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Metallogel-based six membered sensor arrays show applications in multi-analyte detection and fluorescence encryption.

A novel 3D supramolecular polymer network gel (DP5G) was successfully constructed by easy to synthesize tripodal guest (SZ) and thioacetylhydrazone functionalized di-pillar[5]arene host (DP5). Interestingly, the DP5G showed aggregation induced emission (AIE). Moreover, the DP5G displayed a 3D network structure, which was used to dye removal experiments. Notably, the xerogel DP5G could effectively remove cationic dyes (including crystal violet and rhodamine B) from aqueous solution and the removal percentages are 96.3% and 95.4%, respectively. In addition, the maximal adsorption capacity of DP5G towards crystal violet and rhodamine B are 19.65 mg/g and 22.85 mg/g, respectively. The stability of the 3D supramolecular polymer network gel (DP5G) was further investigated, which exhibited excellent stability toward outer stimuli such as pH, competitive agents, oxidant and reducing agent.

An ultrasensitive detection and effective removal material was successfully developed by using a pillar[n]arene-based supramolecular polymer gel (MTP5⊃HB). The MTP5⊃HB can ultrasensitively recognize Cu2+ and Fe3+, and the limits of detection (LODs) for Cu2+ and Fe3+ are 1.55 and 2.68 nmol/L, respectively. Additionally, the in-situ generated metallogel MTP5⊃HB-Cu can exclusively detect CN−, and the LOD for CN− is 1.13 nmol/L. Noticeably, the xerogel of MTP5⊃HB-Cu can effectively remove CN− from aqueous solution with 94.40% removal rate. Test kit based on MTP5⊃HB-Cu is also prepared for convenient detection of CN−.

Light-emitting materials are of significant interest because of their vast potential applications in electroluminescent devices/displays and sensors. Herein, a novel bi-component supramolecular aggregation-induced emission (AIE) hydrogel (PDG) was successfully prepared with p-hydroxybenzonic acid-functionalized pillar[5]arene (SPA) and tri-(pyridine-4-yl)-functionalized trimesic amide (DTB) by a simple host–guest assembly process. The most attractive feature of PDG is its practical white-light-emitting property, which can be used for ultrasensitive detection and separation of Pb2+, Cr3+, and Fe3+ ions. The limits of lowest detection (LODs) of PDG for Pb2+, Cr3+, and Fe3+ are approximately 6.74 × 10−9, 7.18 × 10−9, and 8.25 × 10−9 M, respectively. Strikingly, by rationally introducing these metal ions into the PDG, a series of metal-ion-coordinated supramolecular metallogels PDG-Cr and PDG-Fe was constructed, and these metallogels can selectively detect CN− and H2PO4−, respectively. The LODs of PDG-Cr and PDG-Fe for CN− and H2PO4− reached up to 10−8 M. The prepared PDG-based thin films can act as a smart fluorescent display material and test kit. The xerogel of PDG can adsorb and separate Pb2+, Cr3+, and Fe3+ from aqueous solution, with adsorption rates ranging from 96.73% to 98.95%.

A novel supramolecular polymer network gel (NT), based on bi-pillar[5]arene, which can adsorb and separate organic dyes, has been efficiently constructed. First, a novel supramolecular gelator, NBP5 (host), and a tripodal guest, TG (guest), were successfully designed and synthesized. The host NBP5 and guest TG constructed a stable supramolecular polymer network gel, NT, via π–π interactions, hydrogen bonding interactions and host–guest interactions in DMSO/H2O solution. Interestingly, NT showed multi-responsiveness toward outer stimuli, such as temperature, mechanical, concentration, pH and competitive guests. More importantly, NT can carry out the adsorption and separation of organic dyes such as methylene blue, crystal violet, methyl orange, orange I, sudan I and sudan II by the complex intermolecular interactions. The adsorption rates of this gel for dyes are in the range of 83.15–97.56%, indicating good adsorption properties. Moreover, the xerogel of NT can desorb in ethanol solution, showing good recyclability. The multi-responsiveness and adsorption separation properties are based on the multi-interaction sites that were rationally introduced into the NT. Therefore, this is a convenient method for the preparation of supramolecular polymer network-based multiple functional smart materials.

Aggregation induced emission (AIE) active molecules are widely applied for multi-analyte detection due to their unique advantages over conventional fluorescent probes. Herein, a novel coumarin functionalized pillar[5]arene (PX) has been designed and synthesized. It has strong AIE activity, and the fluorescence quantum yield of PX turned out to be 35.0% in DMF/H2O (7 : 3, v/v) binary solution (1.0 × 10−4 M). Meanwhile, the optimized structure of PX was obtained by theoretical calculation at the B3LYP/6-311G level. Interestingly, the PX displays high sensitivity to multiple analytes, such as Fe3+ and Ba2+. The limits of detection (LODs) of PX for Fe3+ and Ba2+ are 1.67 × 10−7 M and 5.89 × 10−8 M, respectively. In addition, by introducing metal ions into the AIE chemosensor of PX, a metal-coordinated chemosensor (PX–M) was obtained. The PX–Fe and PX–Ba show selective fluorescence “turn on” detection of H2PO4− (LOD = 1.50 × 10−7 M) and CN− (LOD = 6.20 × 10−7 M), respectively. The multi-analyte detection mechanism of PX was based on multiple competitions of “exo-wall π–π” interactions and cation–π interactions. Notably, we have prepared logic gates controlled by Fe3+/Ba2+ and H2PO4−/CN− at the molecular level, which can quickly and efficiently detect ions in aqueous solutions. Moreover, we also prepared test films, and an Fe3+ test kit was prepared by loading PX on a silica gel plate. This study provides a new way for multi-analyte detection.

