title: Extending the short and long wavelength limits of bacteriochlorin near-infrared absorption via dioxo- and bisimide-functionalization.
abstract: Six new bacteriochlorins expanding the range of the strong near-infrared (NIR) absorption (Qy band) to both shorter and longer wavelengths (∼690 to ∼900 nm) have been synthesized and characterized. The architectures include bacteriochlorin-bisimides that have six-membered imide rings spanning the 3,5- and 13,15-macrocycle positions or five-membered imide rings spanning the β-pyrrolic 2,3- and 12,13-positions. Both bisimide types absorb at significantly longer wavelength than the bacteriochlorin precursors (no fused rings), whereas oxo-groups at the 7- or 7,17-positions shift the Qy band to a new short wavelength limit. Surprisingly, bacteriochlorin-bisimides with five-membered β-pyrrolic-centered imide rings have a Qy band closer to that of six-membered bacteriochlorin-monoimides. However, the five-membered bisimides (versus the six-membered bacteriochlorin-monoimides) have significantly enhanced absorption intensity that is paralleled by an ∼2-fold higher fluorescence yield (∼0.16 vs ∼0.07) and longer singlet excited-state lifetime (∼4 ns vs ∼2 ns). The photophysical enhancements derive in part from mixing of the lowest unoccupied frontier molecular orbitals of the five-membered imide ring with those of the bacteriochlorin framework. In general, all of the new bacteriochlorins have excited-state lifetimes (1-4 ns) that are sufficiently long for use in molecular-based systems for photochemical applications.
authors.affiliation: ‡Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States.
authors.forename: Pothiappan
authors.initials: P
authors.lastname: Vairaprakash
authors.affiliation: †Department of Chemistry, Washington University, St. Louis, Missouri 63130-4889, United States.
authors.forename: Eunkyung
authors.initials: E
authors.lastname: Yang
authors.affiliation: ‡Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States.
authors.forename: Tuba
authors.initials: T
authors.lastname: Sahin
authors.affiliation: ‡Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Taniguchi
authors.affiliation: ‡Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States.
authors.forename: Michael
authors.initials: M
authors.lastname: Krayer
authors.affiliation: §Department of Chemistry, University of California, Riverside, California 92521-0403, United States.
authors.forename: James R
authors.initials: JR
authors.lastname: Diers
authors.affiliation: †Department of Chemistry, Washington University, St. Louis, Missouri 63130-4889, United States.
authors.forename: Alfred
authors.initials: A
authors.lastname: Wang
authors.affiliation: †Department of Chemistry, Washington University, St. Louis, Missouri 63130-4889, United States.|∥Photosynthetic Antenna Research Center, Washington University, St. Louis, Missouri 63130-4889, United States.
authors.forename: Dariusz M
authors.initials: DM
authors.lastname: Niedzwiedzki
authors.affiliation: †Department of Chemistry, Washington University, St. Louis, Missouri 63130-4889, United States.
authors.forename: Christine
authors.initials: C
authors.lastname: Kirmaier
authors.affiliation: ‡Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States.
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Lindsey
authors.affiliation: §Department of Chemistry, University of California, Riverside, California 92521-0403, United States.
authors.forename: David F
authors.initials: DF
authors.lastname: Bocian
authors.affiliation: †Department of Chemistry, Washington University, St. Louis, Missouri 63130-4889, United States.
authors.forename: Dewey
authors.initials: D
authors.lastname: Holten
mesh_terms: D066241:Carbon-13 Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D055668:Photochemical Processes; D011166:Porphyrins / Q000138:chemical synthesis / Q000737:chemistry*; D066244:Proton Magnetic Resonance Spectroscopy; D019265:Spectroscopy, Near-Infrared / Q000379:methods
chemical_list: D011166:Porphyrins; C452433:bacteriochlorin