Hybrid materials based on wide band gap semiconductors and dye molecules are intensively studied for photovoltaic applications. However, these materials also possess interesting gas sensitivities, besides these photonic effects. In this Article, we report the study, under visible light illumination, of the porphyrin-functionalized ZnO nanorod photoconductivity changes, modulated by exposure to two volatile organic compounds, ethanol and triethylamine, chosen as model analytes. The sensitivity to triethylamine exceeds that to ethanol by more than two orders of magnitude, showing a selectivity that is not found in other porphyrin-based gas sensors. This feature could open the way to a novel generation sensors, where photoactivation plays a role in determining both sensitivity and selectivity of the resulting device
The interest in assembling porphyrin derivatives is widespread and is accounted by the impressive impact of these suprastructures of controlled size and shapes in many applications from nanomedicine and sensors to photocatalysis and optoelectronics. The massive use of porphyrin dyes as molecular building blocks of functional materials at different length scales relies on the interdependent pair properties, consisting of their chemical stability/synthetic versatility and their quite unique physicochemical properties. Remarkably, the driven spatial arrangement of these platforms in well-defined suprastructures can synergically amplify the already excellent properties of the individual monomers, improving conjugation and enlarging the intensity of the absorption range of visible light, or forming an internal electric field exploitable in light-harvesting and charge-and energy-transport processes. The countless potentialities offered by these systems means that self-assembly concepts and tools are constantly explored, as confirmed by the significant number of published articles related to porphyrin assemblies in the 2015–2019 period, which is the focus of this review.
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