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Natural systems transfer chiral information across multiple length scales through dynamic supramolecular interaction to accomplish various functions. Inspired by nature, many exquisite artificial supramolecular systems have been developed, in which controlling the supramolecular chirality holds the key to completing specific tasks. However, to achieve precise and non-invasive control and modulation of chirality in these systems remains challenging. As a non-invasive stimulus, light can be used to remotely control the chirality with high spatiotemporal precision. In contrast to common molecular switches, a synthetic molecular motor can act as a multistate chiroptical switch with unidirectional rotation, offering major potential to regulate more complex functions. Here, we present a light-driven molecular motor-based supramolecular polymer, in which the intrinsic chirality is transferred to the nanofibers, and the rotation of molecular motors governs the chirality and morphology of the supramolecular polymer. The resulting supramolecular polymer also exhibits light-controlled multistate aggregation-induced emission. These findings present a photochemically tunable multistate dynamic supramolecular system in water and pave the way for developing molecular motor-driven chiroptical materials.

Light-induced 9,10-phenanthrenequinone-electron-rich alkene (PQ-ERA) photocycloadditions are an attractive new type of photoclick reaction, featuring fast conversions and high biocompatibility. However, the tunability of the reaction was hardly investigated up to now. To this end, we explored the influence of substituents on both reaction partners and the reaction rate between the PQs and ERAs. We identified new handles for functionalization and discovered that using enamines as ERAs leads to drastically enhanced rates (>5400 times faster), high photoreaction quantum yields (ΦP, up to 65 %), and multicolor emission output as well as a high fluorescence quantum yield of the adducts (ΦF, up to 97 %). Further investigation of the photophysical and photochemical properties provided insights to design orthogonal reaction systems both in solution and on nanoparticle surfaces for ultrafast chemoselective functionalization by photoclick reactions.

The development of a responsive fluorescent probe for the detection of a particular biomolecule in a specific site at the desired moment is important in the fields of bioanalysis and imaging, molecular biology and biomedical research. In this work, we report the development of a remote-light activatable nanoprobe for the fluorescence detection of sulphite in pure aqueous solution and its imaging applications in living cells. The nanoprobe, Poly-Cm-SP, is fabricated simply by wrapping photochromic molecules (Cm-SP) into a polymer nanoparticle. Upon alternate UV/Vis light irradiation for several seconds, the Poly-Cm-SP nanoprobe exhibits red/blue fluorescence switch due to the inactive/active FRET processes from coumarins to the SP/MR isomers of the photochromic molecule. In the presence of sulphite, the specific reaction of sulphite with the electron deficit "CC" bond of the MR isomer occurs, resulting in an inefficient FRET process and thus exhibiting a constant "ON" blue channel fluorescence signal. After UV-light irradiation, the formation of activated Poly-Cm-MR

Due to the highly selective nature of singlet oxygen as an oxidant, it has received considerable interest in various areas of (organic) chemistry. Two green light activated hydrazone-based boron difluoride triplet photosensitizers possessing high quantum yields for 1O2 formation are reported. These photostable complexes are promising in applications in synthesis and catalysis.

The development of very fast, clean, and selective methods for indirect labeling in PET tracer synthesis is an ongoing challenge. Here we present the development of an ultrafast photoclick method for the synthesis of short-lived 18F-PET tracers based on the photocycloaddition reaction of 9,10-phenanthrenequinones with electron-rich alkenes. The respective precursors are synthetically easily accessible and can be functionalized with various target groups. Using a flow photo-microreactor, the photoclick reaction can be performed in 60 s, and clinically relevant tracers for prostate cancer and bacterial infection imaging were prepared to demonstrate practicality of the method.

An artificial protein-probe hybrid, Cm-Np-B@BSA, was prepared via host-guest interactions between hydrogen peroxide (H2O2)-responsive Cm-Np-B molecule and bovine serum albumin (BSA). The Cm-Np-B@BSA probe exhibited high sensitivity and selectivity towards H2O2 under physiological conditions and had excellent biocompatibility, allowing for sensitive ratiometric detection and imaging of endogenous H2O2 in live cells.

