Tunable Photochromism of Spirobenzopyran via Selective Metal Ion Coordination: An Efficient Visual and Ratioing Fluorescent Probe for Divalent Copper Ion

Crystal Structure Landscape of Diarylethene-Based Crystalline Solids: A Comprehensive CSD Analysis

Diarylethenes (DAEs) are an exciting class of stimulus-responsive organic molecules that exhibit electrocyclization reactions upon exposure to light, heat, or other stimuli. The rational design of DAE-based crystalline materials is, however, complicated by the presence of DAE atropisomers, only one of which is photoactive. Data mining of the CSD produced 1349 unique molecular DAE structures that were subsequently analyzed according to selected chemical and geometric attributes. Additional analyses were performed on 1078 dithienylethene (DTE) structures-the largest subgroup within the ensemble. The crystal structure landscape, based upon D-D parameterization and analysis, revealed a vast array of molecular geometries, many of which may not correspond to energetic minima. The analyses link various chemical and geometric parameters to isomers observed in the lattice and their reactivity; however, potential biases intrinsic to this ensemble of structures complicate the determination of causal relationships. We believe that this retrospective comprehensive analysis of DAE structures represents an important step for understanding more broadly the crystal landscape of this class of materials.

Recent developments in the creation of a single molecular sensing tool for ternary iron (III), chromium (III), aluminium (III) ionic species: A review

Rational design of a molecular sensing tool is an important topic in molecular recognition, signalling, and optoelectronics that has piqued the interest of chemists, biologists, and environmental scientists. Approximately 150 years have passed since the beginning of the fluorescent chemosensor sector. Due to the paramagnetic properties of Cr3+ and Al3+ , it is tough to prepare a photoluminescence plug-in detector. Most dye-based Al3+ sensors must be utilized in organic or mixed solvents for robust hydration of Al3+ in water. The sophisticated molecular design of sensors, conversely, allows for the detection of these metal ions in aqueous medium. The design of chemosensors using various fluorophores and their mechanisms of action have been thoroughly discussed. A literature survey covering the design of chemosensors and their mechanisms of action have been thoroughly discussed covering the period 2010-2022 and that was carried out including innovative and exemplary activities from numerous groups throughout the world that have significantly contributed to this sector. The most important advantages of these probes are their aqueous solubility and quick response with outstanding selectivity and sensitivity for temporal distribution with high fidelity of metals in living cells.

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.

Highly Sensitive and Selective Spiropyran-Based Sensor for Copper(II) Quantification

The metal-binding capabilities of the spiropyran family of molecular switches have been explored for several purposes from sensing to optical circuits. Metal-selective sensing has been of great interest for applications ranging from environmental assays to industrial quality control, but sensitive metal detection for field-based assays has been elusive. In this work, we demonstrate colorimetric copper sensing at low micromolar levels. Dimethylamine-functionalized spiropyran (SP1) was synthesized and its metal-sensing properties were investigated using UV-vis spectrophotometry. The formation of a metal complex between SP1 and Cu²⁺ was associated with a color change that can be observed by the naked eye as low as ≈6 μM and the limit of detection was found to be 0.11 μM via UV-vis spectrometry. Colorimetric data showed linearity of response in a physiologically relevant range (0-20 μM Cu²⁺) with high selectivity for Cu²⁺ ions over biologically and environmentally relevant metals such as Na⁺, K⁺, Mn²⁺, Ca²⁺, Zn²⁺, Co²⁺, Mg²⁺, Ni²⁺, Fe³⁺, Cd²⁺, and Pb²⁺. Since the color change accompanying SP1-Cu²⁺ complex formation could be detected at low micromolar concentrations, SP1 could be viable for field testing of trace Cu²⁺ ions.

A novel isatin-based probe for ratiometric and selective detection of Hg2+ and Cu2+ ions present in aqueous and environmental samples

A novel isatin derivative (1) is UV-Visible active and displays about 90 nm bathochromic shift upon interaction with only Hg²⁺ and Cu²⁺, but not with other common metal ions. Also, the colorless probe 1 turns to brick-red and yellow in the presence of Hg²⁺ and Cu²⁺, respectively. Addition of increasing amounts of Hg²⁺ or Cu²⁺ to 1 leads to the emergence of a new absorption at ~470 nm (due to LMCT), with a concomitant decrease in the intensity of absorption of 1 at ~380 nm, and thereby provides a ratiometric response. Common metal ions and anions do not interfere with the interactions of 1 with Hg²⁺or Cu²⁺ ions. Probe 1 shows very high sensitivity and selectivity towards Hg²⁺ and Cu²⁺ as revealed by their very low detection limits 0.95 × 10^-9 M and 1.5 × 10^-9 M, respectively. Formation of 1:1 complex with Hg²⁺ and 2:1 complex with Cu²⁺ is confirmed using NMR, ESI-MS and FT-IR techniques, Job plot and DFT calculations. Selective detection of Hg²⁺ from Cu²⁺ is established from the ratiometric response caused by β-mercaptoethanol. Advantages of the probe 1 in terms of high sensitivity, stability in the physiological pH and suitability for dual detection are presented. Probe impregnated silica plates for onsite detection of Hg²⁺ and Cu²⁺ present in environmental samples is also demonstrated.

