- Syntheses, Crystal Structures, and Optical Properties of the Hexagonal Perovskites Variants ABX3 (B = Ni, A = Gu, FA, MA, X = Cl, Br; B = Mn, A = MA, X = Br)
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Herein we report on our systematic investigations on the solution processed synthesis and characterization of transition metal halides (guanidinium, formamidinium, and methylammonium nickel bromides and chlorides as well as methylammonium manganese bromide) with the composition ABX3 (A = organic cation; B = Mn, Ni; X = Cl, Br). The investigations were carried out with respect to possible applications of 3d transition metal compounds for the perovskite solar cell. All the compounds represent different variants of the hexagonal perovskite structure (2H). Crystal structures and symmetry relations are discussed. Additionally, (CH3NH3)2MnI4, which consists of tetrahedral coordinated Mn2+, and the water containing compounds (CH3NH3)MnBr3·2H2O, which forms chains of edge sharing octahedra, as well as (CH3NH3)NiCl3·2H2O, which consists of dimers of octahedra, are presented. Investigations on the crystal structures are supported by vibrational and optical spectroscopy.
- Daub, Michael,Ketterer, Ines,Hillebrecht, Harald
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p. 280 - 287
(2018/02/09)
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- HIGHLY TUNABLE COLLOIDAL PEROVSKITE NANOPLATELETS
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Colloidal perovskite nanoplatelets can provide a material platform, with tunability extending from the deep UV, across the visible, into the near-IR. The high degree of spectral tunability can be achieved through variation of the cation, metal, and halide composition as well as nanoplatelet thickness.
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Paragraph 0074; 0075; 0076
(2017/11/29)
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- Reentrant Structural and Optical Properties and Large Positive Thermal Expansion in Perovskite Formamidinium Lead Iodide
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The structure of the hybrid perovskite HC(NH2)2PbI3(formamidinium lead iodide) reflects competing interactions associated with molecular motion, hydrogen bonding tendencies, thermally activated soft octahedral rotations, and the propensity for the Pb2+lone pair to express its stereochemistry. High-resolution synchrotron X-ray powder diffraction reveals a continuous transition from the cubic α-phase (Pm3m, #221) to a tetragonal β-phase (P4/mbm, #127) at around 285 K, followed by a first-order transition to a tetragonal γ-phase (retaining P4/mbm, #127) at 140 K. An unusual reentrant pseudosymmetry in the β-to-γ phase transition is seen that is also reflected in the photoluminescence. Around room temperature, the coefficient of volumetric thermal expansion is among the largest for any extended crystalline solid.
- Fabini, Douglas H.,Stoumpos, Constantinos C.,Laurita, Geneva,Kaltzoglou, Andreas,Kontos, Athanassios G.,Falaras, Polycarpos,Kanatzidis, Mercouri G.,Seshadri, Ram
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p. 15392 - 15396
(2016/12/06)
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- Stabilities of immonium ions derived from N-heterocyclic carbenes probed by collision-induced dissociation mass spectrometry
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We report efficient methods for the synthesis of both symmetrically and non-symmetrically substituted bis(imidazol-2-yliden)ammonium ions and a new family of bis(imidazol-2-ylidene)formamidines. The fragmentation pathways of these cations were studied in detail by electrospray ionization combined with tandem mass spectrometry. Interestingly, in these cations direct C-N bond cleavage leading to loss of alkyl radicals can compete with rearrangement reactions leading to closed-shell fragments. The experimental results for the major fragmentation channels are compared with those derived from DFT calculations. Inter alia, a novel rearrangement of the cationic species involving specific alkyl migrations between the two imidazole subunits has been found. ESI combined with tandem mass spectrometry and DFT have been used for investigation of the fragmentation pathways of substituted bis(imidazol-2- yliden)ammonium ions and bis(imidazol-2-ylidene)formamidinium ions. Interestingly, in these cations direct C-N bond cleavage leading to loss of alkyl radicals can compete with rearrangements leading to closed-shell fragments. Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
- Polyakova, Svetlana M.,Kunetskiy, Roman A.,Schroeder, Detlef
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experimental part
p. 3852 - 3862
(2012/09/21)
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- Novel transition metal complexes with diaminocarbene ligands and their use in reactions catalyzed by transition metals
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The invention relates to novel transition metal complexes containing at least one diaminocarbene ligand, to processes for preparing these transition metal complexes and to their use as catalysts in organic reactions.
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- Sulfonamides and uses
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Sulfonamides of formula I, in which the symbols R1 -R6, X, Y and n have the significance given in the description and which are in part novel compounds, and salts thereof, which can be used as active ingredients for the manufacture of medicaments for the treatment of circulatory disorders, especially hypertension, ischemia, vasospasms and angina pectoris, are described.
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