NIR Clusteroluminescence of Non‐conjugated Phenolic Resins Enabled by Through‐Space Interactions

Abstract

Clusteroluminescence (CL) and through-space interactions (TSIs) of non-conjugated molecules have drawn more attention due to their unique photophysical behaviors that are different from largely conjugated luminogens. However, achieving red and even near-infrared (NIR) emission from such systems is still challenging due to the intrinsic drawbacks of non-conjugated molecules and the lack of theories for structure-property relationships. In this work, six phenolic resins are designed and synthesized based on two molecule-engineering strategies: increasing the number of TSIs units and introducing electron-donating/-withdrawing groups. All phenolic resins are verified as luminogens with CL property (CLgens), and the first example of CLgens with NIR emission (maximum emission wavelength � 680 nm) and high absolute quantum yield (47 %) is reported. Experiments and theoretical analysis reveal that two TSIs types, through-space locally excited state and through-space charge transfer state, play essential roles in achieving CL from these non-conjugated polymers, which could be manipulated via changing structural conformation and electron density or altering electron transition behaviors. This work not only provides an approach to manipulate TSIs and CL of nonconjugated polymers but also endows commercially available phenolic resins with high practical value as luminescence materials.

Cluster-induced aggregation in polyurethane derivatives with multicolour emission and ultra-long organic room temperature phosphorescence

“…These data further suggest that there are a variety of emission aggregates in the PU system that can be excited by the excitation light of different energies. 2,11–13,27,51–53…”

“…For NCLPs, the final aggregation structure is more influential than the isolated chemical structure on the photophysical properties of the material. 35,36,40,52,53 Thus, although the PUs have the same chemical structure, they show different microscopic aggregation structures due to different molecular conformation and aggregation behaviour (Fig. 4).…”