Cation-induced ring-opening and oxidation reaction of photoreluctant spirooxazine-quinolizinium conjugates

Two new spiroindolinonaphthoxazine derivatives with an electron-accepting styrylquinolizinium or styrylcoralyne unit, respectively, were synthesized, and the influence of such an arylvinyl substituent on the chemical and photochemical properties of the compounds was investigated. Specifically, these spirooxazines turned out to be resistant towards the photoinduced merocyanine formation, and the irradiation with light mainly led to photodegradation of the substrates. However, it was shown by colorimetric and fluorimetric screening assays as well as by detailed NMR spectroscopic and mass spectrometric studies that the addition of particular metal ions (Cu2+, Fe3+, and to a certain extent Hg2+) initially induced a ring-opening reaction that was irreversibly followed by a fast ring closure-deprotonation-oxidation sequence to give styryl-substituted naphthoxazole derivatives as the products quantitatively. For the quinolizinium-substituted spirooxazine derivative, the formation of the respective oxidation product caused the development of a broad absorption band between 425 nm and 500 nm and a new emission band at λfl = 628 nm, so that it may be employed as a selective chemosensor or chemodosimeter for the colorimetric and fluorimetric detection of Cu2+ and Fe3+.

The ICT-based fluorescence and colorimetric dual sensing of endogenous hypochlorite in living cells, bacteria, and zebrafish

This work demonstrates a novel chemosensor, SPTPA, that exhibits fluorescence and colorimetric dual sensing of hypochlorite with an ICT ON strategy.

Synthesis of hydrophobically modified berberine derivatives with high anticancer activity through modulation of the MAPK pathway

Linoleic acid-modified berberine derivative induces apoptosis of A549 cells and affects the expression of proteins associated with the MAPK pathway.

Detection and quantification of folic acid in serum via a dual-emission fluorescence nanoprobe

Folic acid (FA) is an essential vitamin in humans, and thus, rapid, accurate, and sensitive methods for its quantification in different biological samples are needed. This work describes a novel, simple, and effective dual-emission fluorescence nanoprobe for FA detection and quantification. The probe was covalently linked to amino-modified orange quantum dots (QDs) and carboxyl-modified blue graphene quantum dots (GQDs). The resulting material exhibited two emission peaks at 401 and 605 nm upon excitation at 310 nm. The probe had good selectivity and sensitivity toward FA with an exceptionally low detection limit (LOD = 0.09 nM). This probe was effectively used to quantify FA in animal serum samples. The method has potential utility for FA analysis in different types of biological samples. Graphical abstract.

Micro-Capillary Coatings Based on Spiropyran Polymeric Brushes for Metal Ion Binding, Detection, and Release in Continuous Flow

Micro-capillaries, capable of light-regulated binding and qualitative detection of divalent metal ions in continuous flow, have been realised through functionalisation with spiropyran photochromic brush-type coatings. Upon irradiation with UV light, the coating switches from the passive non-binding spiropyran form to the active merocyanine form, which binds different divalent metal ions (Zn²⁺, Co²⁺, Cu²⁺, Ni²⁺, Cd²⁺), as they pass through the micro-capillary. Furthermore, the merocyanine visible absorbance spectrum changes upon metal ion binding, enabling the ion uptake to be detected optically. Irradiation with white light causes reversion of the merocyanine to the passive spiropyran form, with simultaneous release of the bound metal ion from the micro-capillary coating.

