Dielectric-Optical Switches: Photoluminescent, EPR, and Magnetic Studies on Organic–Inorganic Hybrid (azetidinium)₂MnBr₄

Abstract

A new organic–inorganic hybrid, AZEMnBr , has been synthesized and characterized. The thermal differential scanning calorimetry, differential thermal analysis, and thermogravimetric analyses indicate one structural phase transition (PT) at 346 and 349 K, on cooling and heating, respectively. AZEMnBr crystallizes at 365 K in the orthorhombic, Pnma , structure, which transforms to monoclinic P 2 1 / n at 200 K. Due to the X-ray diffraction studies, the anionic MnBr 4 2– moiety is discrete. The azetidinium cations show dynamical disorder in the high-temperature phase. In the proposed structural PT, the mechanism is classified as an order–disorder type. The structural changes affect the dielectric response. In this paper, the multiple switches between low- and high- dielectric states are presented. In addition, it was also observed that the crystal possesses a mutation of fluorescent properties between phase ON and OFF in the PT’s point vicinity. We also demonstrate that EPR spectroscopy effectively detects PTs in structurally diverse Mn(II) complexes. AZEMnBr compounds show DC magnetic data consistent with the S = 5/2 spin system with small zero-field splitting, which was confirmed by EPR measurements and slow magnetic relaxation under the moderate DC magnetic field typical for a single-ion magnet behavior. Given the above, this organic–inorganic hybrid can be considered a rare example of multifunctional materials that exhibit dielectric, optical, and magnetic activity.

Reversible Phase Transition and Second-Harmonic Response Based on a Zero-Dimensional Organic–Inorganic Hybrid Compound

“…The organic–inorganic hybrid materials (OIHMs) are a hot scientific topic due to their adjustable structure, easy synthesis, and functional features. − Compared with traditional pure organic or inorganic materials, OHIMs possess more advanced properties. − As one unique property of OHIMs, structural phase transition receives tremendous attention, which can introduce attractive properties, such as switchable dielectric and nonlinear optical switching. − Thus, the OHIMs have great application prospects such as data communications, optoelectronic equipment, memories, actuators, sensors, and capacitors. − …”

Competitive Dual-Emission-Induced Thermochromic Luminescence in Organic–Metal Halides

“…38,39 Due to MnX 4 2− (X = Cl, Br, I) tetrahedral units being separated by organic cations, MnX 4 2− is isolated from each other. 40,41 The optical transition is dominated by independent MnX 4 2− and exhibits green emission due to the large Mn−Mn distance, which eliminates direct spin−spin interaction, 42,43 red emission, which is different from the MnX 4 2− tetrahedron. 44,45 There are some reports on the thermochromic luminescence properties of manganese-based halide hybrid materials, which are basically due to the structural changes caused by temperature.…”

“…Therefore, the need for novel organic–metal halide hybrids free from lead is critical. Mn-based hybrid materials have been continuously researched and developed, and this type of hybrid material usually exhibits green or red emissions depending on the difference in the coordination number of metal cations. , Due to MnX 4 2– (X = Cl, Br, I) tetrahedral units being separated by organic cations, MnX 4 2– is isolated from each other. , The optical transition is dominated by independent MnX 4 2– and exhibits green emission due to the large Mn–Mn distance, which eliminates direct spin–spin interaction, , while the MnX 6 2– (X = Cl, Br) skeleton often takes on multiple dimensions and exhibits red emission, which is different from the MnX 4 2– tetrahedron. , …”

A Cd-based perovskite with optical-electrical multifunctional response

“…The 2D perovskites are formed by n-layered inorganic frameworks, and organic cations interspersed within two adjacent inorganic layers. The extraordinary tunable structures endow these perovskites with diverse properties, such as phase transition, [19][20][21][22][23][24] photoluminescence (PL), [25][26][27] narrow energy band gap, [28][29][30] optoelectronic, [31][32][33] and ferroelastic [34][35][36] or ferroelectric properties. [37][38][39][40][41][42][43] In the past few decades, there have been plenty of reports on the above-mentioned materials.…”