Conformationally Constrained (Coumarin−Triazolyl−Bipyridyl) Click Fluoroionophore as a Selective Al3+ Sensor

Synthesis and cation-binding studies of gold(i) complexes bearing oligoether isocyanide ligands with ester and amide as linkers

Bis(alkynyl)calix[4]arene gold(i) isocyanide complexes with amide linkers show strong binding affinity towards Al³⁺, which turns on the low-energy emission associated with the presence of Au(i)⋯Au(i) interactions.

A robust fluorescent chemosensor for aluminium ion detection based on a Schiff base ligand with an azo arm and application in a molecular logic gate

A new azo based chemosensor for detection of Al³⁺ ion has been reported. The sensor has been well characterized using different techniques like single crystal X-ray, NMR, IR, UV etc. Detection limit of the chemosensor was found to be 6.93 nM.

A long lifetime luminescent iridium(iii) complex chemosensor for the selective switch-on detection of Al3+ ions

A novel luminescent cyclometalated iridium(iii) complex 1 was synthesized and employed as a chemosensor for the detection of Al³⁺ ions. 1 displays a long lifetime luminescence that allow 1 to detect Al³⁺ ions in strong fluorescence media.

A highly selective and sensitive acylhydrazone-based turn-on optical sensor for Al3+

The fluorescence turn-on probing of Al³⁺ in ethanol was realized by the utilization of a type of conjugated acylhydrazone-based compound.

Visual detection of Al(3+) ions using conjugated copolymer-ATP supramolecular complex

A colorimetric Al(3+) sensor based on fluorescence recovery of a conjugated copolymer-ATP complex is proposed. An optimized ratio of two polythiophene (PT) monomers is utilized to synthesize copolymer (CP) that yielded maximized colorimetric response for Al(3+) in deionized (DI) and tap water. The electrostatic disassembly of CP-ATP upon addition of Al(3+) led to an evident visual color change. The lowest concentration of Al(3+) for naked eye observation is around 4 μM, which is below the threshold levels in drinking water according to European Economic Community (EEC) standard. Besides, the proposed assay showed a similar response to Al(3+) in tap water. The proposed methodology showed selective and sensitive detection for Al(3+) in analytically relevant concentration ranges without involving sophisticated instrumentation, illustrating the applicability for on-site drinking water monitoring.

A single probe to sense Al(III) colorimetrically and Cd(II) by turn-on fluorescence in physiological conditions and live cells, corroborated by X-ray crystallographic and theoretical studies

A pyridine-2-carbohydrazide functionalized conjugated fluorophoric Schiff base ligand (L₁) specifically senses Al(3+) and Cd(2+) ions through significant changes in its absorption and emission spectral behavior, respectively, in physiological conditions. The spectral changes are in the visible region of the spectrum and thus facilitate naked eye detection. Apart from the visible changes, an in-field device application was demonstrated by sensing these ions in paper strips coated with L₁. The crystal structure of the L₁-Cd complex provided additional insight of the metal coordination attributes of L₁. Interestingly, fluorescence microscopic studies demonstrated that the ligand L₁ could also be used as an effective probe in imaging experiments for the detection of intracellular Cd(2+) ions in HeLa cells, without any toxicity to these model human cells.

A novel pyrazole biscoumarin based chemosensors for the selective detection of Cu(2+) and Zn(2+) ions

A novel chemosensor based on pyrazole biscoumarin molecule "4-hydroxy-3-((4-hydroxy-2-oxo-2H-chromen-3-yl)(1,3-diphenyl-1H-pyrazol-4-yl)methyl)-2H-chromen-2-one" (PBC) was synthesized by a simple method. The chemosensing properties of PBC towards transition metal ions like Cu(2+) and Zn(2+) by naked eye, UV-Visible and fluorescence spectroscopic methods were described. The PBC solution with Cu(2+) and Zn(2+) ion showed brown and blue colour respectively. The UV-Visible spectra of PBC with Cu(2+) and Zn(2+) ions exposed their corresponding absorption maxima. Further, the Job's plot method confirmed the 1:1 and 2:1 stoichiometry of the complex formation between the PBC with Cu(2+) and Zn(2+) ions respectively. The fluorescence enhancement of PBC on binding with Cu(2+) and Zn(2+) is due to the inhibition of photo induced electron transfer mechanism.

