Metalloporphyrins into Mesoporous Photonic Crystals: Towards Nanostructured Sensing Devices

24 September 2019, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


Metalloporphyrins are molecules capable of optically sensing targets due to their specific reactivity. Shifts in metalloporphyrins spectra are usually in the order of 30 nm, requiring a spectrophotometer for transducing the analyte concentration. Mesoporous oxide thin films photonic crystals (PC) act as optical filters, while their pores can host molecular moieties. In this work used a metalloporphyrin, MnIII meso-tetra(N-methyl-4-pyridyl) porphyrin (MP), to add a recognition functionality to a PC and, at the same time, retain their pore network, in order to develop a versatile and portable sensing device for volatile amines. The hybrid material MP@PC was prepared by immersion of the PC, synthesized from two mesoporous oxides with different refractive index, in an MP solution. The system was characterized by UV-Vis absorption and FTIR spectroscopies, and SEM microscopy. Sensing of small molecules was tested using ethylenediamine (EDA) as a volatile amine model, showing an absorbance increase in the PC spectral window with promising analytical parameters. The hybrid material presents enhanced sensing capabilities compared to MP or PC alone. A prototype device was built, aiming for a future design of simple, low-cost equipment, with a light emitting diode and a light-dependent resistor, including the MP@PC sensor. The device is capable of sensing with only 1.52 μg of MP on a 1 cm2 glass slide and it is easily prepared and showed a very small detection limit.


photonic crystal
hybrid material
optical sensor

Supplementary materials



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