title: Photophysics and nonlinear absorption of cyclometalated 4,6-diphenyl-2,2'-bipyridyl platinum(II) complexes with different acetylide ligands.
abstract: The photophysical properties of a series of 4,6-diphenyl-2,2'-bipyridyl platinum(II) complexes bearing different σ-alkynyl ancillary ligands (1a-1k) were systematically investigated. All complexes exhibit strong (1)π,π* absorption bands in the UV region; and broad, structureless charge-transfer band(s) in the visible region, which systematically red-shift(s) when the electron-donating ability of the para substituent on the phenylacetylide ligand increases. All complexes are emissive in solution at room temperature. When excited at the charge-transfer absorption band, the complexes exhibit long-lived orange emission (λ(max): 555-601 nm), which is attributed to a triplet metal-to-ligand charge transfer/intraligand charge transfer emission ((3)MLCT/(3)ILCT). Most of these complexes exhibit broad triplet transient difference absorption in the visible to the near-IR region, with a lifetime comparable to those measured from the decay of the (3)MLCT/(3)ILCT emission. The reverse saturable absorption (RSA) of these complexes were demonstrated at 532 nm using nanosecond laser pulses. The degree of RSA follows this trend: 1k ≈ 1a > 1c > 1f ≈ 1i > 1h ≈ 1b > 1e > 1d > 1g, which is mainly determined by the ratio of the triplet excited-state absorption cross section to that of the ground-state and the triplet excited-state quantum yield.
authors.affiliation: Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58108-6050, United States.
authors.forename: Rui
authors.initials: R
authors.lastname: Liu
authors.forename: Yunjing
authors.initials: Y
authors.lastname: Li
authors.forename: Yuhao
authors.initials: Y
authors.lastname: Li
authors.forename: Hongjun
authors.initials: H
authors.lastname: Zhu
authors.forename: Wenfang
authors.initials: W
authors.lastname: Sun
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D008024:Ligands; D015394:Molecular Structure; D009944:Organoplatinum Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010777:Photochemistry; D013056:Spectrophotometry, Ultraviolet; D013237:Stereoisomerism
chemical_list: C556628:4,6-diphenyl-2,2'-bipyridyl platinum(II); D000480:Alkynes; D008024:Ligands; D009944:Organoplatinum Compounds