Smart Materials


Modern sensors are electronic devices consisting in two main components: the sensing material (or receptor), which create signals and the transducer, which carries information about the sensed analytes. The sensing materials are of different nature among them metal oxides, polymers and molecular materials. Nowadays, sensors are ubiquitous and found interest in the field of environmental monitoring, control of chemical processes, agricultural and medical applications, food security and many other applications.

Porphyrins, phthalocyanines and related compounds are a well-known family of optically active dyes. Furthermore, their large and flat p-conjugated system, unique electronic characteristics, high thermal and chemical stability make them a good molecular semiconductor materials. Through the axial ligation of small molecules, porphyrins and phthalocyanines can be used to signal interaction with host molecules. All these features have been exploited for the development of versatile porphyrinoid-based chemical sensors, devoted to detecting analytes both in the gaseous and liquid phases. Porphyrins and phthalocyanines are especially suitable to interact with gases and they were used to develop thin film gas sensors for the qualitative and quantitative analysis of various kinds of gases, such as O2, CO, CO2, NO2, volatile organic compounds (VOCs), Cl2 and many others.

L. Wu, L. Feng, J. Ren, and X. Qu, Electrochemical detection of dopamine using porphyrin-funtionalized graphene, Biosensors and Bioelectronics, 2012, 34, 57–62.
C. Peter, K. Schmitt, M. Apitz, and J. Woellenstein, Metallo–porphyrin zinc as gas sensitive material for colorimetric gas sensors on planar optical waveguides, Microsyst Technol, 2012, 18, 925–930.
Y. Sivalingam, E. Martinelli, A. Catini, G. Magna, G. Pomarico, F. Basoli, R. Paolesse, and C. Di Natale, Gas–Sensitive Photoconductivity of Porphyrin–Functionalized ZnO Nanorods, J. Phys. Chem. C, 2012, 116, 9151−9157.

Molecular electronics

The development of molecular electronics is closely associated with the need for miniaturization in microelectronics. Molecular electronics aims to overcome the physical and technical limits which currently prevent the miniaturization below about 10 nm. Functionalized porphyrins and phthalocyanines are well suitable redox-active molecules which can be grafted onto either organic or inorganic materials via strong covalent bonds. They act as switches, connections, and other logic or memory devices. Novel materials such as silicon and carbon nanotubes modified at the surface with porphyrinoids have been developed with the view of designing novel devices with improved performance such as OLEDs, transistors, and memories.

T. Tanaka and A. Osuka, Conjugated porphyrin arrays: synthesis, properties and applications for functional materials, Chem. Soc. Rev., 2015, 44, 943-969.
M. Jurow, A. E. Schuckman, J. D. Batteas, C. M. Drain, Porphyrins as molecular electronic components of functional devices, Coordination Chemistry Reviews, 2010, 254, 2297–2310.

Metal-organic frameworks

Metal-Organic Frameworks (MOFs) are crystalline porous materials with high porosity and large internal surface areas. They are made of metal-ions clusters bound by poly-topic organic linkers, connected by coordination bonds based on reticular chemistry. A large number of porous materials with different properties can be produced depending on the type of organic and inorganic components. The application of these porous materials are based on their specific and unique host-guest interactions between the framework and different guest small molecules. For this reason, they find various applications in gas storage, selective heterogeneous and catalysis, chemical sensing and many others.

Porphyrin based ligands are of particular interest due to their catalytic, absorption and sensing properties. In addition, porphyrins offer a rare example of a four-fold axis of symmetry in organic ligands which is highly desirable for designing new MOF structures. Porphyrins are versatile and robust ligands whose molecular structure can be easily tuned by changing the peripheral substituents and they offer an additional metallation site in their core. Tetraarylporphyrins, such as 5,10,15,20-tetra-(4-pyridyl)porphyrin and 5,10,15,20-tetra-(4-carboxyphenyl)porphyrin, have received much attention in the synthesis of porphyrinic MOFs over the last years.

M. Zhao, S. Ou and C.-D. Wu, Porous Metal-Organic Frameworks for Heterogeneous Biomimetic Catalysis, Acc. Chem. Res., 2014, 47, 1199-1207.
K. Lu, C. He and W. Lin, Nanoscale Metal-Organic Framework for Highly Effective Photodynamic Therapy of Resistant Head and Neck Cancer, J. Am. Chem. Soc., 2014, 136, 16712-16715.
C. Zou, Z. Zhang, X. Xu, Q. Gong, J. Li and C.-D. Wu, A Multifunctional Organic-Inorganic Hybrid Structure Based on MnII-Porphyrin and Polyoxometalate as Highly Effective Dye Scavenger and Heterogenous Catalyst, J. Am. Chem. Soc., 2012, 134, 87−90.