Kubicki, JacekLorenc, MaciejCochelin, PierreMongin, OlivierAmar, AnissaBoucekkine, AbdouGaje, ArnoldHumphrey, MarkMorshedi, MahbodLorenzen, SabineRauch, FlorianScheufler, CharlotteMarder, Todd B.Paul, Frédéric2021-11-082021-11-081932-7447http://hdl.handle.net/1885/251644The D−π–A dyads [(n-Hex)2N(1,4-C6H4)]C≡C[(1,4-C6H4)NO2] (1) and [(n-Hex)2N(1,4-C6H4)]C≡C(1,4-C6H4)C≡C[(1,4-C6H4)NO2] (2) have been studied by ultrafast time-resolved infrared absorption spectroscopy. After excitation into their singlet charge-transfer (1CT) state, a fast decay (ca. 6 ps for 1 and 1 ps for 2) of the initially populated singlet state into a ground state (major pathway) and a longer lived excited state (possibly the triplet state) is observed. The nitro and alkyne groups were used as vibrational reporters to probe the changes induced by the charge-transfer process. For the first time, we confirm experimentally that these changes are consistent with expectations based on the traditional valence-bond representations of the CT states of these push–pull chromophores. An almost identical charge transfer takes place in the two dyads, despite π-bridges of different lengths between the donor and acceptor groups. Complementary DFT calculations support the experimental assignments and have helped clarify the photophysical behavior of 1 and 2.J.K. acknowledges financial support from the Ministry of Science and Higher Education. The CNRS (LIA Redochrom, No. 1194) is acknowledged for financial support. M.G.H. thanks the Australian Research Council for financial support (grant no. DP170100408). T.B.M. thanks the Julius-Maximilians-Universitat Wu ̈ ̈rzburg for support. A.G. thanks the University of the Philippines for financial support.application/pdfen-AU© 2020 American Chemical Society2020-04-1010.1021/acs.jpcc.0c01532