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Imidazole and imine-linked dipodal receptors were decorated on the surface of ZnO nanoparticles. Cation binding assays of these chemosensors showed that receptors 5 and 6 had high selectivity for Al(III) and Zn(II) ions, respectively. The detection limit for Al(III) with receptor 5 was 11 nM, and the detection limit for Zn(II) ion with receptor 6 was 23 nM. [ABSTRACT FROM AUTHOR]

Abstract: A new sensor 1 bearing mixed imine and amide linkages is synthesized with simple condensation reaction of diode amine with catechol carbaldehyde. The amide linkages may define the receptor pseudo cavity as these linkages are generally considered to provide rigidity to receptor design. The imine linkages are expected to be responsible for providing binding site as well as fluorescent signaling sub-unit. The 1 is evaluated for their sensor activities in a diverse range of solvents and it has shown the selective binding affinity for Cs+. In order to evaluate the sensor activity in aqueous medium, fluorescent organic nanoparticles (FONs) of receptor 1 are formed using re-precipitation method. FONs of 1 has shown AIE phenomenon in aqueous medium with enhancement in fluorescence intensity at λ max = 412 nm. Fluorescence emission profiles of these FONs have shown some changes in low and high pH range; however it remains stable in pH range 4–9, thus making them appropriate to use in environmental/biological samples. To the best of our knowledge, 1is representing the first example of FONs as chemosensor for nanomolar detection of Cs+ in aqueous media. [Copyright &y& Elsevier]

Abstract: A tripodal receptor bearing phenol as a hydrogen bond donor site and azo dye as the signaling subunit was synthesized. The receptor had a high binding affinity for CN− as signaled by the change in the color of a solution of sensor 4 upon addition of CN−. Using UV–Vis spectroscopy, the system can be used to quantify 0–19×10−5 molL−1 of CN−, and the sensor was found to successfully function in the presence of other anions. [Copyright &y& Elsevier]

Abstract: We synthesized a novel receptor with benzimidazole moieties in a tripodal framework. The receptor displays rarely observed metal specific fluorescence enhancement at two different wavelengths. The receptor was investigated for the simultaneous analysis of Cu2+ and Fe3+ and successfully quantified the ions without interference over a wide concentration range. [Copyright &y& Elsevier]

Abstract: A novel benzthiazole-based fluorescent receptor was synthesized, and its anion recognition properties were compared with those of similarly designed benzimidazole-based receptors. The selectivity of this receptor for the recognition of dihydrogen phosphate is enhanced by employing hydrogen bonding, in which cooperative polarization effect to the carbonyl group of amide linkages is lacking. [Copyright &y& Elsevier]

Graphical abstract Highlights • A tripodal receptor R1 was used to explore the selective determination of Cu2+. • R1 in the presence of Cu2+ showed a fluorescence turn-on. • R1 –Cu2+ complex showed the selectivity for Br− with a fluorescence turn-off. Abstract A tripodal receptor R1 with a combination of nitrogen and oxygen-based binding sites was designed and used for the selective determination of Cu2+. The fluorescence emission profile of R1 in the presence of Cu2+ showed a marked enhancement in fluorescence intensity, indicating high selectivity among other metal ions. The R1 –Cu2+ complex was further explored as a sensor for anion detection. Upon addition of Br−, switching to a fluorescence "off" state was observed. The Br− selectivity of the complex over a wide range of concentrations was observed via titrimetric analysis through changes in the emission spectra. [ABSTRACT FROM AUTHOR]

Abstract: A new type of benzimidazole-based imine-linked fluorescence chemosensor for Zn2+ was synthesized. Coordination of Zn2+ with the receptor led to enhanced fluorescence while other metals quenched the receptor fluorescence. The resulting complex had a supramolecular assembly with a 1:1 host-guest ratio with variable size. The (1.Zn2+)n assembly showed high selectivity towards the complexation of L-cysteine even in the presence of other potentially competitive biologically important anionic species. [Copyright &y& Elsevier]

Abstract: The naphthalimide-based and imine coupled receptor has been synthesized and this receptor is evaluated for metal recognition properties. The Cu2+ and Co2+ recognition in the coordination sphere of receptor leads to a change in the photo-physical properties of receptor. The receptor and its metal complexes are evaluated for the cytotoxic activities and studies have led to construction of the molecular logic gate. [Copyright &y& Elsevier]

Abstract: We synthesized a benzthiazole-based chemosensor with mixed S,N donor sites. The binding units are incorporated in a highly flexible tripodal framework which facilitates the complexation of the binding of larger-sized metals. The chemosensor resulted in the sensitive and selective recognition of Ba2+ through the enhancement of the fluorescence intensity when studied in a THF/H2O (8:2, v/v) solvent mixture. The sensor offers an interesting opportunity to monitor Ba2+ in biological samples including the cytoplasm of microbes such as Saccharomyces cerevisiae. [Copyright &y& Elsevier]

