Chapter 1
Karen J. Brewer (1961-2014): A Bright Star that Burned Out Far Too Soon

Seth C. Rasmussen

North Dakota State University, Department of Chemistry and Biochemistry, Fargo, ND, 58108-6050, USA

1.1 Introduction

Over the span of her career, first at Washington State University (WSU) and later at Virginia Tech, Karen J. Brewer (Figure 1.1) earned international acclaim as a prolific and pioneering researcher in the photochemistry and photophysics of multimetallic complexes [1, 2]. Ranging from synthesis of new multimetallic complexes to the study of their ground- and excited-state properties, her contributions aimed to elucidate the effect of the specific assembly of such complexes on their respective spectroscopic and electrochemical properties. In the process, Karen studied the application of complexes to molecular photovoltaics, solar H2 production, artificial photosynthesis, electrocatalysis, Pt-based DNA binders, and photodynamic therapy [1-6]. Publishing her first paper in 1985, she accumulated over 125 peer-reviewed research publications in her career, which have in turn garnered over 3000 citations to date [1, 2], and her research pace was as active as ever at the time of her premature death in 2014 (Figure 1.2) [1].

Figure 1.1 Karen J. Brewer (1961-2014) in the Spring of 2014.

(Courtesy of Virginia Tech.)

Figure 1.2 Publications per year from 1985 to 2015.

Although known specifically for her various research contributions, Karen was also an award-recognized educator. She was comfortable teaching chemistry at all levels, from first-year students in general chemistry to graduate students in special topics classes such as electrochemistry and the photophysics of transition metal complexes. Her enthusiasm in the classroom was infectious and she inspired students to change not only their view of chemistry but, in some cases, their major to chemistry [1].

For many, including this author, Karen will be remembered most for her role as mentor and role model. She had tremendous impact on everyone who transitioned through her research laboratory, from undergraduates to postdocs. Throughout her career, Karen was a strong advocate for women and minorities in chemistry and was a role model and mentor for many female students and researchers [1, 2, 5]. Her passion in the promotion of chemistry as a career choice for women was most evident in her extensive outreach efforts to K-12 students. Throughout her career, she regularly visited primary and secondary school classrooms and hosted students in her laboratories at Virginia Tech [1, 2, 5]. In the process, Karen provided a real-life role model for young girls and others with aspirations to work in the physical sciences [1, 5].

Over the years, Karen received significant recognition for her collective efforts in research, teaching, and outreach. This included a College of Arts and Sciences Diversity Award in 1996, shortly after arriving at Virginia Tech [1, 5], as well as various teaching awards [3] and a Popular Mechanics Breakthrough Innovator Award in 2010, which she shared with collaborator Dr Brenda Winkel [2-5]. Most recently, Virginia Tech recognized her outreach efforts with the 2014 Alumni Award for Outreach Excellence [1-4], which she shared with Dr Shamindri Arachchige, Virginia Tech instructor of chemistry and a former postdoctoral researcher from her research group [1, 5, 7].

1.2 Early Years

Karen Sonja Jenks was born on June 27, 1961, in Wiesbaden, Germany to parents Gerda and Henry Jenks [3, 4]. As the daughter of a career military man, Karen moved frequently in her youth (Figure 1.3) [2-4], which provided her the opportunity to see much of the United States and the world as a young girl [3, 4]. The family ultimately settled in Lancaster, South Carolina in 1974, where Karen graduated with honors from Lancaster High School in 1979 (Figure 1.4) [3, 4].

Figure 1.3 Karen in kindergarten at age 5.

(Courtesy of Elise Naughton and the Brewer family.)

Figure 1.4 Karen in her senior year of high school at age 17.

(Courtesy of Elise Naughton and the Brewer family.)

