Gesellschaft Deutscher Chemiker
Keine Benachrichtigungen
Sie haben noch keine Lesezeichen
Abmelden

Artikel

Near‐Infrared Emissive Hypervalent Compounds with Germanium(IV)‐Fused Azobenzene π‐Conjugated Systems

Von Wiley-VCH zur Verfügung gestellt

Ge-fused azobenzene compounds: Hypervalent compounds with a germanium(Ge)-fused azobenzene (GAz) scaffold exhibiting NIR emission despite the compact π-conjugated systems. The synergistic effect between a hypervalent bond and the extension of π-conjugation is a novel and effective strategy for obtaining NIR emissive materials.


Abstract

A novel molecular design for showing near-infrared (NIR) emission is still required for satisfying growing demands for NIR-light technology. In this research, hypervalent compounds with germanium (Ge)-fused azobenzene (GAz) scaffolds were discovered that can exhibit NIR emission (λ PL=690∼721 nm, Φ PL=0.03∼0.04) despite compact π-conjugated systems. The unique optical properties are derived from the trigonal bipyramidal geometry of the hypervalent compounds constructed by combination of Ge and azobenzene-based tridentate ligands. Experimental and theoretical calculation results disclosed that the germanium-nitrogen (Ge−N) coordination at the equatorial position strongly reduces the energy level of the LUMO (lowest unoccupied molecular orbital), and the three-center four-electron (3 c4 e) bond in the apical position effectively rises the energy level of the HOMO (highest occupied molecular orbital). It is emphasized that large narrowing of the HOMO-LUMO energy gap is achieved just by forming the hypervalent bond. In addition, the narrow-energy-gap property can be enhanced by extension of π-conjugation. The obtained π-conjugated polymer shows efficient NIR emission both in solution (λ PL=770 nm and Φ PL=0.10) and film (λ PL=807 nm and Φ PL=0.04). These results suggest that collaboration of a hypervalent bond and a π-conjugated system is a novel and effective strategy for tuning electronic properties even in the NIR region.

Zum Volltext

Überprüfung Ihres Anmeldestatus ...

Wenn Sie ein registrierter Benutzer sind, zeigen wir in Kürze den vollständigen Artikel.