Emission Behavior of Secondary Thioamide‐Based Cationic Pincer Platinum(II) Complexes in the Aggregate State

Abstract

Cationic pincer platinum(II) complexes bearing secondary thioamide units showed aggregation‐induced emission (AIE) activity in chloroform/hexane and methanol/water mixtures. Hydrogen bonding of the thioamide units and interionic interactions contributed to the AIE activities.

Secondary Thioamides as Multidentate Ligands for Functional Metal Complexes

“…Our latest research on this topic deals with the AIEactive phosphorescent cationic pincer Pt(II) complexes bearing a sec-TA ligand. 60,61 The AIE activity was evaluated in three different types of S^C^S Pt complexes, namely neutral sec-TAbased S^C^S Pt, cationic sec-TA-based S^C^S Pt, and cationic tertiary-TA-based complexes (Figure 8). Only the cationic sec-TA-based S^C^S Pt complex formed aggregates in various solvent systems, and the aggregates showed AIE behavior.…”

Aggregation-induced emission behavior of a pincer platinum(II) complex bearing a poly(ethylene oxide) chain in aqueous solution

“…The absorption and emission spectra of 2 in methanol were almost the same as those of 1 (Fig. S5), which exhibits emission through metal-to-ligand charge transfer (MLCT) excited states [9]. These results suggested that MLCT excited states were also involved in the emission of 2.…”

“…Recently, we reported the AIE properties of secondary thioamide-based platinum complex 1, [9]. The AIE activity of 1 was caused by the suppression of molecular motion resulting from aggregate formation upon addition of the poor solvent to the solution.…”

Pincer Complexes with Thione Sulfur Donors

“…Furthermore, owing to hydrogen bonding interactions, addition of different anions (as tetra-n-butylammonium or tetraphenylphosphonium salts) induced an enhancement in the emission intensity of 18 and related complexes 19a,b with NHC(S) moiety, while no effect was observed for their tertiary thioamide counterpart 20. For cationic platinum(II) complex 21 (Scheme 7), the AIE-activity was Cl -observed upon addition of hexane into chloroform solution or water into methanol solution of the platinacycle, resulting in formation of nanosized aggregates [43]. The detected improvement of luminescence properties was again attributed to hydrogen bonding and interionic interactions characteristic for the system.…”

“…From the viewpoint of optical and electroluminescence applications, of special attention are various cyclometallated platinum derivatives [39]. A series of bis(thioamide) Pt(II) pincer complexes possessing valuable luminescence properties were reported by T. Kanbara et al [40][41][42][43]. A platinum(II) counterpart of complex 9a readily obtained by direct cyclometallation of 8a with PtCl 2 (PhCN) 2 (Scheme 4) exhibited strong photoluminescence in the glassy frozen state as well as in the solid state at room temperature [40].…”