Indexed by:期刊论文

Date of Publication:2013-12-01

Journal:DYES AND PIGMENTS

Included Journals:SCIE、EI、Scopus

Volume:99

Issue:3

Page Number:908-915

ISSN No.:0143-7208

Key Words:Photochemistry; Platinum; Coumarin; Phosphorescence; Triplet-triplet annihilation; Upconversion

Abstract:We addressed the impact of coumarin ligands linkage on the photophysics of a series of diimine Pt(II) bisacetylide complexes. The long-lived room temperature phosphorescence of the coumarin unit was observed (lambda(em) = 636 nm, Phi(p) = 0.2%, tau(T) = 20.15 mu s) within the complex Pt(dbbpy)(C  C-phenylene-coumarin)(2), where dbbpy stands for 4,4'-di(tert-butyl)-2,2'-bipyridine and C  C-phenylene-coumarin is 6-(4'-ethynylphenyl)-coumarin. Comparison with the alternative complex Pt(dbbpy)( C-coumarin)(2) which has epsilon = 32,300 M-1 cm(-1) at 404 nm, where C  C-coumarin stands for 6-ethynylcoumarin, revealed that Pt(dbbpy)(C  C-phenylene-coumarin)(2) also showed strong absorption in the visible range (epsilon = 71,900 M-1 cm(-1) at 407 nm). The emissive triplet excited state of Pt(dbbpy)(C  C-phenylene-coumarin)(2) was characterized as (IL)-I-3 and the extension of the pi-conjugation system inside the coumarin ligand was found account for elongation of the lifetime of triplet excited states. Inspired by its unusual phosphorescence behavior, Pt(dbbpy)(C  C-phenylene-coumarin)(2) was used as the sensitizer for the triplet-triplet annihilation based upconversion and the observed upconversion quantum yield was up to 19.7%. (C) 2013 Elsevier Ltd. All rights reserved.