Copper(II)-directed static excimer formation of an anthracene-based highly selective fluorescent receptor

Effects of Metal Ions and Substituents on HOMO-LUMO Gap Evident from UV-Visible and Fluorescence Spectra of Anthracene Derivatives

Controlled intake of complex metal cations and anions in the human body and other biological systems is essential for the health and well-being of the environment. Anthracene and anthracene derivatives are the most widely used sensors for this purpose. Because of their convenience, better detection and results are preferred over colorimetric sensors, which offer better color detection by the naked eye. This review article will present different designs of chemosensors using fluorescence and UV-visible spectroscopy to determine different ions. Density functional theory and Austin model 1 are widely used for theoretical and computational studies of the energy levels of molecules. The Indo/Cis method is used to calculate the geometries of anthracene oligomers. A novel anthracene-based fluorescent probe containing the benzothiazole group BFA was highly sensitive and selective toward trivalent cations (Cr3+ and Fe3+). This sensor is not sensitive to other ions, including Aluminum trivalent ions. (N- ((anthracen-9-yl) methyl)-N-(pyridin-2-yl) pyridin-2-amine) has been designed to detect zinc and copper. Click chemistry using photodimerization can be used to form cellulose nanoparticles. TEMPO-mediated hypohalite oxidation converts hydroxyl groups to carboxylic groups. Amide linkage formation between amine and carboxylic acid was followed by the installation of an alkyne group. Copper (I)-catalyzed Azide-Alkyne Cycloaddition (CuAAC) was used to produce highly photoresponsive and fluorescent cellulose nanoparticles by using coumarin, anthracene, and generated nanomaterials. The effects of naphthalene and phenanthrene on the spectra of anthracene were determined in a dilute solution. Temperature and solvent effects introduce different changes in fluorescence, emission, and absorption bands, leading to some changes in the configuration of anthracene. The solvent and temperature effects on variations of emission maxima of exciplex anthracene-diethylaniline (DEA) are also discussed.

Real scenario of metal ion sensor: is conjugated polymer helpful to detect hazardous metal ion

Metal ions from natural and anthropogenic sources cause pollution to society and the environment is major concern in the present scenario. The deposition and contamination of metal ions in soil and water affect the biogeochemical cycles. Thus, it threatens the everyday life of living and non-living organisms. Reviews on the detection of metal ions through several techniques (Analytical methods, electrochemical techniques, and sensors) and materials (Nanoparticles, carbon dots (quantum dots), polymers, chiral molecules, metal-organic framework, carbon nanotubes, etc.) are addressed separately in the present literature. This review reveals the advantages and disadvantages of the techniques and materials for metal ion sensing with crucial factors. Furthermore, it focus on the capability of conjugated polymers (CPs) as metal ion sensors able to detect/sense hazardous metal ions from environmental samples. Six different routes can synthesize this type of CPs to get specific properties and better metal ion detecting capability in vast research areas. The metal ion detection by CP is time-independent, simple, and low cost compared to other materials/techniques. This review outlines recent literature on the conjugated polymer for cation, anion, and dual ion sensors. Over the last half decades published articles on the conjugated polymer are discussed and compared.

Structural Phase Transitions in Anthracene Crystals

Anthracene (C14 H10 ) and its derivatives, π-conjugated molecules in acenes, have been widely researched in terms of their reactions, physical properties, and self-assembly (or crystal engineering). These molecules can be functionalized to tune reactivities, optoelectronic properties, and self-assembling abilities. Structural changes in the molecular assemblies, solid states, and crystals have recently been discovered. Therefore, a systematic discussion of anthracene's molecular structure, packing, and optical properties based on its intermolecular structure and phase transitions is important for future chemical and structural design. In the present review, we discuss anthracene's molecular design, dimer packing, and crystal structure, focusing on the structural phase transitions of its crystals. We also provide examples of the phase transitions of anthracene crystals. Changes to edge-to-face of CH-π interaction and face-to-face packing of π-π interaction affect the thermodynamic stabilities of various crystal structures. These structures can inform the prediction of structural and physical properties.

