A. Subashini

Synthesis, growth and characterization of 4-bromo-4′-nitrobenzylidene aniline (BNBA): a novel nonlinear optical material with a (3+1)-dimensional incommensurately modulated structure

The organic nonlinear optical material of 4-bromo-4′-nitrobenzylidene aniline (BNBA, C13H9BrN2O2), a new derivative of benzylideneaniline family, was synthesized and purified by repeated recrystallization. Single crystals of BNBA were grown in acetone solvent by slow evaporation at room temperature. Its (3+1)-dimensional incommensurately modulated structure was elucidated from single crystal X-ray diffraction data obtained at 173 K. The non-centrosymmetric structure was solved and refined in the monoclinic superspace group A2(α0γ)0; the unit cell parameters are a = 10.5217(10) A, b = 16.2535(16) A, c = 7.4403(7) A, β = 110.709(7)°, modulation vector q = 0.0658(1)a*–0.2658(1)c*. At 290 K, the structure is partially disordered, however, the local structure of domains is identical to that at 173 K. The 1H and 13C NMR and Fourier Transform Infrared and FT-Raman spectroscopic studies confirmed the molecular structure. The Kurtz powder second-harmonic generation (SHG) test reveals that the SHG efficiency of BNBA is about 9.4 times higher than that of potassium dihydrogen phosphate. According to the thermogravimetric, differential thermal and differential scanning calorimetric analyses, BNBA is a stable phase starting from room temperature and up to the melting point, 436 K. The optical nonlinearity of BNBA was investigated at 532 nm using 5 ns laser pulses, employing the open aperture Z-scan technique.

Quantitative structure and activity relationship on the biological, nonlinear and the spectroscopic properties of the Schiff base material: 4-chloro-4′bromobenzylidene aniline

Abstract The structural and non-linear optical properties of the Schiff base material, 4-chloro-4′bromobenzylidene aniline (CBBA) were analysed using FTIR, FT-Raman, UV and Nuclear Magnetic Resonance spectral techniques together with DFT method and Z-scan technique. Natural Bond Orbital (NBO) analysis method was employed to analyse the intramolecular electronic interactions leading to the stability of the molecule. The complete vibrational assignments were performed based on the scaled quantum mechanical force field procedure. The energies of the frontier orbitals, HOMO–LUMO energy gap and the quantum chemical descriptors such as the electron affinity, ionisation potential, electronegativity, electrophilicity index, global softness, chemical hardness and chemical potential, were calculated in order to quantify the chemical reactivity of the molecule. The non-linear optical (NLO) properties of the CBBA molecule interrelated with the property of 4-bromo-4′chloro benzylidene aniline (BCBA), 4-bromo-4′bromo benzylidene aniline (BBBA), 4-chloro-4′chloro benzylidene aniline (CCBA) and the molecule having hydrogen atom instead of halogen atom (HHBA) was examined. The result provides direct information regarding the relationship between molecular structure and NLO property. Z scan studies performed on the molecule reveal its potential and suitability in optical limiting applications. The molecule was subjected to molecular docking on the active sites of the protein structures of 2B7A, 2E9V, 2OFV and 3E93 to observe binding modes in terms of lowest docking energy.

Dichloridobis(4-fluoro-aniline-κN)zinc.

In the title compound, [ZnCl2(C6H6FN)2], the ZnII atom has a slightly distorted tetrahedral geometry, being coordinated by the N atoms of two 4-fluoroaniline molecules and the two Cl− anions. The two benzene rings are almost perpendicular to one another, making a dihedral angle of 89.96 (13)°. In the crystal, molecules are linked via pairs of N—H⋯Cl hydrogen bonds, forming chains propagating along the b axis. These chains are in turn linked via a second pair of N—H⋯Cl hydrogen bonds, forming a two-dimensional network parallel to the ab plane. The title compound crystallizes in the space group Pca21 and exhibits weak second harmonic generation (SHG) properties.

(E)-N'-(4-Chlorobenzylidene)-, (E)-N'-(4-bromobenzylidene)- and (E)-N'-[4-(diethylamino)benzylidene]- derivatives of 4-hydroxybenzohydrazide.

The 4-chloro- [C(14)H(11)ClN(2)O(2), (I)], 4-bromo- [C(14)H(10)BrN(2)O(2), (II)] and 4-diethylamino- [C(18)H(21)N(3)O(2), (III)] derivatives of benzylidene-4-hydroxybenzohydrazide, all crystallize in the same space group (P2(1)/c), (I) and (II) also being isomorphous. In all three compounds, the conformation about the C=N bond is E. The molecules of (I) and (II) are relatively planar, with dihedral angles between the two benzene rings of 5.75 (12) and 9.81 (17)°, respectively. In (III), however, the same angle is 77.27 (9)°. In the crystal structures of (I) and (II), two-dimensional slab-like networks extending in the a and c directions are formed via N-H···O and O-H···O hydrogen bonds. The molecules stack head-to-tail via π-π interactions involving the aromatic rings [centroid-centroid distance = 3.7622 (14) Å in (I) and 3.8021 (19) Å in (II)]. In (III), undulating two-dimensional networks extending in the b and c directions are formed via N-H···O and O-H···O hydrogen bonds. The molecules stack head-to-head via π-π interactions involving inversion-related benzene rings [centroid-centroid distances = 3.6977 (12) and 3.8368 (11) Å].

N,N′-Bis(4-chloro­benzyl­idene)-3,3′-dimeth­oxy­biphenyl-4,4′-diamine

The title compound, C28H22Cl2N2O2, crystallized with two independent molecules (A and B) in the asymmetric unit. The two molecules differ essentially in the orientation of the outer aromatic rings. These dihedral angles are 56.07 (13) and 27.62 (15) Å for molecules A and B, respectively. In the crystal, A molecules are related as centrosymmetric pairs through a weak π–π interaction [centroid–centroid distance = 3.6959 (15) Å]. There are also a number of intermolecular C—H⋯O, C—H⋯N and C—H⋯π interactions present.