Supriti Sen

A New Half-Condensed Schiff Base Compound: Highly Selective and Sensitive pH-Responsive Fluorescent Sensor

A new probe, 3-[(3-benzyloxypyridin-2-ylimino)methyl]-2-hydroxy-5-methylbenzaldehyde (1-H) behaves as a highly selective fluorescent pH sensor in a Britton-Robinson buffer at 25 °C. The pH titrations show a 250-fold increase in fluorescence intensity within the pH range of 4.2 to 8.3 with a pK(a) value of 6.63 which is valuable for studying many of the biological organelles.

A water soluble copper(II) complex as a HSO4− ion selective turn-on fluorescent sensor applicable in living cell imaging

A water soluble non-fluorescent copper(II) complex (1) of a quinazoline derivative formulated as [Cu(L′)(Cl)] (1) has been synthesized via a facile synthetic method and characterized by physico-chemical and spectroscopic tools along with the single crystal X-ray crystallography for detailed structural analysis. 1 behaves as a highly selective and sensitive for HSO4− ions through the enhancement of fluorescence of the system based on intermolecular hydrogen bonding assisted chelation enhanced fluorescence (CHEF) process in ‘turn-on’ style, which has been confirmed by systematic optical techniques and electrochemical studies. This mode of sensing pathway and binding of HSO4− ions with the receptor 1 has also been validated by optimizing the structures of [Cu(L′)(Cl)] (1) and [Cu(L′)(Cl)]·HSO4− adduct (2) with the help of theoretical calculations. This non-cytotoxic probe senses HSO4− ions as low as 3.18 × 10−7 M in water:DMSO (9:1, v/v) at biological pH (using 1 mM HEPES buffer) and it is also useful for the detection of intracellular HSO4− ions under a fluorescence microscope.

Syntheses, crystal structures, and DNA-binding of some nickel(II) complexes of 1,3-bis(2-pyridylmethylthio)propane and pseudohalides

A series of neutral octahedral nickel(II) complexes of 1,3-bis(2-pyridylmethylthio)propane (L) and pseudohalide (X), formulated as [NiII(L)X2] (where X = azide (1), cyanate (2), and isothiocyanate (3)), was synthesized. The complexes were characterized by physico-chemical and spectroscopic methods, and 1 and 3 also by single-crystal X-ray diffraction analyses. The structural study shows nickel in a distorted octahedral geometry comprised of the tetradentate NSSN ligand with trans pyridines and monocoordinated pseudohalides in cis positions. In dimethylformamide solution, the complexes had quasi-reversible NiII/NiIII redox couples in cyclic voltammograms with E 1/2 values of +0.732, +0.747, and +0.815 V for 1, 2, and 3, respectively. To examine the biological activities of these complexes, interaction of 3 with calf thymus DNA was studied spectroscopically, showing groove-binding interaction.

Efficient and Convenient Methods for Synthesis of Some Phthalazine Derivatives and Their Evaluation of Cytotoxicity

Abstract A systematic study of the reaction of 1,4-dihydrazinophthalazine (DHPH) with 1,3-dicarbonyls [viz., acetylacetone (acac), dibenzoylmethane (bzbz), and 1-benzoylacetone (bzac)] varying the reaction conditions was carried out to obtain the phthalazine derivatives (1–4). One-pot reaction of DHPH with acac led to the formation of two compounds 1 and 2, with various factors such as the presence of the acid or base, amount of the acac, time of reflux, and the temperature. The reaction conditions of DHPH with bzbz or bzac are sort of different to isolate the products 3 and 4, respectively. The derivatives (1–4) have been characterized by elemental analyses, 1H NMR, and electrospray ionization–mass spectrometry (ESIMS) and the cytotoxic activity of the compounds 1–4 was evaluated on HeLa cell line. [Supplementary materials are available for this article. Go to the publishers online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.] GRAPHICAL ABSTRACT