Dendritic Iron(III) Carbazole Complexes: Structural, Optical, and Magnetic Characteristics

Abstract

This paper focuses on the synthesis, structural characterization, and study of the optical, magnetic, and thermal properties of novel architectures combining metal ions as magnetoactive centers and photoactive blocks formed by carbazole units. For this purpose, a series of azomethine complexes of the composition [Fe(L)2]X (L = 3,6-bis[(3′,6′-di-tert-butyl-9-carbazol)-9-carbazol]benzoyloxy-4-salicylidene-N′-ethyl-N-ethylenediamine, X = NO3−, Cl−, PF6−) were synthesized by the reaction of metal salts with Schiff bases in a mixture of solvents. The UV–Vis absorption properties were studied in dichloromethane and rationalized via time-dependent density functional theory (DFT) calculations. Upon excitation at 350 nm, the compounds exhibited an intense dual fluorescence with two emission bands centered at ~445 and ~485 nm, which were assigned to πcarb–π* intraligand and πcarb–dFe ligand-to-metal charge-transfer excited states. EPR spectroscopy and SQUID magnetometry revealed solid-state partial spin crossover in some compounds, and antiferromagnetic interactions between the neighboring Fe(III) ions.

Structure and Magnetic Properties of Pseudo-1D Chromium Thiolate Coordination Polymers

“…Cr metal–organic frameworks in particular have been shown to have strong gas phase selectivity arising from spin interactions with Cr . Additionally, more tractable and controllable coupling schemes have made 1D and 2D systems highly desirable magnetic models for several decades. − Many approaches to design low-dimensional magnetic materials have been taken including coordination polymers (CPs) of ions as well as single molecules, − van der Waals solids, , and cluster chemistries. − However, thus far, the majority of these 1D materials are not highly symmetric, often containing skewed zig-zag motifs, , multiple magnetic sites, or alternating metal coordination geometries . Moreover, many of the most well-studied chains, such as those in the hexagonal perovskite family, are the product of salt melt syntheses which frequently produce electronically limited oxide materials that are not easily tuned.…”

Impacts of Alkali Metals on the Structures and Properties of Fe(III) Heterometallic Cyclobutane-1,1-dicarboxylate Complexes

“…Coordination compounds of iron­(III) are being actively studied due to a spin-crossover phenomenon − or molecular magnet properties, − allowing them to be used in spintronics and quantum engineering. , Complexes of iron­(III) are known to be capable of exhibiting the properties of molecular magnets, i.e., molecules with a directionally bistable magnetic moment, both in the case of polynuclear systems ,, and in the case of mononuclear compounds exhibiting the properties of a magnet at the level of one ion. , The Fe 3+ ions in the complexes show various coordination numbers, from 3 to 7; ,,− however, the magnetic properties of quasioctahedral iron­(III) complexes have insufficiently been studied. Complexes in which Fe 3+ ions are in a distorted octahedral environment are characterized by negative or positive D values. ,− One of the major factors affecting the magnetic properties of coordination compounds of 3d-metals is the coordination environment of the central ion. − Therefore, the choice of an appropriate ligand plays a key role in the design of coordination compounds and, in some cases, enables us to synthesize compounds with the required properties. ,− …”

The Structure and Magnetic Properties of a New Family of 1D Chromium Thiolate Coordination Polymers

“…14 Additionally more tractable and controllable coupling schemes have made 1 and 2D systems highly desirable magnetic models for several decades. [15][16][17][18] Many approaches to design low dimensional magnetic materials have been taken including coordination polymers (CPs) of ions as well as single molecules, [19][20][21][22][23] Van der Waals solids, 24,25 and cluster chemistries. [26][27][28] However, thus far the majority of these 1D materials are not highly symmetric, often containing skewed zig-zag motifs, 29,30 multiple magnetic sites 31 , or alternating metal coordination geometries.…”