Mono- and Bi-Dentate Chiral Ligands Lead to Efficient Circularly Polarized Luminescence in 0D and 3D Semiconducting Copper(I) Iodides

Chiral hybrid Cu(I)-based iodides with d(10) closed shell demonstrate great potential for circularly polarized luminescence (CPL) because of high photoluminescence quantum yield (PLQY). Herein, by incorporating mono- or bi-dentate coordination mode ligands as chiral source, the self-assembly of four pairs of chiral hybrid Cu(I)-based iodides, namely, (R/S)-Cu4I4(Hmpy)(4)center dot H2O (R/S-1), (R/S)-Cu4I4(3Hpy)(4) (R/S-2), (R/S)-Cu4I4(2MePI)(4) (R/S-3), and (R/S)-Cu4I4(3AD)(4) (R/S-4) (where R/S-Hmpy = R/S-2-pyrrolidinemethanol, R/S-3Hpy = R/S-3-hydroxypyrrolidine, R/S-2MePI = R/S-2-methylpiperazine, and R/S-3AD = R/S-3-aminopiperidine), are reported. With the monodentate and bidentate ligands, these materials belong to two different structural types: 0D molecular clusters (R/S-1, R/S-2) and 3D porous metal-organic frameworks (R/S-3, R/S-4). These materials all crystallize in non-centrosymmetric space groups containing similar basic Cu4I4 cubane tetramer building units but with different coordination modes. They are also semiconductors, with optical bandgaps ranging from 2.70 to 2.94 eV. The photoluminescence (PL) and circularly polarized luminescence (CPL) emissions are further characterized, where the highest PLQY of approximate to 95% and CPL dissymmetry factor (g(lum)) of approximate to 7 x 10(-3) are achieved in R/S-1. This work offers a systematic comparison between different structural types with similar building blocks, bridging by the flexible chiral ligands, and shows that the hybrid copper iodides are highly promising candidates for next-generation optoelectronics and chiroptics.