Two-photon absorption properties of an acetylene derivative confined in the interlayer space of a smectite

A composite consisting of synthetic saponite and 4,4′-[4,1-phenylenedi-2,1-ethynediyl]bis[1-methylpyridinium] diiodide (Ac) was fabricated. The two-photon absorption (TPA) characteristics of Ac confined in the interlayer space of synthetic saponite were compared to those in water. The maximum TPA cross-section (σ(2)peak) of Ac in the interlayer space of the synthetic saponite was 2.1 times larger than that in water. This enhancement is explained in terms of the enhanced anisotropy of Ac by confinement within the two-dimensional interlayer space of saponite and by a reduction in the detuning energy.