Ion recognition properties of 2,2'-bibenzimidazole regulated by ammonium-modified pillar[5]arenes.

With the increasing issues of environmental degradation and health problem, the selective detection of toxic ions has attracted considerable attention from researchers. Chemical fluorescent sensors with the advantages of facile operation, high sensitivity, rapid response, and easy visualization are emerging as powerful detection tools towards ions. However, the selective recognition of ions is always hindered by the presence of other interfering substances. Herein, we show that supramolecular host-guest interaction based on a pillar[5]arene provides a new opportunity to regulate the ionic recognition properties of guest molecules. A pillar[5]arene-based host-guest complex HG was constructed through the host-guest interaction between ammonium functionalized pillar[5]arene (HAP5) and 2,2'-bibenzimidazole (G). The host-gust complex HG can realize the successive, highly selective, and sensitive detection of specific ions. It was found that only in the presence of HAP5, the sensitivity towards cations was evidently enhanced, and selective successive recognition for I- and HSO4- was achieved. Those results indicate that the introduction of HAP5 can effectively improve the ion recognition performance of 2,2'-bibenzimidazole, so it is a feasible strategy using supramolecular host-guest interaction to regulate the ionic recognition properties of guest molecules.

A Two-Step Fluorescence-Resonance Energy Transfer System Constructed by Platinum(II) Metallacycle Based Molecular Recognition.

Considerable progress in the construction of efficient fluorescence-resonance energy transfer (FRET) systems has promoted the development of artificial energy transfer materials. However, despite recent advances, the exploration of efficient and easy strategies to fabricate novel supramolecular systems with FRET activities is still a challenge. Here, we report that a two-step FRET system was successfully achieved, driven by platinum metallacycle based host-guest interactions. The two-step FRET system is used for the preparation of a white-light-emitting diode and serves as a nanoreactor for the photosynthetic process. This work offers a strategy for the fabrication of FRET systems and opens opportunities for functional materials constructed by platinum(II) metallacycle based host-guest interactions.

Fulvivirga marina sp. nov. and Fulvivirga sediminis sp. nov., two novel Bacteroidetes isolated from the marine sediment.

Two novel, designated strains 29W222T and 2943T, were isolated from the marine sediment from Aoshan Bay, Jimo, PR China. Growth was observed at pH 6.0-8.5 (optimum, pH 7.5) for strain 29W222T, and pH 5.5-8.5 (pH 7.0) for strain 2943T. Both strains displayed growth in 0.5-6 % NaCl with an optimum at 1 % for 29W222T; 0.5 % for 2943T. Both strains grew optimally at 33 °C. The results of phylogenetic analyses based on 16S rRNA gene sequences indicated that 29W222T and 2943T represented members of the genus Fulvivirga and strain 29W222T was most closely related to Fulvivirga kasyanovii KMM 6220T (97.9 % sequence similarity) and Fulvivirga imtechensis AK7T (95.0 %), and 2943T to Fulvivirga imtechensis AK7T (95.7 %) and Fulvivirga kasyanovii KMM 6220T (94.8 %). The genomic DNA G+C contents of 29W222T and 2943T were 39.9 and 37.7 mol%, respectively. The results of chemotaxonomic analysis indicated that the sole respiratory quinone was menaquinone 7 (MK-7), and the major fatty acid was iso-C15 : 0 for both strains. Average nucleotide identity and average amino acid identity values between strain 29W222T and Fulvivirga kasyanovii KMM 6220T were 78.9 and 83.6 %, respectively; the corresponding values between 2943T and Fulvivirga imtechensis AK7T were 69.8 and 63.6 %, respectively. Therefore, strains 29W222T and 2943T represent to two novel species of the genus Fulvivirga, for which the names Fulvivirga marina sp. nov. (29W222T=KCTC 62848T=MCCC 1K05194T) and Fulvivirga sediminis sp. nov. (2943T=KCTC 62847T= MCCC 1K05144T) are proposed, respectively.

An Organoplatinum(II) Metallacycle-Based Supramolecular Amphiphile and Its Application in Enzyme-Responsive Controlled Release.

