Core-dependent properties of copper nanoclusters: valence-pure nanoclusters as NIR TADF emitters and mixed-valence ones as semiconductors.

We report herein that copper alkynyl nanoclusters show metal-core dependent properties a charge-transfer mechanism, which enables new understanding of their structure-property relationship. Initially, nanoclusters and bearing respective Cu(i) () and Cu(i) () cores were prepared and revealed to display near-infrared (NIR) photoluminescence mainly from the mixed alkynyl → Cu(i) ligand-to-metal charge transfer (LMCT) and cluster-centered transition, and they further exhibit thermally activated delayed fluorescence (TADF). Subsequently, a vanadate-induced oxidative approach to generate a nucleating Cu(ii) cation led to assembly of and featuring respective [Cu(ii)O]@Cu(i) () and {[Cu(ii)O]·[VO]}@Cu(i) () cores. While interstitial occupancy of Cu(ii) triggers inter-valence charge-transfer (IVCT) from Cu(i) to Cu(ii) to quench the photoluminescence of and , such a process facilitates charge mobility to render them semiconductive. Overall, metal-core modification results in an interplay between charge-transfer processes to switch TADF to semiconductivity, which underpins an unusual structure-property correlation for designed synthesis of metal nanoclusters with unique properties and functions.