Water‐Soluble Phospholo[3,2‐b]phosphole‐P,P′‐Dioxide‐Based Fluorescent Dyes with High Photostability

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.

Fused Thiophene-S,S-dioxide-Based Super-Photostable Fluorescent Marker for Lipid Droplets

“…The high photostability and high brightness of fluorescent molecules are also crucial for the applications in organic optoelectronics such as organic light-emitting diodes (OLEDs). , Ladder-type π-conjugated molecules that contain main group elements in the framework are particularly attractive because of their diverse functionalization and wide tunability of optical properties (Figure a). , In this context, we have developed various types of ladder fluorescent molecules containing silicon or phosphorus atoms and demonstrated their high performance, including high fluorescence quantum yields and excellent photostability. − Taking advantages of these features, we have recently disclosed their promising utilities also for fluorescence imaging. We have succeeded in developing fluorescent organelle markers with extremely high photostability, which enabled the observation of ultrastructures of organelle using STED microscopy. − In particular, a carbon-bridged naphthophosphole fluorophore, PB Yellow (Figure b), allowed us to record continuous STED images of organelle membrane dynamics under physiological conditions. , …”

P-Protected Diphosphadibenzo[a,e]pentalenes and Their Mono- and Dicationic P-Bridged Ladder Stilbenes

“…Figure ). The dichalcogenophenes 3f and 3g , for example, have been applied in organic field effect transistors, while equally promising electronic and photophysical properties were uncovered for the B- ( 3a , b ), C- ( 3c ), Si- ( 3d ), N- ( 3e ), and P-bridged ( 3h – i ) ladder stilbenes.…”

“…Thus, electron injection into the highly electron-accepting π-systems of 6 is thermodynamically favored by approximately 1 eV in comparison to uncharged P-bridged ladder stilbenes (cf. CV E LUMO ( 3i ) ≈ – 3.2 eV), suggesting that compounds 6 may be employed as n -type semiconductors. However, future studies will be required to evaluate whether this is indeed the case.…”

A Novel Fluorescent Dye Extracted from Buddleja officinalis for Labeling Mitochondria after Fixation

“…This insensitivity would contribute to the stable staining of BO-dye in physiological environment. More importantly, BO-dye exhibited higher photostability when compared with MitoView™ Green, a commercial MitoTracker, which is beneficial for long-term observation, especially under the irradiation of a high-power laser source [ 33 ].…”