Structure, photoluminescence, and magnetic properties of a Mn(ii)-based metal–organic framework

Fluorescence of a three-dimensional Mn-based framework compound is completely quenched by nitroaromatic compounds and Cu2+ ions. Spin canting is operative in this Mn(ii) system, resulting from the magnetic anisotropy of the Mn(ii) ion in a low-symmetry trigonal bipyramid.

Zn(II) Curcuminate Complexes with 2,2’-bipyridine and Carboxylates

Two novel zinc(II) compounds with curcuminate (abbreviated as cur–), [Zn(CH3COO)(cur)(bpy)](1)·CH3OH·2H2O (bpy = 2,2’-bipyridine) and [Zn(PhCOO)(cur)(bpy)] (2)·CH3OH, have been synthesized and characterized. Their composition has been determined by single-crystal X-ray structure analysis. Complexes 1 and 2 are similar: in both a five-fold coordination environment of zinc(II) consists of a monodentate carboxylate, a chelating bidentate 2,2’-bipyridine, and curcuminate, which is bound via a deprotonated 1,3-dione moiety. In 1, 2,2’-bipyridine nitrogen atoms and curcuminate oxygen atoms form the base of a square pyramid, whereas the acetate oxygen occupies its apex. The O3N2 donor set in 2 defines a polyhedron which more closely resembles a trigonal bipyramid. The packing in the crystal lattices of both compounds is governed by hydrogen-bonds. Complexes 1 and 2 display higher stability than curcumin in buffered media at pH = 7.0, however, the degradation of coordinated cur– is comparable to that of yellow pigment curcumin (curH) when the pH is raised to 7.2. Both complexes 1 and 2 in DMSO exhibit fluorescence with Stokes shifts of 5367 and 4634 cm−1, respectively.

A new form of NaMnAsO4

A new form of NaMnAsO4, sodium manganese(II) orthoarsenate, has been obtained under hydrothermal conditions, and is referred to as the β-polymorph. In contrast to the previously reported orthorhombic α-polymorph that crystallizes in the olivine-type of structure and has one manganese(II) cation in a distorted octahedral coordination, the current β-polymorph contains two manganese(II) cations in [5]-coordination, intermediate between a square-pyramid and a trigonal bipyramid. In the crystal structure of β-NaMnAsO4, four [MnO5] polyhedra are linked through vertex- and edge-sharing into finite {Mn4O16} units strung into rows parallel to [100]. These units are linked through two distinct orthoarsenate groups into a framework structure with channels propagating parallel to the manganese oxide rows. Both unique sodium cations are situated inside the channels and exhibit coordination numbers of six and seven. β-NaMnAsO4 is isotypic with one form of NaCoPO4 and with NaCuAsO4.

New global minima of 6-vertex dicarboranes: classical but unexpected

Two new rule-breaking six-vertex dicarborane global minima, i.e., trigonal bipyramid (R = SH) and butterfly (R = Cl, NH2, OH, F) were predicted.

First-principles study of NaxTiO2 with trigonal bipyramid structures: an insight into sodium-ion battery anode applications

Crystalline structures, energetics, electrode voltage, and electronic structures of NaxTiO2 with trigonal bipyramid structures were obtained with first-principles calculations.

(Acetamide-κO){2,2′,2′′-boranetriyltris[6-tert-butyl-4-methylpyridazine-3(2H)-thione]-κ4 B,S,S′,S′′}copper(I) trifluoromethanesulfonate chloroform disolvate

In the title solvated complex salt, [Cu(C27H39BN6S3)(C2H5NO)](CF3O3S)·2CHCl3, the CuI atom is coordinated by the three S atoms of the pyridazine-3-thione rings in the equatorial plane [Cu—S = 2.3072 (4)–2.3280 (4) Å] and the B atom of the scorpionate ligand and the O atom of an acetamide ligand as the apices of a trigonal bipyramid [Cu—B = 2.0456 (16) Å and Cu—O = 1.9957 (11) Å]. The amide group of the latter ligand is involved in a bifurcated hydrogen bond to the trifluoromethanesulfonate anion.

Fine-tuning the effects of auxiliary ligands on two trigonal-bipyramid cobalt(ii) complexes exhibiting field-induced slow magnetic relaxation

Two trigonal-bipyramid cobalt(ii) complexes exhibit field-induced slow magnetic relaxation effects due to their auxiliary ligands.