New Organic Second-Order Nonlinear Optical Materials Developed By Using The Molecular Design Method

X-ray Crystal Structures, Molecular Mechanics Calculations, and Calculations of the Nonlinear Polarizabilities (β and γ) of Dicyanovinylbenzene and Its Methoxy Derivatives, and Comparison with Experimental Values of β

“…It is interesting to note that the importance of the weak hydrogen bonds NH···O and CH···O, determining the observable crystal packing arrays, was demonstrated recently in the theoretical calculations (AM1, PM3, and SAMI) of the clusters (microcrystals, containing up to 10 molecules) of the p - and m -nitroaniline molecules. A further explanation for the centric and acentric crystal structures of these two compounds (see refs and ) was obtained in this paper from the energetic analysis of the preferable molecular associate configurations.…”

“…The energies of the possible dimer molecular associates of I − IV were also calculated with MM3 using a stochastic search procedure, the total energy being calculated as a sum of the intra- and intermolecular interactions. The advantage of the stochastic procedure in comparison with mapping of intermolecular energy (as a function of interplanar distance and in-plane rotation angle) described by Itoh et al, , is that molecular conformations and relative molecular positions in dimers were not restricted during optimization. As the starting points for a stochastic search, three possible dimers were taken with the parallel, centrosymmetric C i , and C 2 symmetry mutual molecular orientations.…”

“…a Equivalent isotropic U defined as one-third of the trace of the orthogonalized Uij tensor. (as a function of interplanar distance and in-plane rotation angle) described by Itoh et al, 33,34 is that molecular conformations and relative molecular positions in dimers were not restricted during optimization. As the starting points for a stochastic search, three possible dimers were taken with the parallel, centrosymmetric C i , and C 2 symmetry mutual molecular orientations.…”

“…A similar approach was used earlier by Itoh et al , for explanation of the centrosymmetric structure of p -nitroaniline and acentric structure of m -nitroaniline. For these two planar molecules the dependence of the dimer energy from interplanar distance and in-plane molecular rotation angle was mapped, and it was shown that for p -nitroaniline the preferable dimer is centrosymmetric, while it is noncentrosymmetric for m -nitroaniline.…”

Molecular Crystal Structures and Nonlinear Optical Properties in the Series of Dicyanovinylbenzene and Its Derivatives

“…The total energy was calculated as a sum of the intra- and intermolecular interactions. Stochastic procedure has some advantages in comparison with mapping of the intermolecular energy as a function of interplanar distance and in-plane rotation angle as described by Itoh et al 25a,b because the molecular conformations and relative molecular orientations in dimers were not restricted during optimization. Three types of dimers were taken into account with the parallel, centrosymmetric C i , and C 2 symmetries as starting points for a stochastic search.…”