Design and synthesis of calixarene-based cryopolymers for air pollutant treatment and sensing

The release of polluting gases due to public transport, domestic heating and industries is a problem of growing importance for the entire terrestrial ecosystem. Gases such CO, SOx, NOx are responsible for widespread respiratory problems, while CO2 and CH4 are some of the main culprits of global warming [1]. In order to keep the problem of atmospheric pollution under control, it is essential to have techniques that allow the level of these pollutants to be quantified accurately, or to reduce the emission of these substances by capturing them before they are released into the atmosphere. In view of their molecular recognition and self-assembly properties, calixarenes are extensively applied in sensing and capturing of environmental pollutants [2]. In particular, calixarene derivatives with appropriate functionalization and shape of the cavity, interact with NOx gases causing the gas to disproportionate displaying the formation of colored calixarene/NO+ complexes [3]. The development of polymeric material based on calixarenes [4], in the form of cryogel [5], offers new opportunities to enable the detection, monitoring and quantification of hazardous gases and pollutant present in our environment [6]. In this work, the synthesis of new calixarene-based polymeric macroporous cryogels will be reported as well as their performances in sensing and capturing NOx from the atmosphere. 1.Ramanathan, V., Feng, Y.: Air pollution, greenhouse gases and climate change: global and regional perspectives. Atmos. Environ. 43(1), 37-50 (2009). 2.D. S. Kumar, P. R. Sahoo, V. R. Macwan, J. Kaur, Mukesh, R. Sahney : Macrocyclic Receptors for Environmental and Biosensing Applications. CRC Press, Taylor & Francis Group LLC (2022) 3.Rudkevich D.M. Sensing and fixation of NO2 by calixarenes. Kem Ind 54 (2) 57-63 (2005) 4.Zadman R., Hokmabadi F., Jalali M. R., Akbarzadeh A. Recent progress to construct calixarene-based polymers using covalent bonds: synthesis and application. RSC Adv. 10, 32690-32722 (2020). 5.Lozinsky I., Galaev I.Y., Plieva F.M., Savina I.N., Jungvid H., Mattiasson B. Polymeric cryogels as promising materials of biotechnological interest. Trends Biotechnol 21 445-451 (2003) 6.Kumar S., Chawla S., Zou M.C. Calixarene based materials for gas sensing applications: a review. J Incl. Phenom. Macrocycl. Chem. 88, 129-158 (2017).