl bromide (7) was converted to the corresponding thiol with thiourea to afford 4-(12-mercaptododecyl)phenol (2) in 9% yield. Reduction of 16-mercaptohexadecanoic acid with BH3â hTHF afforded 16-mercaptohexadecanol (3) in 53% yield. All new compounds were characterized by ¹H NMR, ¹³C NMR, transmission IR, HRMS, and, where possible, elemental microanalysis. Self-assembled monolayers (SAMs) on gold were prepared using thiols 1, 2, and 3. SAMs were characterized using reflectance-absorbance infrared spectroscopy (RAIRS). Diagnostic vibrational modes were assigned by comparing RAIRS spectra to normal mode frequencies and intensities calculated using DFT methods at the 6-31G* level using commercial software. Water droplet goiniometry found contact angles of 52o, 53o, and 64o for SAMs prepared from 1, 2, and 3, respectively. SAMs of 1 and 2 were found to be hydrophilic. When SAMs prepared from 1, 2, and 3 were silylated with phenyldimethylchlorosilane, the resulting contact angles were 78o, 74o, and 75o respectively. A significant increase in contact angles for silylated SAMs of 1 and 2 indicated facile silanization of the surface hydroxides. RAIRS spectra were also obtained for the functionalized SAMs. Silylated SAMs prepared from 1, 2, and 3 are currently under investigation as models for silica-immobilized metallocene olefin polymerization catalysts. / Master of Science

The cyclic voltammogram of complex 6 shows one successive reversible one-electron redox wave corresponding to the oxidation of the Ruthenium moiety and peak-to-peak separations are smaller than 59 mV(ideal value of one electron transfer with diffusing controlling). In addition, the peak currents are linear to scan rate, i.e., i £\ V. This observation is corresponding to the electrochemical property of SAM, and we would like to suggest that the electron transfer process in the electrochemical measurements is direct controlling. Furthermore, we synthesized a nano-material by using of redox stable Ru(II)-Terpyridyloctanethiol attached to gold cluster (complex 7). The clusters are stable in air, soluble in nonpolar organic solvents and the characters could be examining by traditional chemical instruments such as NMR, UV/Vis, TEM. Finally, complex 7 seif-assembled on gold electrode (complex 8). This observation is corresponding to the electrochemical property of SAM, and we would like to suggest that the electron transfer process in the electrochemical measurements is direct controlling. we would like to suggest that the complex 5 has bi-functionalized property.

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Self-assembled monolayers (SAMs) were investigated with regard to their application as templates to control processes down to the nanometre length scale. With applications of SAM for electrochemical nanotechnology in mind, the range of aspects studied comprises patterning on different length scales, behaviour of SAMs under the conditions of electrochemical metal deposition, and the influence of the head and tail groups on formation and structure of SAMs. On a micrometre scale, laser scanning lithography (LSL) was used to pattern SAM covered Au surfaces. With this technique, localized regions of a SAM are desorbed by scanning the focal spot of a laser beam. Thermal desorption occurs as a result of the high substrate temperature produced by the laser pulses. Patterns with line width as small as 0.9 µm were produced by LSL. It is demonstrated that SAM can not only be patterned by laser radiation but can also be rendered more passive as revealed by electrochemical metal deposition. Such blocking effect is explained by annealing of defects upon irradiation at the appropriate laser energy. This effect can block deposition of bulk copper particles, but does not prevent the underpotential deposition. Based on this passivation effect, large passivation areas can be created, which can be used as substrate for further nano/micro fabrication. The combination of SAM patterning and electrochemical metal deposition was also demonstrated to be an effective way to prepare superhydrophobic surfaces, exhibiting a contact angle of 165° (water droplet). Aiming for the generation of smaller structures, scanning tunneling microscopy (STM) is used as a tool to pattern SAMs. Several phenomena observed in STM based manipulation of SAMs are addressed. The first one is sweeping effect. Deposited metal particles on top of SAM and SAMs are swept by STM tip by choosing appropriate I/V parameters. The closer the tip (higher current, lower bias), the more effective it is. Molecularly resolved images confirm that after sweeping, the scanned area is still covered by SAM molecules. This is explained by diffusion. The sweeping process can be repeated, thus, resulting in a layer by layer etching. The second effect is field-induced desorption. Applying a positive voltage (2.5-5V), a SAM is damaged beneath the area of the tip. The damage depends not only on the bias applied, but also on the current setpoint right before applying the bias. The third effect is nanografting. Nanografting was observed that a SAM having a stronger assembling ability can replace the weaker one (matrix layer) in hexadecane solution by STM scanning under normal I/V parameters combination that are usually used for imaging. It is found that longer chain can replace the shorter chain thiol, alkanethiol can replace biphenyl thiol. This method can be applied to pattern SAM. Defects (punched holes) were created purposely on the SAMs covered Au surface and in situ STM was used to investigate the process of Under-Potential Deposition (UPD) and bulk metal deposition. Bulk metal deposition on punched holes depends on the size. Small scale patterning by punching is sufficient for applications based on UPD but not for bulk metal deposition. Several SAMs assembled on Au(111) surface (1-mercaptoundecanoic acid (MUA), Dodecyl Thiocyanate (C12SCN) and bis(pyrazol-1-yl)pyridine-substituted thiol (bpp-SH) and thiocyanate (bpp-SCN)) were investigated with the aim to expand the type of SAMs that can be used as template for further application, such as metal coordination. High quality thiolate monolayers formed by cleavage of the S-CN bond can be obtained on Au(111). Thus, organothiocyanates appear to be a promising alternative to thiols. Well-ordered MUA monolayers are formed in a few hours at the temperature range of 323-363 K by Physical Vapour Deposition (PVD). Self-assembled monolayers of bpp-SH and bpp-SCN on Au(111)/mica were studied with STM. Preparation conditions such as temperature, solvent, and contamination affect the formation of SAMs on Au(111) much more than other common thiols such as alkanethiols and biphenythiols.

