Carlos E. Crespo-Hernández

Associate Professor and Co-director of the Center for Chemical Dynamics


Ultrafast Spectroscopy, Analytical Chemistry, Biophysical Chemistry, Energy, Photochemistry, Physical Chemistry, Chemical Dynamics and Kinetics, Computational Chemistry,Time-Resolved Spectroscopy


  • BS, University of Puerto Rico, San Juan Campus, 1995
  • PhD, University of Puerto Rico, San Juan Campus, 2002
  • NIH Postdoctoral Fellow, The Ohio State University (2002-05)
  • Research Associate of Chemistry, The Ohio State University (2005-06)
  • Assistant Professor of Chemistry, Case Western Reserve University (2007-2014)
  • Co-director of the Center for Chemical Dynamics, Case Western Reserve University (2008-present)
  • Associate Professor of Chemistry, Case Western Reserve University (2014-present)

Selected Honors and Awards


Crespo Research Group Site »



Research Statement

The Crespo research group focuses on probing and understanding light-induced phenomena in molecules and polymers in solution. There are three major areas of ongoing research: (1) excited-state dynamics and photochemistry of DNA/RNA nucleobases and nucleobase derivatives; (2) design and study of modified sensitizers for photodynamic applications; and (3) excited-state dynamics and photophysics of organic and bioorganic molecules, including B vitamin complexes and pterin derivatives. Our group use analytical instrumentation and time-resolved spectroscopic techniques to produce specific knowledge of the factors controlling these photo-processes. Students involved in these scientific activities acquire expertise in a wide variety of analytical techniques such as high-performance liquid chromatography, circular dichroism, infra-red and ultraviolet-visible spectrophotometric techniques, and time-resolved instrumentation on time scales ranging from femtoseconds to microseconds. The experimental work is complemented with ground- and excited-state computational methods.

