Browsing by Author "Rayes, Ali"

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    A new zero-dimensional (0D) hybrid bismuth (III) halide: Synthesis, crystal structure, thermal analysis, photophysical properties and DFT calculations
    (2024) Msaoura, Selma; Benito, Monica; Molins, Elies; Khirouni, Kamel; Zarate, Ximena; Saavedra-Torres, Mario; Schott, Eduardo; Houas, Ammar; Rayes, Ali
    Low-dimensional organic-inorganic hybrid Bi(III) halides, with organic N, O-heterocycles, are promising solid -state photoluminescent materials, but are underexplored. In this work, we present the synthesis and charac-terization of a novel bismuth (III) hybrid salt, namely (C8H12NO)(4)[Bi2Cl10] (referred as (1)). (1) was synthesized using a solvent-evaporation method and extensively characterized using various techniques. The crystal structure of (1) was determined to be zero-dimensional (0D). In this structure, the individual bioctahedral [Bi2Cl10](4-) dimers, which share edges, are completely isolated from each other. These dimers are separated by large 4-methoxybenzylammonium cations (C8H12NO)(+). The latter are crucial for the crystal structural stability by balancing [Bi2Cl10](4-) dimer charges and maintaining overall integrity. Solid-state diffuse reflectance UV-Vis spectrum demonstrates that (1) is a semiconductor with a band gap of 3.32 eV. Its photoluminescence spectrum exhibits intense blue emission when exposed to UV light, with CIE chromaticity coordinates of (0.22, 0.21). Theoretical calculations suggest that the emission with multiple centers originates both from a charge transition between (C8H12NO)(+) and Bi2Cl104- ions and from excited-state proton transfer (ESPT) processes related to fluo-rescence properties. These ESPT processes occur through C-H center dot center dot center dot pi and C-H center dot center dot center dot O intermolecular hydrogen bonding between the organic cations.
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    Synthesis, structure, and luminescence properties of a 0D organic-inorganic cadmium iodide: Combined experimental and theoretical approach
    (2024) Fandouli, Amna; Ben Hamadi, Naoufel; Guesmi, Ahlem; Sanudo, E. Carolina; Zarate, Ximena; Torres, Mario -Saavedra; Schott, Eduardo; Houas, Ammar; Rayes, Ali
    Hybrid organic-inorganic metal halide materials with zero-dimensional (0D) structures have emerged as a captivating field of research due to their distinctive electronic properties and remarkable broadband emission characteristics. In this study, we successfully synthesized a novel hybrid cadmium iodide compound, (BZA)2CdI4. H2O (BZA+: benzylammonium), in the form of single crystals employing the solvent-evaporation method. The room temperature single-crystal X-ray diffraction analysis revealed that (BZA)2CdI4.H2O possesses a typical 0D crystal structure, where (CdI4)2- anions are spatially isolated and surrounded by (BZA)+ cations and H2O molecules. The crystal packing is intricately governed by various non-covalent intermolecular interactions, including 7C-7C stacking interactions, N-H...I, N-H...O, and O-H...I hydrogen bonds, quantified through Hirshfeld surface analysis. Thermal analysis further demonstrated that the removal of water molecules in the crystal lattice yields a dehydrated phase of (BZA)2(CdI4). Upon 330 nm irradiation, the title compound displayed a broad bluish-white light emission, featuring a primary band at 430 nm and a secondary band at 500 nm. Based on photoluminescence spectra measurements and density functional theory (DFT) calculations, the dual-band emission is assigned to the emission of (BZA)+ organic cations and to excitons confined in the [CdI4]2- isolated inorganic tetrahedron, respectively. Interestingly, the presence of isolated molecular units in the 0-D structure results in strongly localized charges and bluish-white light emission with Commission International de l'Eclairage (CIE) colour coordinates (0.23, 0.28). These results confirm the promise of 0D metal-halide hybrids with dual-band emission as luminescent materials for solid-state lighting.