The field of organic-based opto-electronic devices such as organic light- emitting diodes (OLEDs) or field-effect transistors (OFETs) has grown in interest over the past two decades. Optimizing the performance of these applications requires a better understanding of the processes taking place inside the devices and especially at their interfaces. We focused in this Ph.D. work on the electronic structure of metal/organic interfaces where the charge injection mechanism occurs. The latter process can be modulated and fine tuned by the control of the work function of the metallic electrodes. Chemisorption of self-assembled monolayers (SAMs), i.e., a two-dimensional layer of polar molecules deposited onto metal surfaces proves to be an efficient way to tune the work function of electrodes in OLED and OFET devices. However, the role played by the dipole moment of the adsorbed molecules as well as the description of the electronic effects taking place at the metal/SAM interfaces are not yet well understood. Our Ph.D. work aims at rationalizing at a theoretical level (via quantum- chemical calculations) the electronic processes occurring at metal/organic interfaces. For this goal, we focused our investigations on a well-characterized system : a methanethiolated SAM on gold-(111) surface. The adsorption energy and the influence of the anchoring site on the work function shift were evaluated beforehand in order to validate our methodology. The decomposition of the interfacial dipole moment into its interfacial and molecular components was assessed in a second stage for this system following two different procedures which differ by the treatment of the molecular backbone. The incorporation of a third component, generally not treated in an explicit way, was taken into consideration to unify the description of the interface dipole. The influence of the packing density was also described. In a next step, we have extended this study by changing the SAM chemical structure and by investigating the influence of a modification of the anchoring atom, a fluorination of the methyl group and a change in the nature of the metal surface (Ag, Cu, Pt). In order to probe the influence of intermolecular interactions, we have finally considered longer alkanethiol chains having various terminal chemical functions and analyzed the influence of the structural geometry on the change in the electrostatic potential.

We examine the electrochemical properties of SAM of alkanethiols terminated with biferrocenyl group (complex 7) to understand the interactions between metal surface and molecules. The cyclic voltammogram of complex 8 shows two successive reversible one-electron redox waves corresponding to the oxidation of the biferrocenyl moiety and all peak-to-peak separations are smaller than 59 mV (ideal value of one electron transfer with diffusing controlling). In addition, the peak currents are linear to scan rate, i.e., i£\V. This observation is corresponding to the electrochemical property of SAM, and we would like to suggest that the electron transfer process in the electrochemical measurements is direct controlling. Furthermore, we synthesized a nano-material by using of redox stable biferrocenylalkanethiol attached to gold cluster (complex 10). The clusters are stable in air, soluble in nonpolar organic solvents and the characters could be examining by traditional chemical instruments such as NMR, IR, UV/Vis, TEM. The cyclic voltammogram shows that the electron transfer process in the electrochemical measurements is also direct controlling. Finally, the well-known mechanism of intramolecular electron transfer in mixed-valence biferroceniums and the stable biferrocene on Au (111) surface and on gold clusters let to the more advanced concept. We believe that the microstructure of biferrocene assembled on an electrode surface or on gold clusters might enable to carry out a particular function extraordinarily well, for example, optical switch.

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