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Scintillators are essential in converting ionizing X‐rays and γ‐rays into visible light, with applications in medical diagnosis, security inspection, and non‐invasive detection. However, current scintillating materials exhibit unclear structure–function relationships. The performance of scintillators is intricately linked to their electronic band structure, particularly the intrinsic properties of excited states. Therefore, investigating the structural factors affecting scintillation performance is crucial for developing new scintillators. Therefore, Ba‐SMOF 1 ([Ba2(PyTS)(CH3OH)2(H2O)4]n) is synthesized using a pyrene‐based organic motif and metal Ba(II) ions, where PyTS4− refers to pyrene‐1,3,6,8‐tetrasulfonate. For the first time, the excited state of a pyrene‐based X‐ray scintillating metal–organic framework (MOF) is determined through comprehensive all‐electron excitation studies, including in situ experimental electron density and wave‐function analysis. The electron density maps exhibit a continuous overlap, attributed to the associative exciton behaviors among the closely packed PyTS4− linkers. These linkers are identified as the sources of both static and dynamic excimer emissions. The electron density studies reveal the role of excimers in pyrene‐based luminophores, highlighting that interchromophoric interactions are key to enhancing the performance of scintillating MOFs. This discovery opens new avenues for the practical application of scintillating MOFs. [ABSTRACT FROM AUTHOR]

Nonlinear optical (NLO) materials are of immense scientific and technological importance. However, debate has long prevailed theoretically regarding the structural origin of the second harmonic generation (SHG) effect. In this work, the experimental electron density (ED) of controversial β‐BaB2O4 (BBO) is studied by high‐resolution X‐ray diffraction, indicating that the [B3O6]3− motif dominates two large non‐zero SHG tensors (d222 and d311) while Ba atoms contribute mostly to the smallest one (d333), and the atomic SHG contributions of terminal O atoms in [B3O6]3− motifs are much larger than those of B and bridged O atoms, clarifying the disputes on its NLO response mechanism. Besides, the contraction of inner electron shells (5s25p6) of the Ba atom and partial covalent behavior of the Ba─O interaction are first observed experimentally. Furthermore, the SHG coefficients of BBO derived from experimental ED are in excellent agreement with those from bulk crystals, providing a high‐efficient and low‐cost method of screening high‐performance NLO materials with just an easy‐to‐obtain tiny crystal. [ABSTRACT FROM AUTHOR]

The study of facile‐synthesis and low‐cost X‐ray scintillators with high light yield, low detection limit and high X‐ray imaging resolution plays a vital role in medical and industrial imaging fields. However, the optimal balance between X‐ray absorption, decay lifetime and excitonic utilization efficiency of scintillators to achieve high‐resolution imaging is extremely difficult due to the inherent contradiction. Here two thermally activated delayed fluorescence (TADF)‐actived coinage‐metal clusters M6S6L6 (M=Ag or Cu) were synthesized by simple solvothermal reaction, where the cooperation of heavy atom‐rich character and TADF mechanism supports strong X‐ray absorption and rapid luminescent collection of excitons. Excitingly, Ag6S6L6 (SC‐Ag) displays a high photoluminescence quantum yield of 91.6 % and scintillating light yield of 17420 photons MeV−1, as well as a low detection limit of 208.65 nGy s−1 that is 26 times lower than the medical standard (5.5 μGy s−1). More importantly, a high X‐ray imaging resolution of 16 lp/mm based on SC‐Ag screen is demonstrated. Besides, rigid core skeleton reinforced by metallophilicity endows clusters M6S6L6 strong resistance to humidity and radiation. This work provides a new view for the design of efficient scintillators and opens the research door for silver clusters in scintillation application. [ABSTRACT FROM AUTHOR]

Scintillators can convert the ionizing radiation into visible light and are crucial in X/γ‐ray detectors. Commercial detectors often use multiple scintillators with photodetector arrays, where optical crosstalk can degrade the performance. Chiral scintillators, emitting circularly polarized light, offer a promising solution for regulating the direction of light propagation to enhance X‐ray detecting merits. Here novel chiral metal‐organic polymers have been developed via photopolymerization, using chiral polymeric monomers and 0D Mn(II)‐based organic‐metal halide hybrid scintillators, achieving luminescence dissymmetry factors (glum) of 5.823 × 10−2 and −2.877 × 10−2. Two such scintillators, (atpp)2MnCl4·0.5H2O (MnCl4−1) and (atpp)2MnBr4 (MnBr4−2), exhibit excellent X‐ray scintillation rooted in tetrahedral [MnX4]2− crystal field. Compound MnBr4−2, with heavier bromine atoms, shows superior performance with a detection limit of 0.117 µGyair s−1, compared to 0.330 µGyair s−1 of MnCl4−1, both surpassing the medical diagnostic standard of 5.50 µGyair s−1. The chiral metal‐organic polymer film derived from MnBr4−2 has achieved a resolution up to 14.84 lp mm−1, exceeding medical standards for dental (2.0 lp mm−1) and breast cancer (10.0 lp mm−1) imaging. These advancements in chiral scintillators hold significant promise for high‐resolution X‐ray medical imaging applications. [ABSTRACT FROM AUTHOR]

