Porphyrin Optical Sensing: Three Applications

Porphyrin derivatives play an important role in various applications, including optical chemical sensors. The electronic structure of the inner 16-membered ring in porphyrins, which consists of 18 electrons, governs their key optical features. Different classes of porphyrin molecules provide a diverse range of ring structures and substitutions, which can be effectively utilized to tune or modify specific spectral properties. Additionally, these properties are influenced by chemical modifications or changes in the pyrrole rings. Porphyrin is a highly symmetrical molecule with two pairs of low-energy excited states: quasi-forbidden Q states in the visible region and strongly allowed B states in the near-UV region. Over the past 30 years, our research group, in collaboration with other organizations, has played a key role in developing a wide array of optical porphyrin-based sensors by exploring the complex spectral properties of porphyrin derivatives. Here, we present three applications of optical porphyrin-based sensors: continuous blood-oxygen measurements for intensive care unit (ICU) use, pressure-sensitive paint for aeronautic wind tunnel measurement, and pH imaging in cementitious materials.