Enzyme-responsive nanomaterials are emerging as important candidates for bioanalytical and biomedical applications due to their good biocompatibilities and sensitivities. However, the lack of promising operation platforms compatible with enzyme responsiveness greatly limits the scope and functionality of smart materials. Herein, we report the design and synthesis of a naphthalene-functionalized organoplatinum(II) metallacycle 1 by means of coordination-driven self-assembly, which is subsequently exploited as the organometallic platform to enable enzyme-responsive supramolecular materials. Specifically, a [2 + 2] self-assembled metallacycle 1 first self-assembles into nanosheets in aqueous solution, which can further transform into vesicles with the introduction of ß-cyclodextrin (ß-CD) because of the formation of a bola-type supramolecular amphiphile ß-CD-1. Interestingly, these vesicles show rare α-amylase responsiveness, as demonstrated by structurally transforming back into nanosheets after the addition of α-amylase to their solutions due to the enzyme-induced degradation of cyclodextrins. We also demonstrate the potential application of the self-assembled vesicles in amylase-responsive controlled release.

Fluorinated leaning pillar[6]arene: synthesis, structure and selective iodide anion binding by anion-π interactions.

Anion recognition has continuously attracted significant attention due to its important role in environmental and biological sciences. Here, we have designed and synthesized an electron-deficient fluorinated leaning pillar[6]arene 1 that contains two tetrafluoro-benzene units. The electron-deficient fluorinated leaning pillar[6]arene 1 is capable of selectively recognizing iodide anions to form a host-guest complex with 1 : 1 stoichiometry driven by anion-π interactions. Our work ascribes this selective recognition to the preorganization of macrocycles, suitable cavity size, and the effect of anion-π interactions. The innovative application of this macrocycle offers us a new avenue for the design of selective receptors for anions and electron-deficient macrocyclic arenes.

CT and MRI findings of intra-parenchymal and intra-ventricular schwannoma: a series of seven cases.

OBJECTIVE: To analyze the computed tomography (CT) and magnetic resonance imaging (MRI) features of patients with intra-parenchymal and intra-ventricular schwannoma. METHODS: The CT and MRI features of seven cases with intra-parenchymal and intra-ventricular schwannoma were analyzed retrospectively. RESULTS: There were four men and three women (median age, 25 years; range, 12-42 years) in this study. The median tumor size was 4.4 cm (range, 3.1-6.5 cm). The mass was, respectively, round in four cases (57.1%), lobulated in two cases (28.6%) and oval in one case (14.3%). All tumors were well-circumscribed. Septa in the mass could be observed in three cases (42.9%), and nodular calcification was observed in two cases (28.6%), which peritumoral edema (n = 3, 42.9%) and hydrocephalus (n = 3, 42.9%) could be observed. Most of these lesions (n = 6) presented iso-hypointensity on T1-weighted images and iso-hyperintensity on T2-weighted images, except one lesion showing low intensity on T2WI. In addition, a fluid-fluid level was observed in one case. After contrast agents' injection, all masses illustrated heterogeneously moderate to marked enhancement. CONCLUSIONS: A well-defined solid and cystic mass with calcification and moderate to marked delayed enhancement may be an objective account of intra-parenchymal or intra-ventricular schwannoma.

A simple pillar[5]arene assembled multi-functional material with ultrasensitive sensing, self-healing, conductivity and host-guest stimuli-responsive properties.

Multi-functional materials have received wide attention due to their potential applications in various fields; therefore, developing a simple and easy strategy for the preparation of multi-functional materials is an interesting issue. In this work, a novel supramolecular gel, TP-QG, has been successfully constructed via the assembly of a simple methoxyl-pillar[5]arene host (TP) and a tripodal (tri-pyridine-4-yl)-amido-benzene guest (Q). Interestingly, TP-QG could act as a multi-functional material and showed strong fluorescence, good self-healing, host-guest stimuli-responsiveness and conductive properties. Due to these properties, TP-QG shows a fascinating application prospect. For instance, TP-QG could exhibit ultrasensitive fluorescence response for Fe3+ and F- in water via the fluorescence "ON-OFF-ON" pathway; the lowest detection limit (LOD) of TP-QG for Fe3+ was 2.32 × 10-10 M and the LOD of TP-QG-Fe for F- was 4.30 × 10-8 M. These properties permit TP-QG to act as not only a Fe3+ and F- sensor, but also an "ON-OFF-ON" fluorescence display material and an efficient logic gate. Meanwhile, the xerogel of TP-QG could remove Fe3+ from water, and the adsorption ratio was 98.68%; the xerogel of TP-QG-Fe could also remove F- from water; the removal ratio was about 87.92%. This work provides a feasible way to construct multi-functional smart materials by host-guest assembly.

