Ground State Coexistence of Twisted and Planar States in a Donor–Acceptor‐Based Naphthalene Dye: The Case of an Unconventional Intramolecular Charge Transfer‐Active Molecule

A novel fluorophore (E)‐4‐(2‐(2‐methoxynaphthalen‐1‐yl)vinyl)‐1‐methylpyridin‐1‐ium iodide (MVMI) was investigated by spectrodynamic experiments and quantum chemical calculations. Our studies indicated that MVMI serves as a unique example of an intramolecular charge transfer (ICT) probe existing in an equilibrium between the twisted and the planar forms with respect to the donor and acceptor units. Excitation of the twisted form leads to emission from the twisted excited state (T*) with emission from the planar excited state (P*) formed by a twisting from T* to P*. The excitation of the planar form leads to ICT‐type single emission from P*.The current report is of particular importance as the photobehaviour of MVMI is totally reversed from conventional ICT probes, obeying the twisted intramolecular charge transfer model, where an otherwise planar fluorophore undergoes twisting in the excited state to furnish a transient twisted excited state, the latter deemed as the origin of the CT emission band. The current results shall act as a cornerstone to stabilize and tune unusual, twisted states in the ground state, as well as to extract combined emission signals from locally excited and ICT states.