Electronic Absorption, Emission, and Two-Photon Absorption Properties of Some Extended 2,4,6-Triphenyl-1,3,5-Triazines

We report herein the linear optical properties of some extended 2,4,6-triphenyl-s-triazines formula 2,4,6-[(1,4-C6H4)C≡C(4-C6H4X)]3-1,3,5-(C3H3N3) (3-X; X = NO2, CN, OMe, NMe2, NPh2) and related analogues 4 7-X (X H, NPh2), before briefly discussing their two-photon absorption (2PA) cross-sections. Their 2PA performance is discussed in relation to values previously measured for closely octupoles such as N,N′,N″-triphenylisocyanurates (1-X, 5, 6-X) or 1,3,5-triphenylbenzenes (2-X). While s-triazines are usually much better absorbers near-IR range than these molecules, especially when functionalised by electron-releasing substituents at periphery, they present a decreased transparency window visible due red-shifted first 1PA peak, particular compared with corresponding isocyanurates analogues. In contrast, significantly larger brilliancy, appear more promising latter fluorescence bio-imaging purposes. Rationalisation unexpected outcomes proposed based on DFT calculations.