Fluorescent Dyes with Directly Connected Xanthone and Xanthene Units

Abstract

Unexpected dimerization of a methoxymethyl-protected xanthone occurred upon treatment with an aryl lithium reagent generated from 2-bromo-1,3-dimethylbenzene and n-butyllithium. The hydrogen between two directing ethereal oxygen atoms was not abstracted, but that adjacent to the carbonyl group was removed to afford a dimeric compound containing two directly connected fluorescent xanthone and xanthene units. Starting from this discovery, three dimeric dyes were constructed, and their optical properties were examined. Although the two fluorescent units were orthogonal in each dye, efficient energy transfer was observed in dimeric dye 16 in three solvent systems. In contrast, solvent-dependent energy transfer was detected for another dimeric dye, 5. After close investigation, we found that the orientation factor (κ) is the main factor influencing Förster resonance energy transfer in these dyes.

Tissue-Specific Near-Infrared Fluorescence Imaging

“…Before NIR imaging successfully emerges in the clinic, contrast agents must be designed to satisfy a very particular set of parameters that are requisite to future successes . Many classes of known fluorescent structures have been used successfully and they encompass three unique classes: (1) the small molecule fluorophores (the most studied class), such as cyanines, porphyrin-based fluorophores, metal complexes, xanthene dyes, squaraine rotaxanes, and phenothiazine-based fluorophores, (2) synthetic nanoparticles such as quantum dots, − and (3) biologics such as green fluorescent protein . All of these representative agents must be tailored to achieve sufficient stability, specificity, and safety (as listed in Table ) for human use.…”

Deep-Red and Near-Infrared Xanthene Dyes for Rapid Live Cell Imaging

“…Recently, the hybridization of two classical fluorescent dyes has also become a promising strategy for the design of long-wavelength fluorescent dyes . For example, our group reported a family of coumarin-fused pyronin dyes ( CP dyes) with deep-red emissions for subcellular organelle imaging .…”

Choline chloride and itaconic acid-based deep eutectic solvent as an efficient and reusable medium for the preparation of 13-aryl-5H-dibenzo[b,i]xanthene-5,7,12,14(13H)-tetraones

“…To further expand the potential of this approach as a tool for the construction of xanthenes, we investigated the reaction of benzaldehyde with b-naphthol (4) or dimedone (5). As shown in Scheme 4, benzaldehyde could react smoothly with b-naphthol or dimedone to give the desired 14-phenyl-14H-dibenzo[a,j]xanthene (6) [27] and 3,3,6,6-tetramethyl-9-phenyl-3,4,5,6,7,9-hexahydro-1H-xanthene-1,8(2H)-dione (7) [47] in high yields.…”

“…Xanthenes can also be used in the preparation of stable laser dyes [5], fluorescent sensor [6,7], and protein labelling fluorophores [8]. Consequently, various well-designed methodologies have been developed to assemble these interesting scaffolds.…”