Nishith R. Modi

Ultrasensitive and specific detection of dimethoate using a p-sulphonato-calix[4]resorcinarene functionalized silver nanoprobe in aqueous solution

We demonstrate a facile strategy for preparing highly stable silver nanoprobe modified p-sulphonato-calix[4]resorcinarene in aqueous media. We also report the efficient and selective sensing properties of the novel assembly for organophosphorus insecticides and its great potential for application to real-time in situ detection of organophosphorus pesticides in waste water.

Azo calix[4]arene based neodymium(III)-selective PVC membrane sensor

We found that the PVC membrane, containing azo calix[4]arene is a suitable ionophore, exhibited a Nernstian response for neodymium (Nd(3+)) ions (with slope of 19.8±0.2 mV decade(-1) for the triply charged ion) over a wide linear range of 4.0×10(-8) to 1.0×10(-1) mol L(-1) with a detection limit 1.0×10(-8) mol L(-1), a relatively fast response time, in the whole concentration range (<10 s), and a considerable life time at least for four months in the pH range of 4.0-8.0. Furthermore, the electrode revealed high selectivity with respect to all the common alkali, alkaline earth, transition and heavy metal ions, including the members of the lanthanide family other than Nd(3+). Concerning its applications, it was effectively employed for the determination of neodymium ions in industrial waste water as well as in lake water.

Novel monohydrogenphosphate ion-selective polymeric membrane sensor based on phenyl urea substituted calix[4]arene.

A highly selective and sensitive PVC membrane, containing phenylurea substituted calix[4]arene was found to be a suitable ionophore for monohydrogen phosphate (HPO(4)(2-)) ions that exhibited a Nernstian response (with a slope of -29.4 ± 0.3 mV decade(-1)). The working concentration range of the electrode was 6.0 × 10(-8)-1.0 × 10(-1) mol L(-1) with a detection limit of 2.0 × 10(-8) mol L(-1). The response time of the sensor in the whole concentration range is very short (<8s), with a considerable lifetime of at least 15 weeks. The sensor possesses the advantages of short response time, low detection limit and a high selectivity towards a large number of inorganic anions. The developed sensor was used as an indicator electrode in potentiometric titration of monohydrogen phosphate ion with barium chloride. The proposed sensor was successfully applied for the direct determination of monohydrogen phosphate in real life samples.

Novel Cationic Quinazolin-4(3H)-one Conjugated Fullerene Nanoparticles as Antimycobacterial and Antimicrobial Agents

A series of novel cationic fullerene derivatives bearing a substituted‐quinazolin‐4(3H)‐one moiety as a side arm were synthesized using the 1,3‐dipolar cycloaddition reaction of C60 with azomethine ylides generated from the corresponding Schiff bases of substituted quinazolinones. The synthesized compounds 5a–f were characterized by elemental analysis, FT‐IR, 1H NMR, 13C NMR, and ESI‐MS and screened for their antibacterial activity against Mycobacterium tuberculosis (H37RV) and antimicrobial activity against selected Gram‐positive (Staphylococcus aureus and S. pyogenes) and Gram‐negative (Pseudomonas aeruginosa, Klebsiella pneumonia and Escherichia coli) bacterial and fungal strains (Candida albicans, Aspergillus clavatus, and A. niger), respectively. All the compounds exhibited significant activity, with the most effective compounds having MIC values and zones of inhibition comparable to those of standard drugs.

A highly efficient PET switch on–off–on fluorescence receptor based on calix[4]arene for the selective recognition of Cd2+ and Sr2+

A novel PET (photoinduced electron transfer) based substituted calix[4]arene fluoroionophore has been synthesized and used for the selective recognition of Cd(2+) and Sr(2+) by emission spectra. The detection limit of the synthesized receptor was found to be 0.94 pM for Cd(2+) and 1.04 pM for Sr(2+). Moreover, this probe has been applied to the recognition of Cd(2+) and Sr(2+) in waste water.

Effect of p-sulfonatocalix[4]resorcinarene (PSC[4]R) on the solubility and bioavailability of a poorly water soluble drug lamotrigine (LMN) and computational investigation

As a part of our research investigations to unfold the chemistry of calixresorcinarene, we studied the formation of an inclusion complex with p-sulfonatocalix[4]resorcinarene (PSC[4]R) of a poorly water soluble drug lamotrigine (LMN). The complete complexation of the drug was achieved after 48 h of stirring with PSC[4]R in water and evaporation of the water to give a solid complex. The inclusion complex between PSC[4]R and LMN was studied by different analytical techniques including FT-IR, PXRD and UV-VIS spectroscopy. The complexation was determined by thermal analysis and a phase solubility study. The prepared complexes exhibited improved in vitro dissolution profile and decreased in vivo acute oral toxicity compared to the pure drug. The results of the phase solubility experiments are in good conformity to signify the formation of 1 : 1 PSC[4]R : LMN complexes. Computational studies were performed to understand the intermolecular association of this inclusion complex using docking and short dynamic simulations. The purpose of this study was to enhance solubility resulting in high dissolution rate and bioavailability of this essentially poorly water soluble drug LMN.

Synthesis, mesomorphism and dielectric behaviour of novel basket shaped scaffolds constructed on lower rim azocalix[4]arenes

A newly designed series of lower rim azocalix[4]arene basket type mesogens were synthesised and fully characterized. The proposed supramolecular organization displays needle shaped, rod like, focal conic and schlieren textures. These compounds were studied for their dielectric properties in the frequency range 100 Hz–2 MHz at variable temperatures (50–110 °C).