TY - JOUR
T1 - Excimer formation in cofacial and slip-stacked perylene-3,4
T2 - 9,10-bis(dicarboximide) dimers on a redox-inactive triptycene scaffold
AU - Margulies, Eric A.
AU - Shoer, Leah E.
AU - Eaton, Samuel W.
AU - Wasielewski, Michael R.
PY - 2014/10/15
Y1 - 2014/10/15
N2 - Excitation energy transfer in perylene-3,4: 9,10-bis(dicarboximide) (PDI) aggregates is of interest for light-harvesting applications of this strongly absorbing and π-π stacking chromophore. Here we report the synthesis and characterization of two PDI dimers in which the chromophores are covalently linked by a redox-inactive triptycene bridge in orientations that are cofacial (1) and slip-stacked along their N-N axes (2). Femtosecond transient absorption experiments on 1 and 2 reveal rapid exciton delocalization resulting excimer formation. Cofacial π-π stacked dimer 1 forms a low-energy excimer state absorption (λmax = 1666 nm) in τ = ∼2 ps after photoexcitation. Inserting a phenyl spacer on the bridge to generate a slip-stacked PDI-PDI geometry in 2 results in a less stable excimer state (λmax = 1430 nm), which forms in τ = ∼12 ps due to decreased electronic coupling. The near-infrared (NIR) excimer absorption of cofacial dimer 1 is ∼120 meV lower in energy than that of slip-stacked dimer 2, further highlighting electronic differences between these states.
AB - Excitation energy transfer in perylene-3,4: 9,10-bis(dicarboximide) (PDI) aggregates is of interest for light-harvesting applications of this strongly absorbing and π-π stacking chromophore. Here we report the synthesis and characterization of two PDI dimers in which the chromophores are covalently linked by a redox-inactive triptycene bridge in orientations that are cofacial (1) and slip-stacked along their N-N axes (2). Femtosecond transient absorption experiments on 1 and 2 reveal rapid exciton delocalization resulting excimer formation. Cofacial π-π stacked dimer 1 forms a low-energy excimer state absorption (λmax = 1666 nm) in τ = ∼2 ps after photoexcitation. Inserting a phenyl spacer on the bridge to generate a slip-stacked PDI-PDI geometry in 2 results in a less stable excimer state (λmax = 1430 nm), which forms in τ = ∼12 ps due to decreased electronic coupling. The near-infrared (NIR) excimer absorption of cofacial dimer 1 is ∼120 meV lower in energy than that of slip-stacked dimer 2, further highlighting electronic differences between these states.
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U2 - 10.1039/c4cp03107e
DO - 10.1039/c4cp03107e
M3 - Article
AN - SCOPUS:84907967281
VL - 16
SP - 23735
EP - 23742
JO - Physical Chemistry Chemical Physics
JF - Physical Chemistry Chemical Physics
SN - 1463-9076
IS - 43
ER -