A veratraldehyde-appended organosilicon probe and its hybrid silica nanoparticles as a dual chemosensor for colorimetric and fluorimetric detection of Cu2+ and Fe3+ ions

Schiff bases of veratraldehyde based organosilatranes have been synthesized. The colorimetric and fluorimetric detection of 3a and its hybrid silica nanoparticles (V-NPs) revealed significant sensorial ability only towards Cu2+ and Fe3+ ions.

Multi-anthracene containing fluorescent probe for spectrofluorimetric iron determination in environmental water samples

An anthracene-based fluorescence (FL) system was synthesized via a general synthetic procedure. Fourier transform infrared spectroscopy (FTIR), MALDI-MS, and nuclear magnetic resonance spectroscopy (¹³C and ¹H NMR) were carried out to characterize the multi-anthracene containing probe. The photophysical properties of the probe were illustrated via 3D-FL analysis and excitation-emission matrix (EEM) measurements. Density-functional theory (DFT) was applied to optimize the structure of the prepared probe and investigate its molecular interactions with Fe³⁺. The FL proficiency of the probe was appraised by spectroscopic measurements like Ultraviolet-Visible (UV-Vis) and FL spectroscopies. The simple and highly sensitive probe was able to diagnose ferric ions' low concentrations and detection limit reached upto 0.223 µM with linear working range between 0.22 and 92.00 µM for Fe³⁺ ions. The efficacy of this fluorescent probe was confirmed by testing for iron determination in environmental samples. Various fluorophores or ionophores could be applied for achieving novel probes by the proposed procedures and for diagnosing diverse metal ions.

Thiazoline-pyrene selective and sensitive fluorescence "turn-on" sensor for detection of Cu2

A thiazoline and pyrene containing sensor 1 was synthesized via one-pot reaction and utilized as a highly selective and sensitive fluorescence "turn-on" sensor for Cu²⁺ detection, via the fluorescence enhancement of pyrene monomer emission. The 2:1 stoichiometry of 1 and Cu²⁺ was calculated from Job's plots based on fluorescent titrations, and the complexation of 1 with Cu²⁺ was also supported by mass spectra, Fourier transform infrared spectra, proton NMR spectra and density functional theory analysis. The fluorescence intensity of 1 at 389 nm and 410 nm increased significantly upon the addition of Cu²⁺. Limit of detection and association constant value of 1-Cu²⁺ were calculated using standard deviations and linear fittings, respectively. Results showed that 1 was active for Cu²⁺ detection in the wide pH range of 2.0-11.0.

Competing Allosteric Mechanisms for Coordination-Directed Conformational Changes of Chiral Stacking Structures with Aromatic Rings

This work revealed that significant asymmetric nonlinear effects can be found in a coordination-directed conformational alteration through competing allosteric mechanisms. Toward this aim, we have prepared new chiral bridging ligands [( S, S)- and ( R, R)-Im₂An] containing an anthracene ring as a spacer with two ethynyl-linked chiral imidazole groups at the 9,10-positions. The ( S, S)- and ( R, R)-Im₂An ligands (L) spontaneously form the assemblies with Zn²⁺ ions (M) in solution phase, giving L₄M₂-type assemblies with a general formula [( S, S)- or ( R, R)-Im₂An]₄(Zn²⁺)₂. NMR studies revealed that the [( S, S)-Im₂An]₄(Zn²⁺)₂ assembly has an anthracene dimer structure with a parallel-displaced geometry, leading to relatively small circular dichroism (CD) signals, as expected for nonchiral objects. Conversely, subsequent addition of chiral coligands [( R)- or ( S)-Ph-box] to [( S, S)-Im₂An]₄(Zn²⁺)₂ afforded an alternative Zn²⁺ assembly with general formula [( R)- or ( S)-Ph-box]₂[( S, S)-Im₂An]₂(Zn²⁺)₂, where the chiral coligands expel two of the ( S, S)-Im₂An ligands that were singly bound to the Zn²⁺ ions in the original [( S, S)-Im₂An]₄(Zn²⁺)₂ assembly. This ligand-exchange reaction causes conformational alteration from a parallel-displaced structure to a twisted stacking between the anthracene rings inside the Zn²⁺ assembly, which results in a significant enhancement of CD signals due to excitonic interactions of the chiral anthracene dimer. Dissymmetry factor ( g_CD) for CD due to chiral stacking structures shows a significant inverse sigmoidal response to the enantiomeric excess of the chiral coligands. The observed nonlinear phenomena are results of the two conflicting mechanisms, homochiral cooperative association (homochiral self-sorting) to form CD-active assemblies [( S)- or ( R)-Ph-box]₂[( S, S)-Im₂An]₂(Zn²⁺)₂ versus heterochiral cooperative dissociation of [( S, S)-Im₂An]₄(Zn²⁺)₂ by sequestering of Zn²⁺ inside the assembly through formation of a heterochiral 2:1 Zn²⁺ complex ([( R)-Ph-box][( S)-Ph-box]Zn²⁺). The presented mechanisms provide a new strategy for generating switch-like OFF/ON states in chiral systems.

