Despite the impressive progress in forward osmosis (FO) membranes and pilot scale testing of FO process, lack of draw solutes that can be efficiently regenerated is still a limiting factor for more ...prolific commercial applications of FO technology. In the past decade, a large variety of draw solutes have been investigated. While many promising concepts were discussed, efforts are still needed to search for an ‘ideal’ draw solute which could enable the next breakthrough in FO technology. Besides giving a critical review on the development of FO draw solutes, we attempt to clarify some of the most important issues about draw solutes, to define the criterion for draw solutes, and to offer insights into challenges and opportunities concerning their future development. We intentionally avoid very detailed discussion on the issue of viability of FO, which was covered in several earlier reviews. Draw solutes are categorized into either non-responsive or responsive type according to their response toward external stimuli, such as heat and electromagnetic field. While the focus is on responsive draw solutes whose regeneration relies on their smart response to stimuli, non-responsive draw solutes are also discussed not only for a historic reason, but also for the valuable lessons learnt from these earlier systematic studies.
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•FO draw solutes have been comprehensively and critically reviewed.•FO enabled by responsive draw solutes can have a significant energy cost saving.•FO has advantages in niche applications where RO alone is unsuitable.•Ideal draw solute development calls for interdisciplinary efforts.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Highly efficient light‐harvesting systems were successfully fabricated in aqueous solution based on the supramolecular self‐assembly of a water‐soluble pillar6arene (WP6), a salicylaldehyde azine ...derivative (G), and two different fluorescence dyes, Nile Red (NiR) or Eosin Y (ESY). The WP6‐G supramolecular assembly exhibits remarkably improved aggregation‐induced emission enhancement and acts as a donor for the artificial light‐harvesting system, and NiR or ESY, which are loaded within the WP6‐G assembly, act as acceptors. An efficient energy‐transfer process takes place from the WP6‐G assembly not only to NiR but also to ESY for these two different systems. Furthermore, both of the WP6‐G‐NiR and WP6‐G‐ESY systems show an ultrahigh antenna effect at a high donor/acceptor ratio.
Light‐harvesting systems were fabricated in aqueous solution by supramolecular self‐assembly of a water‐soluble pillar6arene (WP6), a salicylaldehyde azine derivative (G, acting as donor), and two different fluorescence dyes, Nile Red or Eosin Y. The dye is loaded within the WP6‐G assembly and acts as an acceptor.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
An artificial light‐harvesting system with sequential energy‐transfer process was fabricated based on a supramolecular strategy. Self‐assembled from the host–guest complex formed by water‐soluble ...pillar5arene (WP5), a bola‐type tetraphenylethylene‐functionalized dialkyl ammonium derivative (TPEDA), and two fluorescent dyes, Eosin Y (ESY) and Nile Red (NiR), the supramolecular vesicles achieve efficient energy transfer from the AIE guest TPEDA to ESY. ESY can function as a relay to further transfer the energy to the second acceptor NiR and realize a two‐step sequential energy‐transfer process with good efficiency. By tuning the donor/acceptor ratio, bright white light emission can be successfully achieved with a CIE coordinate of (0.33, 0.33). To better mimic natural photosynthesis and make full use of the harvested energy, the WP5⊃TPEDA‐ESY‐NiR system can be utilized as a nanoreactor: photocatalyzed dehalogenation of α‐bromoacetophenone was realized with 96 % yield in aqueous medium.
It takes two to FRET: An artificial light‐harvesting system with a two‐step sequential energy‐transfer process in a relay mode was fabricated using a supramolecular strategy. It can be used as a nanoreactor for efficient photochemical catalysis. Moreover, bright white light emission can be successfully achieved with a CIE coordinate of (0.33, 0.33).
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Current enzyme‐responsive, fluorogenic probes fail to provide in situ information because the released fluorophores tend to diffuse away from the reaction sites. The problem of diffusive signal ...dilution can be addressed by designing a probe that upon enzyme conversion releases a fluorophore that precipitates. An excited‐state intramolecular proton transfer (ESIPT)‐based solid‐state fluorophore HTPQ was developed that is strictly insoluble in water and emits intense fluorescence in the solid state, with λex/em=410/550 nm, thus making it far better suited to use with a commercial confocal microscope. HTPQ was further utilized in the design of an enzyme‐responsive, fluorogenic probe (HTPQA), targeting alkaline phosphatase (ALP) as a model enzyme. HTPQA makes possible diffusion‐resistant in situ detection of endogenous ALP in live cells. It was also employed in the visualizing of different levels of ALP in osteosarcoma cells and tissue, thus demonstrating its interest for the diagnosis of this type of cancer.
