The metal halide structure and the extent of distortion control the photo-physical properties of luminescent zero dimensional organic-antimony(iii) halide hybrids

Abstract

Antimony(III) halide based zero dimensional hybrids have gained attention as broadband emitters. Until now, quadrangular pyramidal SbX₅ based and octahedral SbX₆ based 0D hybrids have been reported utilizing different organic ligands demonstrating some structural tunability affecting their emissive properties. Utilizing a common organic ligand, here we demonstrate the structural tunability (quadrangular pyramidal, octahedral, or a combination thereof) of the metal halide unit in Sb(III)Cl 0D hybrids with contrasting photo-physical properties (broadband, Stokes shift, strong/weak colored emission). The structure–property–mechanism correlation of the synthesized compounds [1 (C₁₂H₅₂Cl₁₈N₈O₄Sb₃; tris Sb green); 2 (C₁₂H₅₀Cl₁₄N₈O₃Sb₂; tris Sb red); 3 (C₂₄H₈₈Cl₂₅N₁₆O₄Sb₃; tris Sb yellow)] identifies crucial factors that control their emissive properties. The X-ray analysis reveals the structure (1-octahedral; 2-quadrangular pyramidal; 3-combination thereof) and the order of the extent of structural distortion as 1–3 ≪ 2. The metal halide coordination environment asymmetry and its structure are observed to dictate PL emission energy (1-green; 2-red; 3-yellow) as supported by a qualitative Molecular Orbital scheme. The extent of structural distortion guides the observed Stokes shifts (1–165 nm; 2–290 nm; 3–200 nm; 1–3 < 2). Interestingly, the extent of distortion is found to be well correlated with the observed PLQY (1–45%; 2–6%; 3–43%; 1–3 ≫ 2). This report clearly demonstrates the structural tunability and the effect of the metal halide unit structure/distortion in shaping the emissive properties of 0D organic Sb(III) halide hybrids.