Solvent effects on the electronic structure of a newly synthesized two-photon polymerization initiator

Abstract

Time-dependent hybrid density functional theory in combination with polarized continuum model has been applied to study the solvent effects on the geometrical and electronic structures, as well as one- and two-photon absorption processes, of a newly synthesized asymmetrical charge-transfer (CT) two-photon absorption (TPA) organic molecule. The TPA cross section calculated from a generalized two-state model and solvatochromic shift of the CT state are found to be solvent dependent, for which a nonmonotonic behavior with respect to the polarity of the solvents has been observed. The calculated properties are in good agreement with the experimental data available. The character of the CT state is visualized by plotting its charge density difference from ground state, in which an excess of electron density on the donor side of the molecule is found. This implies that the excited molecule is ready to donate its electron to the surroundings. The energetic aspect of the electron donation is discussed by examining the solvent dependence of the molecular ground state oxidation potential. The importance of the electron correlation for describing the two-photon absorption is also demonstrated.

Solvent and branching effect on the two-photon absorption properties of push–pull triphenylamine derivatives

“…34,35,49,50 However, it is unclear why 1L exhibits enhanced 2PA properties in toluene and its 2PA efficiency decreases monotonically as the solvent polarity increases. Maybe this is due to specic solvent-solute interactions in polar solvents redistributing the energetics of the excited state and changing the excitation transition dipole moments.…”

A new series of two-photon polymerization initiators: Synthesis and nonlinear optical properties

“…Our experimental results show that the four new compounds have large enough TPA cross-sections which can induce polymerization of acrylate. The photopolymerization mechanism of the four initiators is still unknown, according to Wang et al [23] .…”

Investigation of mechanism of photo induced polymerization excited by two-photon absorption

“…In the presence of the monomer bulk, polar acrylate, the energy barrier can be drastically reduced by the short-range molecular interaction. As a result, the electron hopping to the monomer way rapidly initiated [11]. The interaction of antibonding with bonding orbitals result in a loss of energy, which is proportional to the contribution of intra-exciplex [14].…”

“…It was suggested that the polymerization rate is associated with the pumping rate of the CT state of the initiator [10,11]. As for molecules having the general structural motif D--D are sufficiently electron rich, it was noted that they could activate the polymerized reaction by an electron transfer, subsequent to two-photon excitation [3,9,12,13,22].…”

“…It was proposed that molecules having the general structural motif D-core-D are sufficiently electron rich, they could transfer an electron to the monomer to activate the polymerized reaction upon two-photon excitation. Recently, Ren and Wang reported the acceptor--donor type of chromophore effectively initiated the polymerization of acrylate through two-photon absorption, where the existence of strong intramolecular charge transfer (intra-CT) state in the excited state is considered to be the precondition for the photo-polymerization [10,11]. The growth rate of the polymer is associated with the pumping rate of the CT state of the initiator.…”