Organic–Inorganic\nHybrid Glasses of Atomically\nPrecise Nanoclusters

Abstract

Organic–inorganic atomically precise nanoclusters\nprovide\nindispensable building blocks for establishing structure–property\nlinks in hybrid condensed matter. However, robust glasses of ligand-protected\nnanocluster solids have yet to be demonstrated. Herein, we show [Cu₄I₄(PR₃)₄] cubane nanoclusters\ncoordinated by phosphine ligands (PR₃) form robust melt-quenched\nglasses in air with reversible crystal–liquid–glass\ntransitions. Protective phosphine ligands critically influence the\nglass formation mechanism, modulating the glasses’ physical\nproperties. A hybrid glass utilizing ethyldiphenylphosphine-based\nnanoclusters, [Cu₄I₄(PPh₂Et)₄], exhibits superb optical properties, including >90% transmission\nin both visible and near-infrared wavelengths, negligible self-absorption,\nnear-unity quantum yield, and high light yield. Experimental and theoretical\nanalyses demonstrate the structural integrity of the [Cu₄I₄(PPh₂Et)₄] nanocluster, i.e.,\niodine-bridged tetranuclear cubane, has been fully preserved in the\nglass state. The strong internanocluster CH−π interactions\nfound in the [Cu₄I₄(PPh₂Et)₄] glass and subsequently reduced structural vibration account for\nits enhanced luminescence properties. Moreover, this highly transparent\nglass enables performant X-ray imaging and low-loss waveguiding in\nfibers drawn above the glass transition. The discovery of “nanocluster\nglass” opens avenues for unraveling glass formation mechanisms\nand designing novel luminescent glasses of well-defined building blocks\nfor advanced photonics.