Near-infrared BODIPY-based two-photon ClO− probe based on thiosemicarbazide desulfurization reaction: naked-eye detection and mitochondrial imaging

Near-infrared two-photon ClO⁻ fluorescent probe based on the desulfurization reaction of the thiosemicarbazide group.

A highly selective turn-on fluorescent sensor for glucosamine from amidoquinoline-napthalimide dyads

Three amidoquinoline-naphthalimide dyads are designed and synthesized in 67-73% overall yields in 3 steps from commercially available starting materials. Compounds with unsubstituted and nitro naphthalimide (1 and 2) show excellent selective fluorescent responses towards glucosamine with the enhancement of fluorescence quantum yields by 14 folds. The determination of HOMO-LUMO levels by linear sweep voltammetry suggests that the sensing mechanism likely involves the inhibition of photo-induced electron transfer (PET) between the aminoquinoline and naphthalimide moieties by glucosamine. The association constants of 1.55×10(4) and 1.45×10(4)M(-)(1), along with the glucosamine detection limits of 1.06 and 0.29µM are determined for 1 and 2, respectively. The application of 2 as a fluorescent probe for real-time detection of cellular glucosamine at micromolar level in living Caco-2 cells is also demonstrated.

Selective interactions of trivalent cations Fe³⁺, Al³⁺ and Cr³⁺ turn on fluorescence in a naphthalimide based single molecular probe

Synthesis and fluorescence turn-on behavior of a naphthalimide based probe is described. Selective interactions of trivalent cations Fe(3+), Al(3+) or Cr(3+) with probe 1 inhibit the PET operating in the probe, and thereby, permit the detection of these trivalent cations present in aqueous samples and live cells. Failure of other trivalent cations (Eu(3+), Gd(3+) and Nb(3+)) to inhibit the PET process in 1 demonstrates the role of chelating ring size vis-à-vis ionic radius in the selective recognition of specific metal ions.

Two Schiff-base fluorescent sensors for selective sensing of aluminum (III): Experimental and computational studies

Two Schiff-base fluorescent sensors have been synthesized, which both can act as fluorescent probes for Al(3+), upon addition of Al(3+), they exhibit a large fluorescence enhancement which might be attributed to the formation of 1:1 ligand-Al complexes which inhibit photoinduced electron transfer (PET) progress, and that the proposed binding modes of the sensors and Al(3+) are identified by theoretical calculations.

Selective chromo-fluorogenic detection of trivalent cations in aqueous environments using a dehydration reaction

Trivalent cations induced a dehydration reaction of a chemodosimeter in water that is coupled with colour and emission changes.

ESIPT blocked CHEF based differential dual sensor for Zn2+ and Al3+in a pseudo-aqueous medium with intracellular bio-imaging applications and computational studies

A novel H3SAL-NH probe exhibits ESIPT from the phenolic OH group to the azomethine N atom in the excited state. This is blocked in the presence of Zn²⁺ and Al³⁺ giving turn on fluorescence which is useful for imaging in live HepG2 cells.

Carbazole–benzimidazole based dyes for acid responsive ratiometric emissive switches

Three carbazole conjugated benzimidazole dyes have been synthesized and their acid/base induced photophysical properties have been studied.

FRET-based fluorescence ratiometric and colorimetric sensor to discriminate Fe3+ from Fe2+

A new benzothiazole–quinoline–rhodamine-6G-based probe was synthesised. The probe can exclusively detect Fe³⁺ through a ratiometric manner in a mixed aqueous system with a detection limit in the 10⁻⁸ M range.

A new visible-light-excitable ICT-CHEF-mediated fluorescence 'turn-on' probe for the selective detection of Cd(2+) in a mixed aqueous system with live-cell imaging

A new quinoline based sensor was developed and applied for the selective detection of Cd(2+) both in vitro and in vivo. The designed probe displays a straightforward approach for the selective detection of Cd(2+) with a prominent fluorescence enhancement along with a large red shift (∼38 nm), which may be because of the CHEF (chelation-enhanced fluorescence) and ICT (internal charge transfer) processes after interaction with Cd(2+). The interference from other biologically important competing metal ions, particularly Zn(2+), has not been observed. The visible-light excitability of the probe merits in the viewpoint of its biological application. The probe enables the detection of intracellular Cd(2+) with non-cytotoxic effects, which was demonstrated with the live RAW cells. The experimentally observed change in the structure and electronic properties of the sensor after the addition of Cd(2+) were modelled by the density functional theory (DFT) and time-dependent density functional theory (TDDFT) computational calculations, respectively. Moreover, the test strip experiment with this sensor exhibits both absorption and fluorescence color changes when exposed to Cd(2+) in a mixed aqueous solution, which also makes the probe more useful. The minimum limit of detection of Cd(2+) by the probe was in the range of 9.9 × 10(-8) M level.

