Systematic Investigation of Photoinduced Electron Transfer Controlled by Internal Charge Transfer and Its Consequences for Selective PdCl2Coordination

A Boron Dipyrromethene-Based Fluorescence 'OFF-ON' Probe for Sensitive and Selective Detection of Palladium(II) Ions and Its Application in Live Cell Imaging

A novel boron dipyrromethene (BODIPY)-based fluorescent probe BDP-Pd was designed and synthesized. Upon coordination with Pd²⁺ , the emission of the probe at 508 nm significantly increased, showing an 'OFF-ON' fluorescence response. The complexation of BDP-Pd with Pd²⁺ in both acetonitrile and aqueous solution were then studied by absorption and fluorescence spectra. The binding stoichiometry between the probe and Pd²⁺ was found to be 1 : 2, and the binding constant was determined to be 8.5×10¹⁰  M^-2 and 8.2×10¹⁰  M^-2 in acetonitrile and aqueous solution, respectively. The probe exhibited a detection limit as low as 0.72 ppb toward Pd²⁺ with no obvious interference from up to 21 species of common metal ions, suggesting BDP-Pd as a sensitive and selective fluorescent probe for Pd²⁺ detection. The fast fluorescence 'OFF-ON' phenomenon of the probe upon coordination with Pd²⁺ ions could be easily observed by a hand-hold UV lamp under naked eye in solution as well as on homemade test trips. Density functional theory (DFT) calculations were carried out to give the optimized structure of complex BDP-Pd : 2Pd²⁺ and rationalize the detection mechanism through a prohibited intramolecular photoinduced electron transfer (PET) process. The bio-imaging application of the probe was investigated and it showed excellent cell permeability for fluorescent imaging of Pd²⁺ ions in A549 human non-small cell lung cancer cells.

Design and synthesis of new functionalized 8-(thiophen-2-yl)-1,2,3,4-tetrahydroquinolines as turn-off chemosensors for selective recognition of Pd2+ ions

Functionalized 8-thienyl-1,2,3,4-tetrahydroquinoline was synthesized as a fluorescent turn-off chemosensor for selective recognition of Pd²⁺ ions with a low detection limit.

Selective fluorescent turn-off sensing of Pd2+ ion: applications as paper strips, polystyrene films, and in cell imaging

Pyridine-2,6-dicarboxamide based scaffolds with appended naphthyl groups act as fluorescent probes for the selective detection of Pd²⁺ ions in aqueous medium and have applications as paper-strip sensors, as polystyrene films, and in cell imaging.

A two-photon ratiometric ESIPT probe for fast detection and bioimaging of palladium species

A two-photon ratiometric ESIPT probe for fast detection of palladium species, which can be used for bioimaging has been designed.

A fluorescent and colorimetric probe containing oxime-ether for Pd(2+) in pure water and living cells

Palladium contamination causes potential danger to the environment, and a study of its biological safety is still on the way. Here, a fluorescent and colorimetric probe (compound 1) containing oxime-ether for Pd(2+) has been developed. 1 can detect Pd(2+) in aqueous samples with high selectivity and sensitivity. 1 can also work well in biological samples, which gives access to detect Pd(2+) in an organism.

A simple and effective fluorescent probe based on rhodamine B for determining Pd2+ ions in aqueous solution

It is demonstrated that the mechanism of the probe to Pd²⁺ and images under a UV lamp.

An azodye–rhodamine-based fluorescent and colorimetric probe specific for the detection of Pd2+ in aqueous ethanolic solution: synthesis, XRD characterization, computational studies and imaging in live cells

An azodye–rhodamine hybrid colorimetric fluorescent probe (L) has been designed and synthesized.

A naked-eye and ratiometric near-infrared probe for palladium via modulation of a π-conjugated system of cyanines

The modulation of π-conjugated electrons in cyanine dyes can result in a ratiometric fluorescence change with a large Stokes shift (270 nm), especially for realizing palladium detection in aqueous samples using indicator paper and in living cells by ratiometric mode.

Colourimetric and fluorescent probes for the optical detection of palladium ions

In recent years, the development of optical probes to analyse trace palladium ions (Pd(2+)) has attracted great attention because of the residual palladium released by catalytic converters or from various Pd-catalysed reactions. These residual palladium ions may cause potential health hazards. This review provides a brief introduction to the new methods used to determine trace amounts of Pd(2+), which then mainly focuses on the different reporting systems and unique mechanisms of the colourimetric and fluorescent probes used to detect Pd(2+), including Pd(2+) complex formation or Pd-catalysed reactions.

Construction of a near-infrared fluorescence turn-on and ratiometric probe for imaging palladium in living cells

A new NIR fluorescent probe, NIR-Pd, for palladium species was designed and synthesized, based on a HD NIR fluorophore and deprotection of aryl propargyl ethers by palladium. The probe NIR-Pd displayed either a large NIR fluorescence turn-on or ratiometric response to palladium with high sensitivity and selectivity. Additionally, the novel NIR probe can monitor palladium species in live HeLa cells by NIR fluorescence imaging.

Photoinduced electron transfer (PET) based Zn2+ fluorescent probe: transformation of turn-on sensors into ratiometric ones with dual emission in acetonitrile

Ratiometric sensors for the detection of metal ions have gained increasing attention due to its self-calibration tendency for the environmental effects. In this context, we have synthesized and characterized a dual emitting ratiometric Zn(2+) probe (1) having acridinedione as a fluorophore and N,N-bis(2-pyridylmethyl)amine (BPA) as a receptor unit. Existence of two different conformation of the molecule with photoinduced electron transfer (PET) from amine moiety to the acridinedione fluorophore leads to dual emission, namely locally excited (425 nm) and anomalous charge transfer emission (560 nm) in aprotic solvents. In the presence of one equivalent of Zn(2+), a 15-fold fluorescence enhancement in the locally excited state together with the quenching of charge transfer emission is observed. The intensity changes at the two emission peaks allow a ratiometric detection of Zn(2+) under PET signaling mechanism. The utilization of PET process for the ratiometric fluorescence change will further signify the importance of PET mechanism in sensing action. Addition of Zn(2+) to 1 in acetonitrile/water mixtures shows a single emission peak with fluorescence enhancement.