DFT/TD-DFT Framework of Mixed-Metal Complexes with Symmetrical and Unsymmetrical Bridging Ligands-Step-By-Step Investigations: Mononuclear, Dinuclear Homometallic, and Heterometallic for Optoelectronic Applications.

Dawid Zych

doi:10.3390/ma14247783

Abstract

Recently, mono- and dinuclear complexes have been in the interest of scientists due to their potential application in optoelectronics. Herein, progressive theoretical investigations starting from mononuclear followed by homo- and heterometallic dinuclear osmium and/or ruthenium complexes with NCN-cyclometalating bridging ligands substituted by one or two kinds of heteroaryl groups (pyrazol-1-yl and 4-(2,2-dimethylpropyloxy)pyrid-2-yl) providing the short/long axial symmetry or asymmetry are presented. Step-by-step information about the particular part that built the mixed-metal complexes is crucial to understanding their behavior and checking the necessity of their eventual studies. Evaluation by using density functional theory (DFT) calculations allowed gaining information about the frontier orbitals, energy gaps, and physical parameters of complexes and their oxidized forms. Through time-dependent density functional theory (TD-DFT), calculations showed the optical properties, with a particular emphasis on the nature of low-energy bands. The presented results are a clear indication for other scientists in the field of chemistry and materials science.

Highlights

Step-by-step investigations starting from mononuclear followed by homo- and heterometallic dinuclear osmium and/or ruthenium complexes with NCN-cyclometalating bridging ligands substituted by one or two kinds of heteroaryl groups
The thorough knowledge of mononuclear and homometallic dinuclear osmium and/or ruthenium complexes was crucial to understanding the properties of heterometallic dinuclear Os/Ru coordination compounds
In the case of mononuclear complexes, when two kinds of heteroaryl groups participate in the coordination of metal, the contribution of pyrazolyl groups is around two times higher than pyridyl substituents

Summary

Introduction

Mono- and dinuclear complexes containing bridging ligands have been in scientists’ interest [1,2,3,4,5]. The reason for such a comprehensive investigation is the wide possibility of applying those kinds of molecules; they can be used in the area of energy-conversion materials and molecular electronics, but the area of application strongly depends on the applied metal centers [6,7,8,9]. In the reported examples of dinuclear heterometallic complexes, such as the bridging ligands, 2,3,5,6-tetrakis(2-pyridyl)pyrazine (tpp) was used most often. Brewer et al initiated investigations in this area by reporting the Ir(III)/Ru(II)

Methods

Results

Conclusion