2-Amino-4-nitroaniline, a Known Compound with Unexpected Properties

High Piezoelectric Output Voltage from Blue Fluorescent N,N-Dimethyl-4-nitroaniline Nano Crystals in Poly-L-Lactic Acid Electrospun Fibers

N,N-dimethyl-4-nitroaniline is a piezoelectric organic superplastic and superelastic charge transfer molecular crystal that crystallizes in an acentric structure. Organic mechanical flexible crystals are of great importance as they stand between soft matter and inorganic crystals. Highly aligned poly-l-lactic acid polymer microfibers with embedded N,N-dimethyl-4-nitroaniline nanocrystals are fabricated using the electrospinning technique, and their piezoelectric and optical properties are explored as hybrid systems. The composite fibers display an extraordinarily high piezoelectric output response, where for a small stress of 5.0 × 10³ Nm^-2, an effective piezoelectric voltage coefficient of g_eff = 4.1 VmN^-1 is obtained, which is one of the highest among piezoelectric polymers and organic lead perovskites. Mechanically, they exhibit an average increase of 67% in the Young modulus compared to polymer microfibers alone, reaching 55 MPa, while the tensile strength reaches 2.8 MPa. Furthermore, the fibers show solid-state blue fluorescence, important for emission applications, with a long lifetime decay (147 ns) lifetime decay. The present results show that nanocrystals from small organic molecules with luminescent, elastic and piezoelectric properties form a mechanically strong hybrid functional 2-dimensional array, promising for applications in energy harvesting through the piezoelectric effect and as solid-state blue emitters.

Influence of substituents on the acceptor properties of the amino groups in the diaminobenzene analogues

The influence of substituents on the geometric parameters and acceptor properties of the amino group in the diaminobenzene analogues has been studied using quantum-chemical calculations and the study of crystal packing from the energetic viewpoint.

Hydrogen bonding in 4-nitrobenzene-1,2-diamine and two hydrohalide salts

The structures of 4-nitrobenzene-1,2-diamine [C6H7N3O2, (I)], 2-amino-5-nitroanilinium chloride [C6H8N3O2(+)·Cl(-), (II)] and 2-amino-5-nitroanilinium bromide monohydrate [C6H8N3O2(+)·Br(-)·H2O, (III)] are reported and their hydrogen-bonded structures described. The amine group para to the nitro group in (I) adopts an approximately planar geometry, whereas the meta amine group is decidedly pyramidal. In the hydrogen halide salts (II) and (III), the amine group meta to the nitro group is protonated. Compound (I) displays a pleated-sheet hydrogen-bonded two-dimensional structure with R2(2)(14) and R4(4)(20) rings. The sheets are joined by additional hydrogen bonds, resulting in a three-dimensional extended structure. Hydrohalide salt (II) has two formula units in the asymmetric unit that are related by a pseudo-inversion center. The dominant hydrogen-bonding interactions involve the chloride ion and result in R4(2)(8) rings linked to form a ladder-chain structure. The chains are joined by N-H···Cl and N-H···O hydrogen bonds to form sheets parallel to (010). In hydrated hydrohalide salt (III), bromide ions are hydrogen bonded to amine and ammonium groups to form R4(2)(8) rings. The water behaves as a double donor/single acceptor and, along with the bromide anions, forms hydrogen bonds involving the nitro, amine, and ammonium groups. The result is sheets parallel to (001) composed of alternating R5(5)(15) and R6(4)(24) rings. Ammonium N-H···Br interactions join the sheets to form a three-dimensional extended structure. Energy-minimized structures obtained using DFT and MP2 calculations are consistent with the solid-state structures. Consistent with (II) and (III), calculations show that protonation of the amine group meta to the nitro group results in a structure that is about 1.5 kJ mol(-1) more stable than that obtained by protonation of the para-amine group. DFT calculations on single molecules and hydrogen-bonded pairs of molecules based on structural results obtained for (I) and for 3-nitrobenzene-1,2-diamine, (IV) [Betz & Gerber (2011). Acta Cryst. E67, o1359] were used to estimate the strength of the N-H···O(nitro) interactions for three observed motifs. The hydrogen-bonding interaction between the pairs of molecules examined was found to correspond to 20-30 kJ mol(-1).

