Carlos E. Crespo-Hernández


Millis Science Building 219


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

Publons Profile







  • 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 (2008-2018)
  • Associate Professor of Chemistry, Case Western Reserve University (2014-2019)
  • Professor of Chemistry, Case Western Reserve University (2019-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 with primary applications in photodynamic therapy and photomedicines. 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 environmental pollutants, heteroatomic polycyclic aromatic compounds, 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, infrared 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

  • Brister, M. M.; Crespo-Hernández, C. E., “Excited-State Dynamics in the RNA Nucleotide Uridine 5′-Monophosphate Investigated using Femtosecond Broadband Transient Absorption Spectroscopy”, J. Phys. Chem. Lett. 2019, 10, 2156-2161. Access article
  • Ashwood, B.; Pollum, M.; Crespo-Hernández, C. E., “Photochemical and Photodynamical Properties of Sulfur-Substituted Nucleic Acid Bases”, Photochem. Photobiol. 2019, 95, 33-58. Invited Review; submitted as part of the Special Issue honoring the 55th Anniversary of Photochemistry and Photobiology. Access article
  • Farrell, K. M.; Brister, M. M.; Pittelkow, M.; Sølling, T. I.; Crespo-Hernández, C. E., “Heavy-Atom Substituted Nucleobases in Photodynamic Applications: Substitution of Sulfur with Selenium in 6-Thioguanine Induces a Remarkable Increase in the Rate of Triplet Decay in 6-Selenoguanine”, J. Am. Chem. Soc. 2018, 140, 11214-11218. Access article
  • Pollum, M.; Minh, L.; Jockusch, S.; Crespo-Hernández, C. E., “Dithionated Nucleobases as Effective Photodynamic Agent Against Human Epidermoid Carcinoma Cells”, ChemMedChem 2018, 13, 1044-1050. Access article
  • Ashwood, B.; Jockusch, S.; Crespo-Hernández, C. E., “Photochemical Reactivity of dTPT3: A Crucial Nucleobase Derivative in the Development of Semi-Synthetic Organisms”, J. Phys. Chem. Lett. 2017, 8, 2387−2392. Access article
  • 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
  • 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
  • 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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