Electrochemical oxidation provides a versatile technique for treating wastewater streams onsite. We previously reported that a two-layer heterojunction Ni-Sb-SnO₂ anode (NAT/AT) can produce both ozone (O₃) and hydroxyl radical (^•OH). In this study, we explore further the applicability of NAT/AT anodes for oxidizing pharmaceutical compounds using carbamazepine (CBZ) and fluconazole (FCZ) as model probe compounds. Details of the oxidation reaction kinetics and subsequent reaction products are investigated in the absence and presence of chloride (Cl^-) and sulfate (SO₄ ^2-). In all cases, faster or comparable degradation kinetics of CBZ and FCZ are achieved using the double-layered NAT/AT anode coupled with a stainless steel (SS) cathode in direct comparison to an identical setup using a boron-doped diamond anode. Production of O₃ on NAT/AT enhances the elimination of both parent compounds and their transformation products (TPs). Very fast CBZ degradation is observed during NAT/AT-SS electrolysis in both NaClO₄ and NaCl electrolytes. However, more reaction products are identified in the presence of Cl^- than ClO₄ ^- (23 TPs vs 6). Rapid removal of FCZ is observed in NaClO₄, while the degradation rate is retarded in NaCl depending on the [Cl^-]. In SO₄ ^2--containing electrolytes, altered reaction pathways and transformation product distributions are observed due to sulfate radical generation. SO₄ ^·- oxidation produces fewer hydroxylated products and promotes the oxidation of aldehydes to carboxylic acids. Similar trend in treatment performance is observed in mixtures of CBZ and FCZ with other pharmaceutical compounds in latrine wastewater and secondary WWTP effluent.

As a major family of red-shifted fluorophores that operate beyond visible light, polymethine dyes are pivotal in light-based biological techniques. However, methods for tuning this kind of fluorophores by structural modification remain restricted to bottom-up synthesis and modification using coupling or nucleophilic substitutions. In this study, we introduce a two-step, late-stage functionalization process for heptamethine dyes. This process enables the substitution of the central chlorine atom in the commonly used 4'-chloro heptamethine scaffold with various aryl groups using aryllithium reagents. This method borrows the building block and designs from the xanthene dye community and offers a mild and convenient way for the diversification of heptamethine fluorophores. Notably, this efficient conversion allows for the synthesis of heptamethine-X, the heptamethine scaffold with two ortho-substituents on the 4'-aryl modification, which brings enhanced stability and reduced aggregation to the fluorophore. We showcase the utility of this method by a facile synthesis of a fluorogenic, membrane-localizing fluorophore that outperforms its commercial counterparts with a significantly higher brightness and contrast. Overall, this method establishes the synthetic similarities between polymethine and xanthene fluorophores and provides a versatile and feasible toolbox for future optimizing heptamethine fluorophores for their biological applications.