A novel AIE-active imidazolium macrocyclic ratiometric fluorescence sensor for pyrophosphate anion

An imidazolium bridged macrocyclophane was synthesized as a ratiometric fluorescence sensor with aggregation-induced emission (AIE) characteristic to detect pyrophosphate anion with high selectivity among various anions. In the presence of zinc ion, macrocyclophane can form aggregates through complexation with pyrophosphate anion and emit ratiometric fluorescence, resulting from an enhancement in its aggregate-state emission and a reduction in its monomer emission. This AIE-active macrocycle showed great potential as a ratiometric fluorescence receptor.

Sharing the salt bowl: Counterion identity drives N-alkyl resorcinarene affinity for pyrophosphate in water

N-Alkyl ammonium resorcinarene chloride receptors, NARX4, have been shown to act as high-sensitivity detectors of pyrophosphate (PPi), a biomarker of disease, in aqueous media through the chloride-to-PPi exchange [NAR(Cl)4 to...

Spectrophotometric, fluorimetric and electrochemical selective pyrophosphate/ATP sensing based on the dimethyltin(IV)-tiron system

Sensing of pyrophosphate anion (PPi) in the presence of nucleotide triphosphates allows the real time monitoring of the polymerase chain reaction. To get a deeper understanding of the factors involved in PPi/nucleotide triphosphate discrimination, a detailed study on the performance of a dimethyltin (IV)-catecholate complex capable of both separate fluorimetric or electrochemical detection of PPi in the presence of adenosine triphosphate (ATP) has been undertaken. Dimethyltin (IV) tightly binds PPi or ATP, and forms a stable 1:1 complex with tiron (4,5-dihydroxy-1,3-benzenedisulfonic acid) in water. The complexation equilibria with all components are characterized quantitatively by potentiometric and spectroscopic titrations. Pyrophosphate anion can be detected owing to its ability to release free tiron from the complex by measuring either a fluorimetric or an electrochemical signal. On the contrary, ATP does not displace tiron but causes an interference with PPi in the fluorimetric detection method due to the formation of a ternary Me₂Sn(IV)-tiron-ATP complex with optical properties intermediate between those of free and bound tiron. In the electrochemical (square wave voltammetry) method, the ternary ATP complex shows a separate peak which does not coincide with the peaks of neither free nor bound tiron, thus making possible the simultaneous detection of ATP in addition to PPi.

Fluorenone based fluorescent probe for selective "turn-on" detection of pyrophosphate and alanine

To sense biologically important entities with different size and dimensions, a fluorenone based fluorescent receptor was designed and synthesized. Probe 1 displayed a distinct fluorescence enhancement emission at 565nm for pyrophosphate and 530nm for alanine in polar solvent. The fluorescence titration experiments confirm 1:1 stoichiometric ratio with high-binding constant and very low limit of detection (LoD) values. Receptor 1 showed a highly selective and sensitive recognition to HP₂O₇^3- and to alanine over other competitive anions and amino acids. In addition, the fluorescence lifetime measurement and reversible binding study results support the practical importance of 1.

cis-Protected palladium(ii) based binuclear complexes as tectons in crystal engineering and the imperative role of the cis-protecting agent

The shape and molecular packing of cis-protected Pd(ii) based binuclear complexes depends upon the ligand and cis-protecting agents.

Pyrophosphate Sensor Based on Principal Component Analysis of Conjugated Polyelectrolyte Fluorescence

