The inner filter effect and multivariate array sensing using conjugated polymers are combined for the detection and challenging discrimination of closely related polycyclic aromatic hydrocarbons.

Azo dyes are ubiquitous pollutants that contaminate water supplies and threaten human, biota, and ecosystem health. Their detection and discrimination are a considerable challenge owing to the numerous structural, chemical, and optical similarities between dyes, complexity of the wastewater in which they are found, and low environmental concentrations. Here, we demonstrate that the inner filter effect (IFE), in combination with conjugated polymer array-based sensing, offers a rapid approach for the quantitative profiling of these pollutants. The array was constructed using three anionic conjugated polyelectrolytes whose varying spectroscopic properties led to distinct IFE patterns in the presence of various dyes. These unique fluorescence response patterns were identified and processed using linear discriminant analysis (LDA), enabling the individual identification of 12 closely related azo dyes. To demonstrate the potential for utility in the environment, the array was used to differentiate between these dyes at nanomolar concentrations in water.

Metal cations are potent environmental pollutants that negatively impact human health and the environment. Despite advancements in sensor design, the simultaneous detection and discrimination of multiple heavy metals at sub‐nanomolar concentrations in complex analytical matrices remain a major technological challenge. Here, the design, synthesis, and analytical performance of three highly emissive conjugated polyelectrolytes (CPEs) functionalized with strong iminodiacetate and iminodipropionate metal chelates that operate in challenging environmental samples such as seawater are demonstrated. When coupled with array‐based sensing methods, these polymeric sensors discriminate among nine divalent metal cations (CuII, CoII, NiII, MnII, FeII, ZnII, CdII, HgII, and PbII). The unusually high and robust luminescence of these CPEs enables unprecedented sensitivity at picomolar concentrations in water. Unlike previous array‐based sensors for heavy metals using CPEs, the incorporation of distinct π‐spacer units within the polymer backbone affords more pronounced differences in each polymer's spectroscopic behavior upon interaction with each metal, ultimately producing better analytical information and improved differentiation. To demonstrate the environmental and biological utility, a simple two‐component sensing array is showcased that can differentiate nine metal cation species down to 500 × 10−12 m in aqueous media and to 100 × 10−9 m in seawater samples collected from the Gulf of Mexico.

Cationic poly(amidoamine) (PAMAM) dendrimers are known as good supramolecular hosts for a variety of smaller water‐soluble guests. We expanded their binding scope to the uptake of very hydrophobic guests such as polycyclic aromatic hydrocarbons (PAH) in neutral aqueous solution. We used anthracene and pyrene as representatives of this family of hydrocarbons, and as capable fluorescent emitters to probe mode and location of interaction for these hydrocarbons with polycationic amine‐terminated PAMAM dendrimers. We used steady‐state and time‐resolved fluorescence emission spectroscopy, as well as fluorescence anisotropy measurements and selective quenching experiments, to establish the mode and location of these binding interactions, demonstrating that, although these probes may look relatively similar, their interaction with PAMAM dendrimers is nevertheless significantly different. The results presented here provide insight into the attractive forces at play in the uptake of featureless hydrophobic PAH guests by hydrophilic PAMAM dendrimer hosts, whose applications span practical challenges including chemical separations, analytical discrimination, solubility and bioavailability enhancement of hydrophobic compounds.

A family of coumarin–enamine chemodosimeters is evaluated for their potential use as fluorescent molecular probes for multiple analytes [cadmium­(II), cobalt­(II), copper­(II), iron­(II), nickel­(II), lead­(II), and zinc­(II)], as their chloride and acetate salts. These fluorophores displayed excellent optical spectroscopic modulation when exposed to ion pairs with different Lewis acidic and basic properties in dimethyl sulfoxide (DMSO). The chemodosimeters were designed to undergo excited-state intramolecular proton transfer (ESIPT), which leads to significant Stokes shifts (ca. 225 nm) and lower-energy fluorescence emission (ca. 575 nm). A more basic anion, e.g., acetate, inhibited the ESIPT mechanism by deprotonation of the enol, producing a binding pocket (N^O– chelate) that can coordinate to an appropriate metal ion. Coordination of the metal ions enhances the fluorescent intensity via the chelation-enhanced fluorescence emission mechanism. Subjecting the spectroscopic data to linear discriminant analysis provided insights into the source of these systems’ markedly different behavior toward ion pairs, despite the subtle structural differences in the organic framework. These compounds are examples of versatile, low-molecular-weight, dual-channel fluorescent sensors for ion-pair recognition. This study paves the way for using these probes as practical components of a sensing array for different metal ions and their respective anions.