Luminescence and Length Control in Nonchelated d⁸‐Metallosupramolecular Polymers through Metal‐Metal Interactions

Abstract

Supramolecular polymers (SPs) of d8 transition metal complexes have received considerable attention by virtue of their rich photophysical properties arising from metal‐metal interactions. However, thus far, the molecular design is restricted to complexes with chelating ligands due to their advantageous preorganization and strong ligand fields. Herein, we demonstrate unique pathway‐controllable metal‐metal‐interactions and remarkable 3MMLCT luminescence in SPs of a non‐chelated PtII complex. Under kinetic control, self‐complementary bisamide H‐bonding motifs induce a rapid self‐assembly into non‐emissive H‐type aggregates (1A). However, under thermodynamic conditions, a more efficient ligand coplanarization leads to superiorly stabilized SP 1B with extended Pt⋅⋅⋅Pt interactions and remarkably long 3MMLCT luminescence (τ77 K=0.26 ms). The metal‐metal interactions could be subsequently exploited to control the length of the emissive SPs using the seeded‐growth approach.

Toward the Design and Construction of Supramolecular Functional Molecular Materials Based on Metal–Metal Interactions

“…In particular, a nonemissive H-aggregate was formed from a rapid, kinetically controlled cooperative assembly assisted by 4fold hydrogen-bonding interactions, while the thermodynamic controlled self-assembly was assisted by extended Pt•••Pt interactions accompanied by MMLCT emission. 235 Due to the kinetically trapped assemblies, the sequential and controlled synthesis of Pd(II) and Pt(II) supramolecular block copolymers has been explored by Che, in which the manipulation of the kinetically trapped aggregates was found to be crucial to the formation of such a sequential block. 236 Distinctive from the aforementioned examples of the utilization of the single-component metal complex to obtain the kinetically trapped states by Manners (Figure 8), Yam adopted another strategy to realize the kinetics of the supramolecular assemblies by the utilization of two-component ensemble systems.…”

“…More recently, they also demonstrated pathway-controllable metal–metal interactions with MMLCT emission based on a non-preorganized, monodentate-ligand-containing platinum­(II) complex. In particular, a nonemissive H-aggregate was formed from a rapid, kinetically controlled cooperative assembly assisted by 4-fold hydrogen-bonding interactions, while the thermodynamic controlled self-assembly was assisted by extended Pt···Pt interactions accompanied by MMLCT emission . Due to the kinetically trapped assemblies, the sequential and controlled synthesis of Pd­(II) and Pt­(II) supramolecular block copolymers has been explored by Che, in which the manipulation of the kinetically trapped aggregates was found to be crucial to the formation of such a sequential block …”

Exploiting halido ligands to control nucleation pathways and Pt⋯Pt interactions in supramolecular co-polymerizations

“…1a, dotted orange line). 22 Analogously, different preparation methods were investigated for 2 (Fig. 1b, for details see Fig.…”

“…[19][20][21] Recently, we have demonstrated that the inclusion of flexible bisamide hydrogen bonding synthons is a successful strategy to achieve PtÁ Á ÁPt contacts and 3 MMLCT with excimeric character in bispyridyldichlorido Pt(II) complexes upon SP (see complex 1, Scheme 1). 22 Given that halogens can have a significant impact on SP, 23,24 we herein investigate the hitherto unknown halogen effects on metal-metal interactions in singleand two-component SPs. We thus designed a new complex 2 with bulkier bromido ligands, keeping the molecular design unaltered.…”

“…Note that no transformation of 1A to 1B occurs over time in the absence of mechanical agitation. 22 The excess of 1A is used to ensure a sufficiently intense emission during the experiments. The initial emission spectra exhibit only a negligible growth of the 3 MMLCT band, which is also reflected in the SEM images recorded within the first 24 h (purple spectrum in Fig.…”