Fig. 1. (A) Overlayed fluorescence spectra of 3 and 4 in THF with spectral overlap of the donor emission spectrum with the acceptor excitation spectrum. (B) Fluorescence spectrum of 1 in THF. Bottom: 3D fluorescence spectra of 3 (C), 4 (D) and 1 (E) in THF with indicated 2D slices of the spectra above.