Synthesis and two-photon absorption property of new π-conjugated dendritic fluorophores containing styrylpyridyl moieties

Four new multi-branched two-photon absorption chrornophores, namely]-(4-bromic benzal)-3,5-bis(4-((E)-2-(pyridin-4-yl)vinyl)phenyl)benzene (4), tris (4- ((E)- 2- (pyridin-4-yl)vinyl)phenyl) -benzene (5), 6-chloro-N2,N4-bis(4-((E)-2-(pyridin-4-yl)vinyl)phenyl)-1,3,5-triazine-2,4diamine (6), tris-[4-(2-pyridin-4-yl-vinyl)-phenyl]-amine (7), have been synthesized and characterized. One-photon fluorescence, fluorescent quantum yields and two-photon fluorescence have been investigated. The experimental two-photon absorption cross-sections of 4-7 in DMF are 6, 11, 13 GM (pumped by 740 nm laser) and 19 GM (pumped by 800 nm laser), respectively. The calculated two-photon absorption cross-sections of 4-7 are 5.41, 7.67, 9.57 and 76.14 GM, respectively. The two-photon induced fluorescent peak wavelengths of 4-7 in DNIF are 421, 425, 474 and 534 nm pumped by 680, 680, 740 and 800 nm laser, respectively. The results show that molecule 7 is a good two-photon absorption fluorophore possessing long two-photon fluorescent lifetime, good fluorescent quantum yield and large two-photon absorption cross-section. The two-photon absorption peak wavelength of molecule 7 is at 800 nm, which is favourable for initiating two-photon photopolymerization. (c) 2006 Elsevier B.V. All rights reserved.