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Thin films of meso-octaethylporphyrinogen with different thickness were deposited on suitable substrates by Langmuir-Blodgett deposition technique in order to realize optical-sensitive active layers using Surface Plasmon Resonance (SPR) technique as transduction methodology. Analysis of the morphology of the sensing layers was performed by Atomic Force Microscopy. In particular, such coatings were tested for the detection of alcohol vapors such as ethanol, methanol and isopropanol. This resulted in a reversible shift in the resonance depth and angular position of the SPR curves, depending on the interactions between the sensing layers and the alcohol vapor molecules. Different sensitivity and rate of response for different alcohol molecules were found and analyzed. Measurements of the sensing response towards successive expositions of the sensing layers to methanol, ethanol and isopropanol vapors were performed in order to analyze the discrimination properties of the active layers towards the analytes.

Synthetic anion receptors that facilitate transmembrane chloride transport are of interest as potential therapeutic agents for cancer and cystic fibrosis. Transporters selective for chloride over protons are desired for therapeutic applications to avoid autophagy inhibition and cytotoxicity. Examples of such compounds are rare because the majority of anion transporters can interact with the carboxylate head groups of fatty acids leading to proton leakage. In this paper, we report the synthesis, anion binding and transmembrane anion transport properties of two novel bis-triazole-functionalized calixpyrroles with extended straps, and compare them to previously reported shorter-strap analogues known to exhibit high Cl $>$ H${}^{+}$ selectivity. We demonstrate improved chloride transport activities of the strap-extended compounds that likely benefit from increased lipophilicity, and reduced Cl $>$ H${}^{+}$ selectivity due to the larger anion binding cavities facilitating interaction with fatty acids. The results are instructive for future design of ideal anion transporters with potent activity and high selectivity against proton leakage.

Calix[3]pyrrole and its furan derivatives exhibited bathochromically shifted lowest-energy electronic transition bands in their absorption spectra compared with their calix[4]- and calix[6]-pyrrole analogues, despite the repeating units being the same. We also observed fluorescence emission for calix[3]-type macrocycles. The Stokes shift of the furan/pyrrole hybrid macrocycles, calix[2]furan[1]-pyrrole, and calix[1]furan[2]pyrrole, substantially varied depending on the solvent polarity. Non-covalent interaction (NCI) analyses indicated enhanced interactions between neighboring aromatic rings in the calix[3]pyrrole macrocycle, whereas such interactions were weak in calix[4]pyrrole, in which the interchromophore distance is remarkably longer than in calix[3]pyrrole. Theoretical analyses indicated that the red-shifted, lowest-energy bands of calix[3]pyrrole correspond to HOMO–LUMO transitions, the energy gap of which was narrow compared with calix[4]pyrroles. The characteristic absorption bands for calix[3]pyrrole and its related macrocycles are useful as probes for distinguishing such macrocycles from higher calix[$n$]pyrrole ($n\ge$ 4) analogues that exhibit almost identical absorption spectra.

Recent progress in the synthesis of calix[3]pyrrole has proven that cyclic polyketones composed of 3,3-dialkylated pentane-2,4-diones as the repeating unit are promising precursors for strained calix-type macrocycles. Toward the synthesis of calix[2]pyrrole and calix[2]furan, which are the most strained congeners among the possible calix[$n$]pyrroles and calix[$n$]furans, we report the synthesis of a cyclic dimer of 3,3-dimethylpentane-2,4-dione and its furanophane derivative. These compounds were produced from a linear tetraketone precursor. Single crystal X-ray diffraction analysis revealed that the furan ring in the furanophane was highly strained with deformation angles $\alpha$ and $\beta$ of 3.69${}^{\circ }$ and 16.00${}^{\circ }$, respectively. These deformation angles were the largest in the series of 1,4-diketone-linked oligofuran macrocycles. Although these two macrocyclic compounds are likely the most promising precursors for calix[2]-type macrocycles, Paal–Knorr-type pyrrole or furan ring formation did not proceed under standard conditions used for calix[3]pyrrole or calix[3]furan. Theoretical calculations indicated that the second aromatic ring formation on the cyclic tetraketone is a highly uphill process whose activation energy cannot be overcome by standard thermal reactions.

Size-selective synthesis of calixpyrrole-related macrocycles remains challenging, particularly for ring-contracted and expanded analogues, although calix[4]-type macrocycles are often obtained as major products via conventional acid-catalyzed condensation reactions of aryl monomers. Here, we found that the strain-based design of thiazole-containing macrocycles enables the size-selective synthesis of calix[$n$]furan[2$n$]thiazoles ($n$ = 1 or 2) in which two thiazole units are linked by a methylene bridge. The DFT calculation through StrainViz analysis revealed that calix[1]furan[2]thiazole bearing a methylene bridge had a total strain of 11.2 kcal/mol, which was smaller than that of calix[3]pyrrole (13.4 kcal/mol). The target calix[1]furan[2]thiazole was almost exclusively formed in 45% yield by a Hantzsch reaction between the corresponding bis($\alpha$-bromoketone) and bis(thioamide) at 0.50 mM concentration. When the substrate concentration was increased above 10 mM, the calix[6]-type product, calix[2]furan[4]thiazole, was formed as the major product. Despite the existence of the meso-CH₂-bridge, the obtained macrocycles were stable to air oxidation. Acid-catalyzed hydrolysis of the furan rings in calix[1]furan[2]thiazole and subsequent Paal–Knorr reaction afforded calix[1]pyrrole[2]thiazole. We also found that the deformation angles $\alpha$ determined from the single crystal X-ray structures show a good correlation with the total strain and synthetic yield of calix[3]-type compounds via direct macrocyclization.