Non-centrosymmetric crystals of new N-benzylideneaniline derivatives as potential materials for non-linear optics
Nenhuma Miniatura disponível
Data
2015
Autores
Souza, Talita Evelyn
Rosa, Iara Maria Landre
Legendre, Alexandre Oliveira [UNESP]
Paschoal, Diego
Maia, Lauro June Queiroz
Santos, Hélio Ferreira dos
Matins, Felipe Terra
Doriguetto, Antonio Carlos
Título da Revista
ISSN da Revista
Título de Volume
Editor
International Union of Crystallography
Resumo
Three new N-benzylideneaniline derivatives [p-nitrobenzylidene-p-phenylamineaniline (I), 2,4-dinitrobenzylidene-p-phenylamineaniline (II) and p-dinitrobenzylidene-p-diethylamineaniline (III)] containing electron-push-pull groups have been prepared. They present a planar N-benzylideneaniline core and neighbouring functional atoms, which are related through an efficient intramolecular charge transfer (CT). Two of the derivatives crystallize in non-centrosymmetric space groups, a necessary condition for non-linear optical (NLO) responses. The NLO properties were calculated for the molecular conformations determined by single-crystal X-ray diffraction as well as for the four molecules packed into each corresponding unit cell, using a quantum-chemical method at the cam-B3LYP/NLO-V level of theory. As expected from antiparallel face-to-face stacking through centrosymmetry, the main NLO descriptors - namely, the first hyperpolarizability (βtot) and its projection on the dipole moment direction (βvec) - are almost zero for the tetramer of derivative III. Interestingly, the calculated first hyperpolarizability decreases in the non-centrosymmetric unit-cell content of derivative II when compared to its single molecule, which may be related to its molecular pillaring, similar to that observed in derivative III. On the other hand, a desirable magnification of the NLO properties was found for packed units of derivative I, which may be a consequence of its parallel face-to-tail stacking with the CT vectors of all molecules pointing in the same direction. Moreover, the CT vector of compound I makes an angle of θ = 33.6° with its crystal polar axis, resulting in a higher-order parameter (cos(3)θ = 0.6) compared with the other derivatives. This is in line with the higher macroscopic second-order NLO response predicted for derivative I, βtot = 120.4 × 10(-30) e.s.u.
Descrição
Palavras-chave
N-benzylideneaniline derivatives, Electron–push–pull, Non-centrosymmetric crystals, Non-linear optics
Como citar
Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials, v. 71, n. pt 4, p. 416-426, 2015.