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- Lyu, Yuanhao, et al.
(författare)
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Unraveling Enyne Bonding via Dehydrogenation-Hydrogenation Processes in On-Surface Synthesis with Terminal Alkynes
- 2024
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Ingår i: Advanced Materials Interfaces. - : WILEY. - 2196-7350.
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Tidskriftsartikel (refereegranskat)abstract
- On-surface reactions of terminal alkynes in ultrahigh vacuum have attracted widespread attention due to their high technological promise. However, employing different precursors and substrate materials often intricate reaction schemes appear far from being well-understood. Thus, recent investigations of alkyne coupling on noble metal surfaces suggest non-dehydrogenative scenarios, contradicting earlier reports. Herein, the study employs noncontact atomic force microscopy (nc-AFM) with high spatial resolution to conclusively characterize exemplary alkyne coupling products. Contrary to initial interpretations proposing dehydrogenative homocoupling on Ag(111), bond-resolved AFM imaging reveals the expression of enyne motifs. Based on complementary, extensive density functional theory calculations, the pertaining reaction mechanisms are explored. It is proposed that enyne formation initiates with a direct carbon-carbon coupling between two alkyne groups, followed by surface-assisted dehydrogenation-hydrogenation processes. Thereby consecutive steps of atomic hydrogen cleavage, surface migration and recombination to a different carbon atom enable bridging via carbon-carbon double bonding. The new results shed light on subtle, but crucial surface-mediated hydrogen transfer processes involved in the chemical bond formation, which are suggested to be of general relevance in on-surface synthesis. Terminal alkyne coupling on Ag(111) in ultrahigh vacuum is conclusively examined by bond-resolved atomic force microscopy and density functional theory modeling. The prevailing bonding motif is the enyne moiety, originating from a distinct surface-mediated dehydrogenation-hydrogenation reaction pathway. The findings highlight the important role of hydrogen transfer in the course of on-surface synthesis procedures. image
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| 3. |
- Zhao, Ningjiu, et al.
(författare)
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Photoinduced Polaron Formation in a Polymerized Electron-Acceptor Semiconductor
- 2022
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Ingår i: The Journal of Physical Chemistry Letters. - : AMER CHEMICAL SOC. - 1948-7185. ; 13:23, s. 5143-5150
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Tidskriftsartikel (refereegranskat)abstract
- Polymerized small molecular acceptor (PSMA) based all-polymer solar cells (all-PSC) have achieved power conversion efficiencies (PCE) over 16%, and the PSMA is considered to hold great promise for further improving the performance of all-PSC. Yet, in comparison with that of the polymer donor, the photophysics of a polymerized acceptor remains poorly understood. Herein, the excited state dynamics in a polymerized acceptor PZT810 was comprehensively investigated under various pump intensities and photon energies. The excess excitation energy was found to play a key role in excitons dissociation into free polarons for neat PSMA films, while free polarons cannot be generated from the polaron pairs in neat acceptor films. This work reveals an in-depth understanding of relaxation dynamics for PSMAs and that the underlying photophysical origin of PSMA can be mediated by excitation energies and intensities. These results would benefit the realization of the working mechanism for all-PSC and the designing of new PSMAs.
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