# Tuning the Coordination Environment of Ru(II) Complexes with a Tailored Acridine Ligand

## TL;DR

This paper explores how a custom-designed ligand affects the properties of ruthenium complexes, revealing unexpected coordination behaviors and lack of luminescence.

## Contribution

The study introduces a new ligand that leads to different coordination modes in ruthenium complexes, impacting their electronic and luminescent properties.

## Key findings

- The ligand showed facial coordination in the homoleptic complex and meridional in the heteroleptic complex.
- Despite favorable electronic properties, neither complex exhibited luminescence at room temperature or 77 K.
- The research emphasizes the complex relationship between ligand design, coordination mode, and luminescence.

## Abstract

A novel tridentate ligand featuring an acridine core and pyrazole rings, namely 2,7- di-tert-butyl-4,5-di(pyrazol-1-yl)acridine, L, was designed and used to create two ruthenium(II) complexes: [RuL2](PF6)2 and [Ru(tpy)L](PF6)2. Surprisingly, the ligand adopted different coordination modes in the complexes: facial coordination for the homoleptic complex and meridional coordination for the heteroleptic complex. The electronic absorption and electrochemical properties were evaluated. Although both complexes exhibited favorable electronic properties for luminescence, neither emitted light at room temperature nor at 77 K. This study highlights the complex interplay between ligand design, coordination mode, and luminescence in ruthenium(II) complexes.