Divya Sareen

Materials-based receptors: design principle and applications.

This review focuses on recent developments and growth potential in colorimetric and/or fluorimetric chemosensors based on rationally designed materials and suitable for use in highly selective and sensitive naked-eye detection of environmental and biological analytes.

Multi-signalling cation sensing behaviour of a bis(pyridin-2-yl methyl)aniline based hetarylazo dye.

We investigated the cation sensing behaviour of a bis(pyridin-2-yl methyl)aniline appended hetarylazo dye via chromogenic and electrochemical transduction channels. The binding pocket constituting both the pyridyl as well as aniline nitrogen atoms acts as recognition site for the cations and consequent perturbation in the intramolecular charge-transfer prevailing in the dye results in the chromogenic response manifested in the form of hypsochromic shift in the intramolecular charge-transfer band and the attendant naked-eye color changes. The dye exhibits significant changes in its electrochemical behaviour in the presence of cations. The experimental results are also rationalized by time-dependent density functional theory (TD-DFT) calculations.

Recent advances in meso-alkylidenyl carbaporphyrinoids

Porphyrins and their structural analogs have drawn continuous attention owing to their physico-chemical properties associated with biological, medical and material chemistry. Consequently, many structural modifications of the porphyrin skeleton have been reported as a fundamental tool for tuning the physico-chemical properties and a variety of new classes of porphyrinoids have emerged. A vast number of applications such as photodynamic therapy (PDT), redox catalysis, chemosensors, nonlinear optical material (NLO) and two photon absorption (TPA) have been studied utilizing these systems. The “so called” meso-alkylidenyl porphyrins have been reported recently as alternative modification methods of the porphyrin skeleton. These compounds possess one or more exocyclic double bonds at meso-positions and are usually non-aromatic systems. The reported spectroscopic as well as structural properties well-corroborate the non-aromatic nature of the macrocycles. However, the protonation behavior and tautomerism are quite different from those of normal porphyrins. Considering the unique properties of meso-alkylidenyl carbaporphyrinoid macrocycles, we present a review on the recent advances in this area of chemistry.

Host-guest complexation behaviour of emissive calix[3]naphthobipyrrole toward aromatic guests

ABSTRACT A new hexapyrrolic macrocycle composed of three naphthobipyrrole units has been synthesized which exhibited different emission changes with hydrogen pyrophosphate and benzoate ions. Phosphate ions caused red shifting of the fluorescence band of calixnaphthobipyrrole while benzoate ions resulted in quenching of the same. The fluorescence quenching was further utilized for investigating binding preferences of the probe with neutral aromatic guest molecules substituted with groups having varied electron withdrawing abilities. The extent of quenching with the neutral guests increased with the increasing electron deficiency on the aromatic ring of the guest. The fluorescence quenching has been ascribed to electron transfer from the host to the guest species. GRAPHICAL ABSTRACT