[Cu₁₅(PPh₃)₆(PET)₁₃]²⁺: a Copper Nanocluster with Crystallization Enhanced Photoluminescence

Abstract

Due to their atomically precise structure, photoluminescent copper nanoclusters (Cu NCs) have emerged as promising materials in both fundamental studies and technological applications, such as bio‐imaging, cell labeling, phototherapy, and photo‐activated catalysis. In this work, a facile strategy is reported for the synthesis of a novel Cu NCs coprotected by thiolate and phosphine ligands, formulated as [Cu15(PPh3)6(PET)13]2+, which exhibits bright emission in the near‐infrared (NIR) region (≈720 nm) and crystallization‐induced emission enhancement (CIEE) phenomenon. Single crystal X‐ray crystallography shows that the NC possesses an extraordinary distorted trigonal antiprismatic Cu6 core and a, unique among metal clusters, “tri‐blade fan”‐like structure. An in‐depth structural investigation of the ligand shell combined with density functional theory calculations reveal that the extended CH···π and π‐π intermolecular ligand interactions significantly restrict the intramolecular rotations and vibrations and, thus, are a major reason for the CIEE phenomena. This study provides a strategy for the controllable synthesis of structurally defined Cu NCs with NIR luminescence, which enables essential insights into the origins of their optical properties.

Copper(I) Alkynyl Clusters with Crystallization-Induced Emission Enhancement

“…48 Similarly, Bakr et al synthesized Cu 15 with CIEE. 49 CPL have a wide range of potential applications. 53 Feng et al reported 4-methylthiophenol-protected copper nanoclusterbased AIE particles and their application in β-galactosidase activity assay.…”

Synthesis of Copper Nanocluster and Its Application in Pollutant Analysis

“…The as-prepared nanoclusters were successfully utilized to detect heparin by aggregation-induced quenching mechanism. Another study synthesized a near infrared emitting copper nanocluster co-protected by thiolate and phosphine ligands [ 47 ]. The structure of this nanocluster is atomically precise with the formula of [Cu 15 (PPh 3 ) 6 (PET) 13 ] 2+ .…”

Structural Isomerization in Cu(I) Clusters: Tracing the Cu Thermal Migration Paths and Unveiling the Structure-Dependent Photoluminescence

“…The unique stability in ambient environment may be caused by the coordination effect between Cu and organic ligands, which then form dense organic protection shell to prevent the oxidation by O 2 in air. 56 In addition, intermolecular interactions including C-H•••π may also facilitate maintaining the crystallinities and stabilities. 57 Unfortunately, the intermediate Cu 15b isolated from CH 2 Cl 2 was unstable after being exposed to the air for hours, probably because that low boilingpoint and volatile CH 2 Cl 2 guest weakens the stability of the crystals.…”

“…58,59 Page 13 of 26 CCS Chemistry that intermolecular C-H•••π interactions would substantially restrict the molecular rotations or vibrations and thus considerably enhance the radiative transitions in the crystalline state. 36,56,65 Isotropic temperature factor (Ueq) is a physical factor that reflects the thermal vibration level of atom in the crystal. 66 We also compared Ueq of C atoms between two isomers at 300K.…”