The pyrophosphate anion (PPi) plays an important role in biochemical processes. Therefore, a simple but reliable analytical technique is essential for selective detection of PPi in biochemical systems. Here, we present a principal component analysis (PCA) method for analytical determination of PPi concentration using a fluorescent conjugated polyelectrolyte (CPE) combined with a polyamine modifier. The CPE has anionic side chains and dissolves molecularly in water, as indicated by its structured fluorescence emission spectrum. However, addition of tris(3-aminoethyl)amine (tetraamine or N4) quenches the CPE fluorescence emission. Tetraamine, which is a polycation at neutral pH, binds multiple anionic CPE chains, leading to aggregate formation, resulting in aggregation-induced fluorescence quenching. Addition of PPi to the polymer-amine aggregate reverses the process, resulting in fluorescence recovery. The relatively higher concentration of PPi compared to that of the polymer allows it to effectively compete to bind the amine, thus releasing molecularly dissolved polymer chains. Fluorescence correlation spectroscopy of the P1/N4 complex and of P1/N4/PPi confirms the change in size of the CPE aggregates that occurs upon reversible aggregation. Application of PCA to the fluorescence emission data set of standard samples yields two principal components, which are used to create a predictive model for PPi analysis. The PCA method is able to directly determine the concentration of PPi with approximately 95% accuracy within the concentration range from 100 μM to 3 mM, without the need for a reference state as is typically needed for ratiometric fluorescence assays.

Cd(II)-terpyridine-based complex as a ratiometric fluorescent probe for pyrophosphate detection in solution and as an imaging agent in living cells

The terpyridine anthracene ligand was synthesized and characterized. is a ratiometric fluorescent probe for Cd(2+) with a recognition mechanism based on intramolecular charge transfer (ICT). An complex was isolated, and its structure was established using single-crystal XRD. The complex was able to serve as a novel reversible chemosensing ensemble to allow ratiometric response to pyrophosphate (PPi) in aqueous media. Moreover, the fluorescence imaging in living cells from these two emission channels suggested that was a ratiometric probe for Cd(2+), and the in situ generated complex was also a ratiometric ensemble for PPi detection in living cells.

Making pyrophosphate visible: the first precipitable and real-time fluorescent sensor for pyrophosphate in aqueous solution

An in situ generated Zn²⁺ complex of di-2-(picoly) amine BINOL–DPA was presented as a precipitable and real-time fluorescent sensor for PPi with a detection limit of 95 nm, and it could be successfully applied in imaging PPi in living cells.

Tetraphenylethylene imidazolium macrocycle: synthesis and selective fluorescence turn-on sensing of pyrophosphate anions

A novel tetraphenylethylene imidazolium macrocycle was found to be able to form an aggregate with a pyrophosphate anion in water, which gives a characteristic aggregation-induced emission fluorescence.

Fluorescent and colorimetric chemosensors for pyrophosphate

In this review, we will cover the fluorescent and colorimetric chemosensors developed for the detection of pyrophosphate (PPi) since 2010.

The selectivity of water-based pyrophosphate recognition is tuned by metal substitution in dimetallic receptors

Indicator displacement assays show that a digallium complex is selective for pyrophosphate even compared with higher concentrations of other common oxoanions like phosphate, ATP, arsenate, nitrate, perchlorate, sulfate, formate, carbonate and acetate.

Dinuclear pyridine-4-thiolate-bridged rhodium and iridium complexes as ditopic building blocks in molecular architecture

A series of dinuclear pyridine-4-thiolate (4-Spy)-bridged rhodium and iridium compounds [M(μ-4-Spy)(diolef)]2 [diolef = 1,5-cyclooctadiene (cod), M = Rh (1), Ir (2); diolef = 2,5-norbornadiene (nbd), M = Rh (3)] were prepared by the reaction of Li(4-Spy) with the appropriate compound [M(μ-Cl)(diolef)]2 (M = Rh, Ir). The dinuclear compound [Rh(μ-4-Spy)(CO)(PPh3)]2 (4) was obtained by the reaction of [Rh(acac)(CO)(PPh3)] (acac = acetylacetonate) with 4-pySH. Compounds 1-4 were assessed as metalloligands in self-assembly reactions with the cis-blocked acceptors [M(cod)(NCCH3)2](BF4) [M = Rh (a), Ir (b)] and [M(H2O)2(dppp)](OTf)2 [M = Pd (c), Pt (d); dppp = 1,3-bis(diphenylphosphino)propane]. The homometallic hexanuclear metallomacrocycles [{M2(μ-4-Spy)2(cod)2}2{M(cod)}2](BF4)2 (M = Rh [(1a)2], Ir [(2b)2]) and the heterometallic hexanuclear metallomacrocycles [{Rh2(μ-4-Spy)2(cod)2}2{Ir(cod)}2](BF4)2 [(1b)2], [{Rh2(μ-4-Spy)2(cod)2}2{M'(dppp)}2](OTf)4 (M' = Pd [(1c)2], Pt [(1d)2]), and [{Ir2(μ-4-Spy)2(cod)2}2{M'(dppp)}2](OTf)4 (M' = Pd [(2c)2], Pt [(2d)2]) were obtained. NMR spectroscopy in combination with electrospray ionization mass spectrometry was used to elucidate the nature of the metalloligands and their respective supramolecular assemblies. Most of the synthesized species were found to be nonrigid in solution, and their fluxional behavior was studied by variable-temperature (1)H NMR spectroscopy. An X-ray diffraction study of the assemblies (1a)2 and (1d)2 revealed the formation of rectangular (9.6 Å × 6.6 Å) hexanuclear metallomacrocycles with alternating dinuclear (Rh2) and mononuclear (Rh or Pt) corners. The hexanuclear core is supported by four pyridine-4-thiolate linkers, which are bonded through the thiolate moieties to the dinuclear rhodium units, exhibiting a bent-anti arrangement, and through the peripheral pyridinic nitrogen atoms to the mononuclear corners.

