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Four novel compounds (S-DCM-1O, S-DCM-2O, S-DCM-3O, and S-DCM-4O) based on sulfur-substituted dicyanomethylene-4H-chromene (S-DCM) and diarylethene were synthesized. The detailed investigations on the fluorescence spectra, absorption spectra, and time-dependent density functional theory calculations (DFT/TD-DFT) were presented. The encapsulation of mPEG2000-DSPE effectively increased the solubility of all the as-prepared samples. The results of TEM showed that the nanoparticles had a good dispersion coefficient. All the nanomaterials (S-DCM-1O@PEG, S-DCM-2O@PEG, S-DCM-3O@PEG, and S-DCM-4O@PEG) exhibited near-infrared emission (650–900 nm) and thus reduced light damage and light scattering for cell imaging in biological applications. Furthermore, PLL (poly- L -lysine hydrobromide) was used to modify the surface of nanoparticles to facilitate easy uptake by A549 cells by changing their electronegativity. The results suggested that S-DCM-2O@PEG@PLL was a highly suitable candidate for cell imaging because of its low toxicity and excellent biocompatibility. [ABSTRACT FROM AUTHOR]

A novel diarylethene‐based ratiometric fluorescent sensor with full symmetric structure, 1o, was designed and synthesized successfully. 1o could identify lysine (Lys) with high selectivity and sensitivity and the fluorescence emission peak was red shifted 85 nm upon addition of Lys, which could realize ratio recognition. It exhibited excellent anti‐interference performance in the presence of various amino acids in CH3CN/H2O (7/3, v/v) solution. Moreover, the limit of detection of 1o to Lys could reach 0.019 μM based on a good linear range of 0–40 μM. In addition, the fluorescence emission intensity of 1o could be turned off/on by ultraviolet/visible light due to the special structure of diarylethene. A logic circuit was designed with three inputs. The ratiometric fluorescent sensor 1o could be as a new tool and provide a new method for detection of Lys. [ABSTRACT FROM AUTHOR]

Abstract Asymmetrical diarylethene with pyridinepiperazine-linked hydroxyquinoline group was synthesized and its multi-controllable switching behaviors induced by light and chemical stimuli were investigated. The diarylethene exhibited a notable fluorescence enhancement with added TFA in the solution. When triggered by Fe3+, its fluorescence intensity notably decreased, accompanied with a color change from light blue to dark, indicating its excellent selectivity to Fe3+ over many other metal ions. Moreover, a 1:1 binding stoichiometry between Fe3+ and the derivative was obtained according to Job's plot and ESI-MS analysis. Graphical abstract Multi-controllable switching behaviors of asymmetrical diarylethene with a pyridinepiperazine-linked hydroxyquinoline unit could be induced with light, TFA/TEA and Fe3+. Image 1 Highlights • Asymmetrical diarylethene with pyridinepiperazine-linked hydroxyquinoline group was synthesized. • This diarylethene derivative had multi-controllable fluorescent switching behaviors with light, acid/base, and Fe3+. • This diarylethene could be used as a fluorescent sensor toward Fe3+ with excellent selectivity and sensitivity. [ABSTRACT FROM AUTHOR]

Abstract A new multi-responsive fluorescent switch DTE-Pip-Rho 1O has been designed and synthesized in this study. For this molecule, the reactive site of spirolactam ring is far away from the diarylethene unit through the intramolecular piperazine. It exhibited high selectivity and sensitivity to Hg2+ in addition to obvious color change (colorless-pink) and fluorescence "off-on" (dark-orange) during this process. It is believed that the color change is due to Hg2+-assisted hydrolysis of rhodamine hydrazide. Therefore, the new molecule can be used as colorimentric and fluorescent chemosensor for Hg2+ with high selectivity. The detection limits of absorbance and fluorescence for Hg2+ were calculated to be 1.15 μM and 1.16 μM, respectively. The resulting DTE-Pip-Rho 1O-Hg 2+ could also function as a reversible fluorescence photo-switch in response to UV/vis light owing to FRET mechanism. Moreover, it has been demonstrated that the photo-switchable system displayed excellent fatigue resistance and remarkable anti-photobleaching capability. Graphical abstract A new multi-responsive diarylethene-based fluorescence switching system by using rhodamine as a fluorophore and the piperazine as the linker group was designed and synthesized, and its sensing behaviors for detecting Hg2+ and photo-switchable fluorescence were studied systematically. Image 1 Highlights • A new multi-responsive diarylethene-based fluorescent switching system was designed and synthesized. • The DTE-Pip-Rho 1O can serve as colorimetric and fluorescent sensor for specifically detecting Hg2+. • The corresponding detection mechanism was identified by HPLC and ESI-MS spectra. • The fluorescence of DTE-Pip-Rho 1O-Hg 2+ can be readily tuned under alternating irradiated with UV and visible lights. [ABSTRACT FROM AUTHOR]