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The current study describes the chemical identification, antimicrobial, and mosquito larvicidal activities of essential oils from Meistera caudata and Conamomum vietnamense, growing in Vietnam. Essential oils were extracted from the leaves and rhizomes, and characterized by the GC-FID/MS (gas chromatography-flame ionization detection/mass spectrometry) analysis. Monoterpenes (33.1–89.2 %) were the main chemical class found in these oils. β-Pinene (30.8 %) and α-pinene (23.8 %) were two major compounds in M. caudata leaf oil. C. vietnamense leaf and rhizome essential oils were dominated by 1,8-cineole (47.9–62.0 %) and limonene (10.3–16.2 %). With the same MIC (minimum inhibitory concentration) value of 25 μg/mL, C. vietnamense leaf and rhizome essential oils strongly inhibited the growth of Gram-positive bacteria Staphylococcus aureus ATCC 29213 and Bacillus subtilis ATCC 6501, respectively. For 24 and 48-h treatments, C. vietnamense leaf essential oil strongly controlled the growth of mosquito Aedes aegypti with the respective LC50 values of 7.67 and 6.73 μg/mL, and the respective LC90 values of 13.37 and 10.83 μg/mL. In the same manner, C. vietnamense rhizome essential oil also showed strong mosquito larvicidal activity against Aedes albopictus with the LC50 values of 12.37 and 12.00 μg/mL, and the LC90 values of 20.56 and 18.58 μg/mL, respectively. C. vietnamense essential essential oils containing a high amount of 1,8-cineole are generally better than M. caudata essential essential oils in both two biological assays.

Heavy metal contamination in the environment due to anthropogenic activities in industrial and agricultural areas represents stress for the living ecosystem including soil microorganisms. The adaptive response of bacterial communities to these pollutants can be observed through the increasing proportion of resistant bacteria. Our study aimed at evaluating the effect of metal contamination to the emergence of bacteria resistant to 3 common antibiotics, ie., gentamycin, sulfamethoxazole, and norfloxacin in Tan Long Pb-Zn mining site, Thai Nguyen province by a culture-dependent approach. The results showed that under moderated Pb contamination, a significant increase in prevalence of gentamycin-resistant bacteria was observed. Antibiotic susceptibility test showed 45% of isolates resistant to at least two antibiotics among gentamycin, norfloxacin, tetracyclin, imipenem, andsulfamethoxazole, and 10.4 % of isolates resistant tho three antibiotics. More detailed investigations in molecular analysis are needed to identify and genetically characterize of multi-drug resistant isolates as well as to better understand the link between metal resistance and (multi)resistance to antibiotics.

The hydro-distilled essential oil from the fresh aerial part of Orchidantha vietnamica K. Larsen collected from Lamdong-Vietnam was analyzed by GC-FID (Gas Chromatography-Flame Ionization Detection) and GC-MS (Gas Chromatography-Mass Spectroscopy) for the first time. The oil was characterized by the presence of volatile compounds type terpenoids, in which oxygenated monoterpenes (30.04 %) and sesquiterpene hydrocarbons (37.32 %) are the major components. The oxygenated monoterpene linalool reached the highest percentage of 16.66 %, followed by the sesquiterpene hydrocarbons (E)-caryophyllene (11.4 %), α-humulene (8.00 %), and bicyclogermacrene (6.93 %). Monoterpene hydrocarbons, oxygenated sesquiterpenoids, oxygenated diterpenes, carotenoids, and others are also detected in this oil (< 3.00 %). The essential oil of O. vietnamica aerial part showed antimicrobial activity against two pathogenic bacterial strains Escherichia coli ATCC 8739 and Candida albicans ATCC 10231 with the same MIC (Minimum Inhibitory Concentration) value of 200 µg/mL.

