Paul S. Wagenknecht

Paul Wagenknecht

Professor, Chemistry

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Paul grew up in Clearwater, Florida and obtained his B.S. in Chemistry from Furman University in 1986. He was awarded a graduate fellowship from the National Science Foundation to attend Stanford University, and received his Ph.D. in Inorganic Chemistry in 1991.

Following postdoctoral studies at Colorado State University, he accepted a one-year adjunct teaching position at Occidental College in Los Angeles, California before beginning a tenure track position at San Jose State University in 1996. In 2004, he moved back to his alma mater, Furman University. Over his career, he has secured nearly $3 million in external funding for support of undergraduate research in his group and department from agencies including the National Science Foundation, National Institutes of Health, William F. Keck Foundation, Arnold and Mabel Beckman Foundation, Research Corporation, Camille and Henry Dreyfus Foundation, and American Chemical Society.

Since beginning his independent career with undergraduate researchers, he has published nearly 40 peer-reviewed research articles (mostly with student coauthors) and two patents. He is the recipient of the Henry Dreyfus Teacher-Scholar Award (2003), the South Carolina Governor’s Award for Excellence in Scientific Research (2020) and the Council on Undergraduate Research ChemCUR Outstanding Mentorship Award (2022). When not in the classroom or laboratory, he enjoys competing on the tennis courts and honing his competition BBQ skills (as AlQuemy BBQ).

Education

  • Ph.D., Stanford University
  • B.S., Furman University

Honors & Awards

  • Council on Undergraduate Research ChemCUR Outstanding Mentorship Award (2022)
  • South Carolina Governor’s Award for Excellence in Scientific Research (2020)
  • Henry Dreyfus Teacher-Scholar Award (2003)

Research

Adventures in transition-metal photophysics

State-of-the-art phosphorescent materials are integral to devices such as flat screen displays and modern, energy-efficient lighting. Such materials efficiently convert electricity (energy) into light. The reverse process, the conversion of light into electricity or fuels is perhaps even more technologically desirable. Our group studies complexes of metals such as titanium, copper, iron, silver, and platinum as possible materials to improve these technologies.

Emissive titanocenes

Complexes with charge-transfer (CT) excited states are used as photocatalysts or photosensitizers in a broad range of applications including organic synthesis and solar cells.  Most of these materials make use of rare and expensive second- and third-row transition metals. Thus, there is a great deal of interest in charge-transfer complexes of earth-abundant first-row transition metals.  Very recently, complexes of d0 metals with emissive LMCT states have come to the forefront as a new class of phosphors and photocatalysts. However, emissive Ti complexes have been elusive.  We have recently demonstrated that complexes of  d0 titanocenes with arylalkynylamine ligands are brightly emissive from their ligand-to-TiIV 3LMCT states at 77 K and some that are even emissive in room-temperature solution (Figure 1).  A combination of experimental and computational (TDDFT) work has provided a blue-print for Ti complexes that may have long-lived excited states in room-temperature fluid solution.

Emission spectrum of Ph[Cp*Ti]CuBr in THF solution along with image showing visible emission from excitation with a blue laser pointer.

Figure 1.  Emission spectrum of Ph[Cp*Ti]CuBr in THF solution along with image showing visible emission from excitation with a blue laser pointer.

Photophysics of Pt complexes with electron deficient alkyne ligands

It is well-known that both ligand identity and the rigidity of the environment impact emission characteristics of Pt phosphors for possible use in OLEDs. Recently we have investigated the impact of the strongly electron-withdrawing trifluoropropynyl ligand on the photophysics of emissive Pt complexes.  We have demonstrated that at high concentration, these complexes show blue emission from the monomer form and orange emission from the excimer form.  The combination results in a soft-white emission that is of interest for single-component white organic light emitting diodes (Figure 2).

Structure of a trifluoropropynyl complex of Pt along with images of its emission in dilute solution and concentrated solution.

Figure 2.  Structure of a trifluoropropynyl complex of Pt along with images of its emission in dilute solution and concentrated solution.