Metal-Free White Light-Emitting Fluorescent Material Based on Simple Pillar[5]arene-tripodal Amide System and Theoretical Insights on Its Assembly and Fluorescent Properties.

The booming of host-guest assembly-based supramolecular chemistry provides abundant ways to construct functional systems and materials. Attracted by the important application prospect of white light emission and aggregation-induced emission (AIE) materials, herein, we report an efficient way for fabricating metal-free white light-emitting AIE materials through the supramolecular assembly of simple organic compounds: methoxyl pillar[5]arene (MP5) and tri-(pyridine-4-ylamido)benzene (TAP). By host-guest assembly, MP5 and TAP formed a supramolecular polymer (MP5-T); meanwhile, the MP5-T xerogel powder emitted white light at CIE coordinates (0.29 and 0.29). The supramolecular assembly and white light-emitting mechanisms were carefully investigated by experiments as well as quantum chemical calculations including density functional theory (DFT), reduced density gradient, electrostatic surface potential, independent gradient model, and frontier molecular orbital (highest-occupied molecular orbital-lowest-unoccupied molecular orbital) analyses. Interestingly, according to the experiments and calculations, the supramolecular assembly is critical in the white light-emitting phenomenon. Moreover, in this work, the quantum chemical calculations could not only support experimental phenomena but also provide deep understanding and visualized presentation of the assembly and emission mechanism. In addition, the obtained MP5-T solid powder could serve as a novel and easy means to make material for white light-emitting devices.

A fluorescent supramolecular gel and its application in the ultrasensitive detection of CN- by anion-π interactions.

Supramolecular gels have been widely reported on account of their unique superiority and application prospects. In this work, we constructed a novel supramolecular gel (HD-G) by using hydroxy-naphthaldehyde decorated with naphthalimide in DMSO solution, which exhibited excellent selectivity and ultrasensitive sensing properties toward CN- (the lowest detection limit is 1.82 × 10-10 M). The sensing mechanism of this supramolecular gel takes advantage of π-π stacking interactions and anion-π interactions, which is different from the other familiar methods.

Transparency and AIE tunable supramolecular polymer hydrogel acts as TEA-HCl vapor controlled smart optical material.

Stimuli-responsive optical materials attract lots of attention due to their broad applications. Herein, a novel smart stimuli-responsive supramolecular polymer was successfully constructed using a simple tripodal quaternary ammonium-based gelator (TH). The TH self-assembles into a supramolecular polymer hydrogel (TH-G) and shows aggregation-induced emission (AIE) properties. Interestingly, the transparency and fluorescence of the TH-G xerogel film (TH-GF) could be reversibly regulated by use of triethylamine (TEA) and hydrochloric acid (HCl) vapor. When alternately fumed with TEA and HCl vapor, the optical transmittance of the TH-GF was changed from 8.9% to 92.7%. Meanwhile, the fluorescence of the TH-G shows an "ON/OFF" switch. The reversible switching of the transparency and the fluorescence of the TH-GF is attributed to the assembly and disassembly of the supramolecular polymer TH-G. Based on these stimuli-response properties, the TH-GF could act as an optical material and shows potential applications as smart windows or fluorescent display material controlled by TEA and HCl vapor.

A rhodamine-based dual chemosensor for the naked-eye detection of Hg2+ and enhancement of the fluorescence emission for Fe3.

A novel fluorescent chemosensor based on trimesoyl chloride-rhodamine (TR) was successfully synthesized. Rising chromogenic and fluorogenic spectral enhancements could be observed in trimesoyl chloride-rhodamine (TR) probes when Hg2+ and Fe3+ were added, respectively. TR has shown selectivity for Hg2+ and Fe3+ with high sensitivity due to metal ion complexation induced photophysical "turn-on" signaling responses. The detection limit towards Hg2+ was 2.46 × 10-8 M as determined by the 3σ method. At the same time, fluorogenic spectral enhancements were observed in TR, which exhibits a superior sensitive and selective recognition towards Fe3+ with 4.11 × 10-8 M of the detection limit. The test strips were used for colorimetric and simple detection towards Hg2+, which might finally enable the advancement of the Hg2+ sensor in the field of on-site detection.

Tailoring an HSO4- anion hybrid receptor based on a phenazine derivative.