The current report describes the chemical investigation and biological activity of extracts produced by three fungal strains Fusarium oxysporum, Penicillium simplicissimum, and Fusarium proliferatum isolated from the roots of Piper nigrum L. growing in Vietnam. These fungi were namely determined by morphological and DNA analyses. GC-MS identification revealed that the EtOAc extracts of these fungi were associated with the presence of saturated and unsaturated fatty acids. These EtOAc extracts showed cytotoxicity towards cancer cell line HepG2, inhibited various microbacterial organisms, especially fungus Aspergillus niger and yeast Candida albicans (the MIC values of 50-100 µg/mL). In α-glucosidase inhibitory assay, they induced the IC50 values of 1.00-2.53 µg/mL were better than positive control acarbose (169.80 µg/mL). The EtOAc extract of F. oxysporum also showed strong anti-inflammatory activity against NO production and PGE-2 level. Four major compounds linoleic acid (37.346%), oleic acid (27.520%), palmitic acid (25.547%), and stearic acid (7.030%) from the EtOAc extract of F. oxysporum were selective in molecular docking study, by which linoleic and oleic acids showed higher binding affinity towards α-glucosidase than palmitic and stearic acids. In subsequent docking assay with inducible nitric oxide synthase (iNOS), palmitic acid, oleic acid and linoleic acid could be moderate inhibitors.

A bifunctional glycoside hydrolase GH78 from the ascomycete Xylaria polymorpha (XpoGH78) possesses catalytic versatility towards both glycosides and esters, which may be advantageous for the efficient degradation of the plant cell-wall complex that contains both diverse sugar residues and esterified structures. The contribution of XpoGH78 to the conversion of lignocellulosic materials without any chemical pretreatment to release the water-soluble aromatic fragments, carbohydrates, and methanol was studied. The disintegrating effect of enzymatic lignocellulose treatment can be significantly improved by using different kinds of hydrolases and phenoloxidases. The considerable changes in low (3 kDa), medium (30 kDa), and high (> 200 kDa) aromatic fragments were observed after the treatment with XpoGH78 alone or with this potent cocktail. Synergistic conversion of rape straw also resulted in a release of 17.3 mg of total carbohydrates (e.g., arabinose, galactose, glucose, mannose, xylose) per gram of substrate after incubating for 72 h. Moreover, the treatment of rape straw with XpoGH78 led to a marginal methanol release of approximately 17 μg/g and improved to 270 μg/g by cooperation with the above accessory enzymes. In the case of beech wood conversion, the combined catalysis by XpoGH78 and laccase caused an effect comparable with that of fungal strain X. polymorpha in woody cultures concerning the liberation of aromatic lignocellulose fragments.

We studied zircon U-Pb geochronology, Sr-Nd-Hf isotopes, and whole-rock geochemistry of Mesoarchean-Paleoproterozoic igneous rocks in the Phan Si Pan zone, NW Vietnam. The Mesoarchean-Paleoproteroz...

Herein, a novel fluorescent sensor has been developed for the detection of biothiols based on theoretical calculations of the stability constant of the complex between a Cu2+ ion and (E)-3-((2-(benzo[d]thiazol-2-yl)hydrazono)methyl)-7-(diethylamino) coumarin (BDC) as a fluorescent ligand. In this study, on the basis of density functional theory method, the Gibbs free energy of ligand-exchange reaction and the solvation model were carried out using thermodynamic cycles. The obtained results are in good agreement with the experimental data. The BDC–Cu2+ complex can be used as a fluorescent sensor for the detection of biothiols in the presence of non-thiol containing amino acids, with a detection limit for cysteine at 0.3 μM. Moreover, theoretical calculations of excited states were used to elucidate variations in the fluorescence properties. The computed results show that the excited doublet states D2 and D1 are dark doublet states, which quench the fluorescence of the complex.

