Cooperative, Close and Remote Steric Effects on the Structural and Optical Properties of Copper(I) Bis‐Phenanthroline Complexes

• Published in: European journal of inorganic chemistry 2024-08, Vol.27 (25), p.n/a
• Main Authors: Appleton, Jordan L., Ballerini, Lavinia, Choua, Sylvie, Gourlaouen, Christophe, Ruppert, Romain, Mauro, Matteo
• Format: Article
• Language: English
• Subjects: Benchmarks; Coordination; Copper; Density functional theory; Homoleptic complexes; Optical properties; Phenanthroline; Photochemistry; Photoluminescence; Prolongation; Remote control; Steric effects; Steric hindrance; Structural analysis
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.202400278

The synthesis as well as the structural, optical and computational characterization of seven new highly hindered homoleptic copper(I) phenanthroline complexes (namely C1–C7) is reported along with the comparison with the benchmark derivatives. Despite limited steric hindrance in direct proximity of the copper(I) coordination site, X‐ray structures show that the higher hindered derivatives of the series display a more optimal tetrahedral geometry with minimal D2 symmetry distortion. A novel remote control of the geometry, with steric hindrance away from the coordination site, leads to a favorable arrangement as demonstrated by structural and computational data. In addition, electrochemical and steady‐state and time‐resolved photophysical studies are presented which further support the beneficial effects on the ground‐state redox and excited‐state properties when both remote and close steric effects are exploited. Indeed, both an increase of the photoluminescence quantum yield and a prolongation of the excited state lifetime is observed for the highly‐substituted derivative C6 compared to benchmark counterparts on account of the reduced excited‐state flattening distortions imparted by the additional steric constraints. Seven copper(I) phenanthroline complexes have been synthesized with steric hindrance present at and away from the coordination site, coined as remote control. This technique allowed for the synthesis of highly hindered stable homoleptic complexes which presented interesting ground and excited state properties that were corroborated by DFT calculations.