Karen then attended Wofford College in Spartanburg, South Carolina [2-4, 6] on a Reserve Officers' Training Corps (ROTC) scholarship [8]. It was an interesting time to attend Wofford College, as it had formerly been an all-male school and had transitioned to a coeducational institution only 3 years before she began her studies there [8]. Karen soon decided that the military was not what she wanted to do with her career and enrolled in Wofford's K-12 education program, where she was involved in teacher training at the middle school level [8]. Her father had instilled a love of learning and teaching [8] and this probably influenced her decision. Ultimately, however, she developed an interest in chemistry and she finished her undergraduate studies in the chemistry program. While at Wofford she also participated in women's basketball and became a member of both Alpha Phi Omega and the American Chemical Society during her senior year [2, 6]. The Wofford chemistry faculty thought highly of Karen as a student [9] and she received her BS degree in chemistry in 1983 [2-4, 6]. After the completion of her undergraduate studies, she married Ralph Gary Brewer (who went by Gary), with their wedding held on the same day as their Wofford graduation ceremonies on Sunday, May 15, 1983. Following her marriage, Karen was known both personally and professionally as Karen Jenks Brewer.

1.3 Graduate Studies and Clemson University

Karen then entered the Chemistry graduate program at Clemson University in the fall of 1983, where she began working under the supervision of Dr John D. Petersen (b. 1947, PhD University of California, Santa Barbara 1975) (Figures 1.5 and 1.6). Notable coworkers during her time in the Petersen group included Ronald Ruminski (Professor, University of Colorado Colorado Springs; PhD University of New Mexico 1980; Petersen postdoc 1981-1984) [10], Wyatt Rorer Murphy, Jr (Professor, Seton Hall University; PhD University of North Carolina at Chapel Hill 1984; Petersen postdoc 1984-1986) [11], and D. Brent MacQueen (PhD Clemson 1989) [12].

Figure 1.5 John D. Petersen (b. 1947).

(Courtesy of John Petersen.)

Figure 1.6 Karen Brewer's academic genealogy.

Karen began her research in the Petersen laboratory by joining ongoing efforts to develop bimetallic complexes capable of converting radiation to usable chemical potential energy. The basic design of such species included three components (Figure 1.5): (i) a strongly absorbing, but photochemically unreactive, metal center (antenna complex); (ii) a second metal center capable of undergoing a useful chemical reaction from a nonspectroscopic excited state (reactive complex); and (iii) a bridging ligand (BL) that both couples the two metal fragments and facilitates intramolecular energy transfer between the two metal centers [12, 13]. While others had previously studied electron transfer in bimetallic complexes utilizing primarily monodentate BLs (Figure 1.7), the Petersen group focused on the application of bidentate BLs (Figure 1.8) as a method to increase stability of the bimetallic species during excitation. Karen's first publication was as fourth author on a 1985 paper published in Coordination Chemistry Reviews that presented this design and discussed the optimization of the three basic components [13].

Figure 1.7 Basic design of bimetallic complexes capable of efficient photochemical processes.

Figure 1.8 Polypyridyl ligands referenced throughout the chapter.

Karen's research initially focused on evaluating the effect of bidentate BLs such as dpp on the photophysics of Ru(II)-based antenna complexes. This resulted in the publication of her initial first-author paper in 1986, which reported the synthesis of [Ru(dpp)3]2+ along with its photophysical and electrochemical properties [14]. The conclusion of this work was that in comparison to [Ru(bpy)3]2+, the dpp analogue exhibited similar electronic absorption and emission spectra, as well as a similar luminescence quantum yield. As such, the application of dpp should allow the tethering of Ru(II)-based antenna complexes of reactive metal centers without the loss of the desired photophysical properties [12, 14].

The ultimate focus of the majority of her graduate work was the potential application of bimetallic complexes to the photochemical elimination of molecular hydrogen. These efforts began with an intermolecular sensitization study using Fe(bpy)2(CN)2 as the donor and the dihydride species [Co(bpy)(PEt2Ph)2H2]ClO4 in order to evaluate the relative energy levels of the visible light accessible excited state of the Fe(II) antenna and the reactive state of the cobalt dihydride model reactive fragment [12, 15]. It was found that when either Fe(bpy)2(CN)2 or [Co(bpy)(PEt2Ph)2H2]+ was irradiated alone at 577 nm, no reaction occurred. Irradiation of a mixture of Fe(bpy)2(CN)2 and [Co(bpy)(PEt2Ph)2H2]+ at 577 nm, however, would result in the production of H2. The hydrogen generated was due to the initial excitation of the Fe(II) complex, followed by energy transfer to the Co(III) dihydride and resulting in loss of...