A catechol-functionalized phenazine imidazole (PD) was tailored with 2,3-diaminophenazine and 3,4-dihydroxy benzaldehyde, and it served as a hybrid acceptor for capturing HSO4- anions. The selectivity and sensitivity of the PD receptor for anion sensing were studied. It was found that the PD receptor could not only display a preferable sensitivity to HSO4- ions with a "turn-off" fluorescence response, but also have a strong anti-interference ability toward other common anions, especially basic anions such as CH3COO-, HPO42-, and H2PO4-. The anion recognition mechanism of PD towards HSO4- is based on multiple hydrogen bond interactions. Finally, the strips for anion detection were prepared, which were verified to be a convenient and high-efficiency test kit for detecting HSO4- ions with the naked eye.

N-(2-Aminoethyl)-2-(hexylthio) Acetamide-Functionalized Pillar[5]arene for the Selective Detection of l-Trp through Guest-Adaptive Multisupramolecular Interactions.

Tryptophan (Trp) is very necessary for biosystems; therefore, high-efficient detection of Trp is an important subject. Hereof, based on our early research works on fluorescent sensors, we rationally designed and synthesized a fluorescent sensor (SNP5) based on N-(2-aminoethyl)-2-(hexylthio) acetamide-functionalized pillar[5]arene, which showed high selectivity and sensitive recognition for l-Trp (LOD = 2.19 × 10-8 M). Moreover, SNP5 exhibited aggregation-induced emission enhancement fluorescence. Within SNP5, the pillar[5]arene group could act as N-H···π- and C-H···π-interaction sites, as well as a H-bond-interaction site; meanwhile, the N-(2-aminoethyl)-2-(hexylthio) acetamide group also served as a multihydrogen-bonding site. As a result, SNP5 could selectively detect l-Trp through the synergy of the pillar[5]arene group and the N-(2-aminoethyl)-2-(hexylthio) acetamide group. Compared with previous work, the results of this work support the strategy that changing the functionalized group of the pillar[5]arene can adjust the selectivity of the pillar[5]arene-based sensor and achieve the detection of different amino acids. The detection mechanism was specifically researched through experiments and theoretical calculations including frontier orbitals, electrostatic potential, and the independent gradient model approach. Interestingly, these theoretical calculations not only supported the experimental results but also provided a visualized understanding of guest-adaptive multisupramolecular interactions between SNP5 and l-Trp.

Pillar[5]arene-based spongy supramolecular polymer gel and its properties in multi-responsiveness, dye sorption, ultrasensitive detection and separation of Fe3.

Herein, a novel way to design and construct multi-functional spongy supramolecular polymer gels through an easy to make tripodal guest (TA) and a naphthalimide functionalized-pillar[5]arene host (AP5) has been developed. According to this approach, a novel pillar[5]arene-based supramolecular polymer gel (SHG) was constructed via multi-non-covalent interactions such as host-guest inclusion, C-Hπ, ππ and hydrogen bonds and so on. Interestingly, the SHG exhibits a spongy structure and strong aggregation induced emission (AIE). Furthermore, the SHG also exhibited multi-responsiveness toward outer stimuli such as heating-cooling, pH, competitive agents and mechanical. More importantly, the SHG xerogel shows separation properties for Fe3+, methyl orange, methylene blue and sudan I dyes. The separation rates of SHG xerogel for Fe3+ ions and organic dyes can reach up to 99.8%. Simultaneously, the SHG could ultrasensitively detect Fe3+ (LOD is 0.9 nM). In addition, a thin film based on SHG was also prepared, which was confirmed to be a convenient test kit for detecting Fe3+.

Super metal hydrogels constructed from a simple tripodal gelator and rare earth metal ions and its application in highly selective and ultrasensitive detection of histidine.

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.

A bi-component supramolecular gel for selective fluorescence detection and removal of Hg2+ in water.

A bi-component supramolecular gel (RQ) was successfully constructed by the assembly of the gelators 4-aminophenyl functionalized naphthalimide derivative (R) and tri-(pyridine-4-yl)-functionalized trimesic amide (Q) in DMSO-H2O (6.1 : 3.9, v/v) binary solution. The gel RQ exhibits excellent self-healing capacity. Interestingly, the RQ could fluorescently detect and reversibly remove Hg2+ from water through cation-π interactions with high selectivity, efficient adsorption and quick response. The limit of lowest detection (LOD) of the RQ for Hg2+ is 4.52 × 10-8 M and the separation ratio is 91.14%. Moreover, the RQ could be efficiently recycled and regenerated with little loss via a simple treatment by I-. Notably, thin films based on RQ and RQ + Hg2+ were prepared, which could serve as convenient and efficient test tools for the detection of Hg2+ and I-, respectively. This work provided an efficient method and novel supramolecular gel material for the separation and detection of Hg2+.

