[NH4][Ni(phen)3]BiI6: Synthesis, structure, photocatalytic property and theoretical study of a discrete iodobismuthate

Three Iodoargentate-Based Hybrids Decorated by Metal Complexes: Structures, Optical/Photoelectric Properties and Theoretical Studies

So far, the development of new iodoargentate-based hybrids, especially those compounds with metal complex cations, and the understanding of their structure-activity relationships have been of vital importance but full of challenges. Herein, using the in-situ-generated metal complex cations as structural directing agents, three new iodoargentate-based hybrids, namely, [Co(phen)3]Ag2PbI6 (phen = 1,10-phenanthroline; 1), [Ni(5,5-dmpy)3]Ag7I9·CH3CN (5,5-dmpy = 5,5-dimethyl-2,2-bipyridine; 2) and [Co(5,5-dmpy)3]Ag5I8 (3), have been solvothermally prepared and then structurally characterized. Compound 1 represents one new heterometallic Ag-Pb-I compound characteristic of the chain-like [Ag2PbI6]n2n- anions. Compound 2 features the straight one-dimensional (1D) [Ag7I9]n2n- anionic moieties, while compound 3 contains infrequent two types of curved [Ag5I8]n3n- anions. Optical properties reveal that the title compounds exhibit interesting semiconductor behaviors with the band gaps of 1.59-2.78 eV, which endow them with good photoelectric switching performances under the alternate light irradiations. We also present their Hirshfeld surface analyses, and the theoretical studies (band structures, density of states (DOS) and partial density of states (PDOS)).

Syntheses, structures, photoelectric properties and photocatalysis of iodobismuthate hybrids with lanthanide complex cations

New iodobismuthate hybrids with lanthanide complex counter cations, [Ln(DMF)₈][Bi₂I₉] (Ln = La (1), Eu (2)) and [Tb(DMF)₈]₂[Bi₂I₉]₂ (3) (DMF = N,N-dimethylformamide), were prepared using solvated Ln(III) complexes formed in situ as structure-directing agents. The dimeric [Bi₂I₉]^3- anion moieties of compounds 1-3 are aggregated by two slightly twisted BiI₆ octahedra through face-sharing mode. The different crystal structures of 1-3 are due to the different I⋯I and C-H⋯I hydrogen bond interactions. Compounds 1-3 have narrow semiconducting band gaps at 2.23, 1.91 and 1.94 eV, respectively. Under Xe light irradiation, they exhibit steady photocurrent densities that are 1.81, 2.10 and 2.18 times higher than that of pure BiI₃, respectively. Compounds 2 and 3 exhibited higher catalytic activities than 1 in the photodegradation of organic dyes CV and RhB, which are attributed to the stronger photocurrent response derived from the redox cycles of Eu³⁺/Eu²⁺ and Tb⁴⁺/Tb³⁺.

Copper- and Silver-Containing Heterometallic Iodobismuthates: Features of Thermochromic Behavior

Nine heterometallic iodobismuthates with the general formula Cat₂{[Bi₂M₂I₁₀}] (M = Cu(I), Ag(I), Cat = organic cation) were synthesized. According to X-ray diffraction data, their crystal structures consisted of {Bi₂I₁₀} units interconnected with Cu(I) or Ag(I) atoms through I-bridging ligands, forming one-dimensional polymers. The compounds are thermally stable up to 200 °C. Optical band gaps (E_g), estimated at room temperature via diffuse reflectance measurements, range from 1.81 to 2.03 eV. Thermally induced changes in optical behavior (thermochromism) for compounds 1-9 were recorded, and general correlations were established. The thermal dependence of E_g appears to be close to linear for all studied compounds.