• A benzothiazole-based heterodipodal chemosensor has been synthesized. • Cu2+ ions were detected in aqueous media using fluorescence spectroscopy. • Limit of detection for Cu2+ ions in aqueous media was in nanomolar range. • The Cu2+ complex of chemosensor recognized CN– anions in aqueous media. A simple and selective chemosensor, A , was developed for recognizing Cu2+. The emission spectra of receptor A showed a fluorescence quenching response upon addition of Cu2+ with a low detection limit of 4.51 nM, significantly less than the WHO recommended guideline for drinking water. In addition, the formed A∙ Cu2+ complex was examined for secondary sensing of anions. The A∙ Cu2+ complex showed selectivity for CN– via a recovering emission profile of A. [ABSTRACT FROM AUTHOR]

A benzimidazole-based dipodal receptor was designed and synthesized. The receptor recognized Cu 2+ ions selectively in an aqueous medium in the presence of other metal ions. The resultant complex displayed selective sensing ability toward H 2 PO 4 − via a metal displacement process. The detection limits of the receptor to Cu 2+ , and the resultant complex to H 2 PO 4 − , were calculated to be 9.76 and 1.41 μM, respectively. These values are sufficiently low indicating that this system shows good potential for application in biological and environmental sample analyses. [ABSTRACT FROM AUTHOR]

Anti-human immunodeficiency (HIV)-drug azidothymidine interferes with the reverse transcriptase enzyme, which results in reduced activity of HIV thereby inhibiting the growth of the virus. Owing to the side effects of high doses and short half-life of this antiviral drug azidothymidine (AZT): a fast and convenient method for its detection would be helpful for HIV patients getting treated with AZT. Referring to this, we synthesized a Biginelli based receptor R1 and evaluated its sensing properties towards AZT with different techniques (UV–Visible, circular dichroism (CD), cyclic voltammetry (CV) by preparing its organic nanoparticles (ONPs) and gold-coated ONPs (AuNP@ONP). The formation of AuNP@ONP was confirmed by UV–Visible spectroscopy, cyclic voltammetry, and HRTEM. It was observed that both the probes selectively sense AZT among various thymidine analogs but AuNP@ONP showed better response on CV, Differential pulse voltammetry (DPV) and, linear sweep voltammetry (LSV) with a detection limit of 6 nM. Proton NMR (1H NMR) reveals that the azide group present at the 3' position is responsible for the selective response of AZT with probes. Quantitative determination by the probes in the pharmaceutical sample gives the recovery percentage above 97%. Hence, economic, affordable, ready-to-use chemosensor for AZT (in an aqueous medium) with low detection limit having satisfactory utility for HIV supplements have been developed. We have developed gold nanoparticle based sensor system for the selective detection of Azidothymidine. [Display omitted] • First chromogenic/electrochemical receptor which can selectively determine Azidothymidine among different thymidine analogs. • Our receptor shows a good limit of detection value of 6 nM. • Selective sensing of Azidothymidine was done by three different parameters (UV–Vis, CD, CV) to ensure the binding. • All studies were performed in an aqueous medium to limit the use of organic solvent and promote green chemistry. [ABSTRACT FROM AUTHOR]

A colorimetric and fluorescent 'on-off' chemosensor 1 was developed for the selective and sensitive detection of Cu2+ over the other examined metal ions. Upon addition of Cu2+, sensor 1 exhibits moderate enhancement in the absorbance intensity with a naked-eye detectable colour change from colourless to yellow in DMSO/H2O (50:50, v/v). Also, the emission of 1 was selectively quenched in the presence Cu2+ with fast response and the detection limit was found to be 50 nM. [ABSTRACT FROM AUTHOR]

Abstract: The sensors have been developed using silver nanoparticles coated with organic ligands and are fully characterized with spectroscopic methods. The energy-dispersive X-ray (EDX) analysis revealed the presence of organic receptors on the surface of metal nanoparticles. These chemosensors were tested against a range of biological and environmentally relevant cations in the HEPES buffered DMSO/H2O (8:2, v/v) solvent system. The fluorescence intensity of these chemosensors was quenched upon coordination with open shell metal ions such as Cu2+/Fe3+. Anion recognition properties of the corresponding metal complexes have been studied and the original fluorescence intensity of sensors was restored upon addition of phosphate (0–20µM). Thus, a highly selective chemosensor has been devised for the micromolar estimation of phosphate in semi-aqueous medium. [Copyright &y& Elsevier]

