Analysis of the Isotopic Purity of D₂O with the Characteristic NIR-II Phosphorescence of Singlet Oxygen from a Photostable Polythiophene Photosensitizer

Abstract

D2O plays important roles in a variety of fields (such as the nuclear industry and bioorganic analysis), and thus its isotopic purity (H2O contents) is highly concerned. Due to its highly similar physical properties to H2O and large excess amounts of H2O over D2O, it is challenging to distinguish D2O from H2O. On the basis of the characteristic NIR-II phosphorescence of singlet oxygen (1O2), and the fact that H2O is a more efficient quencher for 1O2 than D2O, here, we proposed to simply use the 1275 nm emission of 1O2 for the analysis of the isotopic purity of D2O. In normal cases (a xenon lamp for excitation), such steady-state emission is extremely weak for valid analytical applications, we thus employed laser excitation for intensification. To this goal, a series of photosensitizers were screened, and eventually polythiophene PT10 was selected with high singlet oxygen quantum yield (ΦΔ = 0.51), high H2O/D2O contrast, and excellent photostability. Upon excitation with a 445 nm laser, a limit of detection (LOD, 3σ) of 0.1% for H2O in D2O was achieved. The accuracy of the proposed method was verified by the analysis of the isotopic purity of several D2O samples (with randomly added H2O). More interestingly, the hygroscopicity of D2O was sensitively monitored with the proposed probe in a real-time manner; the results of which are important for strengthening the care of D2O storage and the importance of humidity control during related investigations. Besides D2O isotopic purity evaluation, this work also indicated the potential usefulness of the NIR-II emission of singlet oxygen in future analytical detection.

Highly Facile Strategy for Detecting D2O in H2O by Porphyrin-Based Luminescent Probes

“…As illustrated in Figure , the intensity of ECL increased significantly with the increase in D 2 O concentration from 5 to 50 nM. There was a good linear relationship between the ECL intensity and the D 2 O concentration ( R 2 = 0.9984), and the calculated detection limit was only 0.29 nM, which was superior to UV–vis and PL analysis and also demonstrated the unique advantages of this ECL detection with water solubility, good specificity, high sensitivity, and easy controllability compared with some reported detection methods because of the extremely lower content of D 2 O at ppm level in nature (Table S5, Supporting Information). − In order to prove the reliability, the content of D 2 O in the actual sample (tap water) was determined by the new ECL method. It was found that the D 2 O content was 23.48 nM and exhibited a more accurate quantification in the determination of actual samples compared with the widely used gas chromatography–mass spectrometry (Tables S6 and S7, Supporting Information).…”

Polythiophene as a near full pH photo-antimicrobial

“…S12 and S13, ESI †). Therefore, a polythiophene photosensitizer (herein PT10 was explored for investigation 21 ) is theoretically stable in a wide pH range, which is an excellent choice for full pH photo-antimicrobial.…”

“…18 Besides, polythiophene typically exhibits a high singlet oxygen quantum yield (e.g., PT10, F D = 0.51). 14 Therefore, PT10 may satisfy the essential requirements of a near full pH photoantimicrobial. It was found that PT10 could realize PDAT for a broad band of microbials (bacterial, cyanobacteria, and fungal) in the pH range of 2-13, which compared favorably to antibiotics and other traditional photosensitizers.…”

“…In addition, organic photo-antimicrobials typically suffer from photobleaching. 7 c ,14 Considering their broad-spectrum antimicrobial activity, it is desirable to design photo-antimicrobials with inert pH responsiveness and good photostability.…”

Ratiometric fluorescent and colorimetric dual-modal sensing strategy for discrimination and detection of D2O from H2O

“…Recently, many techniques have been successfully developed for discriminating H 2 O from organic solvents, whereas discrimination between D 2 O and H 2 O is limited in its reporting and more challenging, due to their physical and chemical similarity. Traditional detection methods for D 2 O include NMR, Fourier transform infrared spectroscopy, fluorescence, phosphorescence, 5 and atomic absorption spectroscopy. 4 c Despite fluorescent organic sensors ranking as one of the most powerful tools to detect various analytes because of their advantages of low cost, fast response, high sensitivity, and real-time detection, 6 to the best of our knowledge, organic sensors for D 2 O are rarely described.…”