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[Display omitted] • Uncaging efficiency is retained in dimeric DEAC conjugated structures. • Two-photon absorption properties (2PA) are enhanced by up to two order of magnitude. • The aromatic cores influence both the uncaging efficiency and the 2PA properties. • Both electron-releasing and electron-withdrawing cores lead to unprecedented 2P uncaging sensitivities (550 GM). A series of symmetrical conjugated dimeric coumarinyl cages has been synthesized by grafting 7-diethlyaminocoumarin (DEAC) cages via π-linkers onto different aromatic cores displaying various electronic character (electron-withdrawing: benzobisthiazole BBTz, electron-donating: carbazole or ambivalent: fluorenyl). Due to their symmetrical design, all conjugated dimeric derivatives showed enhanced two-photon absorption at 730 nm, the electron-withdrawing core leading to the highest response (over 3000 GM). All dimeric derivatives retained the uncaging ability of the DEAC cage, with a strong influence of the nature of the core on the uncaging quantum yield. While the fluorenyl core led to an uncaging quantum yield similar to DEAC, the BBTz core led to a twice larger uncaging quantum yield and the carbazole core to even larger uncaging quantum yield (60 %). As a result, both electron-donating and electron-withdrawing cores lead to symmetrical dimeric DEAC derivatives showing unprecedented two-photon uncaging photo-sensitivity (up to 550 GM). [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesis of molecular photoswitches based on 2-substituted N H and N CH 3 imidazole. • Tuning of switching properties by preventing imidazole tautomerism and benzene substitution. • Pentafluorosulfanyl derivative showed the highest stability of the (Z)–isomer. • Insertion of SF 5 group proved to be useful strategy towards a bistable photoswitch. Azo–imidazole photoswitches based on N H– and N –methylimidazole were designed and prepared via a convenient synthetic route. These azo-compounds were investigated by means of XRD analysis, cyclic voltammetry, thermal analysis, UV–Vis absorption spectroscopy and DFT calculations. The photoswitching was mostly affected by imidazole N -substitution with the half-life of (Z)–isomers found within the range of tens of seconds (N H-imidazoles) vs. tens of hours (N -methylimidazoles). N -Methylimidazole switches can be further tuned by altering electronic effects of the appended substituents (acyl, bromine, trifluoromethyl and pentafluorosulfanyl). The latter group proved to be particularly interesting in stabilizing (Z)–isomer. Its large half-life (∼24 h), high photoconversion (89 %) and diminished nonlinear optical response in contrast to the (E)-isomer (β E / Z = 3.82) point to a very useful strategy in introducing SF 5 group in the structure of molecular switches. In summary, this detailed study demonstrates that photoswitching properties of azo-imidazoles can be significantly tuned in a broad extent by (preventing) imidazole tautomerism as well as by altering electronic effects of appended substituents. [ABSTRACT FROM AUTHOR]