Exceptional near-infrared fluorescence quantum yields and excited-state absorptivity of highly conjugated porphyrin arrays.
We show that meso-to-meso ethyne-bridged (porphinato)zinc(II) oligomers (PZnn structures) define exceptional low band gap organic materials that possess both large magnitude NIR S1 --> S0 fluorescence quantum yields and substantial S1 --> Sn absorptive cross-sections, tunable over a wide 850-1400 nm spectral window. These PZnn species possess fluorescence quantum yields (phif values) comparable to the highest reported for NIR laser dyes in the 750-900 nm regime; importantly, these emitters do not suffer from commonly cited tricarbocyanine dye drawbacks of poor photostability and substantial phif sensitivity to solvent polarity. Furthermore, tauo (kr-1) values determined using the Strickler-Berg method highlight the close correlation of fluorescence quantum yields with S0 --> S1 integrated oscillator strength and demonstrate a rare if not unique example of broad NIR spectral domain fluorescence energy modulation, where phif magnitudes follow a simple Strickler-Berg relationship.
Duncan
Timothy V
TV
Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA.
Susumu
Kimihiro
K
Sinks
Louise E
LE
Therien
Michael J
MJ
D015394:Molecular Structure; D011166:Porphyrins / Q000737:chemistry*; D013054:Spectrophotometry, Atomic / Q000379:methods*; D019265:Spectroscopy, Near-Infrared / Q000379:methods*
D011166:Porphyrins