Structure, Optical and Magnetic Properties of Two Isomeric 2-Bromomethylpyridine Cu(II) Complexes [Cu(C6H9NBr)2(NO3)2] with Very Different Binding Motives

Two isomeric 2-bromomethylpyridine Cu(II) complexes [Cu(C₆H₉NBr)₂(NO₃)₂] with 2-bromo-5-methylpyridine (L¹) and 2-bromo-4-methylpyridine (L²) were synthesized as air-stable blue materials in good yields. The crystal structures were different with [Cu(L¹)₂(NO₃)₂] (CuL¹) crystallizing in the monoclinic space group P2₁/c, while the 4-methyl derivative CuL² was solved and refined in triclinic P1¯. The orientation of the Br substituents in the molecular structure (anti (CuL¹) vs. syn (CuL²) conformations) and the geometry around Cu(II) in an overall 4 + 2 distorted coordination was very different with two secondary (axially elongated) Cu-O bonds on each side of the CuN₂O₂ basal plane in CuL¹ or both on one side in CuL². The two Br substituents in CuL² come quite close to the Cu(II) centers and to each other (Br⋯Br ~3.7 Å). Regardless of these differences, the thermal behavior (TG/DTA) of both materials is very similar with decomposition starting at around 160 °C and CuO as the final product. In contrast to this, FT-IR and Raman frequencies are markedly different for the two isomers and the UV-vis absorption spectra in solution show marked differences in the π-π* absorptions at 263 (CuL²) or 270 (CuL¹) nm and in the ligand-to-metal charge transfer bands at around 320 nm which are pronounced for CuL¹ with the higher symmetry at the Cu(II) center, but very weak for CuL². The T-dependent susceptibility measurements also show very similar results (µ_eff = 1.98 µ_B for CuL¹ and 2.00 µ_B for CuL² and very small Curie-Weiss constants of about -1. The EPR spectra of both complexes show axial symmetry, very similar averaged g values of 2.123 and 2.125, respectively, and no hyper-fine splitting.

Crystal engineering and structural diversity of 2-aminopyridinium hypodiphosphates obtained by crystallization and dehydration

Organic-inorganic salts and ionic co-crystals of hypodiphosphoric acid (H4P2O6) with 2-aminopyridne (2ap) have been synthesized and characterized by X-ray crystallography, thermogravimetry, element analysis and Fourier-transform infared spectroscopy. (2apH)4(H3P2O6)2(H2P2O6)∙2H2O (1), (2apH)2(H2P2O6)∙2H2O...

Inorganic-Organic Hybrid Molecular Materials: From Multiferroic to Magnetoelectric

Inorganic-organic hybrid molecular multiferroic and magnetoelectric materials, similar to multiferroic oxide compounds, have recently attracted increasing attention because they exhibit diverse architectures, a flexible framework, fascinating physics, and potential magnetoelectric functionalities in novel multifunctional devices such as energy transformation devices, sensors, and information storage systems. Herein, the classification of multiferroicity and magnetoelectricity is briefly outlined and then the recent advances in the multiferroicity and magnetoelectricity of inorganic-organic hybrid molecular materials, particularly magnetoelectricity and the relevant magnetoelectric mechanisms and their categories are summarized. In addition, a personal perspective and an outlook are provided.

Synthetic strategy towards halometallates with imidazo[1,5-a]pyridinium-based counterions

The interaction between formaldehyde, amine and 2-pyridinecarbaldehyde with MX_n (X = halide) in the presence of HX enables creation of a large range of chemical and structural variations for systematic investigation of the entailing properties.

Properties and growth of large single crystals of one-dimensional organic lead iodine perovskite

Here, we demonstrate for the first time the growth of 2 mm × 4 mm × 8 mm sized single crystal one dimensional organic lead iodine perovskite – DMAPbI₃ ((CH₃)₂NH₂PbI₃).