Probe Location within Interfacial Layer of CTAB Reverse Micelle System

To understand the chemistry of the interfacial region of reverse micelles (RM), we studied RM system made with the cationic surfactant cetyltrimethylammonium bromide (CTAB), alkanol cosurfactants dissolved in cyclohexane with water core. Spectroscopic methods, specifically UV-Vis absorption of Coumarin 343 (C343) as a probe molecule, were used to determine basic properties of RM systems. However, the probe location was difficult to determine because the spectrum (absorbance), when dissolved in RM solution, didn’t match the spectra in any of the pure components. Our data suggests that the interfacial layer of RM cannot be thought of behaving only the characteristic of single one of the components; rather, it behaves as a mixture of multiple components with unique characteristics. The interfacial layer appears to have roughly three distinct regions. By combining two components at a time, our data shows that C343 is most likely to reside in the middle or outer interfacial regions, which is surprising because C343 is polar enough that it would be expect to preferentially migrate into the water cor

The Effects of Sugar Osmolytes on Reverse Micelle Systems

Reverse Micelles (RM) are nanoscopic pools of water encapsulated by an amphipathic surfactant molecule that allows the water pool to be suspended in a nonpolar solvent. We use RM systems because they allow for the study of water and dissolved osmolyte interactions in confinement. Gaining an understanding of how sugars interact with water in confinement has significant implications for biological systems. This project seeks to understand the effects of galactose as an osmolyte on the interactions, loading limits, and size of RMs when compared to RMs containing only water and RMs containing glucose. Galactose and glucose have slight structural differences, varying in the position of the hydroxyl group on the fourth carbon of each molecule allowing us to probe the structural nuances that often have large biochemical effects. RMs prepared using the surfactant Docusate Sodium (AOT) and the nonpolar solvent isooctane (2,2,4- trimethylpentane) were made in sizes of w0=5, 10, and 20 where w0 represents the ratio of the concentration of water to the concentration of surfactant ([water]/[surfactant]). The loading limit of galactose in RMs was determined to be less than that of glucose over a range of RM sizes with the highest loading limit found in w0= 10 RMs. RM systems were also analyzed using Dynamic Light Scattering (DLS) to determine the impact of the osmolyte on RM size. We observed a reduction in the size of RMs when loaded with a sugar osmolyte, which we postulate happens because the interaction of the sugar with AOT headgroups disrupts the shape of RMs and causes a change in AOT surface area

Dynamical Behavior of Probe Molecules and Dominant Role of Cosurfactants in Reverse Micelles

Reverse micelles (RM) are nanopools of water surrounded by surfactant molecules in a non-polar solvent. Our studies investigated properties of RM probe molecules in the interfacial boundary between water and non-polar solvents. Reichardt’s dye, a probe molecule, was used to uncover properties of RM. UV/vis spectroscopy of Reichardt’s dye reveals information about polarity and the dye’s approximate residential location and also helps confirm molecular orbital energy diagram. We discovered an interesting phenomenon with Reichardt’s dye in RM. Surprisingly, the UV/vis spectrum of Reicahrdt’s dye in CTAB RM with octanol as a cosurfactant exhibits decreasing absorbance and a blue shift. Reichardt’s dye in solely octanol shows an irreversible color change and similar UV/vis spectrum. Consequently, we conclude that Reichardt’s dye resides near the interfacial layer/solvent boundary. Other cosurfactants do not result in the time dependent behavior suggesting a more dynamic interaction between octanol and Reichardt’s dye

Investigating Sucrose and D-trehalose in AOT Reverse Micelles

Reverse micelles are nanosized structures that encapsulate small water pools and allow us to investigate the fundamental interactions of small organic molecules in nanoconfinement. The behavior of small organic molecules, sometimes referred to as osmolytes, differs in bulk solution and confinement. Because reverse micelles are a good model for biological nanoconfinement, investigating osmolytes in reverse micelle systems can help us to better understand the role they play in biological systems. Optical spectroscopy such as UV-Vis, Fluorescence, and Red Edge Excitation (REES) was used to probe the environment of the reverse micelles. Three small organic molecules were studied: a monosaccharide, d-glucose, and two disaccharides, d-trehalose and sucrose. Spectroscopy results indicate that nanoconfinement affects the interactions had by the osmolytes. Dynamic Light Scattering was used to determine the size of the reverse micelles. Size data results suggest that size increases as w0 increases, and as the concentration of saccharide added decreases, the variability of size increases

Investigating the effects of the Sugar Alcohol Osmolytes Glycerol and Erythritol in AOT Reverse Micelles

Water is a polar molecule that participates in hydrogen bonding and proton transfer. Geometric confinement and water’s interactions with osmolytes (small water soluble compounds) affect the ability of water molecules to hydrogen bond and transfer charges. Study of this behaviour of water with different osmolytes in controlled environments will help us develop predictive models. In our study, we have prepared Sodium bis(2-ethylhexyl)sulfosuccinate (AOT) reverse micelles (RM) in 2,2,4-Trimethylpentane (Isooctane). Our principle osmolytes were the straight chain sugar alcohols glycerol and erythritol. Study of water-osmolyte behaviour in the small and confined pool of a reverse micelle allows us examine the difference in water-osmolyte interaction in nanoscopic solution as compared to bulk solution. Additionally, we also aim to explore the effects of glycerol and erythritol in the stability of AOT reverse micelles

