- Pt(II) diimine complexes bearing varied alkyl chains: Synthesis, tunable photophysical properties and aggregation-induced optical power limiting enhancement
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A series of Pt(II) diimine complexes with varied alkyl chains on 2,2′- dipyridyl ligands (Pt-C1–Pt-C3) have been synthesized and characterized. The photophysical properties and nonlinear absorption properties were elucidated using UV–vis absorption, emission and transient absorption spectroscopy, density functional theory (DFT) calculations and electrochemical experiments. It was found that increasing the alkyl chain led to regular changes in the photophysical properties of Pt-C1–Pt-C3. The original conjugated skeleton of the Pt(II) complexes were affected when the alkyl chain was introduced and extended. All complexes exhibited an obvious aggregation-induced phosphorescence emission (AIPE) in a mixed solution comprised of tetrahydrofuran/water. The formation of nanoparticles in the aggregated state induced these complexes to exhibit different excited state properties. When the water content increased, the emission intensity increases 3 ~ 13-flod and the excited state lifetime increased 98-flod due to the formation of Pt(II) complex nanoparticles. As a result, the optical power limiting (OPL) performance of these complexes was greatly improved. Based on the systematical investigation of nonlinear optical complexes in aggregated state, this work provided a theoretical basis for the development of new OPL materials. Furthermore, the Pt(II) complex nanoparticles will be more conducive to the potential application of OPL devices.
- Chen, Zhiyuan,Hu, Lai,Liu, Rui,Wang, Hongzhi,Zhu, Hongjun,Zhu, Senqiang
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- Evaluation of bis-cyclometalated alkynylgold(III) sensitizers for water photoreduction to hydrogen
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Well-defined gold sensitizers for hydrogen production from water remain extremely rare despite decades of interest, and are currently limited to systems based on ruthenium, iridium or platinum complexes. This report details the synthesis and characterization of a series of neutral cyclometalated gold(iii) complexes of the type [(RC^N^CR)Au(CC-R′)] (R = H or tert-butyl group; R′ = aryl groups) that have been found to be good candidates to function as harvesting materials in light-induced electron transfer reactions. We established the efficacy of systems with these gold(iii) complexes as photosensitizers (PSs) in the production of renewable hydrogen in the presence of [Co(2,2′-bipyridine)3]Cl2 or [Rh(4,4′-di-tert-butyl-2,2′-bipyridine)3](PF6)3 as a H2-evolved catalyst and triethanolamine (TEOA) as a sacrificial electron donor in acetone-water solution. All complexes are active, and there is a more than threefold increase over other candidates in photocatalytic H2 generation activity. Under the optimal reaction conditions, hydrogen evolution took place through a photochemical route with the highest efficiency and with a turnover number (TON) of up to 1441.5 relative to the sensitizer over 24 hours. In the initial photochemical path, the reductive quenching of the excited gold(iii) complex by TEOA due to the latter's greater concentration in the system followed by electron transfer to the catalyst species is proposed to be the dominant mechanism. A photo-to-H2 quantum yield of approximately 13.7% was attained when illuminated with monochromatic light of 400 nm. Such gold(iii) complexes have demonstrated significant utility in solar-to-hydrogen reactions and thus represent a new effective class of light-harvesting materials. These results open possibilities for pursuing more efficient photosensitizers featuring gold(iii) complexes in photocatalytic solar energy conversion.
- Yu, Zhen-Tao,Liu, Xiao-Le,Yuan, Yong-Jun,Li, Yong-Hui,Chen, Guang-Hui,Zou, Zhi-Gang
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p. 17223 - 17232
(2016/11/13)
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- Easily oxidizable triarylamine materials with naphthalene and binaphthalene core: structure–properties relationship
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We devised and synthesized a series of electron-rich compounds featuring diphenylamine, carbazole or dibenzo[c,g]carbazole connected via phenylacetylene linkers to an aromatic central unit. The key synthetic step was a high yielding cross coupling reaction between halogenated (bi)naphthalene and organometallic reagents prepared in situ from terminal alkynes (side-arms). By masking one of the iodo functions with a diethyltriazenyl group in the side-arm precursors, we efficiently circumvented the formation of doubly aminated by-products. Although one step longer, this approach led to higher yields of terminal alkynes than the direct coupling route. Spectroscopic and electrochemical measurements supported by computational evidence revealed that conjugation in the 1,4-disubstituted naphthalene backbone is superior to the 1,5 or 2,6 substituted cores. The diphenylamine derivative gets oxidized more readily when compared to its carbazole analogs. Expanding the core to binaphthalene did not alter electronic properties, but influenced the physical characteristics significantly.
