Supramolecular Control of Photonic Response and Sensing of Nitricoxide using Iron(III) Corrole Monolayers and Their Stacks

• Published in: ChemPlusChem (Weinheim, Germany) Germany), 2023-03, Vol.88 (3), p.e202200260-n/a
• Main Authors: Graewe, Lennart, Hupfer, Maximilian L., Schulz, Martin, Mahammed, Atif, Gross, Zeev, Presselt, Martin
• Format: Article
• Language: English
• Subjects: corroles; Langmuir; Langmuir-Blodgett; nitric oxide; sensors
• ISSN: 2192-6506; 2192-6506
• DOI: 10.1002/cplu.202200260

In this work, we assemble amphiphilic iron(III) corroles at air‐water interfaces into well‐defined quasi‐two‐dimensional molecular monolayers and theirs stacks for sensing of nitric oxide (NO). For this purpose, we use the Langmuir‐Blodgett (LB) technique, which allows varying the packing density of iron(III) corroles anchored to the aqueous subphase via one molecular side. The stacks of ten down to three molecular monolayers on the front and back sides of the substrates are sufficiently optically dense to detect NO binding to the layers photometrically. This sensing with few layers demonstrates the potential for electronic detection, where very thin surface functionalizations enable efficient electronic communication between the layer and the (semi)conductor. Despite increasing optical densities, the spectral responses to NO exposure become smaller with increasing packing density until the collapse point of the monolayers is reached. This demonstrates that the highest molecular efficiency for binding and detection of NO is achieved at the smallest packing densities. This finding is relevant to all molecular sensor films with axial binding of analytes to the sensor molecules and demonstrates the advantage of sensor molecule assembly into monolayers on water‐air interfaces using the LB technique. The sensitivity of amphiphilic iron(III) corrole sensing layers for the detection of nitric oxide (NO) can be controlled by lateral compression during deposition of the monolayers at the air‐water interface. The spectral responses of the monolayer stacks to NO exposure increase with decreasing lateral compression during deposition and thus exhibit the highest molecular sensing efficiency when the layers are deposited at low surface pressure Π.