Composition-tuned metal-organic thin-film structures based on photoswitchable azobenzene by ALD/MLD

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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

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en

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7

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Dalton Transactions, Volume 49, issue 32, pp. 11310–11316

Abstract

We demonstrate the fabrication of in-situ crystalline thin films of various azobenzene (AZO) based metal-organic structures using the atomic/molecular layer deposition (ALD/MLD) technique; these are highly intriguing materials as azobenzene is one of the prototype organic molecules experiencing photoisomerization. Our Li-, Ca and Fe-AZO thin films deposited from Li(thd) (thd = 2,2,6,6-tetramethyl-3,5-heptanedione), Ca(thd)2, FeCl3 and azobenzene-4,4'-dicarboxylic acid precursors in the temperature range of 250-360 °C exhibit metal-AZO structures not known from bulk samples. In all these structures, the AZO linker molecules are free to undergo the characteristic trans-cis photoisomerization reaction upon UV (360 nm) irradiation. However, this lowers the degree of crystallinity. To address the issue, we investigate hetero-organic structures where TPA (terephthalic acid) is used as another linker component together with AZO. This allows the trans-cis reaction of the AZO moieties to occur without compromising the film crystallinity. Finally, we demonstrate the growth of MOF-on-MOF type Ca-ADA@Ca-TPA thin films also showing the efficient photoisomerization reaction.

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| openaire: EC/FP7/339478/EU//LAYERENG-HYBMAT

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Khayyami, A, Philip, A, Multia, J & Karppinen, M 2020, 'Composition-tuned metal-organic thin-film structures based on photoswitchable azobenzene by ALD/MLD', Dalton Transactions, vol. 49, no. 32, pp. 11310–11316. https://doi.org/10.1039/d0dt02062a