Elongated push–pull diphenylpolyenes for nonlinear optics: molecular engineering of quadratic and cubic optical nonlinearities via tuning of intramolecular charge transfer

Bulk photovoltaic effect in an organic polar crystal

“…The fluorescence band shows a large solvatochromic red shift that increases with increasing solvent polarity. 7 This is consistent with net photoinduced transfer of charge from the side of the molecule bearing the methoxy substituent to the side carrying the fluoromethyl group. Importantly, because of the alignment of the molecules of 1 in the crystal, photoexcitation of the crystal will result in a net transfer of charge from one side of the crystal to the other along the crystallographic c-axis.…”

“…6 Here we investigate the 1,4-diphenylbutadiene derivative 1 (Chart 1), carrying an electron donating methoxy-and an electron withdrawing trifluoromethyl-substituent. 7 The asymmetric substitution introduces donor-acceptor character and results in a considerable static dipole moment for 1, determined to be 3.8 Debye in dioxane solution. The dipolar vector is oriented along the long axis of the molecule.…”

Enhanced Two‐Photon Absorption of Organic Chromophores: Theoretical and Experimental Assessments

“…Substituted bistyryl derivatives were reported to have significant NLO response and experimental NLO data of similar compounds are available. [89,90,254] We start our calculations with geometry optimization of both molecules (insets in Fig. 3) at HF/6-31G level with planarity constraint, and then compute up to 26 singlet electronic states for each molecule using TD-DFT coupled with different functionals listed in Table 1: adiabatic local density approximation (ALDA, also known as Slater exchange), gradientcorrected functional (BLYP), and hybrid functionals (B3LYP, PBE1PBE, MPW1PW91, and BHandH), which contain an increasing portion of exact HF exchange.…”

Geometry Relaxation of Photoexcited States in Conjugated Molecules

“…However, these methods are rarely applied to larger molecules because of an enormous increase of computational effort. The semiempirical ESMD still remains viable to compute such systems as, for example, donor-acceptor molecules (containing electronwithdrawing and electron-donating groups connected by a conjugated bridge), which FIGURE 2 Top: structures of donor-acceptor substituted diphenyl-polyene oligomers; Bottom: deviations of magnitudes of computed vertical excitation energies from the corresponding experimental values averaged over all molecules (Alain et al, 1999;Tretiak et al, 2001). undergo interesting photochemical reactions such as intramolecular relaxation involving long-range electron transfer and molecular conformation, and featuring large nonlinear responses (Tretiak et al, 2001). The ground-state optimal geometry of the donor-acceptor molecule shown in Fig.…”

“…The results of computations of several conjugated molecules showed that the Hamiltonians designed for the ground state (AM1 and PM3) reproduce well the vertical excitation energies with accuracy comparable to approaches specifically fitted to the excited states (INDO/S). Figure 2 shows the structures of several donor-acceptor molecules studied in a search for large nonlinear optical responses, and the average deviation of the computed lowest state excited state (band-gap) energies from experimental values (Alain et al, 1999) for different semiempirical models. The agreement with experiment is very good, and furthermore it significantly improves when the solvation effects are taken into account (Fig.…”