Selected Publications

  • Martínez-Fernández, L.; Granucci, G.; Pollum, M.; Crespo-Hernández, C. E.; Persico, M.; Corral, I. “Decoding the Molecular Basis for the Population Mechanism of the Triplet Phototoxic Precursors in UVA Light-Activated Pyrimidine Anticancer Drugs”, Chem. Eur. J. 2017, in press. Access article
  • Mai, S.; Pollum, M.; Martínez-Fernández, L.; Dunn, N.; Marquetand, P.; Corral, I.; Crespo-Hernández, C. E.; González, L. “The Origin of Efficient Triplet State Population in Sulfur-Substituted Nucleobases”, Nature Commun. 2016, 7, 13077 (DOI: 10.1038/ncomms13077). Access article
  • Pollum, M.; Ashwood, B.; Jockusch, S.; Lam, M; Crespo-Hernández, C. E. “Unintended Consequences of Expanding the Genetic Alphabet”, J. Am. Chem. Soc. 2016, 138, 11457-11460. Access article
  • Ashwood, B.; Pollum, M.; Crespo-Hernández, C. E. “Can a Six-Letter Alphabet Increase the Likelihood of Photochemical Assault to the Genetic Code?”, Chem. Eur. J. 2016, 22, 16648-16656. Access article
  • Brister, M. M.; Piñero-Santiago, L. E.; Morel, M.; Arce, R.; Crespo-Hernández, C. E.; “The The Photochemical Branching Ratio in 1,6-Dinotropyrene Depends on Excitation Energy”, J. Phys. Chem. Lett. 2016, 7, 5086-5092. Access article
  • Pollum, M.; Guan, L.; Ahsanuddin, S.; Baron, E.; Lam, M.; Crespo-Hernández, C. “Photoactivation of sulfur-modified DNA and RNA analogs induces cytotoxicity in epidermoid carcinoma cells”, J. Invest. Dermatol. 2016, 136, S105. Access article
  • Brister, M.; Crespo-Hernández, C. E. “Direct Observation of Triplet-State Population Dynamics in the RNA Uracil Derivative 1-Cyclohexyluracil”, J. Phys. Chem. Lett. 2015, 6, 4404-4409. Access article
  • Pollum, M.; Jockusch, S.; Crespo-Hernández, C. E. “Increase in the Phooreactivity of Uracil Derivatives by Doubling Thionation”, Phys. Chem. Chem. Phys. 2015, 17, 27851-27861. Access article
  • Crespo-Hernández, C. E.; Martínez-Fernández, L.; Rauer, C.; Reichardt, C.; Mai, S.; Pollum, M.; Marquetand, P.; González, L.; Corral, I. “Electronic and Structural Elements that Regulate the Excited-State Dynamics in Purine Nucleobase Derivatives”, J. Am. Chem. Soc. 2015, 137, 4368-4381. Access article
  • Pollum, M.; Martínez-Fernández, L.; Crespo-Hernández, C. E.; “Photochemistry of Nucleic Acid Bases and their Thio- and Aza-Analogues in Solution”, Top. Curr. Chem. 2015, 355, 245-327. Invited Review Chapter. Access article
  • Pollum, M.; Jockusch, S.; Crespo-Hernández, C. E.; “2,4-Dithiothymine as a Potent UVA Chemotherapeutic Agent”, J. Am. Chem. Soc. 2014, 136, 17930-17933. Access article
  • Vogt, R. A.; Gray, T. G.; Crespo-Hernández, C. E.;”Subpicosecond Intersystem Crossing in Mono- and Di-(Organophosphine)gold(I) Naphthalene Derivatives in Solution”, J. Am. Chem. Soc. 2012, 134, 14808–14817. Access article
  • K. de La Harpe; C. E. Crespo-Hernández; B. Kohler. “Deuterium Isotope Effect on Excited-State Dynamics in an Alternating GC Oligonucleotide”, J. Am. Chem. Soc. 2009, 131, 17557-17559 .Access article
  • C. T. Middleton; K. de La Harpe; C. Su; Y. K. Law; C. E. Crespo-Hernández; B. Kohler. “DNA Excited-State Dynamics: From Single Bases to the Double Helix”, Annu. Rev. Phys. Chem. 2009, 60, 217-239. Access article
  • C. E. Crespo-Hernández; K. de La Harpe; B. Kohler. “Ground-State Recovery Following UV Excitation is Much Slower in G•C-DNA Duplexes and Hairpins Than in Mononucleotides”, J. Am. Chem. Soc. 2008, 130, 10844-10845. Access article
  • T. Takaya; C. Su; K. de La Harpe; C. E. Crespo-Hernández; B. Kohler. “UV Excitation of DNA and RNA Strands Produces High yields of exciplex states between two stacked bases”, Proc. Natl. Acad. Sci. USA 2008, 105, 10285-10290. Access article
  • W. J. Schreier; T. E. Schrader; F. O. Koller; P. Gilch; C. E. Crespo-Hernández; V. N. Swaminathan; T. Carell; W. Zinth; B. Kohler. “Thymine Dimerization in DNA is an Ultrafast Photoreaction”. Science2007, 315: 625-629. Access article
  • P. M. Hare; C. E. Crespo-Hernández; B. Kohler. “Internal Conversion to the Electronic Ground State Occurs via Two Distinct Pathways for Pyrimidine Bases in Aqueous Solution”. Proc. Natl. Acad. Sci. USA2007, 104: 435-440. Access article
  • C. E. Crespo-Hernández; B. Cohen; B. Kohler, “Molecular spectroscopy: Complexity of Excited-State Dynamics in DNA (Reply)”, Nature 2006, 441, E7-E8. Access article
  • C. E. Crespo-Hernández; B. Cohen; B. Kohler. “Base Stacking Controls Excited-State Dynamics in A·T-containing DNA”. Nature2005, 436: 1141-1144.  Access article

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Millis Science Building 219

Other Information

Education: PhD, University of Puerto Rico