Low Optical Loss and Bent Waveguides: Crystals of a One-Dimensional Pt1Ag14 Nanocluster

Photoluminescent nanoclusters are promising materials for optical waveguides. However, their photon transmission under mechanical stress is very challenging. Here, we report an low-loss metallic nanocluster crystal, [Pt₁Ag₁₄(DPPP)₆Cl₄](SbF₆)₂ (DPPP = 1,3-bis(diphenylphosphino) propane), which exhibits stable optical performance with an optical loss coefficient of 7.15 × 10^–4 dB·μm^–1─lower than most reported inorganic, organic, and hybrid materials. The Pt₁Ag₁₄ crystals maintain excellent optical stability under mechanical deformation, with an optical loss difference of only 0.15 × 10^–3 dB·μm^–1 before and after mechanical stress. Reasonable molecular design endows Pt₁Ag₁₄ crystals with robust mechanical flexibility, resulting in their bending radius being smaller than that of nanocluster crystals with similar structures. Structural analysis has shown that multiple π···π, C–H···π, and C–H···F intra- and intermolecular interactions originating from the ligands and between the ligands and counterions ensure molecular and crystal stability under mechanical stress. Metallic nanocluster crystals with low loss and mechanical flexibility generated by rational molecular design offer promising candidates in the fields of active waveguides and flexible electronic materials.