A semiconductive copper iodobismuthate hybrid: structure, optical properties and photocurrent response

Pursuits of new types of Pb-free heterometallic halides adequate for photovoltaic applications are still urgent but challenging. In this study, by using in situ-produced [(Me)₂-(DABCO)]²⁺ (DABCO = 1,4-diazabicyclo[2.2.2]octane; Me = methyl) cations as structure-directing agents, we successfully constructed a non-perovskite copper iodobismuthate hybrid, namely [(Me)₂-(DABCO)]₂Cu₂Bi₂I₁₂ (1), which features discrete [Cu₂Bi₂I₁₂]^4- anionic moieties formed by the building units of [CuI₄] tetrahedra and [BiI₆] octahedra. UV-Vis diffuse reflectance analyses showed that compound 1 possesses semiconductive behaviors with a narrow optical bandgap of 1.80 eV. More importantly, it exhibits excellent photoelectric switching abilities, and its photocurrent density (2.30 μA cm^-2) far exceeds those of some high-performance halide-based counterparts. Different from many heterometallic analogues, noteworthily, it also has dispersive band structure and strong electronic coupling near the Fermi level, resulting in a material with small effective masses that may be responsible for the good photoelectricity. This study may offer new guidance for the design and synthesis of eco-friendly heterometallic halides with unique structures and desirable properties.

A new metal complex-templated silver iodobismuthate exhibiting photocurrent response and photocatalytic property

An organic-inorganic hybrid silver iodobismuthate characteristic of the infrequent [Ag₂BiI₆L₂] cluster (L = I or I₃) and with a unique Ag/Bi molar ratio (2/1), namely, [Zn(bipy)₃]₂Ag₂BiI₆(I)_1.355(I₃)_1.645 (bipy = 2,2'-bipyridine; 1), was solvothermally synthesized, and structurally, optically, and theoretically studied. Intriguingly, compound 1 exhibited semiconductor behavior with an optical band gap of 2.33 eV, which endowed it with excellent photoelectric and photocatalytic properties. Electronic structure calculations further revealed that the relative separate conduction band (CB) and valence band (VB) in compound 1 may be responsible for the good optical activity. This study also includes the Hirshfeld surface analyses, thermogravimetric measurements and X-ray photoelectron spectroscopy (XPS) characterization.

Two [Co(bipy)3]3+-Templated Silver Halobismuthate Hybrids: Syntheses, Structures, Photocurrent Responses, and Theoretical Studies

Employing in situ-generated metal complexes as structural decorating agents, we, for the first time, isolated two [Co(bipy)₃]³⁺-templated silver halobismuthate hybrids, namely [Co(bipy)₃]₂Ag₄Bi₂X₁₆ (X = Br (1), I (2); bipy = 2,2'-bipyridine). Compounds 1 and 2 belong to the isomorphic phrases and exhibit the nonperovskite structures characteristic of the discrete [Ag₄Bi₂X₁₆]^6- anions. UV-vis absorption spectra analyses showed that the optical band gaps of compounds 1 and 2 are 2.40 and 1.95 eV, respectively, implying the visible light responding semiconductor properties. Moreover, under the alternate light illumination, the title compounds exhibited "on/off" photocurrent behaviors, with high photocurrent densities comparable to many metal halide hybrids. Presented in this work also involved the Hirshfeld surface analyses and X-ray photoelectron spectroscopy studies together with the theoretical band structures, density of states, and electron wave functions.

Four Discrete Silver Iodobismuthates/Bromobismuthates with Metal Complexes: Syntheses, Structures, Photocurrent Responses, and Theoretical Studies

Using in situ formed metal complexes of [Fe(bipy)₃]²⁺ or [Ni(bipy)₃]²⁺ (bipy = 2,2'-bipyridine) as templates, four new Ag-Bi-X (X = I and Br) compounds are first isolated in the metal-complex-decorated heterometallic halobismuthate family, namely [M(bipy)₃]AgBiI₆ (M = Fe (1), Ni (2)), [Fe(bipy)₃]AgBiBr₆ (3), and [Ni(bipy)₃]AgBiBr₆ (4). Compounds 1-4 feature discrete [AgBiX₆]_n^2n- anions, exhibiting three polymorphisms that may be ascribed to the different stackings and the flexible condensations of [BiX₆] octahedrons and [AgX₄] tetrahedra/[AgX₃] triangles. UV-vis diffuse reflectance analyses reveal that they are narrow band gap semiconductor materials (ca. 1.82-2.13 eV). Intriguingly, the title compounds display excellent photoelectrical switching properties, with photocurrent density following the order 3 > 4 > 2 > 1. In addition, the comparative studies of intermolecular interactions, theoretical band structures, density of states, and effective masses of three polymorphisms have also been investigated.