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Non-centrosymmetric (NCS) structure is an indispensable prerequisite for second-order nonlinear optical (NLO) material. Currently, the mainstream approach for designing new NCS structures still relies on chemical substitution, necessitating an urgent infusion of fresh ideas. In this work, two isomorphic sulfides AeMn6Ga6S16 (Ae = Ca, 1; Sr, 2) are afforded by modifying the skeleton of centrosymmetric (CS) Mn2Ga2S5via introducing strong electropositive alkaline-earth cations. Concretely, the incorporation of Ca2+/Sr2+ cations allows the elementary [MnGaS9]∞ chains to reconfigure into bumpy [MnS6]-[GaS4] layers in a new engagement manner, thus enabling the conversion from CS to NCS structure. Such modifications cause not only strong second-harmonic generation (SHG) responses (∼1.5 × benchmark AgGaS2 @1,700 nm), but also significantly feasible bandgaps (2.60–2.64 eV) compared to the sulfide Mn2Ga2S5 (1.36 eV), which ultimately facilitate ultrahigh laser-induced damage thresholds (4.4–6.6 × AgGaS2 @1,064 nm for compounds 1 and 2). The present study offers an ingenious approach for the transformation of CS to NCS structure. [ABSTRACT FROM AUTHOR]

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]