A new fluorescent chemosensor based on the calix[4]arene of partial cone conformation possessing a dansyl moiety has been synthesized. The chemosensor demonstrates selective optical recognition of Hg(2+) and Cu(2+) in two contrasting modes. The receptor exhibited ratiometric sensing of Hg(2+) and "ON-OFF" type of fluorescence behavior in the presence of Cu(2+). The compound behaves as a fluorescent molecular switch upon chemical inputs of Hg(2+) and Cu(2+) ions.

New hetero-oligophenylene derivative (2) was synthesized which exhibits aggregation-induced emission enhancement (AIEE) in H(2)O/THF (80:20). The aggregates serve as a biological probe for three different proteins, that is bovine serum albumin (BSA), cytochrome c, and lysozyme, and DNA in contrasting modes. Further, among 29 metal ions tested, the contrasting fluorescence behavior of aggregates of 2 is observed with only Pb(2+) and Pd(2+) ions. Multiple output logic circuits based upon the fluorescence behavior between BSA and cytochrome c and between Pb(2+) and Pd(2+) ions are constructed.

A chemosensor based on the thiacalix[4]arene of 1,3-alternate conformation has been designed and synthesized. The binding behavior of this chemosensor has been studied toward different metal ions by fluorescence spectroscopy, and it was observed that the chemosensor selectively senses Cu(2+) ions. The chemical inputs of Cu(2+) and F(-) in a sequential manner generate an output which mimics the functions of a security keypad lock.

A new fluorescent "on-off" switchable chemosensor 2 based on a thiacalix [4] arene with a 1,3-alternate conformation and two different types of cation binding sites has been synthesized. Two pyrene moieties linked to a cation recognition unit composed of two imine groups form a strong excimer in solution. Of the metal ions tested, the fluorescence of 2 was

An organic solid-state near-infrared (NIR)-emitter (λ em = 738 nm) exhibiting large Stokes shift (Δλ = 293 nm) through the excited-state intramolecular proton transfer phenomenon has been synthesized and characterized. The present discovery points to the possibility of achieving a new family of solid-state NIR emitters starting from simple aldehyde and amine precursors.

Based on the mechanism of hydrolytic cleavage of Schiff bases, a 1-aminopyrene based fluorescent chemodosimeter, 3, is reported for the selective detection of Nb(5+) ions in solution. Among the 21 metal ions tested, the chemodosimeter shows a selective fluorogenic 'turn-on' response toward Nb(5+) ions in mixed aqueous media.

No abstract

A series of new π-conjugated oligomeric compounds, 2,2'-(arylenedivinylene)bis-8-hydroxyquinolines, having two vinylene-8-hydroxyquinoline moieties structured around a phenol ring, have been synthesized by the reaction of 8-hydroxyquinaldine with aromatic dialdehydes. Crystal structure of one of the compounds has been described, which shows a twisted molecular geometry and interesting supramolecular interactions leading to a 2-D sheet-like structure in the crystal lattice. The photo-luminescence properties analyses revealed that the fluorescence emission wavelengths of these compounds vary in the range 480-638 nm depending on the electronic effects of the substituents on the central phenol ring. These compounds were found to act as selective and sensitive fluorescence turn-off chemosensors for Co 2 + ions and the detection limits exhibited by these chemosensors varied in the range 15.00-23.09 nM. Analytical application of these compounds for sensing cobalt from tap water in nanomolar levels is demonstrated. Preliminary investigations conducted using HeLa cells revealed their potential for sensing cobalt in biological systems.