CdMoO4/g-C3N4/GO composites were first synthesized by a hydrothermal process for the photocatalytic degradation of rhodamine B (RhB) under visible light illumination. The findings show that CdMoO4 is highly dispersed onto g-C3N4 and graphene oxide (GO) sheets. The surface area of the composite increased 27–30.5 times that of CdMoO4, and its band gap energy decreased by about 1.26 times. These features significantly improve the photocatalytic activity of the composite in the RhB decomposition reaction under visible light. The RhB degradation efficiency of the CdMoO4/g-C3N4/GO composite is 5.7, 1.36, and 1.65 times that of CdMoO4, CdMoO4/g-C3N4, and CdMoO4/GO composites, respectively. The active species trapping experiments show that the main forms in RhB degradation are •O2– , •OH, and h+. The stability of the photocatalyst is retained even after the 5th reuse. In addition, RhB degradation products were identified with the high-performance liquid chromatography-mass spectrometry method, and the pathway of photocatalytic degradation was also addressed.

Essential oils of the leaves of 4 Vietnamese Zingiberaceae species were first obtained by hydro-distilled, and their chemical compositions were identified by gas chromatography-flame ionization detection/mass spectrometry . β-Pinene (21.7%), sabinene (12.8%), and α-pinene (8.0%) were the main compounds in Wurfbainia tenella leaf oil. The essential oil of Hedydium villosum var. tenuifolium leaf was dominated by β-pinene (23.7%), β-caryophyllene (21.6%), and 1,8-cineole (14.0%). β-Pinene (27.4%), α-pinene (21.2%), limonene (12.1%), and myrcene (8.6%) were the characteristic components of Meistera sudae leaf oil, and β-pinene (32.8%) and ( E)-methyl cinnamate (15.8%) of Alpinia hongiaoensis leaf oil. The 4 oil samples exhibited antimicrobial activity against Bacillus subtilis (American Type Culture Collection [ATCC] 27212), Staphylococcus aureus (ATCC 12222), Escherichia coli (ATCC 8739), Pseudomonas aeruginosa (ATCC 25923), Aspergillus niger (ATCC 9763), Fusarium oxysporum (ATCC 48112), Candida albicans (ATCC 10231), and Saccharomyces cerevisiae (ATCC 2601) at different levels. Especially, the leaf oil of M sudae showed strong activity against B subtilis, S aureus, and S cerevisiae with a minimum inhibitory concentration (MIC) value of 25.0 µg/mL.

The bacterial communities of Caulerpa lentillifera were studied during an outbreak of an unknown disease in a sea grape farm from Vietnam. Clear differences between healthy and diseased cases were observed at the order, genus, and Operational Taxonomic Unit (OTU) level. A richer diversity was detected in the diseased thalli of C. lentillifera, as well as the dominance of the orders Flavobacteriales (phylum Bacteroidetes) and Phycisphaerales (Planctomycetes). Aquibacter, Winogradskyella, and other OTUs of the family Flavobacteriaceae were hypothesized as detrimental bacteria, this family comprises some well‐known seaweed pathogens. Phycisphaera together with other Planctomycetes and Woeseia were probably saprophytes of C. lentillifera. The Rhodobacteraceae and Rhodovulum dominated the bacterial community composition of healthy C. lentillifera. The likely beneficial role of Bradyrhizobium, Paracoccus, and Brevundimonas strains on nutrient cycling and phytohormone production was discussed. The bleaching of diseased C. lentillifera might not only be associated with pathogens but also with an oxidative response. This study offers pioneering insights on the co‐occurrence of C. lentillifera‐attached bacteria, potential detrimental or beneficial microbes, and a baseline for understanding the C. lentillifera holobiont. Further applied and basic research is urgently needed on C. lentillifera microbiome, shotgun metagenomic, metatranscriptomic, and metabolomic studies as well as bioactivity assays are recommended., The co‐occurrence of bacteria in sea grape (green caviar) Caulerpa lentillifera under two health state conditions was studied. The role of potentially detrimental and beneficial bacteria was discussed. A baseline for understanding the C. lentillifera holobiont was presented.

