The structures of polymorphs of N-(p-dimethylaminobenzylidene)-p-nitroaniline

Nakai, Hiroshi; Ezumi, Kiyoshi; Shiro, Motoo

doi:10.1107/s0567740881002483

Cited by 22 publications

(12 citation statements)

References 2 publications

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“…For instance, all four crystallographically independent molecules adopt a non-planar structure in the non-centrosymmetric structure (P2 1 2 1 2 1 ) of N-(p-dimethylaminebenzylidene)-p-nitroaniline [polymorph (IV)]. They are present with twist angles of 15.1 (6)-50.4 (6) for the aniline group with respect to the azomethine bridge (Nakai et al, 1981). In the monoclinic form, derivative (II) of N-(pmethylbenzylidene)-p-methylaniline (Bar & Bernstein, 1977), which also crystallizes in a chiral space group (P2 1 ), has a twisted conformation, as in the former analogue, with an angle of 41.7 between its central C-C N-C moiety and the aniline plane.…”

Section: Resultsmentioning

confidence: 99%

“…In most cases, an inversion centre occurs in the lattice, which results in the disappearance of the macroscopic second-order polarizability. A related example that overcomes this undesirable crystal-packing trend from an NLO point of view is one of the four known polymorphs of p-nitrobenzylidene-p-dimethylamineaniline [form (IV)], which exhibits a non-centrosymmetric crystal structure (Nakai et al, 1981). Regarding state-of-the-art for organic NLO materials, Marder et al (1994) have synthesized chromophores with very large first hyperpolarizability values.…”

Section: Introductionmentioning

confidence: 99%

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Non-centrosymmetric crystals of newN-benzylideneaniline derivatives as potential materials for non-linear optics

Souza

Rosa

Legendre

et al. 2015

Acta Crystallogr Sect B

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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.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Non-centrosymmetric crystals of newN-benzylideneaniline derivatives as potential materials for non-linear optics

Souza

Rosa

Legendre

et al. 2015

Acta Crystallogr Sect B

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“…The marked difference between these torsion angles θ and φ results from a combination of steric, inductive and mesomeric effects, and is in agreement with earlier obtained crystallographic data for other substituted organic benzylidene anilines. 29,[31][32][33] When going through the series from the more electron donating (ED) Me-group to the more electron withdrawing (EW) CN-group, φ hardly changes while θ becomes larger. Particularly noteworthy is the large θ angle between fragments A and B in 5.…”

Section: Dalton Transactions Papermentioning

confidence: 99%

Organometallic benzylidene anilines: donor–acceptor features in NCN-pincer Pt(ii) complexes with a 4-(E)-[(4-R-phenyl)imino]methyl substituent

et al. 2014

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A series of organometallic 4,4'-substituted benzylidene aniline complexes 4-ClPt-3,5-(CH2NMe2)2C6H2CH[double bond, length as m-dash]NC6H4R'-4', abbreviated as PtCl[NCN(CH[double bond, length as m-dash]NC6H4R'-4')-4], with R' = NMe2, Me, H, Cl, CN (, respectively), was synthesized via a Schiff-base condensation reaction involving reaction of PtCl[NCN(CH[double bond, length as m-dash]O)-4] () with the appropriate 4-R'-substituted aniline derivative () in toluene. The resulting arylplatinum(ii) products were obtained in 75-88% yield. Notably, product was also obtained in 68% yield from a reaction in the solid state by grinding solid with aniline . The structures of , , and in the solid state (single crystal X-ray diffraction) showed a non-planar geometry, in particular for compound . The electronic interaction between the donor benzylidene fragment PtCl(NCN-CH) and the para-R' aniline substituent through the azomethine bridge was studied with NMR and UV/Vis spectroscopy. Linear correlations were found between the azomethine (1)H, the (195)Pt NMR and various (13)C NMR chemical shifts, and the substituent parameters σF and σR of R' at the aniline site. In common with organic benzylidene anilines, the azomethine (1)H NMR chemical shift showed anomalous substituent behavior. The (195)Pt NMR chemical shift of the platinum center can be used as a probe for the electronic properties of the delocalized π-system of the benzylidene aniline framework, to which it is connected. The dual substituent parameter treatment of the azomethine (13)C NMR shift gave important insight into the unique behaviour of the Pt-pincer group as a substituent. Inductively, it is a very strong electron-withdrawing group, whereas mesomerically it behaves like a very strong electron donating group.

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“…The benzene rings of this aromatic Schiff base are buckled out of the plane in which the double bond of the N:=C--H subunit lies (Biirgi & Dunitz, 1970). Such a conformation is confirmed by the torsion angles C2---C1--C7--N1 (Nakai, Shiro, Ezumi, Sakata & Kubota, 1976;Nakai, Ezumi & Shiro, 1981;Bar & Bemstein, 1982;Baumeister, Hartung & Gdaniec, 1987;Ondr~i~ek, Kov~iFov~i, Maixner & Jursik, 1993).…”

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confidence: 72%

“…If the terminal phenyl rings of benzylideneaniline are substituted by different substituents, the general pattern of two long and one short bond distance is not preserved. On the contrary, the shortening of N---Car and C(sp2)--Car to 1.424 (3) and 1.463 (3)/~,, respectively, and the lengthening of N==C(sp 2) to 1.277 (3)/~, is observed in (I) and in similar structures (Nakai et al, 1976;Nakai et al, 1981;Bar & Bemstein, 1982;Baumeister et al, 1987;Ondni~ek et al, 1993). The Cll---C14 bond distance of 1.506 (4) ,~ is in good agreement with Car--C(sp 3) bond lengths.…”

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confidence: 81%