Cationic Iridium Dendrimers: Synthesis and Photophysical Properties

2011 ◽  
Vol 64 (9) ◽  
pp. 1211 ◽  
Author(s):  
Bin Du ◽  
Si-Chun Yuan ◽  
Jian Pei
Keyword(s):  
Solid State ◽  
Photophysical Properties ◽  
Dendritic Structure ◽  
Benzimidazole Derivatives ◽  
Iridium Complex ◽  
Iridium Complexes ◽  
Efficient Energy Transfer ◽  
Ancillary Ligands ◽  
Synthetic Strategy ◽  
Yellow Orange

Two dendrimers, D1 and D2, containing the cationic iridium complexes (C1 and C2) as cores and truxene-functionalized chromophores as the branches, have been developed by a convergent synthetic strategy. The cationic complexes employ 3-(pyridin-2-yl)-1H-1,2,4-triazole and 2-(pyridin-2-yl)-benzimidazole derivatives as the ancillary ligands. To avoid the change in emission colour arising from the iridium complex, the conjugation between the dendron and the ligand is decoupled by separating them using the alkyl chain. An investigation of their photoluminescent features reveals that efficient energy transfer happens from the dendrons to the core in the solid state. Likewise, the charged dendritic structure is demonstrated to be an efficient method to improve the compatibility between the polar charged iridium complexes and typical hydrophobic hosts with the additional benefit of excellent solution processability. Both dendrimers exhibit strong solvatochromic behaviours in solvents and exclusive green and yellow-orange light in the solid state.

scholarly journals Synthesis and phosphorescent properties of the copolymers of N-vinylcarbazole, methyl methacrylate and iridium complex

2014 ◽  
Vol 32 (2) ◽  
pp. 206-213
Author(s):  
Wen Wang ◽  
Minglu Zhou ◽  
Luying Liang ◽  
Meijuan Lin ◽  
Qidan Ling
Keyword(s):  
Energy Transfer ◽  
Solid State ◽  
Visible Light ◽  
Methyl Methacrylate ◽  
Radical Copolymerization ◽  
Emission Peak ◽  
Iridium Complex ◽  
Iridium Complexes ◽  
Ft Ir ◽  
Uv Visible

AbstractThe copolymers containing carbazole unit and iridium complexes, such as (Ir(bpy)2Cl, Ir(mbpy)2Cl and Ir(Brbpy)2Cl, were synthesized via radical copolymerization of N-vinylcarbazole, methyl methacrylate and iridium complex. The synthesized copolymers were characterized by FT-IR, UV-Vis absorption spectroscopy and photoluminescence (PL) spectroscopy, respectively. According to the results, the copolymers (Ir(Brbpy)2Cl/PVK and Ir(mbpy)2Cl/PVK) exhibit yellow phosphorescence with an emission peak at around 553 nm under UV-visible light in the solid state. The results also reveal almost complete energy transfer from the host carbazole segments to the guest Ir complex in the copolymer film when the Ir content reaches 1.0 wt.%. The synthesized copolymers are good candidates as blue or yellow phosphorescent materials for PLED applications.

Bis-cyclometalated iridium complexes with electronically modified aryl isocyanide ancillary ligands

2017 ◽  
Vol 46 (15) ◽  
pp. 5008-5016 ◽  
Author(s):  
Hanah Na ◽  
Ayan Maity ◽  
Thomas S. Teets
Keyword(s):  
Photophysical Properties ◽  
Iridium Complexes ◽  
Ancillary Ligands ◽  
Isocyanide Ligands

Bis-cyclometalated iridium complexes with electronically modified aryl isocyanide ligands are described, and the effects on the photophysical properties are noted.

scholarly journals Fluorinated azobenzenes as supramolecular halogen-bonding building blocks