Spiropyran-Isoquinoline Dyad as a Dual Chemosensor for Co(II) and In(III) Detection

Spiropyran derivatives have been studied as light-regulated chemosensors for a variety of metal cations and anions, but there is little research on chemosensors that simultaneously detect multiple metal cations. In this study, a spiropyran derivative with isoquinoline, SP-IQ, was prepared and it functions investigated as a light-regulated sensor for both Co²⁺ and In³⁺ cations. A colorless nonfluorescent SP-IQ converts to a pink-colored fluorescent MC-IQ by UV irradiation or standing in the dark, and MC-IQ returns to SP-IQ with visible light. Upon UV irradiation with the Co²⁺ cation for 7 min, the stronger absorption at 540 nm and the similar fluorescence intensity at 640 nm are observed, compared to when no metal cation is added, due to the formation of a Co²⁺ complex with pink color and pink fluorescence. When placed in the dark with the In³⁺ cation for 7 h, the colorless solution of SP-IQ changes to the In³⁺ complex with yellow color and pink fluorescence, which shows strong absorption at 410 nm and strong fluorescence at 640 nm. Selective detection of the Co²⁺ cation with UV irradiation and the In³⁺ cation in the dark could be possible with SP-IQ by both absorption and fluorescence spectroscopy or by the naked eye.

Near-infrared aza-BODIPY fluorescent probe for selective Cu2+detection and its potential in living cell imaging

A near-infrared (NIR) fluorescent sensor1composed of an aza-boron-dipyrromethene (aza-BODIPY) core covalently bound to two di-2-picolylamine moieties was prepared for Cu²⁺detection in aqueous solutions.

Fluorescent oligomer as a chemosensor for the label-free detection of Fe(3+) and dopamine with selectivity and sensitivity

In this article, a sensitive and selective turn-off fluorescence chemosensor, Tyloxapol (one kind of water soluble oligomer), was developed for the label-free detection of Fe(3+) ions in aqueous solution. Fluorescence (FL) experiments demonstrated that Tyloxapol was a sensitive and selective fluorescence sensor for the detection of Fe(3+) directly in water over a wide range of metal cations including Na(+), K(+), Ag(+), Hg(2+), Cd(2+), Co(2+), Cu(2+), Cr(3+), Mn(2+), Ba(2+), Zn(2+), Ni(2+), Mg(2+), Ca(2+), and Pb(2+). Moreover, the fluorescence intensity of Tyloxapol has shown a linear response to Fe(3+) in the concentration range of 0-100 μmol L(-1) with a detection limit of 2.2 μmol L(-1) in aqueous solution. Next, based on a competition mechanism, another turn-on sensing application of the Tyloxapol/Fe(3+) platform to probe dopamine (DA) against various other biological molecules such as other neurotransmitters or amino acids (norepinephrine bitartrate, acetylcholine chloride, alanine, valine, phenylalanine, tyrosine, leucine, glycine, histidine) were also investigated. It is expected that our strategy may offer a new approach for developing simple, cost-effective, rapid and sensitive sensors in biological and environmental applications.

Fabrication of an electrochemical sensor based on spiropyran for sensitive and selective detection of fluoride ion

In the past decades, numerous electrochemical sensors based on exogenous electroactive substance have been reported. Due to non-specific interaction between the redox mediator and the target, the instability caused by false signal may not be avoided. To address this issue, in this paper, a new electrochemical sensor based on spiropyran skeleton, namely SPOSi, was designed for specific electrochemical response to fluoride ions (F(-)). The breakage of Si-O induced by F(-) based on the specific nucleophilic substitution reaction between F(-) and silica would directly produce a hydroquinone structure for electrochemical signal generation. To improve the sensitivity, SPOSi probe was assembled on the single-walled carbon nanotubes (SWCNTs) modified glassy carbon electrode (GCE) through the π-π conjugating interaction. This electrode was successfully applied to monitor F(-) with a detection limit of 8.3 × 10(-8) M. Compared with the conventional F(-) ion selected electrode (ISE) which utilized noncovalent interaction, this method displays higher stability and a comparable sensitivity in the urine samples.

Fluorescent probes for the selective detection of chemical species inside mitochondria

This feature article systematically summarizes the development of fluorescent probes for the selective detection of chemical species inside mitochondria.

The role of atropisomers on the photo-reactivity and fatigue of diarylethene-based metal–organic frameworks

Stabilization of unfavorable rotational isomers within the nanoporous crystalline matrix reduces the useful lifetime of this photo-switchable material.

A self-assembled triphenylamine-based fluorescent chemosensor for selective detection of Fe3+ and Cu2+ ions in aqueous solution

Triphenylamine-based fluorescent chemosensor m-TAPA (S) shows high selectivity and sensitivity toward Fe³⁺/Cu²⁺ in natural and drinking water. Additionally, the TCL strips serve as a simple method for detection of Fe³⁺/Cu²⁺ at the nanomolar range.

Fluorescent chemodosimeter based on spirobenzopyran for organophosphorus nerve agent mimics (DCP)

A new chromogenic as well as fluorogenic protocol based on the spirobenzopyran system for the selective detection of nerve agent mimics (diethyl chlorophosphate or DCP vapour) within a few seconds (∼30 s) is designed, synthesized and characterized in this study.