title: Electronic properties of 4-substituted naphthalimides.
abstract: This paper describes a study of excited-state properties of naphthalimide (NI) and four 4-substituted derivatives: 4-chloronaphthalimide (Cl-NI), 4-methylthionaphthalimide (MeS-NI), 4-nitronaphthalimide (O(2)N-NI), and 4-(N,N-dimethylaminonaphthalimide (Me(2)N-NI). Steady-state absorption and fluorescence spectra were collected in solvents of varying polarity to determine the excited-state character of NI derivatives. Furthermore, the excited-state dynamics were studied using femtosecond transient absorption spectroscopy. The experimental findings were compared to calculated data obtained using time-dependent density functional (TD-DFT) methods. We found that light absorption by all NI derivatives leads to the production of the second excited state (S(2)), which was found to have a n,pi* character. Within approximately 40 ps, the S(2) state undergoes internal conversion to produce the S(1) state. The S(1) state is relatively long-lived (approximately 4 ns) and has charge-transfer character in NI derivatives with electron-withdrawing and electron-donating groups (MeS-NI, O(2)N-NI, and Me(2)N-NI). In the case of NI and Cl-NI, the S(1) state has a pi,pi* character and undergoes intersystem crossing to produce the T(1) state within 400 ps.
authors.affiliation: Department of Chemistry, Bowling Green State University, Bowling Green, Ohio 43403, USA.
authors.forename: Pavel
authors.initials: P
authors.lastname: Kucheryavy
authors.forename: Guifeng
authors.initials: G
authors.lastname: Li
authors.forename: Shubham
authors.initials: S
authors.lastname: Vyas
authors.forename: Christopher
authors.initials: C
authors.lastname: Hadad
authors.forename: Ksenija D
authors.initials: KD
authors.lastname: Glusac