SummaryThe bacterial communities of the sea grape Caulerpa lentillifera were studied during a disease outbreak in Vietnam. The Rhodobacteraceae and Rhodovulum dominated the composition of healthy C. lentillifera. Clear differences between healthy and diseased cases were observed at order, genus and Operational Taxonomic Unit (OTU) level. Bacterial diversity was lower in healthy C. lentillifera, probably because of antimicrobial compounds from the macroalgae and/or from Clostridium, Cutibacterium or Micrococcus bacteria. The likely beneficial role of Bradyrhizobium, Paracoccus and Brevundimonas strains on nutrient cycling and phytohormone production was discussed. The white coloration of diseased C. lentillifera may not only be associated with pathogens but also with an oxidative response. Aquibacter, Winogradskyella and other OTUs of the family Flavobacteriaceae were hypothesized as detrimental bacteria, this family comprises some well-known seaweed pathogens. Moreover, Thalassobius OTU 2935 and 1635 may represent detrimental Rhodobacteraceae. Phycisphaera together with other Planctomycetes and Woeseia were probably saprophytes of C. lentillifera. This study offers pioneering insights on the co-occurrence of C. lentillifera-attached bacteria, potential detrimental or beneficial microbes, and a baseline for understanding the C. lentillifera holobiont. Further metagenomic and biotechnological approaches are needed to confirm functions of some microbes on this macroalgae to enhance food security in the tropics.

A bifunctional glycoside hydrolase GH78 from the ascomycete

Chemical investigation of the Kappaphycus alvarezii-derived endophytic fungus Aspergillus micronesiensis lead to the isolation of three novel dibenzospiroketals, aspermicrones A-C (1-3). Their chemical structures were determined by extensive analysis of HR-ESI-MS and NMR spectral data. The absolute configurations of them were determined by experimental and TD-DFT theoretical calculated circular dichroism spectra. Compound 2 exhibited selective cytotoxic effect toward HepG2 cell line (IC50 = 9.9 μM). Additionally, both of compounds 2 and 3 displayed anti-microbial activity against Staphylococcus aureus (MIC = 123.2 μM for each compound). Compound 1 was inactivity in both cytotoxic and antimicrobial assays. Fil: Luyen, Nguyen Dinh. Vietnam Academy of Science and Technology; Vietnam. Graduate University of Science and Technology; Vietnam Fil: Huong, Le Mai. Vietnam Academy of Science and Technology; Vietnam. Graduate University of Science and Technology; Vietnam Fil: Thi Hong Ha, Tran. Vietnam Academy of Science and Technology; Vietnam Fil: Cuong, Le Huu. Vietnam Academy of Science and Technology; Vietnam Fil: Thi Hai Yen, Duong. Institute of Marine Biochemistry; Vietnam Fil: Nhiem, Nguyen Xuan. Graduate University of Science and Technology; Vietnam. Institute of Marine Biochemistry; Vietnam Fil: Tai, Bui Huu. Graduate University of Science and Technology; Vietnam. Institute of Marine Biochemistry; Vietnam Fil: Gardes, Astrid. Leibniz Centre for Tropical Marine Research; Alemania Fil: Kopprio, Germán Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentina. Leibniz Centre for Tropical Marine Research; Alemania Fil: Van Kiem, Phan. Graduate University of Science and Technology; Vietnam. Institute of Marine Biochemistry; Vietnam

