Six strongly fluorescent four-coordinate organoboron N,Cchelates, containing an arylisoquinoline skeleton, were prepared. Remarkably, the fluorescence quantum yields reach values of up to 0.74 in oxygen-free toluene. The strong B-N interaction was corroborated by the single-crystal X-ray analysis of two dyes. The intramolecular charge-transfer (ICT) character of the fluorophores was evidenced by solvatochromic studies and time-dependent density-functional-theory calculations at the PCM(toluene)/CAM-B3LYP/6-311++G(2d,p)//PCM(toluene)/B3LYP/6-311G(2d,p) level of theory. The compounds combine high chemical stability with high photostability (especially when equipped with electron-donating substituents). The strong fluorescence and the large Stokes shifts predestine these compounds for their use in confocal fluorescence microscopy. This was demonstrated for the imaging of the N13 mouse microgial cell line. As a surplus, significant two-photon absorption cross sections (up to 61 GM) allow the use of excitation wavelengths in the near-infrared region (> 800 nm).

Background: Selective reactions to clavulanic acid (CLV) account for around 30% of immediate reactions after administration of amoxicillin-CLV. Currently, no immunoassay is available for detecting specific IgE to CLV, and its specific recognition in patients with immediate reactions has only been demonstrated by basophil activation testing, however with suboptimal sensitivity. The lack of knowledge regarding the structure of the drug that remains bound to proteins (antigenic determinant) is hampering the development of in vitro diagnostics. We aimed to identify the antigenic determinants of CLV as well as to evaluate their specific IgE recognition and potential role for diagnosis.Methods: Based on complex CLV degradation mechanisms, we hypothesized the formation of two antigenic determinants for CLV, AD-I (N-protein, 3-oxopropanamide) and AD-II (N-protein, 3-aminopropanamide), and designed different synthetic analogs to each one. IgE recognition of these structures was evaluated in basophils from patients with selective reactions to CLV and tolerant subjects. In parallel, the CLV fragments bound to proteins were identified by proteomic approaches.Results: Two synthetic analogs of AD-I were found to activate basophils from allergic patients. This determinant was also detected bound to lysines 195 and 475 of CLVtreated human serum albumin. One of these analogs was able to activate basophils in 59% of patients whereas CLV only in 41%. Combining both results led to an increase in basophil activation in 69% of patients, and only in 12% of controls.