Birefringent materials are of great significance to the development of modern optical technology; however, research on halide birefringent crystals with a wide transparent range remains limited. In this work, mercuric bromide (HgBr 2 ) has been investigated for the first time as a promising birefringent material with a wide transparent window spanning from ultraviolet (UV) to far-infrared (far-IR) spectral regions (0.34-22.9 μm). HgBr 2 has an exceptionally large birefringence (Δ n , 0.235 @ 546 nm), which is 19.6 times that of commercial MgF 2 . The ordered linear motif [Br-Hg-Br] with high polarizability anisotropy within the molecule is the inherent source of excellent birefringence, making it an efficient building block for birefringent materials. In addition, HgBr 2 can be easily grown under mild conditions and remain stable in air for prolonged periods. Studying the birefringent properties of HgBr 2 crystals would provide new ideas for future exploration of wide-spectrum birefringent materials., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The study of facile-synthesis and low-cost X-ray scintillators with high light yield, low detection limit and high X-ray imaging resolution plays a vital role in medical and industrial imaging fields. However, the optimal balance between X-ray absorption, decay lifetime and excitonic utilization efficiency of scintillators to achieve high-resolution imaging is extremely difficult due to the inherent contradiction. Here two thermally activated delayed fluorescence (TADF)-actived coinage-metal clusters M 6 S 6 L 6 (M=Ag or Cu) were synthesized by simple solvothermal reaction, where the cooperation of heavy atom-rich character and TADF mechanism supports strong X-ray absorption and rapid luminescent collection of excitons. Excitingly, Ag 6 S 6 L 6 (SC-Ag) displays a high photoluminescence quantum yield of 91.6 % and scintillating light yield of 17420 photons MeV -1 , as well as a low detection limit of 208.65 nGy s -1 that is 26 times lower than the medical standard (5.5 μGy s -1 ). More importantly, a high X-ray imaging resolution of 16 lp/mm based on SC-Ag screen is demonstrated. Besides, rigid core skeleton reinforced by metallophilicity endows clusters M 6 S 6 L 6 strong resistance to humidity and radiation. This work provides a new view for the design of efficient scintillators and opens the research door for silver clusters in scintillation application., (© 2023 Wiley-VCH GmbH.)

Noncentrosymmetric phosphides have garnered significant attention as promising systems of infrared (IR) nonlinear optical (NLO) materials. Herein, a new quaternary diamond-like phosphide family I-III-IV 2 -V 4 and its inaugural member, namely, CuInSi 2 P 4 (CISP), were successfully fabricated by isovalent and aliovalent substitution based on ZnGeP 2 . First-principles calculations revealed that CISP has a large NLO coefficient ( d 14 = 110.8 pm/V), which can be attributed to the well-aligned tetrahedral [CuP 4 ], [InP 4 ], and [SiP 4 ] units. Remarkably, the extremely small thermal expansion anisotropy (0.09) of CISP enables it to exhibit a considerable laser-induced damage threshold (LIDT, 5.0 × AgGaS 2 @1.06 μm) despite the relatively narrow band gap (0.81 eV). This work improves the chemical diversity of inorganic phosphide and promotes the development of phosphide systems, which may provide valuable perspectives for future exploration of IR NLO materials.

The typical chalcopyrite AgGaQ 2 (Q = S, Se) are commercial infrared (IR) second-order nonlinear optical (NLO) materials; however, they suffer from unexpected laser-induced damage thresholds (LIDTs) primairy due to their narrow band gaps. Herein, what sets this apart from previously reported chemical substitutions is the utilization of an unusual cationic substitution strategy, represented by [[SZn 4 ]S 12 + [S 4 Zn 13 ]S 24 + 11ZnS 4 ⇒ MS 12 + [M 4 Cl]S 24 + 11GaS 4 ], in which the covalent S x Zn y units in the diamond-like sphalerite ZnS are synergistically replaced by cationic M x Cl y units, resulting in two novel salt-inclusion sulfides, M[M 4 Cl][Ga 11 S 20 ] (M = A/Ba, A = K, 1; Rb, 2). As expected, the introduction of mixed cations in the GaS 4 anionic frameworks of 1 and 2 leads to wide band gaps (3.04 and 3.01 eV), which exceeds the value of AgGaS 2 , facilitating the improvement of high LIDTs (9.4 and 10.3 × AgGaS 2 @1.06 µm, respectively). Furthermore, compounds 1 and 2 exhibit moderate second-harmonic generation intensities (0.84 and 0.78 × AgGaS 2 @2.9 µm, respectively), mainly originating from the orderly packing tetrahedral GaS 4 units. Importantly, this study demonstrates the successful application of the cationic substitution strategy based on diamond-like structures to provide a feasible chemical design insight for constructing high-performance NLO materials., (© 2023 Wiley-VCH GmbH.)