Physical Chemistry

"Physical chemistry is the study of how matter behaves on a molecular and atomic level and how chemical reactions occur."

American Chemical Society

Physical session has been scheduled for  Tuesday Afternoon.

If you find any errors in our listing please let us know at chemistrybuffalogss@gmail.com

Tuesday Afternoon

Session 5B - Room NSC 218 - Moderator: Julia Bulmahn

1:20 p.m. - 1:40 p.m.

Colorimetric Analysis of Sonicator Homogeneity using Imine Sonochemistry  

Eric Sylvester, Muhammad Usmani, Travis Mitchell, Jason Benedict 

The State University of New York at Buffalo, Department of Chemistry

Sonochemistry, a newly recognized subcategory of mechanochemistry, has been popularized as an efficient and green alternative to many traditional chemical reactions. This includes high throughput co-crystallization using a floating foam rack that allows for multiple sonochemical reactions to proceed simultaneously. However, the placement of the vials relative to different positions of the sonicator bath has not been specified or noted in significance in past literature. We proposed a new colorimetric analysis using the floating foam rack method and sonochemical imine formation to allow for a visual confirmation of the homogeneity of any sonicator bath. 

1:40 p.m. - 2:00 p.m.

Comparative Studies of Organic/Water Mixtures on Solid/Liquid Interface Using Sum-Frequency Generation 

Thomas Bui, Kyle Banecker, Luis Velarde  

The State University of New York at Buffalo, Department of Chemistry

Acetone/water binary mixture on fused quartz was probed at the liquid/solid interface as a chromatographic model system and compared with the predominant solvent acetonitrile/water for separation techniques to examine structural orientation of bulk liquid layers using sum-frequency generation. Acetonitrile is a highly used solvent in hydrophilic interaction liquid chromatography, but acetone is a more attractive solvent due to the low-cost, easy waste maintenance and non-toxic, and shown to perform similar separations as acetonitrile. As simple as these molecules are there is no definite explanation for the retention mechanism of these solvents, but a consensus that analytes partition between the enriched-organic layer and enriched water-layer, so chemistry at the surface may shine light on the controversy. Due to the strict selection rules of non-linear vibrational sum frequency generation, this spectroscopic technique is capable of studying buried molecular structures at the interface while excluding interferences from the bulk media, making this technique surface selective and ideal to study these bulk systems. 

2:00 p.m. - 2:20 p.m.

The Design and Synthesis of Photoswitchable Crystalline materials utilizing Halogen bonding  

Zoe Marr, Travis Mitchell, Xiaotang Zhang, Jason Benedict 

The State University of New York at Buffalo, Department of Chemistry

Halogen bonding, a non-covalent interaction analogous to hydrogen bonding, occurs when the electrophilic region on a halogen bonds to a nucleophilic region on another atom. In crystal engineering, halogen bonding has been used tune and control supramolecular assembly processes in the solid state. The goal of this research is to co-crystalize diarylethenes (DAEs), a class of photochromic molecules, with halogen bond donor/acceptor conformers in order to investigate how changing the local environment affects supramolecular assembly of the DAE and the coformer in the solid state as well as potential impacts on the photophysical properties of the DAEs. Based on previously produced photoactive co-crystals, the hydrogen acceptors were systematically replaced by halogens (I, Br, Cl, and F) to make halogen bonded co-crystals. Using a combination of X-ray charge density analysis-quantum crystallography and solid-state spectroscopy, we hope that these fundamental studies will provide new insights into the role of halogen bonds in the structure and properties of photoactive co-crystals. 

2:20 pm - 2:40 p.m.

Investigating the Interactions of Carbamate Insecticides with Environmental Surfaces via Sum-Frequency Generation Spectroscopy   

Jerry Cartagena, Pablo Videla, Amendra Fernando, Victor Batista, Leander Bromley III, Luis Velarde 

The State University of New York at Buffalo, Department of Chemistry

The latest United States Environmental Protection Agency (EPA) investigation on domestic pesticide usage, from 2007, reports that over 1 billion pounds of pesticides are used in the country every year (EPA Report, 2011). Some of the most significant occurrences of groundwater contamination have been related to carbamate pesticides used for agriculture and household applications. However, little is known about how interactions of these molecules with mineral surfaces may affect the fate and transport of these type of pesticides in the environment. By combining the capabilities of sum frequency generation vibrational spectroscopy (SFG-VS) and density functional theory (DFT) we determine the interfacial interactions that regulate the binding mechanisms and surface orientation of carbaryl and propoxur, two common carbamate pesticides. The surface silanols play an important role on pesticide binding through the N-H group of the carbamate moiety. An analysis by phase-resolved SFG reveals the absolute orientation of these pollutants, supporting the SFG homodyne and DFT results. Due to differences in molecular structure between propoxur and carbaryl, the latter shows aggregation behavior. The findings of this investigation will impact our understanding on how carbamates interact at mineral surface environments and how these interactions might influence their surface orientation, and potentially its environmental fate. 

2:40 p.m. - 3:00 p.m.

A new approach to photoactive crystalline systems: Fists of Furyl  

Shea Myers, Travis Mitchell, Jason Benedict 

The State University of New York at Buffalo, Department of Chemistry

Diarylethene based photoswitches have garnered a lot of attention in recent literature as they often exhibit superb thermal-stability and fatigue resistance. These properties make them worth investigating as candidates for use in photoswitchable materials designed for many different applications such as molecular devices, bioimaging, targeted drug delivery, and memory storage. The vast majority of reports examine the photophysical properties of these molecules exclusively in solution. Understanding how this important class of photoswitches behaves in solid state systems such as Metal-Organic Frameworks (MOFs) and co-crystals is critical to the pursuit of photoswitchable materials 'by design'. The design and characterization of several novel diarylethene based photoswitches and subsequent attempts to produce photoactive crystalline solids will be discussed.