Iron(III)-Selective Chelation-Enhanced Fluorescence Sensing for In Vivo Imaging Applications

A "turn-on" pattern Fe(3+) -selective fluorescent sensor was synthesized and characterized that showed high fluorescence discrimination of Fe(3+) over Fe(2+) and other tested ions. With a 62-fold fluorescence enhancement towards Fe(3+) , the probe was employed to detect Fe(3+) in vivo in HeLa cells and Caenorhabditis elegans, and it was also successfully used to elucidate Fe(3+) enrichment and exchange infected by innexin3 (Inx3) in hemichannel-closed Sf9 cells.

Cd(2+) Triggered the FRET "ON": A New Molecular Switch for the Ratiometric Detection of Cd(2+) with Live-Cell Imaging and Bound X-ray Structure

On the basis of the Förster resonance energy transfer mechanism between rhodamine and quinoline-benzothiazole conjugated dyad, a new colorimetric as well as fluorescence ratiometric probe was synthesized for the selective detection of Cd(2+). The complex formation of the probe with Cd(2+) was confirmed through Cd(2+)-bound single-crystal structure. Capability of the probe as imaging agent to detect the cellular uptake of Cd(2+) was demonstrated here using living RAW cells.

Cyclic aromatic imides as a potential class of molecules for supramolecular interactions

Prospects of stacking interactions of imides beneficial to generation of new soft materials are projected by analysing examples of primary building blocks that provide a basis for understanding at the molecular level.

A single hybrid optical sensor based on nanoporous silica type SBA-15 for detection of Pb2+and I−in aqueous media

Simple two-steps post synthesis procedure achieved the functionalized nanoporous SBA-15 as a single hybrid optical sensor for detecting Pb²⁺and I⁻ions in aqueous media.

A new ICT and CHEF based visible light excitable fluorescent probe easily detects in vivo Zn2+

A new chelator and ICT donor based visible light excitable Zn²⁺ sensor was designed and developed by integrating quinoline and 2-hydroxy-3-(hydroxymethyl)-5-methylbenzaldehyde.

A differentially selective molecular probe for detection of trivalent ions (Al3+, Cr3+and Fe3+) upon single excitation in mixed aqueous medium

A chemosensor was developed which could selectively detect and differentiate trivalent metal ions (Al³⁺, Cr³⁺and Fe³⁺) upon single excitation at two different wavelengths in aqueous medium.

Water-soluble host–guest system from β-cyclodextrin as a fluorescent sensor for aluminium ions: synthesis and sensing studies

In this paper, a simple small molecule (L) derived from 4-(diethylamino)-2-hydroxy-benzaldehyde and carbohydrazide has been synthesized, and a water-soluble host–guest system from β-cyclodextrin and L was obtained that exhibited characteristic fluorescence behavior toward Al³⁺.

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.

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 rhodamine–quinoline based chemodosimeter capable of recognising endogenous OCl− in human blood cells

A rhodamine–quinoline based chemodosimeter (RHQ) has been designed, synthesized and characterized in this paper.

CHEF induced highly selective and sensitive turn-on fluorogenic and colorimetric sensor for Fe3+

A new fluorescent probe was synthesized from rhodamine-6G and 6-(hydroxymethyl) picolinohydrazide for the sensing of Fe(3+) in an aqueous environment. The structure of the sensor was confirmed through its single crystal X-ray study. It exhibits a high specificity and sensitivity towards Fe(3+) over other interfering heavy and transition metal ions (HTM). The turn-on greenish-yellow fluorescence and a colorimetric change from colourless to pink were observed upon addition of Fe(3+) which evokes almost 116- and 23-fold enhancement in absorbance and emission intensity respectively in an acetonitrile-water (1:1, v/v, 25 °C) solution at a neutral pH (pH = 7.2). The Fe(3+) promoted ring opening of the spirolactam framework to the open chain amide platform of the sensor is responsible for its visible colour change and turn-on fluorescence activity. It also exhibits an excellent performance in the "dip stick" method. Moreover the limit of detection of the probe is in the 10(-8) M range.