An Unsymmetrical Squaraine‐Dye‐Based Chemical Platform for Multiple Analyte Recognition

Abstract

The design of fluorescent molecular platforms capable of responding to multiple analytes is a topic of great interest. Herein, the use of a Zn -complexed unsymmetrical squaraine dye, Sq-Zn , as a chemical platform for recognizing structurally distinct analytes is reported. The squaraine ring is substituted on one side with a dipicolylamine unit, which acts as the metal ion receptor, whereas the other part of the molecule carries a dibutylaniline moiety, which is an electron donor. The molecular system is unique because it can respond specifically to different types of analytes, namely, atmospheric carbon dioxide, cyclic phosphates, and picric acid. Moreover, the interaction of these analytes can be monitored colorimetrically and fluorimetrically, which favors both qualitative and quantitative analyses. The distinct response towards cyclic and linear phosphates, as well as the selective response towards picric acid, among the various nitroaromatic compounds was achieved with sensitivity at the ppm level. The flexible coordination offered by Zn plays a significant role in the discrimination of these analytes with high specificity. Dye Sq-Zn introduced herein is a single-molecule construct that can be used for the selective and sensitive response towards analytes of environmental and biological relevance.

Helicity Control in the Aggregation of Achiral Squaraine Dyes in Solution and Thin Films

“…Inspired by reports on the giant intrinsic circular dichroism of prolinol‐derived squaraines in thin film, [19] we designed two novel types of symmetrical dyes as depicted in Scheme 1, with the aim to explore the unique photophysical properties of squaraine dyes with application in organic electronics and spintronics. Previous studies on squaraine dyes have focused often on nitrogen‐based heterocycles [4, 16, 37–39] or N , N ‐dialkylaminoaryl substituted derivatives [6, 12, 40] since the formation of the squaraine unit succeeds only when the nucleophilicity of the reagent used for the condensation reaction with squaric acid is sufficiently high [41] . Squaraine dyes that comprise para ‐hydroxy substitution have received less attention [42–44] .…”

“…[1][2][3] The unique photophysical properties arise from the intramolecular charge-transfer between the electron-poor quadratic core and the fused electron-rich arene substituents. Previous studies have shown that squaraine dyes can be used in various applications such as (bio-)labelling, [4][5][6] photodynamic therapy, [7] dye-sensitised solar cells [8][9][10][11] and organic bulk heterojunction solar cells. [12] Despite numerous studies investigating the photophysical properties of squaraine dyes, the number of reports dealing with chiral analogues is limited.…”

A Harmonized Applied and Theoretical Exploration for Nanomolar Level Recognition of Perilous F− and CN− by Multichannel Chemosensor: Proposition of Hg2+‐Mediated Logic Gate Imitator

“…The advancement of multifunctional chemosensors, susceptible to perceive more than one analyte by means of a single sensor molecule is acquiring noteworthy consideration in the field of supramolecular chemistry. [1,2,54] At the present time, various sensor molecules, containing dissociable proton donors, have been investigated in order to recognize anions effectively. [1,48] Among more than a few explored chemosensors, the colorimetric one is considered to be superior as the signaling output is visually demonstrable without any expensive instrumentation.…”

“…The advancement of multifunctional chemosensors, susceptible to perceive more than one analyte by means of a single sensor molecule is acquiring noteworthy consideration in the field of supramolecular chemistry . At the present time, various sensor molecules, containing dissociable proton donors, have been investigated in order to recognize anions effectively .…”

Electronic Nature of Neutral and Charged Two-Photon Absorbing Squaraines for Fluorescence Bioimaging Application

“…The synthesis and investigations of new squaraine derivatives are of great interest for a diverse range of fields, including organic photovoltaics, 1−4 ion sensing, 5−8 nonlinear optics, 9−12 optical data storage, 13−15 photodynamic therapy, 16−19 and fluorescence bioimaging. 20−23 Most of the known symmetrical squaraines are neutral compounds with electron-deficient C 4 O 2 central squarainyl ring playing the role of the electron acceptor part (A), flanked by the electron-donating terminal groups (D).…”