Four new two-photon polymerization initiators with varying donor and conjugated bridge: Synthesis and two-photon activity.

Highlights: [•] We have synthesized four D–π–D dyes with two-photon absorption. [•] Four dyes contain phenothiazines/carbazoles with styrene/biphenylethyne as bridge. [•] Photophysical properties of four dyes were investigated. [•] Donors have larger contribution to σ value than that of conjugated bridge. [•] Four dyes can be used as organic two-photon photopolymerization initiators. [Copyright &y& Elsevier]