Abstract

In very recent work we have developed design strategies which allow us to independently control the strength, position, fluorescence quantum yield and intersystem crossing rates for two-photon absorbing dyes. The position and strength of the band of the two-photon absorption peak in conjugated molecules can be controlled by varying the conjugation length (specifically by varying the double bonds or phenylene-vinylenc groups in the molecules) and also by appropriate substitution of the molecule with electron donating and electron withdrawing groups. In particular, we have developed several new two-photon fluorophores, as shown in Table 1 below, that have strong two- photon absorptivities and two-photon absorption wavelengths that are ideally suited for imaging of tissue using a Ti:sapphire laser operating between 700 and 950 nm. Compound 1 below is representative of conventional agent (bis-MSB) whereas compounds 2 - 4 are represenative of the new agents that we have developed.

© 1998 Optical Society of America