Abstract: Imine linked “on–off” multi-responsive and selective chemosensor has been synthesized and evaluated for cation recognition properties. The receptor shows high sensitivity and selectivity for Zn2+ through changes in fluorescence intensity based on ESIPT and charge transfer (CT) mechanism. The Zn2+ complex of the receptor can be used for phosphate quantification and for recognition of phosphorylated biomolecules through cation displacement approach. [Copyright &y& Elsevier]

Abstract: A benzthiazole-based multifunctional chemosensor was designed with siderophores like binding sites for recognition of Fe3+ and both hydrogen bond donor and acceptor binding sites for oxyanion . The sensor recognizes Fe3+ selectively through enhancement of fluorescence emission intensity at 440 nm and recognizes through a bathochromic shift in UV–vis spectra from 315 nm to 365 nm with clear isosbestic points at 345 nm and 395 nm. The recognition of both Fe3+ and is free from the interference from the other cations and anions, respectively. [Copyright &y& Elsevier]

Abstract: A dipodal sensor detects Al3+ in HEPES buffered THF/H2O (7:3, v/v) through excited state proton transfer, representing a quenching at 355nm and enhancement at 480nm. The resulting aluminium complex (1.Al 3+ ) displays a highly selective response to perchlorate anion over other anions through the emergence of a new band at 428nm. The chemical inputs of Al3+ and ClO4 − satisfies the conditions of AND molecular logic gates and in a sequential manner generates an output which mimics the functions of a security keypad lock. [Copyright &y& Elsevier]

Abstract: A dipodal receptor bearing imine linkages is decorated on the surface of ZnO nano-particles. The cation recognition properties of pure dipodal receptor are compared with the assembly having same receptor decorated on ZnO. The remarkable changes in the recognition profile are established and the ZnO coated with dipodal receptor system authenticates its use as a sensitive and selective sensor for Mg2+ in semi-aqueous medium. The ZnO coated dipodal receptor can be used to recognize the Mg2+ in cells of Saccharomyces cerevisiae. [Copyright &y& Elsevier]

Abstract: Imine linked chemosensor has been synthesized and examined for cation recognition properties. The sensor shows strong affinity for Al3+ over other cations such as Na+, K+, Mg2+, Ca2+, Ba2+, Sr2+, Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+, Ag+, Hg2+, Pb2+, Zr4+, Th4+ and VO4+. The resultant Al3+ complex has been synthesized and characterized on the basis of elemental analysis, mass spectra, and IR spectra. The recognition behavior of this complex was tested towards various anions and the complex has offered an interesting opportunity for the ratiometric determination of HSO4 − in DMF/H2O (7:3, v/v) solvent system. This is the first Al3+ complex used for the ratiometric determination of HSO4 − in semi-aqueous medium. [Copyright &y& Elsevier]

Abstract: We synthesized an imine-linked, benzimidazole-based chemosensor that can be used for chromogenic recognition of Mg2+ and fluorescent recognition of Cr3+. The chemosensor shows sensitive, selective, and ratiometric recognition of Cr3+ through concurrent quenching at one wavelength and enhancement of fluorescence intensity at another wavelength. It can also be used to detect Mg2+ via UV–vis absorption spectroscopy. DFT calculations support these phenomena. The sensor can be used to strain microbe cells without breakage. [Copyright &y& Elsevier]

Abstract: A dipodal receptor was synthesized by condensation of isophthalaldehyde and p-toluenesulfonylhydrazide. The receptor was found to be selective for Cu2+ recognition in CH3CN. The resultant Cu2+ receptor complex selectively recognized iodide through cation displacement assay in a CH3CN/H2O (8:2, v/v) solvent system. [Copyright &y& Elsevier]

Organic nanoparticles (N1) were prepared by dispersing thiophene-conjugated rhodamine derivative 1 in a buffer solution (10 mM TRIS, pH 7.4, containing 1% DMSO, v /v). N1 selectively recognized Al3+ ions through the "OFF-ON" switching mechanism of the spirolactam ring in rhodamine. The resulting N1 ·Al3+ complex recognized the biologically important molecule adenosine monophosphate (AMP) through a cation displacement process with a detection limit of 2 nM. N1 was capable of determining the concentration of Al3+ ions in environmental and biological samples. Portable test strips of N1 were prepared for the recognition of Al3+ ions and AMP for practical uses. Furthermore, it was demonstrated that the N1 ·Al3+ complex facilitated real-time monitoring of AMP concentration in the hydrolysis of ATP and ADP. Unlabelled Image • Rhodamine-based organic nanoparticles N1 has been prepared. • Al3+ ions were detected in aqueous media using fluorescence spectroscopy. • N1 ·Al3+ ensemble recognized AMP with a detection limit of 2 nM. • N1 ·Al3+ ensemble was utilized for real-time monitoring AMP in the hydrolysis of ATP and ADP. [ABSTRACT FROM AUTHOR]