Photochromic molecules can achieve reversible isomerization upon alternate light irradiations, which offers a great opportunity to improve the precision of analytes detection and imaging in complicated biological environments. Previous reported photochromic probe exhibited only mono-color switching and an initially fluorescence-ON state that may cause high background signal and impose an adverse impact on the desired sensing precision. To overcome this set-back, we developed a novel photochromic probe with an analyte-activation mode for ratiometric sensing of toxic thiols in both real water samples and live cells. The dynamic dual-fluorescence signal is released only after the fast and selective cleavage of the 2,4-dinitrophenyl sulfonate by the targeted thiophenol derivatives. Consequently, a "double-check" with synchronized dual-fluorescence blinking for analyte detection is successfully employed upon alternate light triggers with rapid response (k=7.2x10(-2) s(-1)), high sensitivity (LOD=6.1 nM) as well as selectivity of thiophenol derivatives over other common thiol species (e.g., GSH, Cys and Hcy). The photochromic probe was successfully introduced to the fast and on-site detection of highly toxic thiophenols in real waste water samples. Moreover, by using confocal laser-scanning microscopy (CLSM) and flow cytometric analysis, the potential applications of this ratiometric photochromic probe for trace toxic thiol sensing in live cells are examined.

A new probe for precise and accurate bioimaging contributes significantly to advancing biomedical research for early disease diagnosis and treatment monitoring. Through wrapping a photochromic molecule (SP-Np-B) within a polymer nanoparticle, a new light-controlled multicolour fluorescence nanoprobe (Poly-SP-Np-B) is developed for precise fluorescence subcellular bioimaging. Poly-SP-Np-B shows an "OFF-ON" red-emitting fluorescence response upon alternate UV/Vis light irradiation. After activation by hydrogen peroxide (H2O2), a green-emitting Poly-SP-Np nanoparticle is generated, thus allowing light-controlled fluorescence response simultaneously, i.e., green and yellow switch upon alternate UV/Vis light irradiation for 10 and 20 s, respectively. Such a "blinking" fluorescence signal change is not possible by only using a photochromic molecule probe (SP-Np-B) with alternate UV/vis light irradiation for over 5 min. Poly-SP-Np-B has large isomerization kinetic constants (kSP-MR = 0.4543 s-1 and kMR-SP = 0.0809 s-1), excellent biocompatibility and lysosome distribution capability, enabling multicolour fluorescence imaging in live cells. With exo-/endogenous H2O2 activation in lysosomes, light-controlled "double-check" fluorescence imaging at the subcellular level is successfully achieved. More specifically, the change in fluorescence imaging is reversible in green, red and yellow channels in live cells upon excitation under alternate UV and visible light. This work thus provides a new strategy to develop switchable photochromic probes for precise fluorescence bioassay and bioimaging.

Despite the rapid development of imaging techniques, precise probe localization and modulation in living cells is still a challenging task. Here we show that the simple hybridization between a photochromic fluorescent glycoprobe and human serum albumin (HSA) enables a unique fluorescence "double-check" mechanism for precisely localizing and manipulating probe molecules in living cells. Docking of a carbohydrate-modified naphthalimide (Naph)-spiropyran (SP) dyad to a hydrophobic pocket of HSA produces the glycoprobe-protein hybrid, causing the protein conformation to fold as determined by small-angle X-ray scattering. We show that the Naph and merocyanine (the photo isomer of SP) fluorescence of the resulting hybrid can be reversibly switched by light in buffer solution and in target cells overexpressing the carbohydrate receptor.

In order to obtain a low-cost and effective adsorbent for separating valuable rare-earth ions from wastewater, a surface rich carboxyl decorated kaolinite composite (PAA-KLN) was fabricated through poly(acrylic acid) grafting via an integrated UV-initiated grafting approach, involving surface hydrophobic modification under ordinary temperature and the coating of liquid photosensitizer (benzophenone) film to meet the specific initiator/substrate combination. The successful grafting was characterized by XRD, SEM/TEM, FTIR and TG/DTG/DSC. Due to the good hydrophilic property of poly(acrylic acid) brushes, their free-end would extend into the solution to form a surface villus layer, bringing lots of highly accessible adsorption sites. The resultant PAA-KLN exhibited outstanding adsorption capacity for Ce3+ of 189.63 mg/g and rapid adsorption rate (reaching equilibrium within 40 min). Furthermore, PAA-KLN displayed an excellent reusability with high desorption ratio even at low concentration stripping liquid (0.2 M HCl), demonstrating its excellent application potential in recycling valuable metal from wastewater.

A series of galactosyl naphthalimide-piperazine derivatives have been synthesized as intracellular pH and lysosome-targeting imaging probes for live human hepatoma cells. The probes show good sensitivity in both aqueous buffer and intracellular environments. Incorporation of the galactose moiety with the pH probes facilitates their specific endocytosis and, thus targeted trafficking to lysosome, by the asialoglycoprotein receptor of human hepatoma cells. The acidic intracellular pH of live human hepatoma cells gives rise to a fluorescence “turn-on” signal of the probes probably via a modulation of the photo-induced electron transfer (PET) mechanism. Additionally, galactosylation of the probes enhances their selective accumulation in lysosome and decreases the cytotoxicity.