Photophysical and Magnetic Properties in Zero-Dimensional (H₂DABCO)MX₄·nH₂O (M = Mn and Cu; X = Cl and Br; n = 0, 1, and 4)

Abstract

We report five new manganese and copper organic–inorganic hybrid (OIH) halides based on 1,4-diazabicyclo[2.2.2]­octane (DABCO: C6H12N2). The materials obtained have general formula (H2DABCO)­MX4·nH2O where M = Mn and Cu, X = Cl and Br, and n = 0, 1, and 4. The compounds (H2DABCO)­MnX4·4H2O (X = Cl and Br) crystallize in a chiral P212121 structure with unique zero-dimensional (0D) manganese octahedra, whereas anhydrous (H2DABCO)­MnBr4 exhibits a monoclinic crystal structure (space group P21/c) with isolated MnBr4 tetrahedra. While (H2DABCO)­MnCl4·4H2O is nonluminescent, the bromine analogue displays red emission with a photoluminescence quantum yield (PLQY) of 10.8%. Interestingly, anhydrous (H2DABCO)­MnBr4 demonstrates intense green emission due to the tetrahedral coordination of Mn2+ ion. The PLQY for (H2DABCO)­MnBr4 is 52.16%, and it shows a longer lifetime of the photoexcited electrons than the hydrated compound. In contrast, the copper OIH halides (X = Cl and Br) reveal an identical 0D tetrahedral structure crystallizing with one water molecule in the P21/c space group. Both manganese and copper OIH halides exhibit a magnetocaloric effect at low temperatures.

Elucidating Structure–Property Correlation in Perovskitoid and Antiperovskite Piperidinium Manganese Chloride

“…In contrast, compound 2 does not order down to 1.8 K (Figure d), indicating the paramagnetic nature. The obtained θ CW of 1.5 K and magnetic field-dependent isotherms are consistent with the paramagnetic compounds (Figure d,e) . Since compound 1 consists of 1D infinite chains, the magnetic ordering might occur by interchain interaction, which is mediated by two halides pathway (Mn–Cl···Cl–Mn), where the Cl···Cl distance is about 4.321 Å .…”

“…In addition, the cell parameter b gets doubled in LTP compared to RTP, consistent with the order–disorder transition. To understand the additional role of SPT, we have calculated the bond length (Δ d ) and bond angle (σ oct 2 ) distortion parameters using the formula normalΔ d = ( 1 n ) ∑ n true[ d n − d av d av true] 2 and σ oct 2 = 1 11 ∑ i = 1 12 false[ α i − 90 false] 2 . In RTP, the Δ d and σ oct 2 are 9.38 × 10 –5 and 51.97, respectively, revealing that compound 1 is associated with moderate distortion.…”

Electron–Phonon Coupling Mediated Self-Trapped-Exciton Emission and Internal Quantum Confinement in Highly Luminescent Zero-Dimensional (Guanidinium)6Mn3X12 (X = Cl and Br)

“…Recently, some investigations demonstrated that the emission in Mn 2+ -tetrahedra-based OIH compounds results from the recombination of self-trapped excitons (STEs). − STEs are Frenkel-like bound excitons trapped in a deformable lattice and result from the synergistic effect of reduced lattice dimensionality, structural distortion, lattice softness, and halogen vacancies. − In such compounds, a longitudinal optical phonon scatters the charge carriers and restricts its delocalization via Fröhlich interaction, leading to the formation of STEs. , However, the Mn 2+ octahedral emission shows a larger Stokes shift and a broader emission band compared to the Mn 2+ tetrahedral emission, indicating the possibility of STE recombination in the octahedral emission. , In this paper, we report evidence for STE emission in an Mn 2+ -octahedra-based OIH halide, (Guanidinium) 6 Mn 3 Br 12 [GuMBr], which crystallizes in a trimeric zero-dimensional (0D) structure and exhibits intense red emission with a large Stokes shift, a broad emission band, and long-lived photoexcited electrons. Analysis of the temperature-dependent photoluminescence (PL) line width and Raman spectra confirms electron–phonon coupling.…”

Sc1−xErxAlO3perovskites: high-pressure synthesis, photoluminescence properties, andin vitrobioimaging

“…Although the line width and peak shape did not change with increasing temperature, the intensity deteriorated. This is the thermal quenching effect and can be understood using the Arrhenius model: 49 Here I 0 and I T are the emission intensities measured at 300 K and temperature T . A is the ratio of the nonradiative rate to the radiative rate and termed as the quenching frequency factor.…”

“…Although the line width and peak shape did not change with increasing temperature, the intensity deteriorated. This is the thermal quenching effect and can be understood using the Arrhenius model: 49 ln…”