Synthesis of Novel Diketopyrrolopyrrole-Rhodamine Conjugates and Their Ability for Sensing Cu2+ and Li+

Abstract

The search for accurate and sensitive methods to detect chemical substances, namely cations and anions, is urgent and widely sought due to the enormous impact that some of these chemical species have on human health and on the environment. Here, we present a new platform for the efficient sensing of Cu2+ and Li+ cations. For this purpose, two novel photoactive diketopyrrolopyrrole-rhodamine conjugates were synthesized through the condensation of a diketopyrrolopyrrole dicarbaldehyde with rhodamine B hydrazide. The resulting chemosensors 1 and 2, bearing one or two rhodamine hydrazide moieties, respectively, were characterized by 1H and 13C NMR and high-resolution mass spectrometry, and their photophysical and ion-responsive behaviours were investigated via absorption and fluorescence measurements. Chemosensors 1 and 2 displayed a rapid colorimetric response upon the addition of Cu2+, with a remarkable increase in the absorbance and fluorescence intensities. The addition of other metal ions caused no significant effects. Moreover, the resulting chemosensor-Cu2+ complexes revealed to be good probes for the sensing of Li+ with reversibility and low detection limits. The recognition ability of the new chemosensors was investigated by absorption and fluorescence titrations and competitive studies.

Structure–metal ion selectivity of rhodamine-based chemosensors

“…Similarly, the spectroscopic signals of the rhodamine-based probes were used for construction of molecular logic circuitry. 70,95,101 During the designing of the probe, apart from salicylaldehyde, other aromatic aldehydes such as 2-hydroxy-1-naphthaldehyde, pyridine carboxaldehyde, thiophene carboxaldehyde, coumarin carboxaldehyde, etc. have been utilized for the construction of rhodamine based chemosensors.…”

“…Similarly, the spectroscopic signals of the rhodamine-based probes were used for construction of molecular logic circuitry. 70,95,101…”

“…Absorption and fluorescence intensity of 87 increased considerably upon addition of Cu 2+ selectively in CH 2 Cl 2 . The LOD for Cu 2+ detection was found to be 1.6 Â 10 À7 M. 101 Compound 88 selectively detected Hg 2+ in 80% aqueous DMF by exhibiting a change in absorption and fluorescence spectra. 102 Hg 2+ induced opening of the spirocyclic ring and subsequently formed complex (2 : 1) via amide oxygen and azomethine nitrogen atoms.…”

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.…”

Multicolor Emissive Phosphorescent Iridium(III) Complexes Containing L-Alanine Ligands: Photophysical and Electrochemical Properties, DFT Calculations, and Selective Recognition of Cu(II) Ions

“…Thus, scientists are committed to developing accurate and dependable detective methods for Cu 2+ . Among various methods for the detection of Cu 2+ , fluorescence and phosphorescence detection methods based on changes in photophysical properties have received wide attention due to their high selectivity, rapid response, and simple operation [ 6 , 7 , 8 ]. Hence, the design and synthesis of novel luminescent materials to sense Cu 2+ becomes a primary task.…”