Highly Emissive Chiral Mn(II) Bromide Hybrids for UV‐Pumped Circularly Polarized LEDs and Scintillator Image Applications

Abstract

Organic–inorganic hybrid metal halides are a promising platform for the design of materials for circularly polarized luminescence (CPL) and X‐ray detection applications. Meanwhile, despite the recent progress in this hot field, hybrid metal halides, simultaneously endowed with efficient CPL and high photoluminescence quantum yield (PLQY), are still limited to a few examples. Herein, the efficient, stable, and low‐cost CPL‐active Mn(II) hybrids are developed via blending of luminogenic [MnBr4]2− anions with N/OH‐bond free R/S‐[MBA‐Me3]+ cations in a single ionic structure. The synthesized R/S‐[MBA‐Me3]MnBr4 hybrids display brightly green Mn2+‐centered circularly polarized phosphorescence with near‐unity PLQY and a high glum factor of 0.0045. Single crystals of R/S‐[MBA‐Me3]MnBr4 are used to fabricate UV‐pumped circularly polarized light‐emitting diodes (LEDs) displaying a high optical selectivity upon exposure to right‐handed and left‐handed circular polarization conditions. Moreover, the titled compounds are found to emit strong X‐ray radioluminescence with excellent linear response to X‐ray dose rate that is used for X‐ray imaging demonstration. These findings reveal a great potential of R/S‐[MBA‐Me3]MnBr4 as low‐cost materials for CPL‐LEDs, scintillators, and X‐ray imaging applications.

Thermal/Water-Induced Phase Transformation and Photoluminescence of Hybrid Manganese(II)-Based Chloride Single Crystals

“…In the crystal structure of (1-mpip) 2 MnCl 6 , one Mn­(II) atom coordinates with four Cl atoms, forming a four-coordinated tetrahedron {MnCl 4 }, which forms a 0D structure together with two free Cl – ions and two organic cations 1-mpip, as shown in Figure c. Because of the obstruction of the bulky 1-mpip cation, the adjacent tetrahedrons {MnCl 4 } are separated far away with a distance of 8.053 Å, which is similar to the previous reports. ,,,, The bond length of Mn–Cl varied from 2.3521(11) to 2.3910(10) Å, and the bond angle of Cl–Mn–Cl varied from 103.39(4) to 115.80(5)° for (1-mpip) 2 MnCl 6 , as depicted in Tables S2 and S3. Besides, powder X-ray diffraction (PXRD) patterns of (1-mpip)­MnCl 4 ·3H 2 O and (1-mpip) 2 MnCl 6 agree well with their simulated single-crystal XRD patterns, which indicate the high phase purity and uniform crystal structures, as shown in Figure b,d.…”

“…Because of the obstruction of the bulky 1-mpip cation, the adjacent tetrahedrons {MnCl 4 } are separated far away with a distance of 8.053 Å, which is similar to the previous reports. 34,35,43,44,50 The bond length of Mn−Cl varied from 2.3521(11) to 2.3910(10) Å, and the bond angle of Cl−Mn− Cl varied from 103.39(4) to 115.80 (5)°for (1-mpip) 2 MnCl 6 , as depicted in Tables S2 and S3. Besides, powder X-ray diffraction (PXRD) patterns of (1-mpip)MnCl 4 •3H 2 O and (1mpip) 2 MnCl 6 agree well with their simulated single-crystal XRD patterns, which indicate the high phase purity and uniform crystal structures, as shown in Figure 2b,d A 1 (S) ground state to the 4 T 1 (F), 4 T 1 (P), 4 E(D), and 4 A 1 .…”

Strong Magnetically‐Responsive Circularly Polarized Phosphorescence and X‐Ray Scintillation in Ultrarobust Mn(II)–Organic Helical Chains

“…More importantly, Mn(II) compounds exhibit long-lived room temperature phosphorescence [via d-d transitions in Mn 2+ ], [18][19][20] which is used in OLED devices [21,22] and phosphor-converted LEDs. [23] Meanwhile, the CPL-active Mn(II)-organic hybrids are scarce, and their g lum /PLQY ratios are not ideal. For instance, most of the halomanganates with chiral ammonium cations possess relatively low g lum and PLQY of 0.002-0.008, 12-67%, respectively.…”

“…[ 24–28 ] The most recently reported Mn(II)‐based OIMs, [ R / S‐ PhCH(Me)NMe 3 ]MnBr 4 , showed a record‐high PLQY of 98%, but their CPL performance was moderate ( g lum = 0.0045). [ 23 ] As demonstrated in 2022, [ 29 ] direct coordination of chiral organic cations to halomanganate units can double the g lum magnitude. The constructed zwitterionic hybrid, [( R / S ‐3‐quinuclidinol·H)MnBr 3 ], can reach both a relatively high g lum value (0.023) and a PLQY of 67%.…”

Methanol‐Induced Crystallization of Chiral Hybrid Manganese (II) Chloride Single Crystals for Achieving Circularly Polarized Luminescence and Second Harmonic Generation

“…[49] Recently, plenty of chiral hybrid Mn(II)-based metal halides with the outstanding optical properties have been reported and served as a class of scintillators, such as (R/S-1-PPA) 2 MnBr 4 (R/S-1-PPA = R/S-1-phenylpropan-1-amine), [50] (R/S-3-aminopyrrolidinedihydrochloride) 6 (Mn 3 Cl 12 )(Cl) 6 and (R/S-1,2-diaminopropanedihydrochloride) 3 (Mn 3 Cl 12 ) [40] and R/S-[MBA-Me 3 ]MnBr 4 . [51] But it is difficult for these above studies to obtain single crystals with regular shapes and high quality. Therefore, it is necessary to search for the growth condition of hybrid Mn (II) halides.…”