Photoswitchable Macroscopic Solid Surfaces Based On Azobenzene‐Functionalized Polydopamine/Gold Nanoparticle Composite Materials: Formation, Isomerization and Ligand Exchange

Abstract

The facile preparation of dynamic interfaces is presented based on the combination of photoisomerizable azobenzenes and polydopamine (PDA)/Au nanoparticle composite materials. Azobenzenes with different spacer lengths (C3, C6) and surface‐binding groups (SH, NH2) were synthesized. The polymer layer on macroscopic quartz surface was prepared by the facile aerobic autopolymerisation of dopamine hydrochloride under basic conditions. The presence of redox‐active catechol moieties meant that gold nanoparticles were formed on the polymer surface. The obtained UV‐Vis spectroscopic results confirmed that following their successful assembly, the switching of azobenzenes on PDA/Au was not affected by the surface binding group and the spacer length of the azobenzene molecules under the measurement conditions. Furthermore, facilitated by the curved nature of the Au particles, the surface‐bound azobenzene layer could be reconstructed by ligand‐exchange processes, and the photochemical characterization of the mixed layer was performed.

Construction and Properties of Donor–Acceptor Stenhouse Adducts on Gold Surfaces

“…Furthermore, a previously reported azobenzenemodified Q-PDA-Au surface did not show any dynamic effect upon interaction with water either. 41 These findings ultimately suggest that the observed water droplet spreading on Q-PDA-Au-DASA is not due to the underlying PDA-Au composite. We also studied the reversibility of the process (Figure 7a).…”

“…Furthermore, the presence of the indoline derivative on the surface was also studied by XPS (Figure ). Although the complexity of the PDA polymer on the surface that contains the same elements (C, O, N) as the attached molecules makes the complete resolution of the states somewhat difficult, the formation of the indoline layer is strongly supported by the XPS results. Importantly, the binding of the thiol, which is present exclusively in the indoline derivative, clearly occurred to the gold particles.…”

“…We have successfully exploited this system recently in the construction of azobenzene-based dynamic interfaces. 41 Poly-(dopamine) (Scheme 2) is a mussel-inspired polymer able to adhere to virtually any surface. 42 We used its monomer, dopamine hydrochloride, to cover quartz slides with the polymer under basic aqueous aerobic conditions.…”

“…To avoid these difficulties associated with flat surfaces, we applied quartz slides covered with poly­(dopamine) (PDA)/gold particle composite materials. We have successfully exploited this system recently in the construction of azobenzene-based dynamic interfaces . Poly­(dopamine) (Scheme ) is a mussel-inspired polymer able to adhere to virtually any surface …”

Photo-assembly of plasmonic nanoparticles: methods and applications

“…1e and f ). Recently, photoswitchable systems using azobenzene-functionalized polydopamine/gold nanoparticle composite materials, and based on large change in molecular size and dipole moment due to trans -to- cis azobenzene isomerization has been constructed by Kunfi et al 33 …”