4,6-Dimeth­oxy­pyrimidin-2-amine–2-(1H-indol-3-yl)acetic acid (1/1)

In the title co-crystal C6H9N3O2·C10H9NO2, the 4,6-dimeth­oxy­pyrimidin-2-amine mol­ecule inter­acts with the carboxyl group of the 2-(1H-indol-3-yl)acetic acid mol­ecule through N—H⋯O and O—H⋯N hydrogen bonds, forming a cyclic hydrogen-bonded R 2 2(8) motif, which is further linked by an N—H⋯N hydrogen bond, forming a supra­molecular chain along the c axis. Neighboring chains are inter­linked via C—H⋯O hydrogen bonds, forming a supra­molecular ladde

2-Amino-4-meth­oxy-6-methyl­pyrimidin-1-ium picrate

In the title salt, C6H10N3O+·C6H2N3O7 −, the dihedral angle between the mean planes of the benzene and pyridine rings is 3.1 (1)°. In the cation, the meth­oxy group is almost coplanar with the pyridine ring [C—O—C—N = −0.6 (2)°]. The p-nitro [C—C—N—O = −1.17 (19)°] and one o-nitro [C—C—N—O = 1.83 (19)°] group in the anion are essentially coplanar with the benzene ring. The other disordered o-nitro group containing the major occupancy [0.868 (6)] O atom is twisted −29.0 (2)° from the mean plane of the benzene ring. A bifurcated N—H⋯(O.O) hydrogen bond and weak C—H⋯O intermolecular inter­action between the cation and anion produce a network of infinite O—H⋯O—H⋯O—H chains along the c axis in the [101] plane which helps to establish crystal packing. Comparison to a DFT computational calculation indicates that significant conformational changes occur in the free state

2-Amino­pyrimidinium picrate

The geometric parameters of the title compound, C4H6N3 +·C6H2N3O7 −, are in the usual ranges. While two nitro groups are almost coplanar with the aromatic picrate ring [dihedral angles 3.0 (2) and 4.4 (3)°], the third is significantly twisted out of this plane [dihedral angle 46.47 (8)°]. Anions and cations are connected via N—H⋯O hydrogen bonds. The mol­ecules crystallize in planes parallel to (11)

Effects of an external electric field on the ferroelectric-paraelectric phase transition in polyvinylidene fluoride-trifluoroethylene copolymer Langmuir-Blodgett films

X-ray diffraction and capacitance measurements have been employed to study the structural and dielectric behavior of the ferroelectric-paraelectric phase transition under the influence of a large external electric field. The samples under study are ultrathin (15–100 nm) Langmuir–Blodgett films of a copolymer of vinylidene fluoride (70%) with trifluoroethylene (30%) deposited on aluminum-coated silicon. In situ θ-2θ x-ray diffraction was used to measure the change in interlayer spacing perpendicular to the film surface, corresponding to the (110) direction and indicating that the polymer chains along (001) lie predominantly in the plane, while capacitance measurements were used to monitor the behavior of the dielectric constant of the film. Application of a large electric field, up to 265 MV&#;m, raises the phase transition temperature and can convert the nonpolar trans-gauche paraelectric phase to the polar all-trans ferroelectric phase in a reversible manner