Enhancing two-photon uncaging sensitivity in symmetrical dimeric conjugated coumarin cages: Role of the coupling core

A series of symmetrical conjugated dimeric coumarinyl cages has been synthesized by grafting 7-diethlyamino-coumarin (DEAC) cages via pi-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 , 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).

Automated summary

A series of symmetrical conjugated dimeric coumarinyl cages was synthesized by grafting 7-diethlyamino-coumarin (DEAC) cages onto different aromatic cores with various electronic characters. These dimeric derivatives showed enhanced two-photon absorption, with the highest response obtained from the electron-withdrawing core. The nature of the core also influenced the uncaging quantum yield, with the carbazole core showing the highest yield.