Extraordinary intense blue Tl⁺ lone-pair photoluminescence from thallium(i) chloride hydroborate Tl₃Cl[B₁₂H₁₂]

Abstract

Previously unknown thallium(i) chloride hydroborate Tl3Cl[B12H12], crystallising with a hexagonal perovskite-type motif, was obtained by the reaction of the carbonate Tl2[CO3] with an aqueous solution of (H3O)2[B12H12] in the presence of Cl− anions.

Synthesis and Characterization of High-Energy Anti-Perovskite Compounds Cs3X[B12H12] Based on Cesium Dodecahydro-Closo-Borate with Molecular Oxoanions (X− = [NO3]−, [ClO3]− and [ClO4]−)

“…The Goldschmidt tolerance factor is a widely employed tool to assess the stability of perovskites, calculated using the formula t G = ( rB + rA )/√2( rX + rA ), where rA , rB , and rX represent the ionic radii of A , B , and X , respectively, and an ideal perovskite ABX 3 has a tolerance factor of 1 [ 21 ]. Calculating the Goldschmidt tolerance factors (t G ) with r ([B 12 H 12 ] 2− ) = 322 pm, r (Cs + ) = 177 [ 21 ], and r ([NO 3 ] − ), r ([ClO 3 ] − ) and r ([ClO 4 ] − ) as 200, 208 and 225 [ 42 ], respectively, yields values of 0.936, 0.917 and 0.878 for compounds ( I )–( III ), respectively. These values fall within a narrow range, indicating a trend that aligns with predictions for the same perovskite-type structure, but not the hexagonal one.…”

“…Anti -perovskites incorporating the dodecahydro- closo -dodecaborate anion [B 12 H 12 ] 2− have been previously synthesized, with a number of examples including Cs 3 Cl[B 12 H 12 ], (NH 4 ) 3 Br[B 12 H 12 ] [ 18 ], K 3 I[B 12 H 12 ] [ 19 ], Cs 3 [BH 4 ][B 12 H 12 ] [ 20 ], and luminescent Tl 3 Cl[B 12 H 12 ] [ 21 ]. Among these compounds, only Tl 3 Cl[B 12 H 12 ] exhibits a hexagonal and not a cubic anti -perovskite structure.…”

Crystal Structure, Raman Spectrum and Tl+ Lone-Pair Luminescence of Thallium(I) Dodecahydro-Monocarba-closo-Dodecaborate Tl[CB11H12]

“…The quantum yield of less than 10 % at room temperature is rather low and can be explained by the low activation energy for thermal quenching, which is also reflected in temperature-dependent measurements showing maximum emission intensity in a range of 77 to 100 K. Compared to the luminescence properties of the already known related thallium(I) salts Tl2[B12H12], Tl2[B10H10] and Tl3Cl[B12H12], the presented Tl[CB11H12] shows no red shifting of the photoluminescence like Tl2[B12H12] or Tl2[B10H10] (emissions at 522 and 510 nm) and has the highest full width at half maximum of 6200 cm −1 compared to 4000 to 4700 cm −1 of the closo-hydroborate salts. In the end, it cannot cope with the strong luminescence properties of Tl3Cl[B12H12]; however, the mixed coordination sphere of chloride and hydridic hydrogen of the [B12H12] 2− anions seem to favour strong emission intensity and a high quantum yield (Figure 13) [6,8].…”

“…In this study, we present the synthesis and characterization of the previously unknown thallium(I) salt Tl[CB 11 H 12 ]. As the combination of cations with electronic lone pairs and closo-hydroborate anions provided salts with interesting photoluminescence properties, such as Tl 2 [B 12 H 12 ] [6,7], Tl 2 [B 10 H 10 ] [6], and Tl 3 Cl[B 12 H 12 ] [8], already it was a matter of particular interest to see, how the luminescence properties of Tl + will change, when a carbon atom is substituted into the closo-borate cage within the [CB 11 H 12 ] − counter anion.…”

“…2 [B 12 H 12 ], Tl 2 [B 10 H 10 ] and Tl 3 Cl[B 12 H 12 ], the presented Tl[CB 11 H 12 ] shows no red shifting of the photoluminescence like Tl 2 [B 12 H 12 ] or Tl 2 [B 10 H 10 ] (emissions at 522 and 510 nm) and has the highest full width at half maximum of 6200 cm −1 compared to 4000 to 4700 cm −1 of the closo-hydroborate salts.In the end, it cannot cope with the strong luminescence properties of Tl 3 Cl[B 12 H 12 ]; however, the mixed coordination sphere of chloride and hydridic hydrogen of the [B 12 H 12 ] 2− anions seem to favour strong emission intensity and a high quantum yield (Figure13)[6,8].Crystals 2022, 12, x FOR PEER REVIEW 13 of 14…”