Perylene-derived calix[4]arenes with potential application in luminescent systems

In this work, perylene-derived molecules, chromophores which possess high quantum yields, were attached to calix[4]arene matrix as a means of creating macromolecules (figure 1) which can be utilized in the development of OLEDs, or as biological markers. The relevance of this work lies in the combination of both perylene chromophores and calixarenes merging their unique properties. Perylene-derived molecules, as an example of the perylene-3,4,9,10-tetracarboxylic dianhydride used in this work, have high lightfastness and are very stable electron-receptors1, but are very insoluble. Calixarenes, on the other hand, are macrocycles which allow functionalization and intermolecular interactions in both its upper and lower rims and have been used in many applications in the host-guest and supramolecular chemistry. In this context, functionalizing calixarenes with such chromophores makes the chromophores soluble in several solvents, and therefore, useful for the applications above-mentioned. The compounds synthesized were the ligand perylene-3,4,9,10-tetracarboxylic acid monoanhydride monopotassium carboxylate (1); 5,11,17,23-tetra(tert-butyl)-25,27-dicyanomethoxy-26,28-dihydroxy-calix[4]arene (2); 5,11,17,23-tetra(tert-butyl)-25,27-diaminoethoxy-26,28-dihydroxy-calix[4]arene (3); 5,11,17,23-tetra(tert-butyl)-25,27-bis(1,8-naphthalic anhydride)-26,28-dihydroxy-calix[4]arene (4); 5,17-bis(tert-butyl)-25,27-dicyanomethoxy-26,28-dihydroxy-calix[4]arene (5); 5,17-bis(tert-butyl)-25,27-diaminoethoxy-26,28-dihydroxy-calix[4]arene (6), among others. The analysis of the reactions was carried out with 1H NMR and infrared spectroscopy. The analysis of the infrared spectrum proved the preparation of the ligand (1) by the shift from the anhydride band at 1773 cm-1 to the carboxylic acid band at 1713 cm-1. The inspection of the 1H NMR spectra allowed the examination of the functionalized calixarenes, as well as its conformations. 1H NMR data indicates the presence of (2) from the calix[4]arene matrix because of the occurrence of the two t-butyl singlets at 0.89 and 1.33 ppm (18H each), the ether at 4.32 ppm (4H) and the two m-ArH singlets at 7.13 (4H) and 6.74 ppm (4H). The reduction of (2) forming (3) is noticed by the approximation of the two t-butyl singlets at 1.23 and 1.12 ppm, by the presence of the NH2 hydrogens at 5.13 ppm (s, 4H) and because of the hydrogens of the ether depicted at 3.38 ppm (t, N-CH2, 4H) and 4.12 ppm (t, O-CH2, 4H). The ligand (4), in turn, showed the absence of the NH2 hydrogens and the presence of the 1,8-naphthalic anhydride hydrogens at 7.77 ppm (dd, 4H), 8.69 ppm (dd, 4H), and 8.18 (dd, 4H). The loss of two t-butyl groups in (2), producing (5) was validated by the presence of only one t-butyl singlet at 0.92 ppm (18H) and also by the presence of three m-ArH shifts at 7,14 ppm (d, 4H), 6,79 ppm (t, 2H) and 6,75 (s, 4H). The reduction of (5) to make (6) was ascertained by the shift of the t-butyl singlet from 0.92 ppm to 1.12 ppm (s, 18H) and by the presence of the ether at 3.38 ppm (N-CH2, 4H) and 4.12 ppm (O-CH2, 4H)