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A series of D-p-A-p-D type chromophores were synthesized by the dehydration reaction of 4-R 2 Nbenzaldehye (R ~Ph, Bu n , Et, Me) and diaminomaleonitrile (corresponding to the chromophores 1, 2, 3 and 4, respectively), in which a polar imino double bond (-CLN-) replaced the double bond (-CHLCH-) in the p-conjugated centers. Femtosecond laser induced fluorescence intensity was used to evaluate two-photon absorption (TPA) cross sections, d, using a USB-2000 CCD. Results show a change of terminal groups from Ph 2 N-to Me 2 N-influenced the d value significantly through a change of the quantum yield, Q. However, the two-photon absorption peak position was only slightly affected. The chromophores 2 and 3 were found to afford polymers in the presence of the functional triacrylate monomer at low laser power at 755 and 820 nm. This demonstrated that the enhanced d value was not a main factor in the improvement of chromophore twophoton photosensitivity. Such information can be useful in the design of more efficient two-photon chromophores for imaging and power-limiting applications.Experimental 1. Chemicals Diaminomaleonitrile (98%) and 4-diphenyl-or 4-dialkyl-aminobenzaldehydes (98%) were purchased from Aldrich. The solvents

Three kinds of the two-photon chromophores are used to investigate the process of electron transfer between the initiator and the multifunctional acrylate monomer in two-photon-induced polymerization. Their molecular structures are simplified as D--d--D, D--D and D--a--D, where D is the strong donor terminal group, is a -conjugated core, d and a are the electron-donating and electron-accepting side group linked with the -conjugated core, respectively. We noticed that the emission of those chromophores is very sensitive to the solvent polarity. Additionally, the red-shift, structureless and long-lived emission was observed in the monomer. Correlated with quantum chemical calculation (MOPAC-PM5), we proposed a process of electron transfer in two-photon-induced polymerization (TPIP). Following the non-irradiation from the high excited state (S 2 ), intramolecular charge transfer (intra-CT) takes place from the terminal group to the core in the primary step, where intra-CT state is named as intra-exciplex. Then the rapid electron hopping from the ion radical core of the chromophore to the monomer was initiated. The electron transfer produces the ion radical pair, attributed to the photopolymerization. Therefore, the rate of two-photon-induced polymerization is determined by an equilibrium of electron transfer and back electron transfer between initiator and monomer to some extent in spite of the contribution of highly sensitivity in two-photon absorption to the number of the excited chromophore.

Langmuir-Blodgett films of four polymers containing benzoate and cinnamate main chains and Disperse Red 19 in the side chains were prepared and characterized by means of BAM and AFM. The poly(para-benzoate) and poly(para-cinnamate) gave LB films with much higher ordered textures than the respective meta-polymers. The para-polymers apparently possess self-assembly capacity, and this is thought to be the cause of their high second order nonlinear optical susceptibility. The X-type films of the para-polymers showed second order nonlinear optical responses, suggesting that the para-polymers form self organized membranes with the chromophores orientated to the direction perpendicular to the substrate.