Essential oils of two Asteraceae plants Blumea riparia DC. and Pluchea pteropoda Hemsl. ex Hemsl., collected from Vietnam, have been studied by hydro-distillation and GC/MS-FID (gas chromatography/mass spectrometry-flame ionization detector) analysis. Oil yields of B. riparia fresh leaves and twigs were in the range of 0.1–0.2%, whereas essential oil in the fresh aerial parts of P. pteropoda reached about 0.5%. Sesquiterpene hydrocarbons and oxygenated sesquiterpenes were the main chemical classes in the essential oils of B. riparia. The leaves and twigs of this species gave essential oils containing germacrene D (33.6-42.6%), ( E)-β-caryophyllene (11.2-11.6%), and bicyclogermacrene (9.3-12.1%) as the major components. Oxygenated monoterpenes and sesquiterpene hydrocarbons achieved the highest amounts in the essential oil of P. pteropoda aerial parts; 2,5-dimethoxy- p-cymene (43.5%), β-maaliene (14.0%), and α-isocomene (9.0%) were characteristic compounds. Particularly, as compared with related Blumea and Pluchea species, B. riparia and P. pteropoda, collected from Vietnam, might be good sources of germacrene D and 2,5-dimethoxy- p-cymene, respectively. The essential oil of B. riparia leaf successfully controlled the growth of the fungus Fusarium oxysporum, with an MIC value of 50.0 µg/mL, and the essential oil of P. pteropoda aerial parts showed significant antimicrobial activity against the Gram positive bacterium Bacillus subtilis and the yeast Candida albicans, with the same MIC value of 50.0 µg/mL.

The composition of the bacterial community of carrageenophyte-attached and planktonic bacteria was studied in two bays of Vietnam with contrasting anthropogenic inputs to assess their role as ecological indicators. Clear differences (~73% dissimilarity) between carrageenophyte-attached bacteria and bacterioplankton were detected in terms of genus composition: mainly Agaribacter, Ruegeria, Alteromonas, the Pir4 lineage and Vibrio for the carrageenophytes and Candidatus Actinomarina, HIMB 11, NS groups and SAR clades for the bacterioplankton. The copiotrophic nature, potential for complex-polymer degradation, and ability to form and defend biofilms were common features inferred for the carrageenophyte-attached microbiome. Significant differences between the bays were detected in the concentration of most inorganic nutrients. More eutrophic conditions and presumptive wastewater pollution in Cam Ranh (CR) bay were primarily indicated by the dominance of Rubripirellula, Leptobacterium, Hypnocyclicus and Porphyrobacter and their correlations with phosphate. In terms of bacterioplankton, the influence of intensive aquaculture in CR bay was suggested by the dominance of the NS5 and NS4 marine groups, the SUP05 cluster, Flavobacteriaceae unclassified and SAR 11 clade III as well as their strong correlations with ammonium and phosphate. The link between silicate and other inorganic nutrients suggests freshwater input in CR bay. Arenicellaceae unclassified and Formosa were also potential indicators of eutrophication. Operational taxonomic units (OTUs) of Marinagarivorans, Cobetia, Vibrio, Alteromonas and Pseudoalteromonas were typical of the carrageenophytes showing ice-ice disease symptoms. Vibrio and Alteromonas were also common among healthy macroalgae, and differences at the OTU level suggested potential succession of species from the healthy to the diseased state. The probable beneficial roles of some bacteria, such as Ruegeria, Cutibacterium and unidentified members of the family Rhizobiaceae, were discussed. This study provides pioneering insights into the bacterial community composition of carrageenophytes and highlights their ecological value as strong indicators of the sources of organic matter, anthropogenic impacts and health status of marine systems. Fil: Kopprio, Germán Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentina. Leibniz - Institute of Freshwater Ecology and Inland Fisheries; Alemania. Vietnam Academy of Science and Technology. Institute of Natural Product Chemistry; Vietnam Fil: Cuong, Le Huu. Vietnam Academy of Science and Technology. Graduate University of Science and Technology; Vietnam. Vietnam Academy of Science and Technology. Institute of Natural Product Chemistry; Vietnam Fil: Luyen, Nguyen Dinh. Vietnam Academy of Science and Technology. Graduate University of Science and Technology; Vietnam. Vietnam Academy of Science and Technology. Institute of Natural Product Chemistry; Vietnam Fil: Duc, Tran Mai. Vietnam Academy of Science and Technology. Nhatrang Institute of Technology Research and Application; Vietnam Fil: Ha, Tran Hong. Vietnam Academy of Science and Technology. Graduate University of Science and Technology; Vietnam Fil: Huong, Le Mai. Vietnam Academy of Science and Technology. Institute of Natural Product Chemistry; Vietnam. Vietnam Academy of Science and Technology. Graduate University of Science and Technology; Vietnam Fil: Gärdes, Astrid. Leibniz - Institute of Freshwater Ecology and Inland Fisheries; Alemania. University of Applied Sciences; Alemania. Alfred-Wegener-Institut. Helmholtz-Zentrum für Polar und Meeresforschung; Alemania