A solid‐state fluorophore (HTPQ) that is well‐suited to confocal microscopy was developed. HTPQ was used to design an enzyme‐responsive, fluorogenic probe (HTPQA) targeting alkaline phosphatase (ALP) as a model enzyme. HTPQA makes possible diffusion‐resistant detection of endogenous ALP in live cells and visualization of ALP levels in Saos‐2 and U‐2OS osteosarcoma cells and tissue.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Nontoxic prodrugs, especially activated by tumor microenvironment, are urgently required for reducing the side effects of cancer therapy. And combination of chemo-photodynamic therapy prodrugs show ...effectively synergetic therapeutic efficiency, however, this goal has not been achieved in a single molecule. In this work, we developed a mitochondrial-targeted prodrug
for near infrared (NIR) fluorescence imaging guided and synergetic chemo-photodynamic precise cancer therapy for the first time.
contains a NIR photosensitizer (
) and an anticancer drug 5'-deoxy-5-fluorouridine (5'-DFUR). These two parts are linked and caged through a bisboronate group, displaying no fluorescence and very low cytotoxicity. In the presence of H
O
, the bisboronate group is broken, resulting in activation of
for NIR photodynamic therapy and activation of 5'-DFUR for chemotherapy. The activated
can also provide a NIR fluorescence signal for monitoring the release of activated drug. Taking advantage of the high H
O
concentration in cancer cells,
exhibits higher cytotoxicity to cancer cells than normal cells, resulting in lower side effects. In addition, based on its mitochondrial-targeted ability,
exhibits enhanced chemotherapy efficiency compare to free 5'-DFUR. It also demonstrated a remarkably improved and synergistic chemo-photodynamic therapeutic effect for cancer cells. Moreover,
exhibits excellent tumor microenvironment-activated performance when intravenously injected into tumor-bearing nude mice, as demonstrated by
fluorescence imaging. Thus,
is a promising prodrug for cancer therapy based on its tumor microenvironment-activated drug release, synergistic therapeutic effect and "turn-on" NIR imaging guide.
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IJS, KILJ, NUK, UL, UM, UPUK
Adsorptive removal of dyes from industrial effluent has attracted intensive interest in the treatment of water pollution. Although we have witnessed great development in adsorbents for treating ...dyeing waste water, super-adsorbent hydrogels still cannot meet the high requirement for huge adsorption capacities towards various dyes. Traditional uncross-linked poly(acrylic acid) (PAA) adsorbents possess a low adsorption capacity towards dyes due to the poor three-dimensional structure in the bulk, which has a negative effect on the exposure of adsorptive sites and the penetration of water within the internal channels of the adsorbent. Thus, other monomers or chemical cross-linkers are introduced to design a well-cross-linked PAA-based super-adsorbent hydrogel with the intention of improving its adsorptive behavior. However, the above-mentioned additives may negatively affect the adsorptive properties of composite adsorbents based on the PAA hydrogel. To the best of our knowledge, adsorption capacities of PAA-based super-adsorbent hydrogels for organic dyes reaching more than 2000 mg g
−1
have rarely been reported as yet. Therefore, it is urgent to explore super-adsorbent hydrogels with high adsorptive properties to alleviate dye-based water pollution. In this work, a novel poly(acrylic acid) (PAA)-based super-adsorbent nanocomposite hydrogel (NC gel) acting as an effective dye adsorbent is prepared
via
free radical
in situ
polymerization of acrylic acid by employing non-aggregated calcium hydroxide (Ca(OH)
2
) nano-spherulites (CNSs) with a diameter less than 5 nm as cross-linkers. The high water penetration of our super-adsorbent NC gel with a high swelling ratio (500 times) allows the internal adsorption sites to be fully exposed to methylene blue (MB). Thus, the adsorption capacity is as high as 2100 mg g
−1
for MB under near neutral pH conditions due to the exposure of a large amount of active sites. This is the first time that it has been reported that a maximum adsorption of more than 2000 mg g
−1
for MB has been obtained using a PAA-based super-adsorbent NC gel. In addition, the adsorption behavior of our NC gel matches well with the pseudo-second-order model and Langmuir adsorption isotherm model. This work confirms that CNSs can create a well-cross-linked structure of a PAA hydrogel without the aid of any other cross-linker and further confirms that the PAA-based super-adsorbent NC gel has a potential application in the removal of organic dyes from dyeing waste water.
