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

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 thefilm crystallinity. Finally, we demonstrate the growth of MOF-on-MOF type Ca-ADA@Ca-TPA thin films also showing the efficient photoisomerization reaction.

Description

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

DOI

10.1039/d0dt02062a

Citation

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

Permanent link to this item

https://urn.fi/URN:NBN:fi:aalto-202009045306

Collections

[article-cris] Kemian tekniikan korkeakoulu / CHEM

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