In Silico Studies and Design of Scrupulous Novel Sensor for Nitro Aromatics Compounds and Metal Ions Detection.

A Novel calix[4]pyrrole system bearing carboxylic acid functionality [ABuCP] has been synthesized and its interaction towards various nitroaromatics compounds [NACs] were investigated. ABuCP showed significant color change with 1,3-dinitro benzene (1,3-DNB) in comparison to the solution of other nitroaromatic compounds such as 2,3-dinitro toluene (2,3-DNT), 2,4-dinitro toluene (2,4-DNT), 2,6-dinitro toluene (2,6-DNT), 4-NBB (4-nitrobenzyl bromide) and 4-nitro toluene (4-NT). The ABuCP-1,3-DNB complex produces a red shift in absorption spectra based on charge transfer mediated recognition. Additionally, the density functional theory calculation confirmed the possible mechanism for the binding of 1,3-DNB as a guest is well supported by the calculation of other parameters such as hardness, stabilization energy, softness, electrophilicity index and chemical potential. The TDDFT calculation facilitates the understanding of the proper binding mechanism in reference to experimental results. Additionally we have also developed its derivative which acts as a new fluorescent sensor which can selectively recognize Sr(II) ions. In this view its aminoanthraquinone derivative of calix[4]pyrrole i.e. ABuCPTAA is synthesized which also results in generation of high fluorescence capability sensor.

Functionalized Silver Nanoparticles as Colorimetric and Fluorimetric Sensor for Environmentally Toxic Mercury Ions: An Overview.

Nanoscience is a multifaceted field which encompasses metal nanoparticles (MNPs) having novel and size-related optical properties significantly different from the bulk level as well as at the atomic level. Amongst noble MNPs, the silver nanoparticles (AgNPs) have unique properties for metal interaction. Presently, there have been expedite reports which are taken under the review in virtue of sensing the mercury ions in aqueous media. Mercury dissemination in various forms contaminates the ecosystem. Globally mercury is ranked as the most toxic element and an urgent threat to humans since it causes major health issues. Employing MNPs, especially AgNPs for the detection of mercury ions is the economic, handy and apt method in contrast to time-consuming methods that use expensive instrumentations. The review highlights a study of colorimetric and fluorimetric detection of the level of Hg (II) ions in aqueous media selectively with high sensitivity in different courses of conditions using AgNPs synthesized by various approaches. Graphical abstract.

A switch-off fluorescence probe towards Pb(II) and cu(II) ions based on a calix[4]pyrrole bearing amino-quinoline group.

A new fluorescence receptor calix[4]pyrrole-N-(quinoline-8-yl) acetamide (CAMQ) containing a pyrrolic ring connected via the meso-position was synthesized, purified and characterized by elemental analysis, NMR and mass spectroscopy. This compound was examined for its fluorescence properties towards different metal ions e.g. Ag(I), Hg(II), Co(II), Ca(II), Ni(II), Zn(II), Cr(II), Ba(II), Fe(II), Cu(II), Pb(II)and Mg(II) ions by spectrophotometry and spectrofluorometry. It was concluded that the compound (CAMQ) possessed significantly enhanced selectivity for Pb(II) and Cu(II) ions in dimethyl sulfoxide (DMSO) even at very low concentrations (1 µM). It exhibit 'turn-on' fluorescence when exposed to Pb(II) and Cu(II) and did so in preference to other metal ions. The binding constants, stoichiometry and quantum yields have been determined. The quenching mechanism was assessed using the Stern-Volmer equation and was also discussed.

Calix receptor edifice; scrupulous turn off fluorescent sensor for Fe(III), Co(II) and Cu(II).

Novel Supramolecular fluorescence receptor derived from calix-system i.e. calix[4]resorcinarene bearing dansylchloride as fluorophore was designed and synthesized. The compound was purified by column chromatography and characterized by elemental analysis, NMR and Mass spectroscopy. Tetradansylated calix[4] resorcinarene (TDCR) shows a boat conformation with C(2)v symmetry. The complexation behaviour of metal cations [Ag(I), Cd(II), Co(II), Fe(III), Hg(II), Cu(II), Pb(II), Zn(II), U(VI) (1 × 10(-4) M)] with tetra dansylated calix[4]resorcinarene (1 × 10(-6) M) was studied by spectophotometry and spectrofluorometry. Red shift in the absorption spectra led us to conclude that there is strong complexation Fe(III), Co(II) and Cu(II) with TDCR. These metal cations also produce quenching with red shifts in the emission spectra. The maximum quenching in emission intensity was observed in the case of Fe(III) and its binding constant was also found to be significantly higher than that of Co(II) and Cu(II). Quantum yield of metal complexes of Fe(III) was found to be lower in comparison with Co(II) and Cu(II) complexes. Stern Volmer analysis indicates that the mechanism of fluorescence quenching is either purely dynamic, or purely static.

An efficient one pot synthesis of water-dispersible calix[4]arene polyhydrazide protected gold nanoparticles--a "turn off" fluorescent sensor for Hg[II] ions.

