Effects of cucurbit[n]uril (n = 7, 8, 10) hosts on the formation and stabilization of a naphthalenediimide (NDI) radical anion

Abstract

Most 1,4,5,8-naphthalenediimide (NDI) derivatives, especially those with mild π-acidity cannot achieve photoinduced electron-transfer (PET). Here we report our investigations on the binding interactions of a NDI diammonium dichloride salt (NDI·Cl2) with cucurbit[n]uril (CB[n], n = 8, 10) and the formation process of a NDI radical anion upon photoexcitation of the NDI derivative in the presence of CB[n] (n = 8, 10). As a comparison, the influence of CB[7] on the PET process was also evaluated. The results show that the NDI core can be partially or fully encapsulated in CB[8] or CB[10] to form inclusion complexes at molar ratios of 1 : 1 (CB[8]·NDI2+) or 1 : 2 (CB[10]·2NDI2+). In the presence of the host, quick formation of the NDI radical anion was observed with respect to no radical anion formation without the host. According to the spectral results, interesting CB[8]-promoted charge-transfer interactions between the NDI radical anion and NDI2+ are assumed during UV irradiation. Moreover, from the UV/Vis and EPR spectra, the observation of intense signals of the NDI radical anion in the presence of CB[10], could presumably be related to a much better stabilized NDI radical anion encapsulated in CB[10].

Expected and unexpected photoreactions of 9-(10-)substituted anthracene derivatives in cucurbit[n]uril hosts

“…( binding between CB [8] and G1 underwent intermediate exchange on the 1 H NMR time scale. 43 ESI-MS showed one ion peak at m/z 826.2, corresponding to 1 :…”

“…Molecular modeling (MMFF) suggested two G1 molecules could adopt an "X" shape in the CB [10]$2G1 complex owing to electrostatic repulsion between the 9,10-substituted positive groups ( Fig. 4), 43 which was not a "reaction ready" state for dimerization. Similar results were obtained for the photoreaction of G1 with various contents of CB [8].…”

“…Broadening of the guest signals again implied that the binding of CB [10] and G2 underwent intermediate exchange on the 1 H NMR time scale. 43 Upon adding excess CB [10], the ratio of CB [10] to G2 was calculated to be 1 : 2 based on the integrals of the host and guest signals ( Fig. S6c †).…”

Probing the efficiency of thermal and photochemical bond homolysis in functionalized nanostructured SBA-15 silicas

“…In the other group, the paramagnetic species associate through non-bonding interactions to afford a wide array of systems capable to provide confinement. Porous materials (zeolite [8,9], AlMCM-41 [10]) and cage molecules (cucurbit [n]urils [11,12,13,14], cyclophanes [15], cyclodextrins [16], single-wall carbon nanotubes [17,18]) can be found in this latter group.…”

Interaction of Phenyl-Substituted Diazaperylenium with Cucurbit[n]uril: Complex versus Supramolecular Polymer

“…Among these hosts, cucurbit­[ n ]­uril has the advantage of high binding constants that are comparable to biological systems. Cucurbit­[ n ]­uril is well known for stabilizing reactive intermediates and redox states and its ability to increase fluorescence properties . Cucurbit­[ n ]­uril is a macrocyclic molecule made of glycoluril and a methylene bridge (Figure ).…”