Experimental and Theoretical Studies of the Photophysical Properties of 2- and 2,7-Functionalized Pyrene Derivatives

Crawford, A.G.; Dwyer, A.D.; Liu, Z.; Steffen, A.; Beeby, A.; Pålsson, L.O.; Tozer, D.J.; Marder, T.B.

Abstract

Pyrene derivatives substituted at the 2- and 2,7-positions are shown to display a set of photophysical properties different from those of derivatives substituted at the 1-position. It was found that, in the 2- and 2,7-derivatives, there was little influence on the S2 ← S0 excitation, which is described as “pyrene-like”, and a strong influence on the S1 ← S0 excitation, which is described as “substituent-influenced”. In contrast, the 1-substituted derivatives display a strong influence on both the S1 ← S0 and the S2 ← S0 excitations. These observations are rationalized by considering the nature of the orbitals involved in the transitions. The existence of a nodal plane passing through the 2- and 7-positions, perpendicular to the molecular plane in the HOMO and LUMO of pyrene, largely accounts for the different behavior of derivatives substituted at the 2- and 2,7-positions. Herein, we report the photophysical properties of a series of 2-R-pyrenes {R = C3H6CO2H (1), Bpin (2; pin = OCMe2CMe2O), OC3H6CO2H (3), O(CH2)12Br (4), C≡CPh (5), C6H4-4-CO2Me (6), C6H4-4-B(Mes)2 (7), B(Mes)2 (8)} and 2,7-R2-pyrenes {R = Bpin (9), OH (10), C≡C(TMS) (11), C≡CPh (12), C≡C-C6H4-4-B(Mes)2 (13), C≡C-C6H4-4-NMe2 (14), C6H4-4-CO2C8H17 (15), N(Ph)-C6H4-4-OMe (16)} whose syntheses are reported elsewhere. Furthermore, we compare their properties to those of several related 1-R-pyrene derivatives {R = C3H6CO2H (17), Bpin (18), C≡CPh (19), C6H4-4-B(Mes)2 (20), B(Mes)2 (21)}. For all derivatives, modest (0.19) to high (0.93) fluorescence quantum yields were observed. For the 2- and 2,7-derivatives, fluorescence lifetimes exceeding 16 ns were measured, with most being ca. 50–80 ns. The 4-(pyren-2-yl)butyric acid derivative (1) has a long fluorescence lifetime of 622 ns, significantly longer than that of the commercially available 4-(pyren-1-yl)butyric acid (17). In addition to measurements of absorption and emission spectra and fluorescence quantum yields and lifetimes, time-dependent density functional theory calculations using the B3LYP and CAM-B3LYP functionals were also performed. A comparison of experimental and theoretically calculated wavelengths shows that both functionals were able to reproduce the trend in wavelengths observed experimentally.

Citation

Crawford, A., Dwyer, A., Liu, Z., Steffen, A., Beeby, A., Pålsson, L., …Marder, T. (2011). Experimental and Theoretical Studies of the Photophysical Properties of 2- and 2,7-Functionalized Pyrene Derivatives. Journal of the American Chemical Society, 133(34), 13349-13362. https://doi.org/10.1021/ja2006862

• Journal Article Type: Article
• Publication Date: Aug 31, 2011
• Deposit Date: Feb 14, 2012
• Journal: Journal of the American Chemical Society
• Print ISSN: 0002-7863
• Electronic ISSN: 1520-5126
• Publisher: American Chemical Society
• Peer Reviewed: Peer Reviewed
• Volume: 133
• Issue: 34
• Pages: 13349-13362
• DOI: https://doi.org/10.1021/ja2006862