Water‐Soluble Phospholo[3, 2‐b]phosphole‐P, P′‐Dioxide‐Based Fluorescent Dyes with High Photostability. Issue 12 (22nd May 2018)

• Record Type: Journal Article
• Authors: Wang, Chenguang; Fukazawa, Aiko; Tanabe, Yoshiyuki; Inai, Naoto; Yokogawa, Daisuke; Yamaguchi, Shigehiro
• Is Part Of: Chemistry, an Asian journal. Volume 13:Issue 12(2018)
• Page Start: 1616
• Page End: 1624
• Publication Date: 2018-05-22
• Subjects: fluorescent dyes -- fluorescence -- isomers -- phospholes -- photostability; Chemistry -- Periodicals; 540.5
• DOI: 10.1002/asia.201800533
• Languages: English
• ISSNs: 1861-4728

Abstract

Abstract: We recently reported that fluorescent dye PB430, which consisted of a 2‐phenyl‐substituted benzophosphole P ‐oxide skeleton that was reinforced by a methylene bridge, showed pronounced photostability and, thus, high utility for applications in super‐resolution stimulated emission depletion (STED) microscopy. Herein, we replaced the methylene bridge with another P=O group to 1) investigate the role of the bridging moieties; and 2) further modulate the fluorescence properties of this skeleton. We synthesized a series of phospholo[3, 2‐ b ]phosphole‐based dyes— trans ‐PO‐PB430, cis ‐PO‐PB430, and trans ‐PO‐PB460—all of which showed sufficient water solubility. Moreover, trans ‐PO‐PB430 and trans ‐PO‐PB460 exhibited intense green and orange fluorescence, respectively, and a high photostability that was comparable to that of PB430. In contrast, cis ‐PO‐PB430 underwent rapid photobleaching upon continuous photoirradiation, which demonstrated the importance of steric shielding of the polycyclic skeleton by the substituents on the bridging moieties. The fluorescence properties of these dyes were insensitive to concentration, pH value, and polarity changes of the environment in solution. In addition, even in the solid state, these dyes showed strong green to orange emissions. These results demonstrate the potential utility of trans ‐PO‐PB430 and trans ‐PO‐PB460 as highly photostable fluorescent dyes. Abstract : P=O faced : Phospholo[3, 2‐ b ]phosphole‐based fluorescent dyes exhibited green‐to‐orange fluorescence with high brightness in aqueous solution. The trans isomer with respect to the relative orientation of the P=O groups displayed exceptionally high photostability, whereas the cis isomer showed substantially lower photostability, owing to weaker steric protection of one side of the cis isomer by the aryl groups on the P atoms.