- People
- Research
- Graduate
- Undergraduate
- Prospective & Transfer Students
- General Chemistry Options
- Policies
- Tutors
- Pre-Health
- Undergraduate Advisors
- Chemistry Major
- Process for Declaring a Major, Minor, DMP, or ACS Certification
- B.A. in Chemistry
- B.S. Chemistry
- B.S. Specialization in Biochemistry
- B.S. Specialization in Chemical Education
- B.S. Specialization in Chemical Physics
- B.S. Specialization in Environmental Chemistry
- B.S. Specialization in Materials Science
- B.A./M.S. or B.S./M.S. in Chemistry ("3+1" Degree Option)
- Undergraduate Research
- Distinguished Majors Program
- Minor
- Forms
- Study Abroad
- Undergraduate FAQs
- Undergraduate Resources
- Safety
- Seminars
- Newsletter
James N. Demas
Professor Emeritus of Chemistry
Research Interests
Photochemistry and photophysics of transition metal complexes
Education
B.S. University of New Mexico, 1964
Ph.D. University of New Mexico, 1970
National Science Foundation Postdoctoral Fellow, University of Southern California, 1970-71
Awards and Honors
Visiting Scientist at Los Alamos National Laboratory, 1983-84, 1995-96, 2009
Photochemistry and Photophysics of Transition Metal Complexes
Professor Demas is not currently accepting graduate students.
Molecules excited by light lose energy by emission of light, transfer of energy or an electron to other molecules, photochemistry, and non-destructive radiationless processes. Solar energy conversion, chemical analysis, and light intensity measurements require information from the study of these processes. The processes can be highly sensitive to environmental factors such as solvent and interactions with organized media such as micelles, cyclodextrins, membranes, proteins, and DNAs. In addition, luminescence properties are very sensitive to the environment in polymer-supported sensors. We are elucidating the nature of these processes, correlating properties with molecular structure and environment, and developing new chemical, instrumental, and mathematical tools for studying these processes.
Our work includes:
- Design, synthesis and characterization of highly luminescent Os, Ir, Re, and Ru complexes.
- Evaluating photochemical properties, excited state ordering, and paths of energy loss.
- Fundamental and applied studies of interactions of photosensitizers with polymers, micelles, membranes and other organized media.
- Developing new luminescence-based sensors (e.g., oxygen, pH, metal ion).
- Design and utilization of metal complexes as probes of the structure and dynamics of organized media such as DNAs and membranes.
- Instrumental and theoretical developments in ultrasensitive, multicomponent fluorometric analyses.
The photoluminescence of a tris(4,7-diphenyl-1,10-phenanthroline)ruthenium (II) complex in a polymer film is shown while the film is being breathed over. The luminescence is quite sensitive to deactivation by oxygen, and the luminescence intensity is a direct measure of the oxygen in the subject’s breath. Less oxygen yields more luminescence. The region immediately after the subject held his breath is revealing.
Recent Publications
Aromatic difluoroboron β-diketonate complexes: effects of π-conjugation and media on optical properties. Xu S, Evans RE, Liu T, Zhang G, Demas JN, Trindle CO, Fraser CL. Inorg Chem. 52:3597-610 (2013).
Viscosity and temperature effects on the rate of oxygen quenching of tris-(2,2′-bipyridine)ruthenium(II). Reynolds EW, Demas JN, DeGraff BA. J Fluoresc. 23:237-41 (2013).
Environmental sensitivity of Ru(II) complexes: the role of the accessory ligands. Dixon EN, Snow MZ, Bon JL, Whitehurst AM, DeGraff BA, Trindle C, Demas JN. Inorg Chem. 51:3355-65 (2012).
Photophysical and analyte sensing properties of cyclometalated Ir(III) complexes. Leavens BB, Trindle CO, Sabat M, Altun Z, Demas JN, DeGraff BA. J Fluoresc. 22:163-74 (2012).
Laser phosphoroscope and applications to room-temperature phosphorescence. Payne SJ, Zhang G, Demas JN, Fraser CL, Degraff BA. Appl Spectrosc. 65:1321-4 (2011).