A highly selective fluorescent probe for Al(3+) based on quinoline derivative

A novel Schiff base fluorescent probe, 1-phenyl-3-methyl-5-hydroxypyrazole-4-carbaldehyde (2'-methylquinoline-4'-formyl) hydrazone (PMHCH), for selective detection of Al(3+) has been designed and synthesized. Upon addition of various metal ions, the receptor only shows 286-fold enhancement of fluorescence intensity which might be attributed to a 1:1 stoichiometry between PMHCH and Al(3+) and the photo-induced electron transfer progress in the present of Al(3+) at 505n m. More importantly, the detection limit of PMHCH for Al(3+) could reach at 10(-7) M level.

A new fluorescent probe for Al(3+) based on rhodamine 6G and its application to bioimaging

A water-soluble rhodamine-based derivative (L) has been rationally designed for selective recognition of Al(3+) in aqueous medium with good sensitivity. The addition of Al(3+) to the aqueous solution of L induces a remarkable fluorescence enhancement along with obvious color change detected by the naked eye, due to the ring-opening mechanism of the rhodamine spirolactam, which has been proved by single crystal diffraction analyses directly. The recognizing behavior has been investigated both experimentally and computationally. Furthermore, the fluorescent probe can also be used as a bioimaging reagent for detection of Al(3+) in living cells.

Nanomolar fluorogenic detection of Al(III) by a series of Schiff bases in an aqueous system and their application in cell imaging

Three positional isomers of a Schiff base containing -OH as end groups have been synthesized and evaluated for selective Al(III) detection due to inhibition of ESIPT, PET and activation of CHEF in 70% aqueous medium. Devoid of any conventional fluorophore, these sensors have nanomolar detection limits with high quantum yields and naked eye sensing of Al(III). Moreover, these probes have been demonstrated to enable the Al(III) detection in live human HeLa cells and rat C6 glioma cells using a confocal microscope.

A polynuclear hetero atom containing molecular organic scaffold to detect Al3+ ion through a fluorescence turn-on response

A simple polynuclear hetero atom (N and O) containing molecular organic scaffold/probe, 3 has been designed and synthesized and explored as a potential chemosensor to detect Al³⁺ (22 nM; ∼0.6 ppb) ion in a HEPES buffer.

Selective detection of Al3+and citric acid with a fluorescent amphiphile

The assembly and disassembly of a fluorescent amphiphile by Al³⁺and citrate, respectively, can be used to sense these analytes by fluorescence spectroscopy.

Selective and sensitive turn-on chemosensor for Al(iii) ions applicable in living organisms: nanomolar detection in aqueous medium

A new crystallographically characterized non-cytotoxic CHEF based highly sensitive Al(iii) ion selective chemosensor (L) is useful to detect the Al(iii) ions' distribution in A549 cell lines and also able to sense Al(iii) ions in tea extract.

A fluorescent “turn on” chemosensor based on Bodipy–anthraquinone for Al(iii) ions: synthesis and complexation/spectroscopic studies

A fluorescent “turn on” Al(iii) chemosensor based-on bodipy–anthraquinone with two triazole ring was prepared and studied for its complexation and spectroscopic properties.

Highly sensitive and selective chemosensors for Cu2+and Al3+based on photoinduced electron transfer (PET) mechanism

Two new fluorescent PET chemosensors were synthesised from an acridine core. The sensors can be used to monitor Cu²⁺and Al³⁺in CH₃CN. The detection limits for7a–Cu²⁺and7b–Al³⁺were calculated to be 2.8 × 10⁻⁷M and 5.8 × 10⁻⁷M, respectively.