Normal coordinate analysis and Nonlinear Optical Response of cross-conjugated system 4,4-Dimethyl Benzophenone

FT-Raman and IR spectra of the nonlinear optical active crystal, 4,4-Dimethyl Benzophenone (4DMBP) have been recorded and analyzed The equilibrium geometry, harmonic vibrational wavenumbers of 4DMBP investigated with the help of density functional theory (DFT) method. The assignments of the vibrational spectra have been carried out with the help of normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology (SQMFF). The calculated hyperpolarizability value shows the nonlinear optical activity of the molecule. The value of HOMO-LUMO energy, Mulliken and the natural charges are calculated and analyzed. The Natural bond orbital analysis confirms the occurrence of intramolecular charge transfer interaction.

The application of the derivative IR-spectroscopy and HPLC-ESI-MS/MS in the analysis of archaeology resin

The applicability of the reducing-difference procedure for the interpretation of the conventional IR-spectroscopy as successful scientific technique for the analysis of ancient and modern resins has been demonstrated. The new temperature tool for modeling of the ancient resin samples has also been shown. The experimental infrared data are supported by the hydride approach of HPLC-MS-MS with ES-ionisation.

2-{2-[2-(4-Methoxybenzoyl)ethylamino]-4-nitroanilino}ethyl acetate: complex sheets built from five independent hydrogen bonds

The molecules of the title compound, C(20)H(23)N(3)O(6), are almost completely planar, apart from the H atoms bonded to tetrahedral C atoms. A combination of five hydrogen bonds, one of the N-H...O type and two each of the C-H...O and C-H...pi(arene) types, links the molecules into complex sheets.

1,10-Phenanthrolinium hydrogensquarate monohydrate--a non-centrosymmetric structure from two non-chiral agents

The novel hydrogensquarate salt of 1,10-phenanthroline has been synthesized, isolated and structurally elucidated by single crystal X-ray diffraction. 1,10-Phenanthrolinium hydrogensquarate monohydrate (1) crystallizes in the non-centrosymmetric P2(1) space group. Its hydrogensquarate anions form a stable dimer by means of ((Sq))OHc...O=C((Sq)) hydrogen bonds with lengths of 2.509, 2.526, 2.510, and 2.524A. The solvent water molecule interacts with the anion dimers by means of strong and moderate hydrogen bonds HOHc...O=C((Sq)) with bond lengths of 2.782 and 2.845A, respectively. The 1,10-phenanthrolinium cation participates in NHc...OH(2) interactions with the water molecule (bond lengths of 2.810, 2.758, 2.779 and 2.760A). Surprisingly, compound contains four independent molecules in the unit cell. Optical properties were elucidated by means of linear-polarized solid-state IR-spectroscopy and UV-spectroscopy. In addition TGA, DSC, DTA data, positive and negative ESI mass spectra as well as (1)H- and (13)C NMR spectra are presented. Quantum chemical methods were used to calculate the electronic structure, vibrational data and electronic spectra as well as non-linear optical properties of neutral 1,10-phenanthroline and its protonated cation. Second harmonic generation measurements of the novel compound demonstrate that the compound possesses effective d coefficients of 1.9+/-0.5 pm V(-1), value that is about three times higher that of the low temperature form of potassium dideuterophosphate.

Esters of 1-coumarinylbenzylphosphonic acid-IR-spectroscopic and theoretical elucidation

The IR-spectroscopic properties of three esters of 1-coumarinylbenzylphosphonic acid are elucidated both in solution and in solid-state. Linear-polarized IR-spectroscopy of oriented colloid suspensions in nematic host is used for experimental IR-characteristic band assignment in solid-state. Theoretical quantum chemical DFT calculations at B3LYP level of theory and 6-31++G** basis set are carried. Theoretical electronic structure and vibrational properties of compounds studied are discussed.

1,8-dinitro-4,5-dihydroxyantraquinone--solid-state linear-polarized IR-spectroscopy of oriented colloid particles as a suspension in nematic liquid crystal

By means of the linear-polarized IR-spectroscopic (IR-LD) tool to study the oriented solids samples as a colloid suspensions in nematic liquid crystal, the influence of the short contacts and pi-pi interactions in crystalline phase on IR-bands assignment and profile, i.e., relationship structure-spectroscopic properties, is studied in model system 1,8-dinitro-4,5-dihydroxyantraquinone. For a higher accuracy of the spectroscopic assignments a predetermination of the crystal structure in the same crystalline sample used in IR-LD spectroscopic elucidation is done. Some important aspects of pi-pi interactions and short contacts in solid phase are described. The advantages of the IR-LD method for an orientation of samples are demonstrated.