In the present paper, the composite of zeolite imidazolate framework-11 (ZIF-11) and activated carbon derived from rice husks (RHAC) was synthesized. The obtained materials were characterized by XRD, SEM, EDX-mapping, and nitrogen adsorption/desorption isotherms. The final composite ZIF-11/RHAC exhibits an even dispersion of ZIF-11 particles on activated carbon matrix. Herein, an electrochemical sensor based on a ZIF-11/RHAC was developed for a rapid determination of triclosan (TCS). It was found that the oxidation of TCS is irreversible and involves the transfer of one electron. The linear range for TCS detection in the optimized experimental conditions was found to be 0.1-8 μM with the limit of detection of 0.076 μM. Finally, the proposed method was successfully employed to detect TCS in different personal care product samples with high accuracy, which was confirmed by a good agreement between these results and those obtained using high-performance liquid chromatography (HPLC).

Supplemental material, sj-pdf-1-chl-10.1177_17475198211043439 for Synthesis of pyrophosphate analogues and their cytotoxic activities by Van-Tai Nguyen, Minh-Quan Pham, Thi-Ha Vu, Thi-Hong-Ha Tran, Duy-Tien Doan, Dinh-Luyen Nguyen, Phong Le and Van-Chinh Luu in Journal of Chemical Research

Herein, a novel fluorescent sensor has been developed for the detection of biothiols based on theoretical calculations of the stability constant of the complex between a Cu

In recent years, a considerable number of studies on the role of microbes in agarwood production have been carried out in plants of the species Aquilaria. Based on the fact that there is a relationship between the microorganisms residing inside the plant and the agarwood formation, we isolated and characterized endophytic fungi associated with A. crassna samples collected from Southern Vietnam. Morphological identification and DNA barcoding analysis of the fungal endophytic isolates indicated that they were classified at least into three groups of diverse genera: Geotrichum, Fusarium and Colletotrichum belonging to families Dipodascaceae, Nectriaceae and Glomerellaceae, respectively. Noteworthy, Geotrichum candium strain SHTr1 isolated from a dark colored woody sample of agarwood was able to produce a fruity odor and exhibited a slight antimicrobial activity against the test bacterium Staphylococcus aureus. Another fungal isolate, Fusarium verticillioides SHTr3’s, showed a moderate antimicrobial activity against a test Gram positive bacteria Bacillus subtillis and S. aureus with MIC values at 50 μg.mL-1. At 200 μg.mL-1, the ethyl acetate extracts of fungal isolates F. verticillioides SHTr3 and Colletotrichum truncatum SHTrHc7 were found to have comparable scavenging abilities on DPPH-free radicals with 53.87 and 71.82%, respectively. The present results contribute to a depiction of a diverse fungal endophytic community in Vietnamese agarwood plant A. crassna and provide important information for further understanding of the role of endophytic fungi in agarwood formation and therapeutic applications of host plants in general.