Chromogenic and fluorogenic chemosensors and reagents for anions. A comprehensive review of the years 2010-2011

This review focuses on examples reported in the years 2010-2011 dealing with the design of chromogenic and fluorogenic chemosensors or reagents for anions.

Highly selective visual distinction of pyrophosphate from other phosphate anions with 4-[(5-chloro-2-pyridyl)azo]-1,3-diaminobenzene in the presence of copper(II) ions

Pyrophosphate (PPi), as a biologically related phosphate anion, plays very important roles in organisms. Here, a highly selective visual method for distinction of PPi was made with commercial available 4-[(5-chloro-2-pyridyl)azo]-1,3-diaminobenzene (5-Cl-PADAB) in the presence of copper(II). The yellow solution of 5-Cl-PADAB exhibits strong absorption at 450.5 nm, and addition of Cu(II) results in a red solution with a new absorption band at 506.0 nm. Upon titration with PPi, the absorption band at 506.0 nm decreases with blueshift, while another new absorption band in the region from 562.0 nm to 750.0 nm appears which gradually splits into two peaks, and the color accordingly changes from red to cyan. Further addition of PPi, the new absorption peaks gradually disappear, and the mixture shows the absorption of 5-Cl-PADAB and recovers to yellow from cyan. This process is highly selective for PPi since other phosphate anions such as nucleotides cannot induce such spectral and color changes. With this method, the detection of PPi concentration in human urine was made with satisfactory results.

Highly selective colorimetric sensing pyrophosphate in water by a NBD-phenoxo-bridged dinuclear Zn(II) complex

A novel NBD-phenoxo-bridged dinuclear Zn(II) complex is found to be an effective colorimetric sensor for pyrophosphate (PPi) in pure aqueous solution over a wide pH range. This sensor shows high binding affinity (K(a)≈ 3 × 10(8) M(-1)) and high selectivity for PPi, and can be also used to assay the activity of pyrophosphatase in real time.

Ratiometric fluorescent sensor for silver ion and its resultant complex for iodide anion in aqueous solution

In aqueous solution, sensor DQAg can selectively detect Ag(+) based on inhibition of the resonance, demonstrating a large hypsochromic shift of 84 nm and remarkable changes in the ratio (F(481 nm)/F(565 nm)) of the emission intensity (R/R(0) up to 26-fold). Furthermore, the resultant Ag-DQAg also displays a ratiometric and highly selective response to iodide anion over other anions due to the liberation of DQAg from the complex by precipitating AgI.

Selective fluorometric detection of pyrophosphate by interaction with alizarin red S-dimethyltin(IV) complex

Highly selective detection of pyrophosphate in the presence of inorganic phosphate, halides, acetate, ATP, other nucleotides and phosphate esters in neutral aqueous solutions is achieved by using fluorescent dimethyltin(iv)-alizarin red S complex.