- Kerner, Luká?,Gmucová, Katarína,Ko?í?ek, Jozef,Pet?í?ek, Václav,Putala, Martin
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p. 7081 - 7092
(2016/10/14)
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- Highly-efficient hybrid white organic light-emitting diodes based on a high radiative exciton ratio deep-blue emitter with improved concentration of phosphorescent dopant
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An improved concentration of phosphorescent dopant for highly-efficient hybrid white organic light-emitting diodes based on a high radiative exciton ratio (80%) deep-blue emitter has been developed. The high radiative exciton ratio for the deep-blue emitter was found to be the transfer from the higher triplet (T5) to the lowest singlet state (S1) by a "hot-exciton" process. Notably, when the concentration of Ir(2-phq)3 is up to 0.9 wt%, the OLED still exhibited white emission with a maximum total EQE, CE and PE of 22.3%, 53.7 cd A-1 and 60.2 lm W-1, respectively. The exciton transfer mechanism in a high concentration of phosphorescent dopant was also discussed. The studies provide a way to obtain high performance F/P hybrid WOLEDs with a simple architecture and improved doping concentration. This journal is
- Ouyang, Xinhua,Li, Xiang-Long,Bai, Yongqi,Mi, Dongbo,Ge, Ziyi,Su, Shi-Jian
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p. 32298 - 32306
(2015/04/27)
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- Synthesis and photochemical properties of 3,6-di-tert-butyl-9H-carbazole derivatives
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Method of synthesis has been developed for a series of 3,6-di-tert-butyl-9H-carbazole derivatives and their photochemical properties have been investigated. The dependence of the Steglich esterification reaction on the nature of the catalyst was studied. The synthesized compounds show fluorescent emission in the range 400-600 nm with a high quantum yield.
- Gruzdev,Chervonova,Venediktov,Rozhkova,Kolker,Mazaev,Dudina,Domracheva
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p. 1431 - 1439
(2015/08/03)
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- Synthesis and photoinduced electron transfer in platinum(ii) bis(N-(4-ethynylphenyl)carbazole)bipyridine fullerene complexes
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Platinum(ii) bis(N-(4-ethynylphenyl)carbazole)bipyridine fullerene complexes, (Cbz)2-Pt(bpy)-C60 and (tBuCbz)2-Pt(bpy)-C60, were synthesized. Their photophysical properties were studied by electronic absorption and emission spectroscopy and the origin of the transitions was supported by computational studies. The electrochemical properties were also studied and the free energies for charge-separation and charge-recombination processes were evaluated. The photoinduced electron transfer reactions in the triads were investigated by femtosecond and nanosecond transient absorption spectroscopy. In dichloromethane, both triads undergo ultrafast charge separation from the 3MLCT/LLCT excited state within 300 fs to yield their respective triplet charge-separated (CS) states, namely (Cbz)2+-Pt(bpy)-C60- and (tBuCbz)2+-Pt(bpy)-C60-, and the CS states would undergo charge recombination to give the 3C60 state, which subsequently decays to the ground state in 22-28 μs. This journal is
- Lee, Sai-Ho,Chan, Chris Tsz-Leung,Wong, Keith Man-Chung,Lam, Wai Han,Kwok, Wai-Ming,Yam, Vivian Wing-Wah
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p. 17624 - 17634
(2015/02/02)
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- Synthesis and Characterization of Monodendrons Based on 9-Phenylcarbazole
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A series of 9-phenylcarbazole ethynylene monodenrons have been prepared by palladium-catalyzed coupling reactions creating well-organized arrays of redox centers. The tert-butyl groups attached to the 3,6-positions of peripheral 9-phenylcarbazole monomers provide adequate solubility to a limited degree. Trimer and 7-mer monodendrons were prepared using a monomer with 3,3-diethyltriazene at its focal point. To facilitate purification, the synthesis of 15-mer monodendron, however, required a monomer bearing a 3-hydroxy-3-methyl-but-1-ynyl group at its focal point as a masking group for the terminal acetylene functionality. Although the solubility was limited, high generation monodendrons were found to be readily soluble in carbon disulfide, a solvent of high polarizability. Spectroscopic studies showed that there is limited through-bond conjugation over the monodendrons, but fluorescence studies suggested the presence of long-range through-space interactions in the higher members of the series.
- Zhu, Zhengguo,Moore, Jeffrey S.
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p. 116 - 123
(2007/10/03)
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