Two-photonabsorption And Fluorescence Fluoride-sensing Properties Of N-octyl-3,6-bis[4-(4-(diphenylamino)phenyl)phenyl]-1,4-diketo-pyrrolo[3,4-c]pyrrolo

A fully aromatic D–π–A–π–D-type molecule3,6-bis[4-(4-(diphenylamino)-phenyl)phenyl]-N-octyl-1,4-diketo-pyrrolo[3,4-c]pyrrole (TDP) was synthesized andcharacterized. This small molecule is the derivative of1,4-diketopyrrolo-[3,4-c]-pyrroles(DPP),which contains two N-H functional groups. In order to enhance the solubility ofthis cormophore in organic solvents, one of the N-H functional groups has beensubstituted by alky unit.And another N-H unit can react with fluoride, then theUV/visabsorption maximum and the emission of this small molecule will be changed.The one-and two-photon absorption and emission properties in the absence orpresence of fluoride anion were investigated. The results show that TDP not only exhibitslarge two-photon absorption (2PA) cross section (δ) up to1030GM and strong redtwo-photon excitation fluorescence but also could operate as one-and two-photonchemosensors selectively for fluoride anion.When TDP react with fluoride in THFsolution, the UV/vis absorption bonds will decrease at around500nm, and increase at620nm. The emission spectrum of TDF will decrease at580nm, and increase at645nm.Interestingly, it is observed that both the detection sensitivity of TDP to fluoride anion andthe ratiometric change in emission spectra induced by fluoride anion are higher upontwo-photon than one-photon excitation, implying that TDP could serve better astwo-photon fluorescence sensors for fluoride anion. The large δ and red-shifted2PA band promoted by triphenylamine end-groups enable TDP to sense fluoride anion under longerexcitation wavelength and lower input laser power.