An Anthracene Excimer Fluorescence Probe on Mesoporous Silica for Dual Functions of Detection and Adsorption of Mercury (II) and Copper (II) with Biological In Vivo Applications

Dual functional activity by the same organic-inorganic hybrid material toward selective metal ion detection and its adsorption has drawn more attraction in the field of sensing. However, most of the hybrid materials in the literature are either for sensing studies or adsorption studies. In this manuscript, a fluorescent active hybrid material SiO₂ @PBATPA is synthesized by covalent coupling of anthracene-based chelating ligand N,N'-(propane-1,3-diyl) bis(N-(anthracen-9-ylmethyl)-2-((3-(triethoxysilyl)propyl) amino) acetamide) (PBATPA) within the mesopores of newly synthesized cubic mesoporous silica. The synthetic strategy is designed to form an exclusively intramolecular excimer on a solid surface, which is then used as a sensory tool for selective detection of metal ions through fluorescence quenching by the destruction of excimer upon metal ion binding. The dual functions of sensing and adsorption studies show selectivity toward Hg²⁺ and Cu²⁺ among various metal ions with detection limits of 37 and 6 ppb, respectively, and adsorption capacities of 482 and 246 mg g^-1 , respectively. This material can be used as a sensory cum adsorbent material in real food samples and living organisms such as the brine shrimp Artemia salina without any toxic effects from the material.

Construction of a novel INHIBIT logic gate through a fine-tuned assembly of anthryl fluorophores via selective anion recognition and host–guest interactions

A novel ligand containing of anthryl fluorophore was achieved. The assembly and disassembly of anthryl fluorophore by Pi and β-CD as chemical inputs and emission around 500 nm as output resulted in the construction of novel INHIBIT gate.

Novel anthracene- and pyridine-containing Schiff base probe for selective “off–on” fluorescent determination of Cu2+ ions towards live cell application

A simple anthracene-based AP probe was synthesized to detect Cu²⁺ ions, via the photoinduced electron transfer mechanism, in live cells.

A new thio-Schiff base fluorophore with copper ion sensing, DNA binding and nuclease activity

Copper ion recognition and DNA interaction of a newly synthesized fluorescent Schiff base (HPyETSC) were investigated using UV-vis and fluorescent spectroscopy. Examination using these two techniques revealed that the detection of copper by HPyETSC is highly sensitive and selective, with a detection limit of 0.39 μm and the mode of interaction between HPyETSC and DNA is electrostatic, with a binding constant of 8.97×10(4) M(-1). Furthermore, gel electrophoresis studies showed that HPyETSC exhibited nuclease activity through oxidative pathway.

Metal ion clip: fine-tuning aromatic stacking interactions in the multistep formation of carbazole-bridged zinc(ii) complexes

A carbazole-based triple bridging ligand (LH) consisting of two imidazole moieties with a diketone unit forms carbazole-bridged zinc(ii) complexes with structures of [(L⁻)₄(Zn²⁺)_n] (n = 2–6), where the strength of aromatic stacking interactions between the carbazole rings increases with an increase in the number of Zn²⁺ ions bridged.