An insulated Pt-acetylide complex was incorporated into a polymer network as a crosslinker to afford a phosphorescent gel.

Although photodegradability is promising for on‐demand tuning of material properties, phototuned materials cannot be utilized under ambient light irradiation owing to their photoinstability. Herein, a novel photostable gel that photodegrades only in the presence of an acid is fabricated. The unique reactivity of a supramolecular platinum‐acetylide complex is uncovered to incorporate into poly(methyl methacrylate) gel as the cross‐linker to exhibit softening and swelling under simultaneous treatment with UV‐light and acid. Conversely, when the acid is removed, the gel reacquires its photostability. A cross‐linker amount of only 0.7 wt.% is sufficient to realize the material property. Notably, the unique cross‐linkers, which change phosphorescence to fluorescence via photocleaving of PtC bonds, enable a photoprocess of optical functions. The controllable optical properties can be applied to information hiding technology and in visualizing the locally modified elasticity of the material, because of the photostability in absence of the acid.

Photopolymerization and photoprocessing are core technologies for molding and tuning polymer materials. However, they are incompatible with single materials owing to their contradictory photoreactivity. Herein, an acid‐induced photocleavable crosslinker, a platinum–acetylide complex covered by permethylated cyclodextrins, enables the fabrication of photoprocessable materials via photopolymerization with N‐(2‐hydroxyethyl)acrylamide. The polymer networks are molded by 365 nm irradiation as well as softened and degraded by a cooperative reaction with HCl as an acidic additive under 365 nm UV light, or 470 nm visible light in the presence of a photosensitizer. Moreover, the crosslinker is applied to a photoadhesive triggered by 365 nm irradiation. The adhesion is detachable on‐demand through acid‐induced photodegradation with the same wavelength and intensity of irradiation. Thus, acid‐induced photocleavage allows the integration of light‐induced molding and processing under various lights of various wavelengths, opening up new strategies for polymer technologies.

A coumarin derivative bearing a [1]rotaxane structure with permethylated -cyclodextrins suppressed unwanted solvation-induced effects and increased luminescent quantum yields in medium- and high-polarity solvents. The non-radiative decay was suppressed by...