An azine-containing bispillar[5]arene-based multi-stimuli responsive supramolecular pseudopolyrotaxane gel for effective adsorption of rhodamine B.

An azine-containing bispillar[5]arene was designed and synthesized by the reaction of aldehyde functionalized-pillar[5]arene and hydrazine. Then, a novel bispillar[5]arene-based supramolecular pseudopolyrotaxane has been successfully prepared via host-guest interaction. Interestingly, by taking advantage of the host-guest interactions, π-π stacking interactions and hydrogen bonding interactions, the multi-stimuli-responsive gel-sol phase transitions of such a supramolecular pseudopolyrotaxane gel were successfully realized under different stimuli, such as acid, temperature, concentration, and competitive guests. Moreover, this supramolecular system could effectively adsorb dye molecule rhodamine B. It is worth noting that this supramolecular pseudopolyrotaxane gel prepared in cyclohexanol solution (BP5·G·C) could be used as an adsorbent material for adsorbing rhodamine B with adsorption efficiency of 98.4%. Meanwhile, the adsorption efficiency was 97.6% for supramolecular pseudopolyrotaxane gel prepared in DMSO-H2O (v : v, 8 : 2) binary solution (BP5·G·D), also indicating the superior adsorption effect of BP5·G·D toward the dye molecule rhodamine B.

A novel supramolecular AIE π-gel for fluorescence detection and separation of metal ions from aqueous solution.

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 AIE-based supramolecular polymer gel serves as an ultrasensitive detection and efficient separation material for multiple heavy metal ions.

Recently, ultrasensitive stimuli-responsive materials have received extensive attention due to their high sensitivity and wide applications. Herein, we report a novel approach to design ultrasensitive responsive materials by rationally introducing the aggregation-induced emission (AIE) effect into supramolecular polymer gels. According to this approach, by rationally introducing self-assembly moieties and a fluorophore, the obtained gelator DNS can act as an AIEgen; it showed strong AIE after aggregating into the supramolecular polymer gel GDNS. More interestingly, because the aggregation of DNS led to amplification of the detective signal, the AIE-based supramolecular polymer gel GDNS could ultrasensitively detect the heavy metal ions Hg2+, Cu2+, and Fe3+ by a signal amplification mechanism; the lowest detection limits reached 10-11 M. In addition, the xerogel of GDNS could adsorb and separate Hg2+, Cu2+, and Fe3+ from aqueous solution with favourable adsorption properties, and the adsorption rates ranged from 94.70% to 99.37%. Furthermore, the gel GDNS could act as a convenient test kit for Hg2+, Cu2+, and Fe3+ as well as a smart fluorescent display material.

Aggregation-induced emission supramolecular organic framework (AIE SOF) gels constructed from tri-pillar[5]arene-based foldamer for ultrasensitive detection and separation of multi-analytes.

In this study, a novel aggregation-induced emission supramolecular organic framework (AIE SOF) with ultrasensitive response, termed FSOF, was constructed using a tri-pillar[5]arene-based foldamer. Interestingly, benefiting from the noise signal shielding properties of FSOF as well as the competition between the cationπ and ππ interactions, the FSOF shows an ultrasensitive response for multi-analytes, such as Fe3+, Hg2+ and Cr3+. The limits of detection (LODs) of the FSOF for Fe3+, Hg2+ and Cr3+ are in the range of 9.40 × 10-10-1.86 × 10-9. More importantly, the xerogel of FSOF exhibits porous mesh structures, which could effect high-efficiency separation above metal ions from their aqueous solution, with adsorption percentages in the range 92.39-99.99%. In addition, by introducing metal ions into the FSOF, a series of metal ions coordinated supramolecular organic frameworks (MSOFs) were successfully constructed. Moreover, MSOFs show selective fluorescence "turn on" ultrasensitive detection CN- (LOD = 2.12 × 10-9) and H2PO4- (LOD = 1.78 × 10-9). This is a novel approach to construct SOFs through a tri-pillar[5]arene-based foldamer, and also provides a new way to achieve ultrasensitive detection and high-efficiency separation.