Resumen de Propiedades fotofísicas de redes metal-orgánicas luminiscentes para la detección de gases.
The present thesis was carried out in the framework of an M-era-Net project entitled “Synthesis of Metal-Organic Frameworks as Optical Gas Sensors” (MOFSENS, PCIN-2015-169-C02-01). The project was carried out by an international consortium involving IMDEA Nanoscience in Madrid, the University of Porto, and University Pablo de Olavide in Seville.
This thesis mainly concerns with the sensing properties of mixed matrix membranes (MMMs) based on MOFs to detect a range of analytes such as volatile organic compounds (VOCs) and different types of amines, including biogenic amines. In addition, the thesis contains a chapter on a slightly different project, concerning the exploitation of flexible polymeric distributed feedback lasers (DFBs) based on cellulose diacetate and conjugated polymers for efficient multi-wavelength lasing emission. The thesis is organized of six chapters: Chapter 1 provides the background of the thesis, starting with the recent environmental crisis taking place at planetary level and a description on materials that can help to minimize or solved these issues with a focus on materials for sensing applications. Luminescent metal-organic frameworks, porphyrins and metalloporphyrin derivatives, and MMMs are then introduced. Elsewhere, we introduce the concept of lasers, their principles of operation, optical gain medium, and optical gain cavity based on conjugated polymers. Chapter 2 describes the experimental methods followed for the preparation and characterization of the materials, the different materials and solvents used, the description of the main techniques, the MMMs preparation procedure, and protocols followed for sensing measurements.
Chapter 3 presents the synthesis and characterization of the luminescent MOFs investigated in this thesis with techniques such as FT-IR, PXRD, TGA, SEM, UV-Vis, and photoluminescence spectroscopy.
Chapters 4 and 5 show in turn the sensing properties of the MMMs based on Zn2(bpdc)2(bpee) LMOF and PCN224 for detecting explosive materials, VOCs, a different types of amines both in gas and aqueous mediums.
Finally, in chapter 6, the lasing properties of the DFBs based on cellulose diacetate and the conjugated polymers emitting in the blue, green, and red spectral ranges are studied.
In summary, we successfully develop freestanding, flexible, permeable, and hydrophobic MMMs based on Zn2(bpdc)2(bpee) and PCN224 MOFs. The Zn2(bpdc)2(bpee) based MMMs showed the capability of distinguishing selectively NH3 among the VOC saturated vapours and also a sub-ppm NH3 detection sensitivity in the aqueous phase. Moreover, the PCN224 based MMMs worked as robust and reversible colorimetric sensors for detecting the biogenic amines released from raw herring. Furthermore, we presented flexible all-polymer nanoimprinted distributed feedback lasers based on cellulose diacetate and conjugated polymers for efficient multi-wavelength lasing emission.
