Summary of Current Research

1. Biphenyl and Terphenyl “Smart” Biaryls: Dihedral Angle Modulation via pH and Redox conditions

In this project we are synthesizing and studying bridged biphenyls and terphenyls. The goal is to understand if we can control dihedral angle reversibly and whether or not there is some distinguishable output depending on the dihedral angle of the biphenyl. By dihedral angle, we mean the angle between the two phenyl rings with the single bond as an axis.  Fluorescence, color, and conductance are highly dependent on the dihedral angle of biphenyl compounds. 

We are primarily interested in the synthesis and study of the fundamental properties of these compounds. However, these “Smart” Biaryls could be useful broadly as sensors, molecular electronic components, molecular machines and in other nanoscience applications.  There are several possible “bridged” compounds in which the dihedral angle could be modulated.

This work has been supported by the ACS-PRF and the Research Corporation for Scientific Advancement. Currently it is supported by the UWEC Blugold Differential and the Wisconsin Alliance for Minority Participation.

Publications:

Dressler, Justin J.; Charlesworth-Seiler, Eva M.; Dahl, Bart J.* “Synthesis of a Triethylene Glycol-Capped Benzo[1,2-c:4,5-c']bis[2]benzopyran-5,12-dione: A Highly Soluble Dilactone-Bridged p-Terphenyl with a Crankshaft Architecture.” Tetrahedron Lett. 2020, 61, 152429. link

Dressler, Justin J.; Miller, Sarah, A.; Meeuwsen, Brian T.; Riel, Asia Marie S.; Dahl, Bart J.* “Synthesis of Dilactone Bridged Terphenyls with Crankshaft Architectures.” Tetrahedron 2015, 71, 283-292. link

Carlson, Erik J.; Riel, Asia Marie S.; Dahl, Bart J.* “Donor-Acceptor Biaryl Lactones: pH Induced Molecular Switches with Intramolecular Charge Transfer Modulation.” Tetrahedron Lett. 2012, 53, 6245-6249. link

2. Soluble Ladder and Star-Type Oligophenylenes

Oligophenyl compounds are excellent candidates for organic-type molecular wires and semiconductors. However, they do have many issues that need to be addressed, including solubility for processing purposes and poor conductance due to dihedral angles. Increasing the number of phenyl groups decreases solubility, and after n=3, oligophenyl molecules become nearly insoluble in all organic solvents. Additionally, because their dihedral angles are > 0, their conductance actually falls off quite drastically. In this project we hope to develop a synthesis of bridged oligophenyls which will hold their dihedral angles at 0 degrees and thus increase their conductance. Also, we propose to add solubilizing groups (long alkyl chains) that will aid in their solubility so that these compounds could be processed into useful materials.

The goal is to develop a modular and step-wise synthesis of bridged oligophenyls than have both linear and dendritic shapes. We will characterize them by UV-vis and fluorescence spectroscopy. Ultimately electrochemical studies will be done.

This work has been supported by the ACS-PRF, Research Corporation for Scientific Advancement, the UWEC Blugold Differential, and the Wisconsin Alliance for Minority Participation.

Publications:

Hintz, Heather A.; Sortedahl, Nicholas J.; Meyer, Samantha M.; Decato, Daniel A.; Dahl, Bart J.* “The Synthesis of Lactone-Bridged 1,3,5-Triphenylbenzene Derivatives as Pi-Expanded Coumarin Triskelions.” Tetrahedron Lett. 2017, 58, 4703-4708. link

3. Synthetic Anthocyanidin-Type Molecules: Benzopyrylium-containing conjugated compounds

Anthocyanidins are common plant pigments based on the flavylium ion or 2-phenylchromenylium, which is a type of oxonium ion (chromenylium is referred also to as benzopyrylium). They are what give many fruits and flowers their colors. Natural anthocyanidins have recently been explored as components of dye-sensitized solar cells. These types of solar cells would be much cheaper, flexible, and possibly more efficient than current silicon-based solar cells. We would like to explore synthetic anthocyanidins with the same goal in mind.

The goal is to develop a modular and step-wise synthesis of new benzopyrylium-containing conjugated compounds (synthetic anthocyanidins) and characterize them by UV-vis and fluorescence spectroscopy. The benzopyrylium moiety has been underutilized as an acceptor group. The pyrylium ion has well known pH-sensitivity as well and these compounds could be useful as sensors as well.

This work has been supported by the NSF-REU, ACS-PRF, the Research Corporation for Scientific Advancement, the UWEC Blugold Differential, and the Wisconsin Alliance for Minority Participation.

Publications:

Meyer, Samantha M.; Charlesworth-Seiler Eva M.; Patrol, Joel G.; Kitzrow, Jonathan, P.; Gerlach, Deidra A.; Reinheimer, Eric W.; Dahl, Bart J.* “Synthesis and Optical Properties of a Library of Isomeric Aryldibenzopyrylium Halochromic Cations.” Tetrahedron 2020, 76, 131222. link

Prust, Erin E.; Carlson, Erik J.; Dahl, Bart J.* “6-Aryldibenzo[b,d]pyrylium Salts: Synthesis and Characterization of a Reversible pH-Driven Optical and Spectroscopic Response.” Tetrahedron Lett. 2012, 53, 6433-6435. link

4. Synthesis of Protected Deuterated-Amino Acids to Study Phosphorylation of Peptides by Nanoparticle-based SERS.

This was a collaborative project with Dr. Laurie Parker while at Purdue University and was funded through an NIH sub-contract. We were working on developing a multistep synthesis of several protected deuterated amino acids for Dr. Parker. The long-term goal of this study is to develop a sensitive, multiplexed detection platform for real-time single-cell monitoring of prognostic kinase activity in tumor samples. The main objective of this work was to develop the first steps towards a multiplex quantification of kinase activity in a breast cancer model system using SERS and peptide-functionalized nanoparticle (NP)-based biosensors.

Last updated: October 17, 2020