Triplet states in a series of Pt-containing ethynylenes

Abstract

By use of optical steady state and time resolved spectroscopy, we studied the evolution of the triplet excited state in a series of six ethynylenic polymers of the structure ͓-Pt(PBu 3 n) 2-CwC-R-CwC-͔ n where the spacer unit R is systematically varied to give optical gaps from 1.7-3.0 eV. The inclusion of platinum in the polymer backbone induces a strong spin-orbit coupling such that triplet state emission ͑phosphorescence͒ associated with the conjugated system can be detected. Throughout the series we find the S 1-T 1 ͑singlet-triplet͒ energy splitting to be independent of the spacer R, such that the T 1 state is always 0.7Ϯ0.1 eV below the S 1 state. With decreasing optical gap, the intensity and lifetime of the triplet state emission were seen to reduce in accordance with the energy gap law.

Large magnetoresistance in nonmagneticπ-conjugated semiconductor thin film devices

“…The 5,8-diethynyl-2,3-diphenylquinoxaline unit and its Pt-containing polymer were prepared according to published procedures [15,16]. The organic polymer was synthesized by palladium-catalyzed polycondensation of 1,4-bis(n-octyloxy)-2,5-diiodobenzene and 5,8-diethynyl-2,3-diphenylquinoxaline in a 1:1 ratio.…”

Electronic structures and optical properties of neutral substituted fluorene-based cyclometalated platinum(II)–acetylide complexes: A DFT exploration

“…The linear geometry of the alkynyl unit and its p-unsaturated character led to metal alkynyls becoming attractive building blocks for molecular wires and polymeric organometallic materials, which can possess interesting properties, such as optical nonlinearity, luminescence, liquid crystallinity, and electrical conductivity [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. Since the applications of organic light-emitting diodes (OLEDs) were tremendously developed by Tang and Van Slyke using the metal-organic Alq 3 (q = hydroxyquinoline) as the fluorescent emitter, the design and synthesis of luminescent transition-metal r-alkynyl complexes have received much attention [27][28][29][30][31][32][33].…”

Evolution of Lowest Singlet and Triplet Excited States with Electronic Structure of Fluorene Group in Metal Polyyne Polymers

“…25 At 11 K, the intense feature at the low-energy regime of the emission spectrum of P2 with the maximum at around 554 nm is due to emission from the triplet excited state (phosphorescence Ti-»S 0 ) and such a triplet emission shows a vibronic structure at low temperature. 11 "" 14 The large energy shift observed between absorption and emission features (about 1.0 eV) ascertains this emitting state as the Ti excited state. This assignment can be further interpreted in terms of the observed temperature dependence of the emission data ( Figure 2).…”