Dynamical Behavior of Probe Molecules and Dominant Role of Cosurfactants in Reverse Micelles

Reverse micelles (RM) are nanopools of water surrounded by surfactant molecules in a non-polar solvent. Our studies investigated properties of RM probe molecules in the interfacial boundary between water and non-polar solvents. Reichardt’s dye, a probe molecule, was used to uncover properties of RM. UV/vis spectroscopy of Reichardt’s dye reveals information about polarity and the dye’s approximate residential location and also helps confirm molecular orbital energy diagram. We discovered an interesting phenomenon with Reichardt’s dye in RM. Surprisingly, the UV/vis spectrum of Reicahrdt’s dye in CTAB RM with octanol as a cosurfactant exhibits decreasing absorbance and a blue shift. Reichardt’s dye in solely octanol shows an irreversible color change and similar UV/vis spectrum. Consequently, we conclude that Reichardt’s dye resides near the interfacial layer/solvent boundary. Other cosurfactants do not result in the time dependent behavior suggesting a more dynamic interaction between octanol and Reichardt’s dye

Ultra-high vibrational and rotational motion of the HF molecule via Infrared (IR) laser excitation

Our goals this summer were to build on previous work in our group modeling ultra-high vibrational and rotational excitation in small molecules via unique pulse sequencing of an infrared (IR) laser. The system was modeled both using Fortran and Mathematica as programming languages. We were able to demonstrate that different numerical techniques for propagating coupled differential equations forward in time led to equivalent levels of vibrational excitation and allowed for identical visualization of molecular state probabilities as a function of time. Work including the rotational motion progressed to the point of being able to see both significant excitation when rotations are included as well as leaking into neighboring rotational states as expected. Much work remains to be done before a full analysis of the rotational excitation can be completed

Impact of Urea on Size and Red-Edge Emission Spectroscopy of Reverse Micelles

We use reverse micelles (RMs) as our model system to study the impact of osmolytes on water at the nanoscale. Reverse micelles are characterized by w0 = [polar component]/[surfactant]. In our experiment, we focus on 5 different w0 (w0 = 1, 5, 10, 20, 40) and 3 concentrations of urea (0.5M, 1M, 2M). The Dynamic Light Scattering (DLS) illustrates a linear relationship between reverse w0 (the ratio) and size. Additionally, the DLS data indicates that the impact of osmolytes on size for small reverse micelles is not significant. Furthermore, Red-Edge Emission Spectroscopy shows a bigger impact on emission for smaller reverse micelles compared to the larger w0 samples

Mentoring Strategies To Recruit and Advance Women in Science and Engineering

Supporting faculty with professional development resources at all career stages is vital to the success of faculty members, their students, and academic institutions. In science and engineering fields where women are underrepresented, practices that promote career advancement, such as formal and informal mentoring programs, can be effective in both increasing the visibility and numbers of senior women and also encouraging female students to pursue technical majors and careers. A symposium at the March 2010 National Meeting of the American Chemical Society will feature an array of successful mechanisms for enhancing the leadership, visibility, and recognition of women faculty members using various mentoring strategies. Supporting faculty with professional development resources at all career stages is vital to the success of faculty members, their students, and academic institutions. In science and engineering fields where women are underrepresented, practices that promote career advancement, such as formal and informal mentoring programs, can be effective in both increasing the visibility and numbers of senior women and also encouraging female students to pursue technical majors and careers. A symposium at the March 2010 National Meeting of the American Chemical Society will feature an array of successful mechanisms for enhancing the leadership, visibility, and recognition of women faculty members using various mentoring strategies

Development of a Horizontal Peer Mentoring Network for Senior Women Chemists and Physicists at Liberal Arts Colleges

Our research project focuses on the distinctive environments of undergraduate liberal arts institutions and the challenges faced by senior women faculty on these campuses to attain leadership roles and professional recognition. The project involves the formation of five-member alliances of senior women faculty members at different institutions for the purpose of -€œhorizontal mentoring.-€ Three of the alliances are comprised of full professors of chemistry, the fourth involves full professors of physics. We have formed these alliances to test a -€œhorizontal mentoring strategy-€ that aims to enhance the leadership, visibility, and recognition of participating faculty members. Alliance members participate in discussions, workshops, and activities focused on career and leadership development through periodic gatherings of alliance members at various locations across the country and through electronic communication via online collaboration tools. The alliances are networked to augment the peer-support structure with a larger cohort of senior women scientists. Outreach activities on home campuses extend the impact of the career development expertise attained by project participants. This NSF-ADVANCE-PAID project is also working to identify and create resources that address career development issues for senior women at liberal arts institutions and disseminate best practices on horizontal mentoring strategies for academic women. We have explored how our institutional structure and culture can profoundly influence the career challenges of academic women and how our mentoring strategy can operate particularly effectively for women from liberal arts colleges