2019 ◽  
Vol 15 ◽  
pp. 2013-2019 ◽  
Author(s):  
Esther Nieland ◽  
Oliver Weingart ◽  
Bernd M Schmidt
Keyword(s):  
Solid State ◽  
Dft Calculations ◽  
Visible Light ◽  
Half Life ◽  
Photophysical Properties ◽  
Bathochromic Shift ◽  
Halogen Bonding ◽  
Building Blocks ◽  
Partial Overlap

ortho-Fluoroazobenzenes are a remarkable example of bistable photoswitches, addressable by visible light. Symmetrical, highly fluorinated azobenzenes bearing an iodine substituent in para-position were shown to be suitable supramolecular building blocks both in solution and in the solid state in combination with neutral halogen bonding acceptors, such as lutidines. Therefore, we investigate the photochemistry of a series of azobenzene photoswitches. Upon introduction of iodoethynyl groups, the halogen bonding donor properties are significantly strengthened in solution. However, the bathochromic shift of the π→π* band leads to a partial overlap with the n→π* band, making it slightly more difficult to address. The introduction of iodine substituents is furthermore accompanied with a diminishing thermal half-life. A series of three azobenzenes with different halogen bonding donor properties are discussed in relation to their changing photophysical properties, rationalized by DFT calculations.

Synthesis and Photophysical Properties of a Conformationally Flexible Mixed Porphyrin Star-Pentamer

2009 ◽  
Vol 62 (7) ◽  
pp. 692 ◽  
Author(s):  
Toby D. M. Bell ◽  
Sheshanath V. Bhosale ◽  
Kenneth P. Ghiggino ◽  
Steven J. Langford ◽  
Clint P. Woodward
Keyword(s):  
Energy Transfer ◽  
Photophysical Properties ◽  
Fluorescence Decay ◽  
High Yield ◽  
Free Base ◽  
Time Resolved ◽  
Zinc Porphyrin ◽  
Relative Contribution ◽  
Synthetic Strategy ◽  
Decay Times

The synthesis of a porphyrin star-pentamer bearing a free-base porphyrin core and four zinc(ii) metalloporphyrins, which are tethered by a conformationally flexible linker about the central porphyrin’s antipody, is described. The synthetic strategy is highlighted by the use of olefin cross metathesis to link the five chromophores together in a directed fashion in high yield. Photoexcitation into the Soret absorption band of the zinc porphyrin chromophores at 425 nm leads to a substantial enhancement of central free-base porphyrin fluorescence, indicating energy transfer from the photoexcited zinc porphyrin (outer periphery) to central free-base porphyrin. Time-resolved fluorescence decay profiles required three exponential decay components for satisfactory fitting. These are attributed to emission from the central free-base porphyrin and to two different rates of energy transfer from the zinc porphyrins to the free-base porphyrin. The faster of these decay components equates to an energy-transfer rate constant of 3.7 × 109 s–1 and an efficiency of 83%, whereas the other is essentially unquenched with respect to reported values for zinc porphyrin fluorescence decay times. The relative contribution of these two components to the initial fluorescence decay is ~3:2, similar to the 5:4 ratio of cis and trans geometric isomers present in the pentamer.

scholarly journals Indenopyrans – synthesis and photoluminescence properties

2016 ◽  
Vol 12 ◽  
pp. 825-834 ◽  
Author(s):  
Andreea Petronela Diac ◽  
Ana-Maria Ţepeş ◽  
Albert Soran ◽  
Ion Grosu ◽  
Anamaria Terec ◽  
...  
Keyword(s):  
Solid State ◽  
Emission Band ◽  
Fluorescence Spectra ◽  
Photophysical Properties ◽  
Quantum Yields ◽  
Band Broadening ◽  
Photoluminescence Properties ◽  
Fluorescence Quantum Yields ◽  
Blue Emitters ◽  
Solid State Fluorescence

New indeno[1,2-c]pyran-3-ones bearing different substituents at the pyran moiety were synthesized and their photophysical properties were investigated. In solution all compounds were found to be blue emitters and the trans isomers exhibited significantly higher fluorescence quantum yields (relative to 9,10-diphenylanthracene) as compared to the corresponding cis isomers. The solid-state fluorescence spectra revealed an important red shift of λmax due to intermolecular interactions in the lattice, along with an emission-band broadening, as compared to the solution fluorescence spectra.

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