Multisite modulation for organic-inorganic hybrid metal halides (OIMHs) plays an important role in the optimization of their photophysical performance. Herein, we proposed an organic cation modification strategy on the phosphorus sites based on 1,2-Bis(diphenylphosphino)ethane (DPPE) by a simple one-pot solvothermal method. Three zero-dimensional (0D) manganese-based OIMHs, two novel MdppeMnCl4·H2O and EdppeMnCl4, as well as the byproduct [Mn(dppeO2)3][MnCl4] were obtained (Mdppe = methyl-coordinated with DPPE; Edppe = ethyl-coordinated with DPPE; and dppeO2 is obtained by oxidation of DPPE). All the samples possess the four-coordinated [MnCl4]2- polyhedron, while [Mn(dppeO2)3][MnCl4] contains another six-coordinated cation [Mn(dppeO2)3]2+ complex. According to the relevant optical measurements, MdppeMnCl4·H2O and EdppeMnCl4 both show bright green emissions with photoluminescence quantum yields of 55.66% and 80.42%, respectively. By contrast, [Mn(dppeO2)3][MnCl4] shows an orange emission that is confirmed to be associated with six-coordinated Mn2+ ions by temperature-dependent PL spectra. Based on the good stability and solution processability of EdppeMnCl4, a luminescent ink was developed and shows potential application in display and information encryption fields. The unique cation modification strategy in this work opens up the ways for designing and developing novel OIMHs and extends the application prospects of manganese-based halides.
Covalence in f-elements plays a pivotal role in distinguishing the fundamental properties of actinides and lanthanides. In this study, trivalent and tetravalent actinide (U-Fm) and lanthanide (Nd-Er) complexes with dithiocarbamate (S2CNH2-) ligands were systematically analyzed. Various methodologies were employed, notably Slater-Condon parameters, metrics in bond critical points (BCP) under the quantum theory of atoms in molecules (QTAIM) framework, and natural localized molecular orbitals (NLMOs). The multiconfigurational nature of the systems and the scalar relativistic and spin-orbit coupling effects were incorporated into the methods used. The findings reveal important differences in covalence between heavy actinides and lanthanides, where a higher covalence is observed in complexes containing metal ions with a higher oxidation state. According to QTAIM results, covalence in heavy actinides is energy-degeneracy driven rather than orbital overlap. Additionally, this suggests that donor atoms softer than oxygen, such as sulfur, promote covalence in heavy actinides, distinguishing them from their lanthanide counterparts and establishing them as softer Lewis acids.
Low-dimensional organic-inorganic hybrid metal halide materials have attracted widespread attention due to their excellent and tunable photoelectric properties. However, the low intrinsic photoluminescence quantum yields (PLQYs) limit their further applications in optoelectronic devices. Here, we report the synthesis of lead-free zero-dimensional hybrid organic-inorganic indium chloride crystals, (FA)3InCl6: xSb3+, with strong red-light emission through controlled Sb3+ doping. The optimal composition, (FA)3InCl6: 20.16% Sb3+, exhibits PLQY up to 30% and emits red broadband light centered at 690 nm. The photoluminescence enhancement of the doped samples was investigated by combining temperature-dependent and wavelength-dependent photoluminescence spectra, revealing the self-trapped exciton (STE) recombination process. The clear elucidation of the self-trapped exciton complexation process has provided a solid theoretical basis for the further optimization of the material properties, which is of great significance for the development of new red light-emitting materials. Far-red light-emitting phosphor-converted LED devices have been constructed with these materials and demonstrate stable and efficient red-light emission at various voltages, exhibiting superior photoluminescence stability. This study highlights the potential of Sb3+-doped metal halides to achieve tunable broadband emission and demonstrates the great potential of these metal halide single crystals for indoor plant lighting, infrared imaging, photodynamic therapy and wound healing.
Using electrochemically responsive metal-organic frameworks (MOFs) as host matrices to afford gating properties for functional guests is rather attractive but remains unexplored. Herein, a series of functionalized Zr-MOFs with viologen-like skeletons were created by engineering 2,2'-bipyridinium bay substitution with different alkyl chains. Of the series, benefiting from the enhanced rigidity, the one bearing N,N'-ethylene bridge, UiO-67-EE, exhibited the strongest electron deficiency due to the lowest LUMO level, thereby leading to efficient electron transfer and favorable redox activity, which further endowed it with outstanding electrochromic properties. More importantly, the highly electron-deficient framework of UiO-67-EE could allow the accommodation of electron-rich guest molecules through host-guest charge transfer (CT) interactions. By leveraging the electroresponsiveness of the viologen-like functionality, UiO-67-EE served as an adaptable platform for controlled guest release and capture through efficient control of dynamic CT interactions upon stimuli of alternate potentials. This smart electrochemical gating behavior of the host-guest systems was also monitored in real time by distinguishable optical changes of the guests. Besides, it was exploited to develop high-performance sensing platforms by integrating a molecular gate constructed from the target-aptamer complex.
In this work, an anionic framework Co-MOF (1) was elaborately constructed, which underwent single-crystal-to-single-crystal (SC-SC) transformation to produce 1-Cr and 1-Fe after immersion in a CrCl3 or FeCl3 solution. Despite the similar crystal structure, the significantly enhanced proton conductivities of 1-Cr and 1-Fe far exceed that of 1 at all humidity and temperature conditions. Even at 30 °C and 98% RH, the proton conductivity of 1-Cr and 1-Fe can reach up to high values of 1.49 × 10-2 and 6.39 × 10-3 S cm-1, respectively, surpassing that of 1 by over 5000 times under identical conditions. The partial alteration of the proton-conducting carriers from metal-water cluster [Co(H2O)6]·6H2O] (1) to metal-hydroxyl-water clusters [Cr(OH)4(H2O)2]·6H2O] (1-Cr) and [Fe(OH)4(H2O)2]·6H2O] (1-Fe) can be attributed for the above-mentioned enhanced performance. The introduction of hydroxyl by SC-SC transformation can establish interconnected proton conduction pathways within the proton channels, which greatly facilitate proton conduction, affording much lower activation energies (0.12 eV for 1-Cr, 0.18 eV for 1-Fe, and 0.28 eV for 1). This research demonstrated that SC-SC transformation not only achieved significantly improved proton conduction but also contributed to a deeper understanding of the structure-property relationships, providing new insights into the design of advanced materials with enhanced proton conductivity.
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