Chemical Sensing with Semiconducting Metal Phthalocyanines

Interaction of Copper Phthalocyanine with Nitrogen Dioxide and Ammonia Investigation Using X-ray Absorption Spectroscopy and Chemiresistive Gas Measurements

“…Positive and negative current changes observed in the CuPc chemiresistors because of exposure to NO 2 or to NH 3 , respectively, can be attributed to the electron transfer between the gas and CuPc sensing layer. In particular, the electron transfer from CuPc to NO 2 has been reported to form holes in CuPc, leading to the increase in current of the p-type CuPc sensing layer. , On the other hand, the electron donation from the NH 3 gas to CuPc results in the depletion of holes, thereby reducing the current, as seen in our results. Although the observations of the changes in the measured current of CuPc devices as exposed to NO 2 or NH 3 can be explained to be because of the electron transfer, the interaction sites at the macrocycle or metal center have not been clarified.…”

Solvent-Directed Self-Assembly of (Aqua)Zinc Phthalocyanine in Crystal Solvates and Its Manifestation in Optical Properties

“…Owing to their 18 electron π-system, metal-centered phthalocyanines (MPc) exhibit high stability and remarkable optical properties, which are exploited in various photovoltaic devices, including photosensitizing materials for solar cells, photodynamic cancer therapy, molecular sensors, and switches. − The extended aromatic system of phthalocyanines induces their ability for supramolecular association via π–π interactions, which may have a dual impact. The propensity for aggregation might be a significant drawback in both solar cells and agents for photodynamic cancer therapy: it leads to low solubility and quenching of luminescence of MPc sensitizers. − On the other hand, self-association or assembly with other donors or acceptors results in highly ordered stacking arrangements playing a crucial role in molecular electronic materials − and might broaden absorption bands in UV/vis spectra, which is beneficial for light harvesting .…”

Engineering Cannabinoid Sensors through Solution-Based Screening of Phthalocyanines

“…11,12 The interaction of analytes with the Pc-derived semiconducting layer can cause performance changes that can be interpreted as a sensing response. 6,13,14 Furthermore, changes to the central metal or substituents, axial or peripheral, can be used to improve the sensing response. 8,15,16 Pc semiconductors in OTFTs have been demonstrated for a variety of liquid-and gas-sensing applications, 6,9,13,17 including our demonstration of the ratiometric detection and differentiation of Δ 9 -tetrahydrocannabinol (THC) and cannabidiol (CBD).…”

“…Pcs typically absorb light at 300–400 and 600–700 nm, appearing visually as brilliant blues and purples, lending them for use in dyes and pigments . Pcs have highly delocalized π electrons facilitating intermolecular charge transport, giving rise to applications in organic solar cells , and organic thin-film transistors (OTFTs). , Metal-free Pc (H 2 Pc) and a variety of metal-Pc (MPc) complexes are possible, which can be peripherally and axially substituted, depending on the metal, allowing for precision tuning of their material properties and optimization of device performance. ,, Charge transport of semiconducting Pcs in OTFTs can be affected by atmospheric parameters , or improved via doping with small molecules. , The interaction of analytes with the Pc-derived semiconducting layer can cause performance changes that can be interpreted as a sensing response. ,, Furthermore, changes to the central metal or substituents, axial or peripheral, can be used to improve the sensing response. ,, Pc semiconductors in OTFTs have been demonstrated for a variety of liquid- and gas-sensing applications, ,,, including our demonstration of the ratiometric detection and differentiation of Δ 9 -tetrahydrocannabinol (THC) and cannabidiol (CBD) …”

“…In Pc-based OTFTs, device architecture, fabrication conditions, and molecular structure determine film crystallinity and morphology, affecting molecular interactions and dictating how well the film can transport charge. ,− Gas or liquid analytes can interact with the Pc semiconducting layer, causing changes in electrical output to elicit a sensing response. ,, However, the large number of variables involved with device engineering and manufacturing can complicate the identification of specific semiconductor materials possessing sensing potential. Spectroelectrochemistry affords the opportunity to easily and rapidly assay conduction mechanisms and molecular interactions in solution that may inform semiconductor–analyte pairing suitability without the need to fabricate and engineer a solid-state device.…”