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Benefiting from the diversity of electron orbitals, such as s, p, and d orbitals associated with a metal center, as well as the various molecular orbitals associated with organic ligands, metal–organic electrochromic materials can achieve different colors in a single device. Moreover, as both the tunability of organic materials (ligand) and the bistability of inorganic materials (metal ions) can be realized by these materials, significant research efforts have been devoted to their study. Metal–organic electrochromic materials with variety bright colors have been developed based on the dynamic coordination of metal ions and molecular switches as well as semi-solid devices. However, the optical modulation ability is limited by an insufficient content of metal ions. In this work, the dynamic coordination between Cu ions and molecular switches which consisted of 2-anilino-6-(dibutylamino)-3-methylfluoran and polymethyl methacrylate (ODBMA) was verified in the solid phase. Based on this coordination, a cuprous iodide (CuI) film was successfully synthesized on an indium tin oxide electrode. Owing to its bistability, the fabricated electrochromic device presents considerable potential for the development of energy-efficient smart windows. [ABSTRACT FROM AUTHOR]

The colors that can be provided by hydrochromic molecular switches, which directly regulate isomerization by water, are very limited, especially for the most used color black, which remains difficult to achieve. Herein, an ideal hydrochromic black display was successfully achieved via the substitution of nitro groups in the non-conjugated chromogenic structure of an acidochromic black fluoran dye. The positional isomerization effect of nitro substitution on the synthesis and hydrochromic properties of the obtained hydrochromic molecular switches both in solution and a solid matrix were explored and discussed in detail. Based on the spectral uniqueness of black dyes, a multicolor water-jet printing display with a single molecular switch was also realized using different 'aqueous inks'. This work not only promotes the development of hydrochromic molecular switches and water-jet rewritable paper but also provides a reference for the design and synthesis of other new stimuli-responsive molecular switches and materials for different purposes. [ABSTRACT FROM AUTHOR]

The development of photoswitchable fluorescence nanomaterials which can exhibit excited-state intramolecular proton transfer (ESIPT) emission in all fluorescent states has been long-awaited in the bioimaging field, as they can more efficiently avoid self-reabsorption and excitation backscattering effects. However, successful examples of this kind of nanomaterial are very rare. Herein, we report a facile strategy for regionalized in situ hydrolysis to achieve optically-manipulated all-ESIPT fluorescent nanomicelles with a new photoswitchable near-infrared ESIPT fluorophore. This method could "directly" and efficiently regulate ESIPT fluorescence switching via photoisomerization and generate another ESIPT fluorophore in situ during the preparation of the nanosystem. This work may promote the development of high-performance dual/multi-ESIPT fluorescent nanomaterials and their applications in biological imaging. [ABSTRACT FROM AUTHOR]

Light‐responsive color‐switching materials (LCMs) are long‐lasting hot fields. However, non‐ideal comprehensive performance (such as color contrast and retention time cannot be combined, unsatisfactory repeatability, and non‐automated coloring mode) significantly hinder their development toward high‐end products. Herein, the development of LCMs that exhibit long retention time, good color contrast, repeatability, and the property of automatic coloring is reported. The realization of this goal stems from the adoption of a bio‐inspired multi‐component collaborative step‐by‐step coloring strategy. Under this strategy, a conventional one‐step photochromic process is divided into a "light+heat" controlled multi‐step process for the fabrication of the desired LCMs. The obtained LCMs can effectively resist the long‐troubled ambient‐light interference and avoid its inherent yellow background, thereby achieving the longest retention time and good repeatability. Multiple colors are generated and ultra‐fast imaging compatible with the laser‐printing technology is also realized. The application potential of the materials in short‐term reusable identity cards, absorptive readers, billboards, and shelf labels is demonstrated. The results reported herein can potentially help in developing and designing various high‐performance, switchable materials that can be used for the production of high‐end products. [ABSTRACT FROM AUTHOR]