Two New Hybrid Iodoplumbates with Chain-like Cations

Abstract

By utilizing in situ-formed MCP ligands (HMCP + = 1-methyl-4-(carboxyl)pyridinium) as decoration agents, two new iodoplumbate hybrids, namely, [Pb(MCP) 2 I]PbI 3 (1) and Cs 2 [Pb-(MCP) 4 ]Pb 3 I 10 (2), have been solvothermally prepared and structurally characterized. Compound 1 features the typical onedimensional (1D) [PbI 3 ] n n− anions, while compound 2 exhibits two-dimensional (2D) [Pb 3 I 10 ] n 4n− slabs perforated with large parallelogram-shaped windows. The intriguing structural characteristic of compounds 1 and 2 is that they contain unique chain-like cations of [Pb(MCP) 2 I] + and [Pb(MCP) 4 ] 2+ , respectively.Interestingly, upon alternate visible-light and full spectrum light irradiation, compounds 1 and 2 show stable and rapid photoelectric switching properties, whose photocurrent densities are comparable or larger than those of many metal halide hybrids. Additionally, their optical properties, Hirshfeld surface analyses, X-ray photoelectron spectra, as well as the theoretical band structures and density of states have also been studied.

Investigation of Metastable Low Dimensional Halometallates

“…The bandgap values correspond well with the respective colors of the materials, and for 1 , 2 and 5 , the values lie in the region of visible-light responsive semiconductors. The recorded values agree with reported hybrid iodoplumbate materials in the literature [ 8 , 12 , 13 , 22 , 35 , 38 ]. In addition, the absorption peak at ~3.91 eV (317 nm) for the reported materials corresponds to the peak at 3.85 eV (322 nm) for pure 1,10-phenanthroline, which may arise due to intraligand π−π * transitions [ 22 , 35 ].…”

“…The calculated band structure for one orientation of the disordered phenanthroline is shown in Figure S18 . There is a significant discrepancy between the calculated band structure and the experimental data (2.87 eV) obtained via diffuse reflectance spectra, which is likely due to the limitations of semi-local DFT functionals that are known to underestimate calculated band gaps [ 12 , 13 ]. Though the band structures fail to accurately predict the band gap for these structures, the calculations do show that the band structure is impacted by the orientation of the phenanthroline molecule.…”

“…Main group halometallate compounds (HMCs) constitute a class of hybrid materials that have been extensively studied for their high structural diversity and tunable optical properties [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ]. These materials often consist of an inorganic halometallate anion and a charge-balancing organic cation.…”

“…The anion, composed of MX n polyhedra (M = main group metal, X = halide, n = integer), can be connected via corner-, edge- or face-sharing arrangements to produce 0D, 1D, 2D or 3D structures [ 19 ]. For example, iodoplumbates, which were extensively studied by Krautscheid et al, exhibit a wide range of anionic polyhedra, including [Pb 2 I 6 ] 2− , [Pb 3 I 8 ] 2− , [Pb 3 I 10 ] 4− , [Pb 7 I 18 ] 4− and [Pb 10 I 28 ] 8− [ 13 , 20 ]. The majority of these HMCs have organic monoamines/polyamines, N-containing organic ligands or metal coordination complexes as the charge balancing cationic species.…”

“…This leads to an extremely large number of potential compositions of novel HMCs that can be crystallized in different structures and different dimensionalities, leading to the ability to compositionally adjust the optical properties. To date, many of the reported HMCs have exhibited semiconductor behavior [ 13 , 14 , 21 , 22 ]. It needs to be stressed that for these materials, the specific products and product structures that form are extremely sensitive to the reaction conditions used, signaling their metastable nature.…”