Kashipur Michael Madhusudhan Mahavidyalaya

Unusual self-sorting of an ion-pair under highly crowded conditions driven by a synthesized intelligent molecule 2-((E)-(3-((E)-2-hydroxy-3-methoxybenzylideneamino)-2-hydroxypropyl imino)methyl)-6-methoxyphenol, hereafter HBP, is described. When a mixture of various metal salts was allowed to react with HBP, only a specific ion-pair ZnII/AcO- in the solution simultaneously reacted, resulting in high-fidelity ion-pair recognition of HBP. This phenomenon was evidenced by significant changes in the absorption spectra and huge enhancement in emission intensity of HBP. The property that one molecule preferring one particular cation-anion pair over others is a rare but interesting phenomenon. Thus, the potential to interact selectively with the targeted ion-pair resulting in the formation of a specific complex recognized HBP as a new class of molecule that might find future applications in real time and on-site monitoring and separation of new molecules.

Harmine, an efficient cancer cell photosensitizer (PS), emits intense violet color when it is incorporated in well established self assembly based drug carrier formed by cationic surfactants of identical positive charge of head group but varying chain length, namely, dodecyltrimethylammonium bromide (DTAB), tetradecyltrimethylammonium bromide (TTAB) and cetyltrimethylammonium bromide (CTAB). Micelle entrapped drug emits in the UV region when it interacts with non-toxic β-cyclodextrin (β-CD). Inspired by these unique fluorescence/structural switching properties of the anticancer drug, in the present work we have monitored the interplay of the drug between micelles and non-toxic β-CDs. We have observed that the model membranes formed by micelles differing in their hydrophobic chain length interact with the drug differently. Variation in the surfactant chain length plays an important role for structural switching i.e. in choosing a particular structural form of the drug that will be finally presented to their targets. The present study shows that in case of necessity, the bound drug molecule can be removed from its binding site in a controlled manner by the use of non-toxic β-CD and it is exploited to serve a significant purpose for the removal of excess/unused adsorbed drugs from the model cell membranes. We believe this kind of β-CD driven translocation of drugs monitored by fluorescence switching may find possible applications in controlled release of the drug inside cells.

Carbazole (CZ) can act as a photo-switch leading to a multifunctional logic system when triggered by fluoride (F-) ions, H2O and light, through efficient interaction of the pyrrole unit with the anions. Here we are reporting a unimolecular platform of CZ (and case specific CZ-F-)that can be configured as NOT, YES, complimentary IMPLICATION and INHIBIT, a new complex logic gate performing IF-THEN and NOT operations and a memory element with cyclic "Erase-Read-Write-Read" ability with feedback loop mechanism. The fluorescence responses of the CZ system also have been exploited to design a potential highly secured molecular keypad lock operating with a purely opto-chemical password composed with optical and chemical input keys. The system displays the applications of light responsive molecules as multifunctional, reconfigurable molecular logic devices that may lead towards true molecular information processing units.

Fluoride ion sensing mechanism of 3,3′-bis(indolyl)-4-chlorophenylmethane has been analyzed with density functional and time-dependent density functional theories. Extensive theoretical calculations on molecular geometry & energy, charge distribution, orbital energies & electronic distribution, minima on potential energy surface confirmed strong hydrogen bonded sensor-anion complex with incomplete proton transfer in S0. In S1, strong hydrogen bonding extended towards complete ESDPT. The distinct and single minima on the PES of the sensor-anion complex for both ground and first singlet excited states confirmed the concerted proton transfer mechanism. Present study well reproduced the experimental spectroscopic data and provided ESDPT as probable fluoride sensing mechanism.

Interactions of Harmine (HM), as hydrogen bond donor with different anions as hydrogen bond acceptors were studied using spectroscopic and computational techniques. Significant gradual changes in absorption and emission spectra were observed upon addition of fluoride anions with selectivity. Wide-ranging theoretical calculations in association with the (HNMR)-H-1 titration in CDCl3 medium were performed to establish the binding decoration of HM with fluoride ion. Interaction energies, bond length variation, NBO charge transfer, NMR response, MEP 3D surface & 2D contour plot, UV-Vis spectral simulation, HOMO-LUMO energy gaps and potential energy curves (PECs) were calculated theoretically employing DFT method for ground state (S-0) and TD-DFT method for first singlet excited electronic state (S-1) in ACN. Calculations revealed the proton transfer as ESPT mechanism [extent of proton transfer in S-0 (58%) and S-1 (87%)] behind the molecular interaction and spectral responses. We believe such a fluoride selective sensor like HM may find application to detect and control fluoride content in different commodity products.