Ultrafast Dynamics of Manganese(III), Manganese(II), and Free-Base Bacteriochlorin: Is There Time for Photochemistry?
- Fabio A. Schaberle

- Artur R. Abreu
- Nuno P. F. Gonçalves
- Gonçalo F. F. Sá
- Mariette M. Pereira
- Luís G. Arnaut
Abstract

Manganese(III) and manganese(II) complexes of halogenated sulfonamide tetraphenylbacteriochlorins were prepared for the first time via a transmetalation reaction and shown to be stable at room temperature. The behavior of the electronic states of the paramagnetic complexes is remarkably different from those of the metal-free bacteriochlorins or diamagnetic metallobacteriochlorins. The Mn3+ complex exhibits eight electronic transitions between different states from 300 to 1100 nm, with a very prominent band (molar absorption coefficient of ca. 50000 M–1 cm–1) at 829 nm. Ultrafast transient absorption showed the formation of an excited singquintet state that decays to a tripquintet state with a femtosecond lifetime. The tripquintet state decays in 5 ps, yielding a tripseptet state with a 570 ps lifetime. The electronic absorption of the Mn2+ complex more closely resembles those of diamagnetic metallobacteriochlorins, but the longest decay lifetime is only ca. 8 ps. The intense photoacoustic waves generated with near-infrared excitation suggest the use of these complexes in photoacoustic tomography.
Cited By
This article is cited by 2 publications.
- Alexandre D. Silva, Carlos Serpa, Luis G. Arnaut. Photoacoustic transfection of DNA encoding GFP. Scientific Reports 2019, 9 (1) DOI: 10.1038/s41598-018-37759-1.
- Li-Li Wang, Su-Hong Peng, Hui Wang, Liang-Nian Ji, Hai-Yang Liu. Photophysical properties of free-base and manganese( iii ) N-confused porphyrins. Physical Chemistry Chemical Physics 2018, 20 (30) , 20141-20148. DOI: 10.1039/C8CP02223B.



