Indium halides

Abstract: Lead halide perovskites have demonstrated promising emission tunability achieved by composition engineering, which makes them viable in several potential applications. Determining how to effectively control the crystalline structural transformation and composition in lead‐free halide perovskites is of great importance. Herein, a controllable synthetic method is reported to obtain the 0D metal halide perovskite derivatives (Cs1−xRbx)2InCl5∙H2O and (Cs1−xRbx)3InCl6, through synergistic regulation of the Cs/Rb feed ratios and the reaction solvent. When hydrochloric acid (HCl) is used as the reaction solvent, (Cs1−xRbx)2InCl5∙H2O is obtained at a high Cs/Rb feed ratio greater than 2:1, while (Cs1−xRbx)3InCl6 is obtained at a low Cs/Rb feed ratio of less than 2:5. However, when anhydrous methanol (MeOH) is used as the reaction solvent, only the (Cs1−xRbx)3InCl6 structure is obtained at all Cs/Rb feed ratios. In addition, a reversible crystalline structural transformation is demonstrated between (Cs0.67Rb0.33)2InCl5∙H2O and (Cs0.67Rb0.33)3InCl6 by immersing the as‐prepared products into MeOH and HCl sequentially, which generates a novel green/yellow reversible emission switch. The Sb3+ ion self‐trapped exciton emission and stability of the synthesized (Cs1−xRbx)2InCl5∙H2O and (Cs1−xRbx)3InCl6 are systematically investigated. The results are helpful for promoting the diverse photonics and optoelectronics applications of these environmentally stable perovskite derivatives.

Abstract: Rapid and complete fluorination of the complexes [MCl3(L)] (L = Me3-tacn, BzMe2-tacn, M = Al, Ga, In) occurs at room temperature via reaction of a MeCN solution of the complex with 3 mol equiv. of KF in water. The Ga and In complexes are also readily fluorinated using R4NF (R = Me or nBu) in MeCN solution, whereas no reaction occurs with the Al species under these conditions. The distorted octahedral fac-trifluoride coordination at M is confirmed in solution by multinuclear (19F, 27Al, 71Ga and 115In) NMR spectroscopic studies, leading to sharp resonances with 19F–71Ga and 19F–115In couplings evident. The [MF3(L)] are extremely stable in aqueous solution and at low pH; they crystallise as tetrahydrates, [MF3(Me3-tacn)]·4H2O, with extended H-bonding networks formed through both F⋯H–O and O⋯H–O contacts. [InF3(BzMe2-tacn)]·1.2H2O also shows intermolecular F⋯H–O hydrogen bonding contacts. The prospects for developing this coordination chemistry further to take advantage of the high metal–fluoride bond energies to enable rapid, late-stage fluorination of large macromolecules under mild conditions for PET imaging applications in nuclear medicine are discussed. This work also demonstrates that F-18 radiolabelling to form [F-18] [GaF3(BzMe2-tacn)] is effected readily at room temperature in aqueous MeCN over 30–60 min on addition of 2.99 mol equiv. of [19F]–KFaq and 0.4 mL [18F]–KFaq (100–500 MBq) to [GaCl3(BzMe2-tacn)] with ca. 30% incorporation.