Suppressing the charge recombination (CR) that follows an efficient charge separation (CS) is of key importance for energy, electronics, and photonics applications. We focus on the role of dynamic gating for impeding CR in a molecular rotor, comprising an electron donor and acceptor directly linked via a single bond. The media viscosity has an unusual dual effect on the dynamics of CS and CR in this dyad. For solvents with intermediate viscosity, CR is 1.5-3 times slower than CS. Lowering the viscosity below ∼0.6 mPa s or increasing it above ∼10 mPa s makes CR 10-30 times slower than CS. Ring rotation around the donor-acceptor bond can account only for the trends observed for nonviscous solvents. Media viscosity, however, affects not only torsional but also vibrational modes. Suppressing predominantly slow vibrational modes by viscous solvents can impact the rates of CS and CR to a different extent. That is, an increase in the viscosity can plausibly suppress modes that are involved in the transition from the charge-transfer (CT) to the ground state, i.e., CR, but at the same time are not important for the transition from the locally excited to the CT state, i.e., CS. These results provide a unique example of synergy between torsional and vibronic modes and their drastic effects on charge-transfer dynamics, thus setting paradigms for controlling CS and CR.

Decorating diketopyrrolopyrroles with strongly electron-rich heterocycles led to donor–acceptor–donor architectures possessing two-photon brightness 850–1900 GM.

Electron-donating functionalities allow modulation of the emission properties of diketopyrrolopyrroles.

Benzofuran has been proven to be the versatile substituent for tuning the optics of diketopyrrolopyrroles.

The influence of a combination of steric and electronic factors on both the preparation and the optical properties of diketopyrrolopyrroles was investigated. The attachment of a cyano group to the electron‐deficient pyridine ring overcame the negative influence of the flanking methyl group on the efficiency of the synthesis of diketopyrrolopyrroles. Diketopyrrolopyrroles possessing pyridine‐N‐oxide moieties were studied for the first time. We have also shown that reactions of cyanopyridines possessing an additional dialkylamino group were very capricious and depending on the relative position of all substituents, can lead to low yields of diketopyrrolopyrroles. The interplay between the dihedral angle between the diketopyrrolopyrrole core and the pyridyl substituents as well as the presence and position of electron‐donating moieties made it possible to modulate the photophysical properties of N,N′‐dialkyldiketopyrrolopyrroles. In particular, it was found that pyridine‐N‐oxides as the aryl moieties had a strong influence on the optical properties of diketopyrrolopyrroles, shifting both absorption and emission bands bathochromically. Two‐photon absorption cross‐sections had low values except for those dyes possessing a clear quadrupolar centrosymmetric nature.