ESIPT and CHEF based highly sensitive and selective ratiometric sensor for Al3+ with imaging in human blood cells

We have synthesised a probe for the fluorescence ratiometric detection of Al³⁺. This probe can be used to image Al³⁺ in living cells.

Binding site-driven sensing properties of a quinazoline derivative with metal cations

A quinazoline derivative showed high sensitivity and selectivity for Al³⁺, Cr³⁺ and Fe³⁺ ions in methanol solution.

Fluorescent sensor for selective detection of Al(3+) based on quinoline-coumarin conjugate

A fluorescence probe, 8-formyl-7-hydroxyl-4-methyl coumarin - (2'-methylquinoline-4-formyl) hydrazone (L) has been synthesized. The chemosensor is found preferential binding to Al(3+) in presence of other competitive ions with associated changes in its optical and fluorescence spectra behavior. Upon addition of Al(3+) to a solution of L, it shows 200-fold enhancement of fluorescence intensity which might be attributed to form a 2:1 stoichiometry of the binding mode of LAl(III) and the chelation enhanced fluorescence (CHEF) process at 479nm in ethanol. The lowest detection limit for Al(3+) is determined as 8.2×10(-7)M.

A highly sensitive C3-symmetric Schiff-base fluorescent probe for Cd2+

A new C3-symmetric Schiff-base fluorescent probe (L) based on 8-hydroxy-2-methylquinoline has been developed. As expected, the probe L can display high fluorescent selectivity for Cd(2+) over Zn(2+) and most other common ions in neutral ethanol aqueous medium. Moreover, the mechanism of the L-Cd(2+) complex has been confirmed by X-ray crystallography and density functional theory calculation results. More importantly, L could be used to image Cd(2+) within living cells.

A remarkable effect of N,N-diethylamino functionality on the optoelectronic properties of a salicylimine-based probe for Al(3+)

A new live-cell permeable, fluorescent probe comprised of a simple salicylimine-based Schiff base (SA1) has been developed for Al3+ with nano-molar sensitivity in aqueous media. SA1 was synthesized through a simple structural modification of a recently reported receptor SA2 by the incorporation of the N,Ndiethylamino (DEA) group as a fine controllable unit. This modification affects the performance of SA1 remarkably in terms of its sensitivity, water compatibility and efficiency as well as its mechanistic aspect. The presence of the DEA group in SA1 led to its dual channel emission due to the TICT state and at the same time its hydrophobic nature was also responsible for controlling the strong hydration of Al3+ ions in aqueous media which ultimately led to the high sensitivity of SA1 for Al3+. The structure of SA1 was confirmed by single crystal X-ray diffraction and its binding with Al3+ was studied in detail using UVvisible, fluorescence and 1H NMR spectral studies along with mass determination. The effort of getting a single crystal of Al3+–SA1 led to single crystals of Cl−/NO3 − complexes of protonated SA1 which were fully characterized by their XRD studies.

A single molecular probe for multi-analyte (Cr³⁺, Al³⁺ and Fe³⁺) detection in aqueous medium and its biological application

An ESIPT based fluorescent sensor 1 was developed, which could selectively detect and differentiate trivalent metal ions Cr(3+), Al(3+) and Fe(3+) in aqueous medium. The cell imaging experiments confirmed that 1 can be used for monitoring intracellular Cr(3+) and Al(3+) levels in living cells.

Selective and sensitive detection of aluminium ions in water via fluorescence "turn-on" with both solid and water soluble sensory polymer substrates

A solid substrate comprised of a cross-linked polymer network is shaped as a film with gel-like behaviour and is used to detect aluminium ions in water; concurrently, a water soluble sensory polymer synthesised towards the same purpose is also discussed. The detection in both systems was achieved via fluorescence "turn-on". The limits of detection for Al(III) were 1.6 and 25ppb for the former and latter materials, respectively; these levels are significantly lower than the EPA recommendations for drinking water.

