Fluorescent Metal–Organic Frameworks for Selective Sensing of Toxic Cations (Tl³⁺, Hg²⁺) and Highly Oxidizing Anions ((CrO₄)²⁻, (Cr₂O₇)²⁻, (MnO₄)⁻)

Abstract

The ligand 4,4′‐(benzothiadiazole‐4,7‐diyl)dibenzoic acid was synthesized and employed for the synthesis of two metal–organic framework (MOF) compounds, [Mn4(C20H10N2O4S)2(HCOO)4(DEF)2] (I; DEF=N,N′‐diethylformamide) and [Pb(C20H10N2O4S)(DMF)] (II; DMF=N,N′‐dimethylformamide). Single‐crystal structure studies revealed that compound I has a three‐dimensional structure and compound II has a two‐dimensional structure. The luminescent nature of the MOFs was gainfully employed as a probe for the detection of highly toxic metal ions such as Tl3+ and Hg2+. The detection limits were found to be in the parts per billion (ppb) level. The presence of an unsubstituted thiadiazole ring in the ligand appears to help in the detection of these highly toxic metal ions in solution as the metal ions interact with S, which was revealed by Raman spectroscopic studies. The compounds were also found to be good candidates for the detection of highly oxidizing anions such as chromate, dichromate, and permanganate, again in ppb levels of concentration in solution. Magnetic studies on compound I indicate antiferromagnetic behavior. The variable‐temperature electrical conductivity studies indicate a semiconducting nature with comparable behavior to well‐known semiconductors such as CdSe, ZnTe, and GaP.

Water‐Stable Coordination Polymers as Dual Fluorescent Sensors for Highly Oxidizing Anions Cr2O72− and MnO4−

“…On the other hand, anions are ubiquitous in nature and organism and play crucial role in various fields, such as chemical, biological and environmental process . Due to the importance of anions and for the purpose of protecting the environment, considerable research efforts have been devoted to the development of materials for detection of anions in recent decades …”

Encapsulation of Silver Nanoparticles in an Amine‐Functionalized Porphyrin Metal–Organic Framework and Its Use as a Heterogeneous Catalyst for CO2 Fixation under Atmospheric Pressure

“…Solvents were purified by standard procedures prior to use. The ligand employed in the present synthesis was prepared from dimethyl 4,4′‐(benzothiadiazole‐4,7‐diyl)dibenzoate, as outlined below …”

“…The ligand employed in the present synthesis was prepared from dimethyl 4,4'-(benzothiadiazole-4,7-diyl)dibenzoate, as outlined below. [24] Synthesis of 1,2-Diamino-3,6-bis(4-methoxycarbonylphenyl)benzene 4,dibenzoate (1.00 g, 2.5 mmol) was dissolved in a1 :1 mixture of 1,4-dioxane/AcOH (200 mL). Zn dust (2.60 g, 40 mmol) was then added slowly.T he resulting mixture was heated at reflux for 12 ha nd filtered hot.…”

Bicolour fluorescent molecular sensors for cations: design and experimental validation

“…In this respect, fluorescent sensing arrays have been developed as a useful alternative based on ensembles of different less selective sensors that exhibit characteristic responses for different analytes. 16 Many different types of fluorescent sensors able to detect metal cations have been described, including nanoparticles, 17 carbon-based quantum dots, 18,19 and dendrimers, 20 as well as metal-organic frameworks (MOF), 21 and biomolecules such as DNA 22 and proteins. 23 These clustered and macromolecular sensors are not included in the present Perspective Article, which is focused on discrete fluorescent molecular sensors.…”

“…Many different types of fluorescent sensors able to detect metal cations have been described, including nanoparticles, 17 carbon-based quantum dots, 18,19 and dendrimers, 20 as well as metal–organic frameworks (MOFs), 21 and biomolecules such as DNA 22 and proteins. 23 These clustered and macromolecular sensors are not included in the present Perspective Article, which is focused on discrete fluorescent molecular sensors.…”