Viren Mehta

A turn-off fluorescence sensor for insensitive munition using anthraquinone-appended oxacalix[4]arene and its computational studies

Herein, a fluorescent oxacalix[4]arene-based receptor, DAQTNOC(5,17-di(N-(9,10-dioxo-9,10-dihydroanthracen-1-yl)acetamide) tetranitrooxacalix[4]arene), was described for the specific recognition of N-methyl-p-nitroaniline (MNA). Among the array of explosives, DAQTNOC shows selective behaviour for MNA in the absorption and as well as emission spectra. The binding constants, stoichiometry, quantum yields, and fluorescence quenching were determined to elucidate the inclusion behaviour. Furthermore, computational insights were rendered for studying the stability and spectroscopic analysis of the inclusion complex using docking, molecular dynamics simulations, and density functional theory (DFT) along with time-dependent density functional theory (TD-DFT). The calculations considerably complement the findings and elucidate the structural geometry and mode of interactions in supramolecular complexation. Herein, we observed that DAQTNOC was selectively stabilized by van der Waals forces and hydrophobic contacts with MNA to generate a low-energy complex. These findings are of wide interest, especially because MNA is a well-known insensitive munition and has been detected for the first time via an oxacalixarenes platform.

Turn-off fluorescence probe for the selective determination of pendimethalin using a mechanistic docking model of novel oxacalix[4]arene

A novel bidansylated oxacalix[4]arene (BDO) fluoroionophore for the selective determination of pendimethalin (PM) was carried out in the linear range of detection between 0.4 μM and 20 μM. Furthermore, computational studies were performed to assess the binding and stability of the complex. For the predicted model, PM faces laterally and interacts via weak intermolecular forces with BDO with a E value of −176.00 kJ mol−1.

Catalytic activity of recyclable resorcinarene-protected antibacterial Pd nanoparticles in C-C coupling reactions

Abstract Novel tetra-methoxy resorcinarene tetra-hydrazide (TMRTH) has been synthesized and used as a reducing agent and a capping agent for the synthesis of water-dispersible stable palladium nanoparticles (PdNPs). The TMRTH-PdNPs were characterized by UV-Vis spectroscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and powder X-ray diffraction. The synthesized nanoparticles are polydispersible with a size of 5 ± 2 nm and were found to be recyclable over five cycles maintaining a catalytic activity in the Suzuki-Miyuara cross-coupling reaction. The nanocatalyst was superior in catalytic performance to conventional palladium catalysts with respect to reaction time, catalyst loading and recyclability. TMRTH-PdNPs show promise for their use in biological applications as they exhibit good antibacterial activity against gram-positive bacteria.

Efficiently functionalized oxacalix[4]arenes: Synthesis, characterization and exploration of their biological profile as novel HDAC inhibitors.

A series of novel substituted oxacalix[4]arene has been synthesized and explored for their biological profile by evaluating anticancer, antifungal and antibacterial properties. The derivatives have been characterized by various spectroscopic techniques such as IR, (1)H NMR, (13)C NMR and Mass spectrometry. Many compounds showed strong inhibition (MIC) in the range of ∼0-50 μM with interesting cytotoxic activities against Hela cells in particular. The compounds were theoretically evaluated by docking studies as potential histone deacetylase inhibitors (HDACi). The study indicates that compounds bound adequately with HDAC, and hence complemented the experimental findings.

Sensing of Ce(III) using di-naphthoylated oxacalix[4]arene via realistic simulations and experimental studies

Here, we report a fluorescent sensor for the detection of Ce(III) using di-naphthoylated oxacalix[4]arene (DNOC). Formation of the DNOC-Ce(III) complex has been confirmed by 1H NMR and mass spectroscopic observations. A dramatic decrease in the emission intensity of DNOC is observed for Ce(III) with no competitive interference due to other divalent and trivalent ions. The linear range of detection was obtained over a concentration range between 18 nM and 2 μM. Furthermore, density functional theory (DFT)-based quantum mechanical calculations were executed to predict the most probable structure of the host–guest system. As the molecular geometry suggests, the nitro groups of DNOC bent and the naphthoyl groups (oxygen centres of alternate calixarene rings) stabilize the cerium inclusion complex in the 1,3-alternate conformation. Thus, a novel analytical approach has been developed for Ce(III) detection using the oxacalixarene framework in solution. Moreover, the selective behaviour of DNOC also facilitates new opportunities for determining Ce(III) in a wide range of real samples.