2026-04-17T15:59:13Zhttps://recercat.cat/oai/request

oai:recercat.cat:2072/5224632024-12-20T18:49:40Zcom_2072_300912com_2072_4427col_2072_301309

Hydrogen-bonded dimeric capsules with appended spiropyran units: towards controlled cargo release Ferreira, Pedro Moncelsi, Giulia Aragay, Gemma Ballester, Pablo 54 We report the synthesis of unprecedented tetra-urea derivatives of calix[4]arene and calix[4]pyrrole containing four spiropyran (SP) units at their upper rim. We investigate the photo- and acid-induced isomerization of the monomeric and homo-dimeric tetra-ureas derivatives using UV-Vis and 1H NMR spectroscopies. At micromolar concentration, irradiation of the samples with 365 nm light induces changes in their absorption spectra that are consistent with SP→MC isomerization. However, analogous experiments at millimolar concentration do not produce noticeable changes in the 1H NMR spectra. The addition of triflic acid to micromolar and millimolar solutions of the tetra-ureas produces the quantitative isomerization of the SP units to the protonated merocyanine form (E-MCH+) and the simultaneous disassembly of the capsular dimers to form ill-defined aggregates. The neutralization of the acid solutions resets the SP form. Under these acid/base treatment conditions, the controlled release of the included guest and the reassembly of the all-SP tetra-urea dimers occurs at different extents depending on its calix[4]arene or calix[4]pyrrole scaffold. 2021-06-07 info:eu-repo/semantics/article info:eu-repo/semantics/acceptedVersion http://hdl.handle.net/2072/522463 https://doi.org/10.1002/chem.202101643 eng MICIN/AEI/FEDER (CTQ2017-84319-P) MICIN/AEI/FEDER (CEX2019-000925-S) NOAH project H2020‐MSCA‐ITN project Ref. 765297 AGAUR (2017 SGR 1123) You have selected the Attribution-NonCommercial-NoDerivatives 4.0 International License. This license is permanently located at http://creativecommons.org/licenses/by-nc-nd/4.0/. info:eu-repo/semantics/openAccess 12675 p. application/pdf RECERCAT (Dipòsit de la Recerca de Catalunya)