Excimer emission based on the control of molecular structure and intermolecular interactions

Abstract

The wavelength of excimer formation and efficiency of an OLED device were controlled through the change of the center position of the triple-core chromophore.

Bright, Multi‐responsive, Sky‐Blue Platinum(II) Phosphors Based on a Tetradentate Chelating Framework

“…[4] Therefore,d eveloping new multi-responsive systems is of great interest. [5] Because excimer formation is ab imolecular and diffusion controlled process,e xcimer emission is highly dependent on temperature and often on pressure as well, [5] and could be controlled effectively by adjusting the strength of the molecular interactions or their medium. [2][3][4] Since the establishment of excimer phenomenon, [5a-c] excimer based luminescent systems have attracted widespread attention.…”

“…There are many approaches to achieve responsive systems including introducing labile/weak intermolecular bonding interactions that can be readily disrupted via physical or chemical means,i ncorporating as tructural motif that can readily undergo isomerization with stimuli, or using donoracceptor systems that change donor-acceptor geometry upon perturbation. [5,6] One example was reported recently by Yamaguchi and co-workers in which am acrocyclic fluorophore dimer confined by two flexible linkers displays temperature-dependent intramolecular excimer fluorescence modulated by the length of the connecting unit. [5] Because excimer formation is ab imolecular and diffusion controlled process,e xcimer emission is highly dependent on temperature and often on pressure as well, [5] and could be controlled effectively by adjusting the strength of the molecular interactions or their medium.…”

“…Thes olid-state emission spectra of both Pt1 and Pt2 are similar to those of 1.0 10 À5 m solution ( Figure 2A and Figure 3B), but F phos in the solid state is lower for both (0.25 and 0.23, respectively), as ar esult of intermolecular interactions.Atconcentrations above 1.0 10 À5 m, ab road, unstructured red emission band appears at 650 nm with al onger decay lifetime (Figure 2A,T able 1) and increases in intensity relative to the peak at 477 nm, characteristic of excimer emission. [5,6] Most remarkable is that both Pt1 and Pt2 display ad istinct phosphorescent color change with T that resembles the concentration-dependent emission color change.T aking Pt1 From 130 Kto345 K, the excimer peak gradually gains intensity and the CIE coordinates of the emission change almost linearly from sky blue to red. Increasing the water content of the THF solution of Pt1 or Pt2 has asimilar effect on the emission color (sky blue, < 70 %w ater;r ed, !…”

“…95 % water, see Supporting Information), consistent with greater aggregation of the Pt II monomer within the "suspension" domain, hence the higher probability of forming excimers. [5] In addition, the radiative rate constant of the monomer emission does not change significantly with T while that of excimer increases rapidly with T (see Supporting Information), one factor for the excimer domination at high T. Theorigin of the excimer emission could be either from metal-metal-to-ligand charge transfer (MMLCT) [8b] or ligand centered p-p interactions.T he excimer decay lifetimes of Pt1 and Pt2 are consistently longer than those of the monomer decay lifetime over aw ide range of T and concentration (see Table 1a nd Supporting Information). This dramatic and distinct emission color change with T can be readily visualized as shown in Figure 2B.The thermochromic response of Pt1 and Pt2 is fully reversible ( Figure 2D).…”

“…[2][3][4] Since the establishment of excimer phenomenon, [5a-c] excimer based luminescent systems have attracted widespread attention. [5] Because excimer formation is ab imolecular and diffusion controlled process,e xcimer emission is highly dependent on temperature and often on pressure as well, [5] and could be controlled effectively by adjusting the strength of the molecular interactions or their medium. [5,6] One example was reported recently by Yamaguchi and co-workers in which am acrocyclic fluorophore dimer confined by two flexible linkers displays temperature-dependent intramolecular excimer fluorescence modulated by the length of the connecting unit.…”