Chemistry & Biochemistry Colloquium | Two stories: Chemical Reactions in Atto-Liter Reactors and Self-Organizing Receptors and Sensors for Phosphate Anions , April 3

The Chemistry & Biochemistry colloquium series presents Pavel Anzenbacher discussing "Two stories: Chemical Reactions in Atto-Liter Reactors and Self-Organizing Receptors and Sensors for Phosphate Anions" on April 3 from 4:10 to 5:05 p.m. in Walter 135.

Anzenbacher is Professor in the Center for Photochemical Sciences at Bowling Green University.

The host is Eric Masson.

Abstract: Some syntheses are too costly, or the products might be too dangerous to produce on a larger scale. Unfortunately, practical small-molecule chemistry on an attomole scale (<10 ^-19 mol) is very challenging. Very small reaction vessels are required to circumvent problems associated with running the reactions in high dilution. Suppose that the average concentrations useful for chemical reactions (10 ^-3 -10 ^-5 M) will be used. To perform such reaction on atto-mole scale, the reaction volumes and corresponding dimensions of reaction vessels must dramatically decrease, perhaps to atto-Liter volumes. Here, we will discuss the possibility of a simple materials science method(s) that could make it possible to perform chemical reactions on ultra-small scales and present examples from the realm of organic chemistry that can be run in this manner. Emphasis will be given to reactions that yield fluorescent compounds because such compounds allow us to visualize the formation of the products and can also be used as fluorescence-based chemical sensors.

Chemical sensors generate analyte-specific information from binding and signal transduction events. In the past, the leading theory for the design of receptors and corresponding sensors was the lock & key theory proposed by Fischer, inspired by the specific interaction between the enzymes and substrates, or, in this case, a receptor (sensor) and an analyte. This approach, while perhaps the most appropriate for sensing analytes of strategic importance or analytes present at exceedingly low concentrations, has one key limitation: Each analyte requires a selective sensor (“one-for-one limitation”). To overcome this limitation and the hardship associated with the design and synthesis of selective sensors, array-based sensors comprising multiple cross-reactive (less selective) sensor elements are used. Conventional wisdom suggests that such arrays, because of the “lower recognition quality (selectivity)” of the sensors, should be composed of a larger number of such sensors forming the array. In this presentation, we will examine if this assumption is correct and what might be the avenues to escape the “one-for-one” limitation. Specifically, we will examine methods for the design of a sensor capable of differentiation of many phosphate-type analytes, whether these analytes are defined as different compounds, different concentrations of the same compound, or perhaps different proportions of compounds in the mixture.