Synthesis and near-infrared luminescence of a deuterated conjugated porphyrin dimer for probing the mechanism of non-radiative deactivation.
beta,meso,beta-Fused porphyrin oligomers have many attractive photophysical features such as strong absorption in the near-IR at wavelengths greater than 1000 nm, and high two-photon cross sections. However their ultrafast S(1)-S(0) deactivation (k(d) > 10(11) s(-1)) limits potential applications. We have synthesised a deuterated fused porphyrin dimer to test whether deuteration influences the rate of non-radiative deactivation. An efficient synthetic strategy was developed, starting with deuteration of dipyrromethane. Deuteration of the zinc porphyrin dimer does not affect its fluorescence quantum yield in CD(2)Cl(2)(Phi(fD)/Phi(fH)= 1.00 +/- 0.05). This implies that the ultrafast non-radiative deactivation is not simply a consequence of the small S(1)-S(0) energy gap. Comparison with other conjugated porphyrin oligomers confirms that the deactivation rate in the edge-fused oligomers is faster than would be expected from the energy gap law. This result indicates that it should be possible to create near-IR dyes with similar S(1)-S(0) energy gaps to the beta,meso,beta-fused porphyrin oligomers but with slower rates of S(1)-S(0) decay.
Frampton
Michael J
MJ
Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, UKOX1 3TA. harry.anderson@chem.ox.ac.uk.
Accorsi
Gianluca
G
Armaroli
Nicola
N
Rogers
Joy E
JE
Fleitz
Paul A
PA
McEwan
Kenneth J
KJ
Anderson
Harry L
HL
D019281:Dimerization; D049449:Luminescence; D009682:Magnetic Resonance Spectroscopy / Q000379:methods / Q000592:standards; D008665:Metalloporphyrins / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D011166:Porphyrins / Q000737:chemistry*; D012015:Reference Standards; D012680:Sensitivity and Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D013237:Stereoisomerism; D015032:Zinc / Q000737:chemistry*
D008665:Metalloporphyrins; D011166:Porphyrins; D015032:Zinc