Synthesis and Characterization of Newly Designed and Highly Solvatochromic Double Squaraine Dye for Sensitive and Selective Recognition towards Cu2+

Abstract

Synthesis and characterization of a novel and zwitterionic double squaraine dye (DSQ) with a unique D-A-A-D structure is being reported. Contrary to the conventional mono and bis-squaraine dyes with D-A-D and D-A-D-A molecular frameworks reported so far, DSQ dye demonstrated strong solvatochromism allowing for the multiple ion sensing using a single probe by judicious selection of the suitable solvent system. The DSQ dye exhibited a large solvatochromic shift of about 200 nm with color changes from the visible to NIR region with metal ion sensitivity. Utilization of a binary solvent consisted of dimethylformamide and acetonitrile (1:99, v/v), highly selective detection of Cu2+ ions with the linearity range from 50 μM to 1 nM and a detection limit of 6.5 × 10−10 M has been successfully demonstrated. Results of the Benesi–Hildebrand and Jobs plot analysis revealed that DSQ and Cu2+ ions interact in the 2:1 molecular stoichiometry with appreciably good association constant of 2.32 × 104 M−1. Considering the allowed limit of Cu2+ ions intake by human body as recommended by WHO to be 30 μM, the proposed dye can be conveniently used for the simple and naked eye colorimetric monitoring of the drinking water quality.

A biocompatible NIR squaraine dye and dye-antibody conjugates for versatile long-term in vivo fluorescence bioimaging

“…Observed in methanol, compared to chloroform, may be attributed to the non-polar nature of chloroform, where hydrogen bonding interactions are minimal, thus reducing the chances of forming H-aggregates. 46 The molar absorption coefficient (e o ) in CHCl 3 was calculated to be 3.445 Â 10 À5 M À1 cm À1 by taking the absorption maxima corresponding to different concentrations of SQ-58 (1 mM, 2 mM, 3 mM, 4 mM, and 5 mM) (Fig. S9, ESI †).…”

“…Solvatochromism is the phenomenon of a molecule's color changing due to an alteration in the molecular environment created by the solvent molecules resulting in various interactions between the dye and solvent molecules. 46 Specifically, indole-based squaraines demonstrate strong photostability and fluorescence intensification in apolar media. Several substituted squaraines' solvent-dependent absorption and emission characteristics have been discovered, suggesting strong interactions in the ground and excited state.…”

Facile Fabrication and Characterization of Oriented and Multilayer Thin Films of Solution Processable Conjugated Polymer

“…[12,13] Another advantage is the ability to incorporate other materials into the film, such as metal nanoparticles or inorganic materials. [14][15][16][17] Several techniques for the solution-processable film fabrication of CPs include solution casting, spin coating, drop casting, and printing techniques. [11] However, intriguing issues like material wastage, large-area thin film fabrication, controlling the molecular orientation, and fabrication of multilayer thin films without any detrimental effect on the preexisting underlying layers must be solved amicably.…”

Naphthalimide-Piperazine Derivatives as Multifunctional “On” and “Off” Fluorescent Switches for pH, Hg2+ and Cu2+ Ions

“…The potent toxicity of mercuric ions to living systems has inspired the development of new fluorescent chemosensing molecules and sensing schemes for detection of Hg 2+ in environmental, industrial and biological samples [ 2 , 20 , 21 , 22 ]. Chemosensors for Cu 2+ , a metal essential for life but also highly toxic to some organisms, have also been the subject of much research and development effort [ 22 , 23 , 24 , 25 ]. It is known that Cu 2+ and Hg 2+ act as quenching agents to many fluorescent probes.…”