A rhodamine-based molecule, Rh-OH, is synthesized. Rh-OH exhibits a reversible mechanochromic luminescent character but a passivating response to UV light. An elastomeric polymer film based on polyurethane with embedded Rh-OH is prepared via a polycondensation reaction. The film shows mechanochromic and photochromic properties with reversible color change, which originates from the isomerization of the Rh-OH molecule from a twisted spirolactam in the ring-closed form to a planarized zwitterionic structure in the ring-open state.

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PAMAM dendrimers of the zeroth to fifth generation (G0-5) have been peripherally modified with phenyl, naphthyl, pyrenyl, and dansyl chromophores. Their fluorescence behaviors are strongly affected by the dendritic architectures at different generations. These dendrimers modified with hydrophobic chromphores can self-organize into vesicular aggregates at the low generations G0-3 in water. The size and aggregation number of these vesicles decrease with increasing generation from G0 to G3. Critical aggregation concentration determined by fluorescence spectroscopy reveals that these aggregates can be favorably formed in the order of G3 > G2 > G1. In contrast to the vesicles made from traditional amphiphilic compounds, these dendrimer-based vesicles are very adhesive due to the H-bonding interaction and entanglement of dendritic branches located in the outer layer. A large number of multivesicle assemblies, i.e., "twins" and "quins" consisting of two and five vesicles, were clearly identifiable with transmission electron (TEM) and atomic force microscopy. For the dendrimers with peripheral pyrenyl chromophores, triangle-like vesicles were observed in water. The hydrophobic interphase thickness of the vesicular bilayer is ca. 2.0-3.2 nm determined by fluorescence resonance energy transfer methods, which agrees well with the thickness directly observed with TEM.

Two novel BODIPY-based conjugated porous polymers were prepared for the adsorption of volatile iodine.

Mechanofluorochromic or piezochromic fluorescence chemistry involves the switching and tuning of the luminescent properties of solid-state materials induced by exogenous forces, such as grinding, shearing, compression, tension, and so forth. Up until now, most reported mechanochromic systems, including liquid crystals, organic molecules, organometallic compounds, polymers, and dye-doped polymers, have displayed reversible two-color changes, which arise from either supramolecular or chemical structure transformations. However, fluorescent materials that undergo mechanically induced multicolor changes remain rare; this Minireview is focused on such materials. Topics are categorized according to the different applied forces that are required to induce the multicolor change, including mechanical control of either the supramolecular structures or the chemical structures, and mechanical control of both the supramolecular structures and chemical structures.

Asserting its independence: A single organic molecule containing pyrene and rhodamine B chromophores separated by a peptide spacer formed a mechanochromic material whose fluorescence could be switched from blue to bluish-green and reddish by grinding. Modulation of the overlapped packing pattern of the pyrene excimer for blue emission was crucial for the reversible tricolored switching observed.

in the past years due to their advantages of low cost, less toxicity, readily accessible structure change, [2] and easy color tuning. [3] Such organic materials show wide applications in bio-imaging/sensing, [4] encryption/anti-counterfeiting, [5] and organic light-emitting diode (OLED), [6] etc. As well known, carbazole (Cz) derivatives are considered as the promising light emitters or hole-transporting materials. In particular, the coplanar configuration of carbazole is in favor of electron communication or charge carrier mobility. [7] Hundreds of papers have been published [8] since the H-aggregation of carbazole derivatives was reported to stabilize the triplet excited states for ultralong organic phosphorescence (UOP) in 2015, [1b] and these molecules provide a new way to fabricate the UOP materials.Interestingly, Liu et al. recently reported their findings that the commercially available carbazole was inevitably mixed with trace carbazole isomer (1H-benzo[ f ] indole, Bd), and Bd was believed to be involved in the origination of UOP. [1c,9] They suggested that Cz and Bd moieties in close proximity acted as a microplanar heterojunction to generate photo-induced charge-separated states, and further to produce intense UOP. Based on their results, the UOP of carbazole derivatives previously presented in the literature are actually integrated luminescent properties of carbazole derivatives and Bd's counterparts. [1b,4c,10] Up to now, the intrinsic photophysical property of the pure Bd's counterpart remains unclear because the purified Bd by refining the commercial Cz via high resolution liquid chromatography (HPLC) unavoidably contains trace carbazole, which limits the clear elucidation of the mechanism of Cz-and Bd-based UOP. Therefore, to understand the truth of Cz-and Bd-based UOP is still an unsolved problem and remains full of challenges.Herein, we report the synthesis of four Cz/Bd derivatives (Figure 1a,b) with different substitution numbers of Bd in the structure and aim to deeply understand the role of Bd in UOP. To physically isolate Cz and Bd, we synthesized Cz and Bd separately in our lab. According to the experimental results, such as temperature-variable photoluminescence (PL) spectra, electron spin resonance (ESR) spectra, dual-component doping The mechanism of carbazole (Cz)-based phosphors is still unclear since its isomer (1H-benzo[f ]indole, Bd) is discovered in 2020. Herein, the successful synthesis of four Cz/Bd derivatives is reported, named as 2CzBr, CzBdBr, 2BdBr, and 3Bd, and the general mechanism for their ultralong organic phosphorescence (UOP) is provided. Bd and its derivatives give double groups of phosphorescence, including the short-wavelength phosphorescence with a short lifetime and the ultralong phosphorescence at long wavelengths, assigned to their neutral molecules and radical cations, respectively. Interestingly, the doped poly(methyl methacrylate) (PMMA) films of CzBdBr and 2BdBr show photo-activated ultralong phosphorescence at room temperature. The activation of ...