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Co‐crystallization of the spin‐crossover (SCO) cationic complex, [Fe(1‐bpp)₂]²⁺(1‐bpp=2,6‐bis(pyrazol‐1‐yl)pyridine) with fractionally charged organic anion TCNQ^δ−(0<δ<1) afforded hybrid materials [Fe(1‐bpp)₂](TCNQ)_3.5 ⋅ 3.5MeCN (1) and [Fe(1‐bpp)₂](TCNQ)₄ ⋅ 4DCE (2), where TCNQ=7,7,8,8‐tetracyanoquinodimethane, MeCN=acetonitrile, and DCE=1,2‐dichloroethane. Both materials exhibit semiconducting behavior, with the room‐temperature conductivity values of 1.1×10⁻⁴ S/cm and 1.7×10⁻³ S/cm, respectively. The magnetic behavior of both complexes exhibits strong dependence on the content of the interstitial solvent. Complex1undergoes a gradual temperature‐driven SCO, with the midpoint temperature ofT_1/2=234 K. The partial solvent loss by1leads to the increase in theT_1/2value while complete desolvation renders the material high‐spin (HS) in the entire studied temperature range. In the case of2, the solvated complex shows a gradual SCO withT_1/2=166 K only when covered with a mother liquid, while the facile loss of interstitial solvent, even at room temperature, leads to the HS‐only behavior.

 

Scintillation based X-ray detection has received great attention for its application in a wide range of areas from security to healthcare. Here, we report highly efficient X-ray scintillators with state-of-the-art performance based on an organic metal halide, ethylenebis-triphenylphosphonium manganese (II) bromide ((C₃₈H₃₄P₂)MnBr₄), which can be prepared using a facile solution growth method at room temperature to form inch sized single crystals. This zero-dimensional organic metal halide hybrid exhibits green emission peaked at 517 nm with a photoluminescence quantum efficiency of ~ 95%. Its X-ray scintillation properties are characterized with an excellent linear response to X-ray dose rate, a high light yield of ~ 80,000 photon MeV⁻¹, and a low detection limit of 72.8 nGy s⁻¹. X-ray imaging tests show that scintillators based on (C₃₈H₃₄P₂)MnBr₄powders provide an excellent visualization tool for X-ray radiography, and high resolution flexible scintillators can be fabricated by blending (C₃₈H₃₄P₂)MnBr₄powders with polydimethylsiloxane.

 

3‐Point annulations, or phenalenannulations, transform a benzene ring directly into a substituted pyrene by “wrapping” two new cycles around the perimeter of the central ring at three consecutive carbon atoms. This efficient, modular, and general method for π‐extension opens access to non‐symmetric pyrenes and their expanded analogues. Potentially, this approach can convert any aromatic ring bearing a ‐CH₂Br or a ‐CHO group into a pyrene moiety. Depending upon the workup choices, the process can be directed towards either tin‐ or iodo‐substituted product formation, giving complementary choices for further various cross‐coupling reactions. The two‐directional bis‐double annulation adds two new polyaromatic extensions with a total of six new aromatic rings at a central core.

 

The photophysical tuning is reported for a series of tetraphenylphosphonium (TPP) metal halide hybrids containing distinct metal halides, TPP₂MX_n(MX_n=SbCl₅, MnCl₄, ZnCl₄, ZnCl₂Br₂, ZnBr₄), from efficient phosphorescence to ultralong afterglow. The afterglow properties of TPP⁺cations could be suspended for the hybrids containing low band gap emissive metal halide species, such as SbCl₅²⁻and MnCl₄²⁻, but significantly enhanced for the hybrids containing wide band gap non‐emissive ZnCl₄²⁻. Structural and photophysical studies reveal that the enhanced afterglow is attributed to stronger π–π stacking and intermolecular electronic coupling between TPP⁺cations in TPP₂ZnCl₄than in the pristine organic ionic compound TPPCl. Moreover, the afterglow in TPP₂ZnX₄can be tuned by controlling the halide composition, with the change from Cl to Br resulting in a shorter afterglow due to the heavy atom effect.

 

Zero‐dimensional (0D) organic metal halide hybrids, in which organic and metal halide ions cocrystallize to form neutral species, are a promising platform for the development of multifunctional crystalline materials. Herein we report the design, synthesis, and characterization of a ternary 0D organic metal halide hybrid, (HMTA)₄PbMn_0.69Sn_0.31Br₈, in which the organic cationN‐benzylhexamethylenetetrammonium (HMTA⁺, C₁₃H₁₉N₄⁺) cocrystallizes with PbBr₄²⁻, MnBr₄²⁻, and SnBr₄²⁻. The wide band gap of the organic cation and distinct optical characteristics of the three metal bromide anions enabled the single‐crystalline “host–guest” system to exhibit emissions from multiple “guest” metal halide species simultaneously. The combination of these emissions led to near‐perfect white emission with a photoluminescence quantum efficiency of around 73 %. Owing to distinct excitations of the three metal halide species, warm‐ to cool‐white emissions could be generated by controlling the excitation wavelength.

 

Mechanochemical synthesis has emerged as a facile method for the preparation of a wide range of organic, inorganic, and polymeric materials. Here, we report the use of mechanochemical synthesis for the preparation of ionically bonded organic metal halide hybrids with a zero‐dimensional (0D) structure at the molecular level. (Ph₄P)₂SbCl₅and (Ph₄P)₂MnCl₄were synthesized by grinding appropriate ratios of organic halide salt Ph₄PCl with inorganic metal halide salts SbCl₃and MnCl₂, respectively. The structural and photophysical properties of mechanochemically synthesized (Ph₄P)₂SbCl₅and (Ph₄P)₂MnCl₄were characterized, which are almost identical to those of single crystals prepared by slow solution growth. By reacting Ph₄PCl with both SbCl₃and MnCl₂, we have been able to produce a mixture of two 0D organic metal halide hybrids that exhibit a dual emission covering a wide range of the spectrum with Commission Internationale de l'Eclairage (CIE) coordinates of (0.4898, 0.4800). Our work has clearly established mechanochemical synthesis as an effective method to produce ionically bonded organic‐inorganic hybrids.

 

Mononuclear heteroleptic complexes [Fe(tpma)(bimz)](ClO4)2 (1a), [Fe(tpma)(bimz)](BF4)2 (1b), [Fe(bpte)(bimz)](ClO4)2 (2a), and [Fe(bpte)(bimz)](BF4)2 (2b) (tpma = tris(2-pyridylmethyl)amine, bpte = S,S′-bis(2-pyridylmethyl)-1,2-thioethane, bimz = 2,2′-biimidazoline) were prepared by reacting the corresponding Fe(II) salts with stoichiometric amounts of the ligands. All complexes exhibit temperature-induced spin crossover (SCO), but the SCO temperature is substantially lower for complexes 1a and 1b as compared to 2a and 2b, indicating the stronger ligand field afforded by the N2S2-coordinating bpte ligand relative to the N4-coordinating tpma. Our findings suggest that ligands with mixed N/S coordination can be employed to discover new SCO complexes and to tune the transition temperature of known SCO compounds by substituting for purely N-coordinating ligands.