Photophysical Enhancement of Triplet Emitters by Coordination-Driven Self-Assembly

Yuzhen Zhang; Cressa Ria P Fulong; Cory E Hauke; Matthew R Crawley; Alan E Friedman; Timothy R Cook

doi:10.1002/chem.201700614

Photophysical Enhancement of Triplet Emitters by Coordination-Driven Self-Assembly

Chemistry. 2017 Apr 3;23(19):4532-4536. doi: 10.1002/chem.201700614. Epub 2017 Mar 15.

Authors

Yuzhen Zhang¹, Cressa Ria P Fulong¹, Cory E Hauke¹, Matthew R Crawley¹, Alan E Friedman¹, Timothy R Cook¹

Affiliation

¹ Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York, 14260, USA.

PMID: 28191708
DOI: 10.1002/chem.201700614

Abstract

The quantum yields of organic fluorophores used as donors in coordination-driven self-assembly often suffer from the heavy atom effect of nearby metal sites. Here, the role of intersystem crossing from a deactivating process to one that delivers emissive triplet states was reversed. A phosphorescent trans bis-N-heterocyclic carbene platinum(II) compound, Pt(dhim)₂ (C≡C-4-py)₂ (D1; dhim=1,3-dihexyl-2-H-imidazol-2-ylidene), was used along with other linear donors 4,4'-bipyridine (D2) and 1,4-bis(4-pyridyl ethynyl)benzene (D3) in self-assembly reactions with Pt(dtbpy)X₂ acceptors (dtbpy=4,4'-di-tert-butyl-2,2'-bipyridine) to afford three metallacycles. Photophysical investigations revealed that, although the building blocks used to construct M1 have relatively low quantum yields (Φ=1.2 and <1 % for D1 and 2, respectively), the metallacycle has a quantum yield of 14 %. This increase reflects a change in radiative rate constant from 3.6×10⁴ s^-1 for D1 to 2.1×10⁵ s^-1 for M1.

Keywords: coordination-driven self-assembly; metallacycle; phosphorescence; photophysics; platinum.