A new fluorescent chemosensor for Al(3+) ion based on schiff base naphthalene derivatives

A new naphthalene derivative receptor (H2L) was synthesized. The chemosensor (H2L) exhibited a strong fluorescence enhancement in the presence of trace amounts of Al(3+), attributable to chelation-enhanced fluorescence (CHEF) effect, which also displayed high selectivity over a series of other metal cations (Na(+), K(+), Cs(+), Mg(2+), Ba(2+), Pb(2+), Cr(3+), Mn(2+), Fe(3+), Fe(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+) and Ag(+)) in ethanol.

A quinoline derivative as an efficient sensor to detect selectively Al³⁺ ion

A quinoline-based Schiff base 1 has been utilized as a fluorescence chemosensor for the selective detection of Al(3+). The receptor 1 exhibited a high association constant (3.67 × 10(5) M(-1)) with submicromolar detection limit (0.18 ppm) towards Al(3+) in CH3CN solution.

A novel pyrene-2-(pyridin-2-ylmethylsulfanyl)ethylamine based turn-on dual sensor for Al3+: experimental and computational studies

A pyrene based pyrene-2-(pyridin-2-ylmethylsulfanyl)-ethylamine (PP) is found to exhibit a turn-on chemo- and fluorogenic dual sensing of Al³⁺ through PET blocking and CHEF effect.

Cascade OFF–ON–OFF fluorescent probe: dual detection of trivalent ions and phosphate ions

A new rhodamine B-based fluorescent probe was developed for the selective cascade signaling of trivalent cations (Fe³⁺, Al³⁺, Cr³⁺) and phosphate anion (PO₄³⁻).

A tetrazole-based fluorescence “turn-on” sensor for Al(iii) and Zn(ii) ions and its application in bioimaging

A dual fluorescent chemosensor for Al³⁺and Zn²⁺ions based on inhibition of ESIPT can be applied in bioimaging.

A Simple Sensitive ESIPT On-Off Fluorescent Sensor for Selective Detection of Al3+ in Water

A highly selective and sensitive fluorescent sensor for Al³⁺ has been developed. The sensor shows great fluorescence turn-on upon binding Al³⁺ in complete water, giving strong blue emission. In addition, the sensor's turn-on exhibits excellent selectivity to Al³⁺ cation, with only a slight interference from Zn²⁺. These findings suggest that the developed Al³⁺ sensor could be a useful molecular probe for practical applications.

Rhodamine-based molecular clips for highly selective recognition of Al3+ ions: synthesis, crystal structure and spectroscopic properties

A novel fluorescent chemosensor based on a rhodamine derivative (L) was designed, synthesized, and used as a selective Al⁺³ ion sensor.

A simple coumarin as a turn-on fluorescence sensor for Al(iii) ions

A simple non-Schiff's base type molecule serves as a selective chemosensor for Al³⁺ based on the chelation-enhanced fluorescence (CHEF) effect.

Two new isomerous fluorescent chemosensors for Al(3+) based on photoinduced electron transfer

Two new isomerous PET fluorescent chemosensors (L and L') for Al(3+) have been designed, synthesized and characterized. The two chemosensors exhibited fluorescence enhancement upon binding Al(3+) in CH3CN by PET inhibition processes from both the sulfur and the nitrogen donors to anthracene. The job's plot, Benesi-Hildebrand plot and (1)H NMR titration experiments indicate that both chemosensors form a 1:1 complex with Al(3+). The binding constants were calculated to be (1.432±0.186)×10(5) and (1.427±0.970)×10(5), respectively. Furthermore, the lowest detection limit for Al(3+) in CH3CN was determined to be 4.8×10(-7)M and 2.2×10(-7)M, respectively.