Spectroscopic properties of mono- and bis-azopyrroles

We use density functional theory and time-dependent density functional theory to evaluate the structure and electronic properties of a series of recently-synthesized mono- and bi-azopyrrole dyes. The selected ab initio approach relies on hybrid functionals, large basis sets and systematic modeling of solvent effects. For simulating the absorption spectra, three functionals are benchmarked (PBE0, BMK, and CAM-B3LYP), and it turns out that these three hybrids are able to provide accurate theoretical estimates (average deviations similar to 0.1 eV) of the longest wavelength of maximal absorption. New structures are proposed to minimize the transition energy and the impact of the relative position of donor and acceptor groups is discussed. The linear and nonlinear optical properties of the proposed dyes are investigated with a long-range corrected approach. (C) 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012