Investigation of optical, dielectric, and conduction mechanism in lead-free perovskite CsMnBr3.

Metallic perovskites have advantageous optical and electrical properties, making them a valuable class of semiconductors for the manufacturing of solar cells. CsMnBr3 is notable among them due to its important optical characteristics. The electrical and dielectric characteristics as a semiconductor are examined in this study. Direct transitions with a 3.29 eV bandgap and an Urbach energy of 0.96 eV are revealed by the results. Through AC conductivity, it demonstrated semiconductor characteristics at 443 K. The dielectric loss varied with frequency and peaked at high frequencies. Furthermore, as temperature rose, a relaxation peak in the electrical modulus was seen to migrate to higher frequencies. Ac conductivity is described by the double power law expression. The conduction in our compound is governed by small polaron tunneling. Based on the optical results reported in the bibliography for this sample, we realize the importance of examining the electrical characteristics to comprehend the semiconductor behavior of CsMnBr3.

[(CH3)2NH2]2PdBr4, a layered hybrid halide perovskite semiconductor with improved optical and electrical properties.

Inspired by the success of three-dimensional hybrid perovskites (CH3NH3)PbX3 (X = Cl, Br, I), two-dimensional (2D) organic-inorganic hybrid metal halides have drawn immense attention due to their highly tunable physical properties. Moreover, although 3D hybrid perovskite materials have been reported, the development of new organic-inorganic hybrid semiconductors is still an area in urgent need of investigation. Here, we used the dimethylammonium cation to construct a palladium-based halide perovskite material [(CH3)2NH2]2PdBr4 with a 2D layered structure. This layered perovskite undergoes one endothermic peak at 415 K corresponding to melting of the organic molecule. The thermal stability of the compound is up to about 500 K. The activation energy and conduction mechanisms are discussed, and the optical study shows a gap energy equal to 2.5 eV. The electrical AC conductivity is in the order of 10-4 Ω-1 cm-1, which confirms the semiconductor character of this material and indicates its importance in the optoelectronic domain.

1,4,8,11-Tetra-azonia-cyclo-tetra-decane tetra-kis-(hydrogensulfate).

In the title salt, C10H28N4 (4+)·4HSO4 (-), the cation lies about an inversion center. In the crystal, O-H⋯O and N-H⋯O hydrogen bonds connect the anions and cations, forming a three-dimensional network.

2-Dihydromethylpiperazinediium-M(II) (M(II) = Cu(II), Fe(II), Co(II), Zn(II)) double sulfates and their catalytic activity in diastereoselective nitroaldol (Henry) reaction.

A series of double dihydromethylpiperazinediium metallic sulfates 1-7 [H(2)mpz]M(II)(SO(4))(2)·nH(2)O (mpz = 2-methylpiperazine, C(5)H(12)N(2)) are prepared by slow evaporation using a racemic (R/S)-mpz (for 1, 2) or enantiopure R-mpz (for 3), S-mpz (for 4-7) and sulfates of Cu(II) (for 5), Fe(II) (for 1, 4), Co(II) (for 7) and Zn(II) (for 2, 3, 6), and characterized by infrared spectroscopy, elemental analysis and single crystal X-ray diffraction. The [M(II)(H(2)O)(6)](2+), [(R/S)-H(2)mpz](2+), [(R)-H(2)mpz](2+) or [(S)-H(2)mpz](2+) cations and 2SO(4)(2-) anions are linked together via two types of hydrogen bonds, Ow-Hw···O and N-H···O, leading to supramolecular arrangements. The use of the racemic 2-mpz provides alternatives in crystallization: a centrosymmetric structure where the enantiomers are related by an appropriate crystallographic symmetry operation or one where the enantiomers occupy the same crystallographic position, generating disorder. Compounds 1-7 act as diastereoselective catalysts for the nitroaldol (Henry) reaction. The diastereoselectivity can be regulated from exclusive threo to exclusive erythro isomer preparation with typical yields of 50-99%, depending on the catalyst and the substrate used.

Synthesis, characterization and magnetic properties of four new organically templated metal sulfates [C5H14N2][M(II)(H2O)6](SO4)2, (M(II) = Mn, Fe, Co, Ni).

A series of novel organically templated metal sulfates, [C(5)H(14)N(2)][M(II)(H(2)O)(6)](SO(4))(2) with (M(II) = Mn (1), Fe (2), Co (3) and Ni (4)), have been successfully synthesized by slow evaporation and characterized by single-crystal X-ray diffraction as well as with infrared spectroscopy, thermogravimetric analysis and magnetic measurements. All compounds were prepared using a racemic source of the 2-methylpiperazine and they crystallized in the monoclinic systems, P2(1)/n for (1, 3) and P2(1)/c for (2,4). Crystal data are as follows: [C(5)H(14)N(2)][Mn(H(2)O)(6)](SO(4))(2), a = 6.6385(10) Å, b = 11.0448(2) Å, c = 12.6418(2) Å, ß = 101.903(10)°, V = 906.98(3) Å(3), Z = 2; [C(5)H(14)N(2)][Fe(H(2)O)(6)](SO(4))(2), a = 10.9273(2) Å, b = 7.8620(10) Å, c = 11.7845(3) Å, ß = 116.733(10)°, V = 904.20(3) Å(3), Z = 2; [C(5)H(14)N(2)][Co(H(2)O)(6)](SO(4))(2), a = 6.5710(2) Å, b = 10.9078(3) Å, c = 12.5518(3) Å, ß = 101.547(2)°, V = 881.44(4) Å(3), Z = 2; [C(5)H(14)N(2)][Ni(H(2)O)(6)](SO(4))(2), a = 10.8328(2) Å, b = 7.8443(10) Å, c = 11.6790(2) Å, ß = 116.826(10)°, V = 885.63(2) Å(3), Z = 2. The three-dimensional structure networks for these compounds consist of isolated [M(II)(H(2)O)(6)](2+) and [C(5)H(14)N(2)](2+) cations and (SO(4))(2-) anions linked by hydrogen-bonds only. The use of racemic 2-methylpiperazine results in crystallographic disorder of the amines and creation of inversion centers. The magnetic measurements indicate that the Mn complex (1) is paramagnetic, while compounds 2, 3 and 4, (M(II) = Fe, Co, Ni respectively) exhibit single ion anisotropy.