We disclose the results of our investigations on the influence that the insertion method of aryl‐extended calix[4]pyrrole into liposomal membranes exerts on their properties as anion carriers. We use the standard HPTS assay to assess the transport properties of the carriers. We show that the post‐insertion of the carrier, as DMSO solution, assigns better transport activities to the “two‐wall” α,α‐aryl‐extended calix[4]pyrrole 1 compared to the “four‐wall” α,α,α,α‐counterpart 2 . Notably, opposite results were obtained when the carriers were pre‐inserted into the liposomal membranes. We assign this difference to an improved incorporation of carrier 2 into the membrane when delivered by the pre‐insertion method. On the other hand, carrier 1 shows comparable levels of transport independently of the method used for its incorporation. Thus, an accurate comparison of the chloride transport activities featured by these two carriers demands their pre‐incorporation in the liposomal membranes. In contrast, using the lucigenin assay with the pre‐insertion method both carriers displayed similar transport efficiencies.

The discovery of stimuli‐responsive high affinity host–guest pairs with potential applications under biologically relevant conditions is a challenging goal. This work reports a high‐affinity 1:1 complex formed between cucurbit[8]uril and a water‐soluble photochromic diarylethene derivative. It was found that, by confining the open isomer within the cavity of the receptor, a redshift in the absorption spectrum and an enhancement of the photocyclization quantum yield from Φ=0.04 to Φ=0.32 were induced. This improvement in the photochemical performance enables quantitative photocyclization with visible light that, together with the near‐infrared light‐induced ring‐opening reaction and the 100‐fold selectivity for the closed isomer, confirms this as an outstanding light‐responsive affinity pair.

A fluorescent bistable pseudorotaxane was devised and shown to display pH-gated photoresponsive ring shuttling. At pH > 7.5 shuttling does not take place after light stimulation while at pH ≈ 5 the macrocycle is quantitatively translocated.

Two photochromic room-temperature ionic liquids (RTILs) based on anionic diarylethene derivative (DTE) were synthesized and characterized. Photochemical (quantum yields for ring closure and opening) and electrochemical (cyclic voltammetry) properties of the [ALIQUAT] 2 [DTE] and [P 6,6,6,14 ] 2 [DTE] compounds as amorphous salts have been investigated. All compounds (including the di-acid precursor and two RTILs) were studied in solution, in their intrinsically pure forms (RTIL as unique media) and in the solid state (BaSO 4 support). Combination with larger organic cations can stabilize the closed-ring form, apparently avoiding the formation of by-products without photodegradation. It is observed that the closed-ring reaction is faster in the case of RTILs comparing to the di-acid starting material. The coloration switches between transparent (initial state) to purple ([ALIQUAT] 2 [DTE]) or pink ([P 6,6,6,14 ] 2 [DTE]). The novel diarylethene-based RTILs as multi-coloured photochromic materials can open attractive perspectives for materials science applications.

We report the synthesis of unprecedented tetraurea 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 1 H NMR spectroscopies. At micromolar concentration, irradiation of the samples with 365 nm light induces changes in their absorption spectra that are consistent with SP!merocyanine (MC) isomerization. However, analogous experiments at millimolar concentration do not produce noticeable changes in the 1 H 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.

A nanomolar affinity photoresponsive host–guest complex formed from cucurbit[8]uril and a diarylethene guest can be actuated with visible and near‐infrared light. (Frontispiece artwork provided by Gaia Barbieri.) For more information see the Communication by A. J. Parola, N. Basílio et al. on page 3477.

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