It is worth noting that Fe3+ is paramagnetic in nature. Thus, in most of the cases, Fe3+ behave as fluorescent quencher which makes it difficult to develop a fluorescent ‘turn-on’ chemosensor. Therefore, it is still a big challenge to devise and synthesise a simple chemosensor that could selectively detect Fe3+ via fluorescent ‘turn-on’ response. In this paper, A simple fluorescence chemosensor T based on N,N-(3,3-dimethyl biphenyl)-bis(2-methoxyphenol) has been synthesised. T could selectively detect Fe3+ via fluorescent ‘turn-on’ response. Meanwhile, the fluorescent spectrum limit of T towards Fe3+ was 0.178 nM, the detection limit was much lowest than previously reported fluorescent chemosensor and has reached to ultrasensitive level. In addition, T could also alternately detect CN−. Intriguingly, IMPLICATION logic gate was successfully constructed. Finally, the test papers and films based on T were prepared, which could be used as a fluorescent display material for the detection of Fe3+ and CN−. In this article, a simple chemosensor (T) for ultrasensitive fluorescent ‘turn-on’ detection of Fe3+ and alternant detection of CN− has been designed and synthesised. The fluorescent spectrum detection limit of T towards Fe3+ was 0.178 nM, the detection limit was much lowest than previously reported fluorescent chemosensor and has reached to ultrasensitive level. Based on the alternant detection property of T for Fe3+ and CN−, the fluorescent ‘ON-OFF-ON’ responding circle, IMPLICATION logic gate and test kits were constructed and prepared successfully, showing potential for practical applications in the detection of metal ions, toxic ions as well as smart material aspects.

A novel bis-component AIE-gel TG was facilely constructed from two "easy-to-synthesize" tripodal gelators by a simple host-guest self-assembly process. Interestingly, the TG shows strong aggregation-induced emission (AIE) and could be used for highly efficient and sensitive detection and separation of ions (CN-, Fe3+ and H2PO4-). The LODs (limits of lowest detection) of TG for CN-, Fe3+ and H2PO4- are in the range of 4.93 × 10-9-7.80 × 10-8 M. Meanwhile, the xerogel of TG could adsorb and separate Fe3+ from aqueous solutions, and the adsorption rate is 96%. In addition, a thin film based on the TG could act as a convenient test kit for the detection of CN- and Fe3+. What is more, the TG-Fe film could not only be used as an erasable secure fluorescent display material, but also as a convenient reversible H2PO4- test kit.

A novel supramolecular aggregation induced emission (AIE) π-gel (ONT) was constructed by using a functionalized trimesic amide (TCP) molecule assembled with a bis-pyridine functionalized naphthalene diimide (ND) molecule using a non-covalent interaction. The ONT showed strong AIE at 468 nm. Furthermore, the ONT could detect and adsorb ferric (Fe3+) or cupric (Cu2+) ions from water. Meanwhile, a thin film based on supramolecular AIE π-gel ONT was prepared, which could be used as a fluorescent security display material for detecting Fe3+ or Cu2+. Thus, the AIE π-gel ONT shows potential for practical applications in efficient multi-analyte detection and separation and as a fluorescent display material.

A novel bis-component AIE-gel TG was facilely constructed from two "easy-to-synthesize" tripodal gelators by a simple host-guest self-assembly process. Interestingly, the TG shows strong aggregation-induced emission (AIE) and could be used for highly efficient and sensitive detection and separation of ions (CN

A series of stable super metal hydrogels (TP-Ms, M = Tb3+, Eu3+, La3+ and Ce3+) with a low critical gelation concentration (2.28 × 10−3 M, 0.1%) was successfully constructed by forming hierarchical assemblies of a tripodal gelator (TP) with rare earth metal ions (Tb3+, Eu3+, La3+ and Ce3+). Interestingly, the super metal hydrogels TP-Eu and TP-La show a specific and ultrasensitive response to histidine (His). The addition of a series of amino acids into the metal hydrogels TP-Eu and TP-La showed that only His could induce distinct fluorescent enhancement for TP-Eu and TP-La, while other amino acids did not significantly interfere with the His sensing process. The LODs of super metal–hydrogel TP-Eu and TP-La for His are (1.83–1.94) × 10−9 and (1.83–1.85) × 10−9 M, respectively. In addition, constructing super supramolecular metal hydrogels by hierarchical assemblies of an easily synthesized tripodal gelator and rare earth metal ions is a novel and efficient approach to the design and development of multi-functional super supramolecular metal hydrogel-based materials.

Multi-functional supramolecular fluorescent materials are an intriguing concern for materials science. Herein, an easily prepared bi-component hydrogel with strong aggregation-induced emission (AIE) (MQ-G) was successfully constructed by the gelators naphthalimide derivative (M) and tri-(pyridine-4-yl)-functionalized trimesic amide (Q) in DMSO-H2O (6 : 4, v/v) via π−π, hydrogen bond and π−electron donor-acceptor interactions. The obtained bi-component hydrogel MQ-G has an excellent self-healing property. Interestingly, the MQ-G exhibits strong orange AIE, the fluorescence quantum yield of the MQ-G was measured as 0.578. Moreover, the MQ-G could successively sense Fe3+ and H2PO4− in water through a fluorescent “ON-OFF-ON” pathway, which suggests the MQ-G could serve as an “ON-OFF-ON” fluorescent material and efficient logic gate. Meanwhile, the xerogel of MQ-G is capable of removing Fe3+ at an adsorption rate of 99.74% in diluted aqueous solution. Moreover, the thin films based on the MQ-G and MQ-G + Fe3+ were also prepared, which could not only act as supramolecular fluorescent material but a simple and efficient tool for detection Fe3+ and H2PO4−, respectively.