A Review of Luminescent Anionic Nano System: d10 Metallocyanide Excimers and Exciplexes in Alkali Halide Hosts.

Xiaobo Li,Howard Patterson

doi:10.3390/ma6072595

Xiaobo Li, Howard Patterson

Open Access

https://doi.org/10.3390/ma6072595

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Abstract

Dicyanoaurate, dicyanoargentate, and dicyanocuprate ions in solution and doped in different alkali halide hosts exhibit interesting photophysical and photochemical behavior, such as multiple emission bands, exciplex tuning, optical memory, and thermochromism. This is attributed to the formation of different sizes of nanoclusters in solution and in doped hosts. A series of spectroscopic methods (luminescence, UV-reflectance, IR, and Raman) as well as theoretical calculations have confirmed the existence of excimers and exciplexes. This leads to the tunability of these nano systems over a wide wavelength interval. The population of these nanoclusters varies with temperature and external laser irradiation, which explains the thermochromism and optical memory. DFT calculations indicate an MLCT transition for each nanocluster and the emission energy decreases with increasing cluster size. This is in agreement with the relatively long life-time for the emission peaks and the multiple emission peaks dependence upon cluster concentration.

Highlights

The term “excimer” was first introduced in 1960 by Stevens and Hutton when studying pyrene luminescence [1]. They defined excimer as a dimer associated in the electronic excited state and dissociated in its ground state, which is different from a stable dimer
We found that due to the formation of different size exciplexes, these nano systems show interesting photophysical and photochemical behaviors, such as emission tunability, thermochromism, and optical memory
All the results indicate the bonding between Au-Au is stronger in the excited state and this confirms the existence of [Au(CN)2−]n excimers and exciplexes

Summary

Introduction

The term “excimer” was first introduced in 1960 by Stevens and Hutton when studying pyrene luminescence [1]. The ab initio calculation results for all [Ag(CN)2−]n nanoclusters indicate a antibonding HOMO to bonding LUMO transition, which is favorable for the formation of excimers and exciplexes. This further confirms the existence of different size nanoclusters in the doped system and the time-resolved luminescence spectra suggest energy transfer processes from dimers to trimers.

Results

Conclusion