A novel poly(acrylic acid) (PAA)-based super-adsorbent nanocomposite hydrogel as an effective dye adsorbent is prepared using non-aggregated calcium hydroxide (Ca(OH)
2
) nano-spherulites (CNSs) as cross-linkers.
The many useful features possessed by pillararenes (PAs; e.g. rigid, capacious, and hydrophobic cavities, as well as exposed functional groups) have led to a tremendous increase in their popularity ...since their first discovery in 2008. In this Minireview, we emphasize the use of functionalized PAs and their assembled supramolecular materials in the field of catalysis. We aim to provide a fundamental understanding and mechanism of the role PAs play in catalytic process. The topics are subdivided into catalysis promoted by the PA rim/cavity, PA‐based nanomaterials, and PA‐based polymeric materials. To the best of our knowledge, this is the first overview on PA‐based catalysis. This Minireview not only summarizes the fabrications and applications of PAs in catalysis but also anticipates future research efforts in applying supramolecular hosts in catalysis.
Pillararenes have become increasingly popular since their first discovery in 2008 because of their rigid, capacious, and hydrophobic cavities as well as their exposed functional groups. This Minireview highlights three types of catalysis with pillararenes: 1) within the confined cavity or by attached pendent groups, 2) by nanomaterials featuring pillararenes in their architecture, and 3) by pillararene‐derived polymeric materials.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Remote control: New strategies for the activation of remote C(sp3)−H bonds by photoredox‐catalyzed (PC) radical translocation via O‐ and N‐centered radicals have recently been described. These ...methods enable the controlled and site‐selective functionalization of inert C(sp3)−H bonds and provide new opportunities for reaction design (HAT=hydrogen atom transfer).
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Radicals are an important class of versatile and highly reactive species. Compared with the wide applications of various C-centred radicals, however, the N-radical species including N-centred ...radicals and radical ions remain largely unexplored due to the lack of convenient methods for their generation. In recent years, visible light photoredox catalysis has emerged as a powerful platform for the generation of various N-radical species and methodology development towards the synthesis of diverse N-containing compounds. In this tutorial review, we highlight recent advances in this rapidly developing area with particular emphases put on the working models and new reaction design.
Light-harvesting, which involves the conversion of sunlight into chemical energy by natural systems such as plants, bacteria, is one of the most universal routine activities in nature. Thus far, ...various artificial light-harvesting systems (LHSs) have been fabricated toward solar energy utilization through mimicking natural photosynthesis in simplified and altered ways. Macrocycles are supramolecular hosts with unique cavities, in which specific guest molecules can be recognized based on non-covalent interactions. They have been widely employed in constructing LHSs due to their ability to form supramolecular assembly and dynamic molecular activity. In this review, we mainly focus on some representative examples reported by our group and other groups. Specifically, the fabrication of LHSs and their related discussions, such as a high donor/acceptor ratio, driving force for the formation of supramolecular assemblies and energy transfer mechanisms using different water-soluble macrocycles such as cyclodextrins (CD), pillararenes (PA), calixarenes (CA), cucurbiturils (CB), and other macrocycles will be included. In addition, how the resulting supramolecular self-assembled LHSs could be potentially utilized for photocatalysis, sensing, and imaging is also explained in detail. Challenges and developing trends for photochemical solar energy conversion will also be presented.
This Feature Article will discuss the fabrication of light-harvesting systems based on water-soluble macrocycles, such as cyclodextrins (CD), pillararenes (PA), calixarenes (CA), cucurbiturils (CB), and other macrocycles.
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