In the present study, we report the synthesis of aqueous stable gold nanoparticles by using calix[4]arene polyhydrazide (CPH) as both reducing and capping agents. The calix[4]arene polyhydrazide reduced gold nanoparticles (CPH-AuNps) were characterized by UV/Vis, particle size analyzer (PSA) and transmission electron mictroscopy (TEM). The records confirmed high stability of CPH-AuNps in aqueous solution over a long period of time and even at varied pH. Additionally, CPH-AuNps have been investigated for its application as "Turn Off" fluorescent sensor for Hg[II]. A concentration of Hg[II] in the limit of 10 nM to 10 microM can be detected based on fluorescence quenching of the CPH-AuNPs and it was also concluded from the spectroscopic data that CPH-AuNPs possess excellent selectivity to Hg[II] over several metal ions like Pb[II], Cu[II], Cd[II], Mn[II], Zn[II] and Ni[II].

Gamma Radiation Processed Polymeric Materials for High Performance Applications: A Review.

The polymeric properties are tailored and enhanced by high energy radiation processing, which is an effective technique to tune the physical, chemical, thermal, surface, and structural properties of the various thermoplastic and elastomeric polymeric components. The gamma and electron beam radiation are the most frequent radiation techniques used for crosslinking, compatibilizing, and grafting of various polymer blends and composites systems. The gamma radiation-induced grafting and crosslinking are the effective, rapid, clean, user-friendly, and well-controlled techniques for the polymeric materials for their properties improvement for high performance applications such as nuclear, automobile, electrical insulation, ink curing, surface modification, food packaging, medical, sterilization, and health-care in a different environment. Similarly, electron beam radiations crosslinking has been a well-known technique for properties development and has economic benefits over chemical crosslinking techniques. This review focuses on the development of polymeric multi component systems (functionalized polymer, blends, and nanohybrids), where partially nanoscale clay incorporation can achieve the desired properties, and partially by controlled high energy radiations crosslinking of blends and nanocomposites. In this review, various investigations have been studied on the development and modifications of polymeric systems, and controlled dose gamma radiation processed the polymer blends and clay-induced composites. Radiation induced grafting of the various monomers on the polymer backbone has been focused. Similarly, comparative studies of gamma and electron beam radiation and their effect on property devlopment have been focused. The high energy radiation modified polymers have been used in several high performance sectors, including automotive, wire and cable insulation, heat shrinkable tube, sterilization, biomedical, nuclear and space applications.

Highly stable antibacterial silver nanoparticles as selective fluorescent sensor for Fe³âº ions.

Calix[4]resorcinarene polyhydrazide (CPH) protected water dispersible fluorescent silver nanaoparticles (AgNps) were prepared by one-pot method using water soluble CPH and AgNO3. (CPH) bearing hydrazide group on its periphery acts as a reducing agent and its web type of structure as a stabilizing agent for the formation of calix protected silver nanoparticles (CPH-AgNps). CPH-AgNps were found to be highly stable over 120 days at room temperature and at varied pH. CPH-AgNps were characterized by UV/Vis-spectroscopy, particle size analyzer (PSA), transmission electron microscopy (TEM) and Energy dispersive X-ray analysis (EDX). Duly characterized nanoparticles were explored for their application as sensitive and selective fluorescent chemosensors for various metal ions. It was found that nanoparticles were selective and sensitive only for Fe(3+) ions with the linear range of detection from 0.1 µM to 10 µM. CPH-AgNps were also found to exhibit good antimicrobial activity when compared with standard Chloramphenicol. The selectivity and antimicrobial activity of CPH-AgNps suggests its potential use as a sensor for Fe(III) ions in ecosystems prone to industrial pollution and as an antimicrobial agent in biological applications.

Highly stable water dispersible calix[4]pyrrole octa-hydrazide protected gold nanoparticles as colorimetric and fluorometric chemosensors for selective signaling of Co(II) ions.

Water dispersible stable gold nanoparticles (AuNps) have been synthesized by using calix[4]pyrrole octa-hydrazide (CPOH) as a reducing as well as stabilizing agent. CPOH-AuNps have been characterized by surface plasmon resonance, particle size analyzer and transmission electron microscopy. CPOH-AuNps are water dispersible, highly stable for more than 150 days at neutral pH with a size of less than 10nm and zeta potential of 15±2 MeV. Ion sensing property of CPOH-AuNps has been investigated for various metal ions Pb(II), Cd(II), Mn(II), Fe(III), Ni(II), Zn(II), Hg(II), Co(II) and Cu(II) by colorimetry and spectrofluorimetry. Among all the metal ions investigated, only Co(II) ions gives sharp colour change from ruby red to blue and is easily detectable by naked-eye. CPOH-AuNps being fluorescent in nature also shows great sensitivity and selectivity for Co(II) ions. Co(II) ions can be selectively detected at very low concentration level of 1 nM in a facile way of fluorescence quenching.