Design of a New Optical Material with Broad Spectrum Linear and Two-Photon Absorption and Solvatochromism

Citations Over TimeTop 10% of 2013 papers

Abstract

A fluorene-bridged squaraine dimer (SD-FLU-SD) was designed with the purpose of combining various chromophores in one molecule and enhancing its two-photon absorption properties using intra- and interchromophore transitions. Linear and nonlinear absorption properties of SD-FLU-SD were investigated with the goals of understanding the nature of one- and two-photon absorption spectra, determining the molecular optical parameters, and performing modeling of the photophysical processes. The optical behavior of this new SD-FLU-SD “hybrid” molecule was compared with its separate squaraine constituent moiety. Linear spectroscopic characterization includes absorption, fluorescence, excitation and emission anisotropy, and quantum yield measurements in solvents of different polarity and viscosity. Spectral positions of the absorption–fluorescence peaks and quantum yields of SD-FLU-SD and its separate squaraine moiety exhibited complex and nontrivial behavior as a function of solvent polarity. Comprehensive study of this unusual solvatochromism was conducted and interpreted using various models. Nonlinear spectroscopic studies included two-photon absorption measurements using the femtosecond Z-scan technique. The two-photon absorption spectrum of SD-FLU-SD was broad, covering the spectral range from 800 to 1400 nm with a maximum two-photon absorption cross section of 2 750 GM (1 GM = 1 × 10–50 cm4 s/photon). Quantum chemical analysis, based on time-dependent density functional theory, agreed with the experimental data and revealed details on the energy-level structure and origin of the linear and nonlinear absorption behavior of this novel SD-FLU-SD compound. These investigations advance the understanding of the nature of electronic transitions and the structure–property relations in long conjugated molecules, which are important for the rational design of new organic optical materials.

Related Papers

• → Solvatochromic Pyrene Analogues of Prodan Exhibiting Extremely High Fluorescence Quantum Yields in Apolar and Polar Solvents(2013)159 cited
• → Prediction of Two-Photon Absorption Properties for Organic Chromophores Using Time-Dependent Density-Functional Theory(2003)179 cited
• → Two-photon solvatochromism III: Experimental study of the solvent effects on two-photon absorption spectrum of p-nitroaniline(2014)27 cited
• → Synthesis, solvatochromism and large two-photon absorption cross-sections of water-soluble dipicolinate-based pyridinium salts(2013)15 cited
• Two-photon standard technique for measuring the two-photon absorption cross section in complex organic molecules(1995)