A new rhodamine-ethylenediamine-nitrothiourea conjugate (RT) was synthesized and its sensing property as a fluorescent chemodosimeter toward metal ions was explored in water media. Analytical results from absorption and fluorescence spectra revealed that the addition of Hg(2+) ions to the aqueous solution of the chemodosimeter RT caused a distinct fluorescence OFF-ON response with a remarkable visual color change from colorless to pink; however, no clear spectral and color changes were observed from other metal ions including: Zn(2+) , Cu(2+) , Cd(2+) , Pb(2+) , Ag(+) , Fe(2+) , Cr(3+) , Co(3+) , Ni(2+) , Ca(2+) , Mg(2+) , K(+) and Na(+) . The sensing results and the molecular structure suggested that a Hg(2+) -induced a desulfurization reaction and cyclic guanylation of the thiourea moiety followed by ring-opening of the rhodamine spirolactam in RT are responsible for a distinct fluorescence turn-on signal, indicating that RT is a remarkably sensitive and selective chemodosimeter for Hg(2+) ions in aqueous solution. Hg(2+) within a concentration range from 0.1 to 25 μM can be determined using RT as a chemodosimeter and a detection limit of 0.04 μM is achieved.

The rising claim for more environmental friendly and healthy agriculture is a strong incentive to find alternative strategies to replace the use of mineral fertilizer and pesticide. Arbuscular mycorrhizal fungi (AMF), a main component of soil microbiota, represent a promising tool as providers of key ecological services. The present work represented one of the first attempts to study, under a morphological and molecular point of view, the AMF communities associated to some strategic crops in Vietnam. The findings about the AMF morphotypes dominant in different crop systems could be a starting point for the development of well performing and adapted inocula suitable for the application in field.

A new rhodamine-ethylenediamine-nitrothiourea conjugate (RT) was synthesized and its sensing property as a fluorescent chemodosimeter toward metal ions was explored in water media. Analytical results from absorption and fluorescence spectra revealed that the addition of Hg(2+) ions to the aqueous solution of the chemodosimeter RT caused a distinct fluorescence OFF-ON response with a remarkable visual color change from colorless to pink; however, no clear spectral and color changes were observed from other metal ions including: Zn(2+) , Cu(2+) , Cd(2+) , Pb(2+) , Ag(+) , Fe(2+) , Cr(3+) , Co(3+) , Ni(2+) , Ca(2+) , Mg(2+) , K(+) and Na(+) . The sensing results and the molecular structure suggested that a Hg(2+) -induced a desulfurization reaction and cyclic guanylation of the thiourea moiety followed by ring-opening of the rhodamine spirolactam in RT are responsible for a distinct fluorescence turn-on signal, indicating that RT is a remarkably sensitive and selective chemodosimeter for Hg(2+) ions in aqueous solution. Hg(2+) within a concentration range from 0.1 to 25 μM can be determined using RT as a chemodosimeter and a detection limit of 0.04 μM is achieved.

We prepared an aminothiourea-derived Schiff base (DA) as a fluorescent chemosensor for Hg2+ ions. Addition of 1 equiv of Hg2+ ions to the aqueous solution of DA gave rise to an obvious fluorescence enhancement and the subsequent addition of more Hg2+ induced gradual fluorescence quenching. Other competing ions, including Pb2+, Cd2+, Cr3+, Zn2+, Fe2+, Co3+, Ni2+, Ca2+, Mg2+, K+ and Na+, did not induce any distinct fluorescence changes, indicating that DA can selectively detect Hg2+ ions in aqueous solution. Copyright © 2012 John Wiley & Sons, Ltd.

A new rhodamine-derived Schiff base (RS) was synthesized and its sensing property to metal ions was investigated by UV/vis and fluorescence spectroscopies. Addition of Hg2+ ions to the aqueous solution of RS gave a visual color change as well as significantly fluorescent enhancement, while other ions including Pb2+, Cd2+, Cr3+, Zn2+, Cu2+, Fe2+, Co3+, Ni2+, Ca2+, Mg2+, K+ and Na+ ions did not induce any distinct color/spectral changes, which constituted a Hg2+-selective fluorescent OFF–ON chemosensor. The Hg2+-induced ring-opening of spirolactam of rhodamine in RS resulted in the dual chromo- and fluorogenic observation.