Dr Venkatramaiah Nutalapati, Associate Professor at the Centre for Interdisciplinary Research has authored a significant study on the oxygen sensing properties of room-temperature phosphorescent (RTP) halogenated hexahydroxanthene derivatives. This work establishes a cost-effective, metal-free design strategy for high-performance optical sensors capable of precise oxygen monitoring in critical biomedical and industrial environments.

Brief Abstract of Research:
In this research work, we have developed a series of room-temperature phosphorescence (RTP) compounds based on hexahydroxanthene (XAN) towards the oxygen-sensing. The structural configuration promotes efficient intersystem crossing (ISC) and suppresses nonradiative decay, enabling pronounced RTP. The high oxygen sensitivity arises from efficient triplet–triplet energy transfer from the XAN’s triplet excited state to ground-state triplet oxygen, leading to nonradiative quenching. XAN-Br and XAN-I containing 1 wt% Zeonex displayed strong RTP with lifetimes up to 4.48 ms. They also showed exceptional ISC quantum yields (93.02 % for XAN-Br and 93.51 % for XAN-I) and large vacuum-to-air photoluminescence intensity ratios (14.67 and 15.33, respectively). With their metal-free composition, efficient RTP, oxygen responsiveness, and good solution-processability into thin films. These features translated to excellent oxygen sensitivity, with Stern-Volmer quenching constants (Ksv) of 6.08 × 10-4 and 1.11 × 10-1 M-1 for XAN-Br and XAN-I, respectively. XAN-Br and XAN-I represent promising candidates for use in optical oxygen sensors for biomedical diagnostics, food preservation and environmental monitoring.

Explanation in Layperson’s Terms:
Imagine you have a toy that glows in the dark. If you put it in a box with lots of air, it might glow less. If you remove the air, it glows more. By watching how bright it is, you can guess how much air is inside. Optical oxygen sensors work in a similar way, but more precise and scientific. It will be used in blood oxygen monitoring, oxygen inside tissues during surgery, checking oxygen in incubators for newborns, monitoring oxygen levels in cell cultures. in medical research
Practical implementation of your research or the social implications associated with it:
These XAN-based materials can be used to make highly sensitive, low-cost oxygen sensors because their glow changes instantly when oxygen is present. They can be incorporated into smart food-packaging labels to detect spoilage, medical sensors for monitoring oxygen in tissues or wounds, and environmental devices for tracking air or water quality. Their metal-free, easily processed design makes them safer and more sustainable, offering practical benefits for public health, food safety, and environmental monitoring.

Your Collaborations:
This research was carried out through strong international collaboration involving multiple leading institutions. The project brought together expertise in materials chemistry, crystallography, nanotechnology, and optical physics. Key collaborators included researchers from the Waterloo Institute for Nanotechnology (Canada), the Chemical Crystallography Laboratory at Khalifa University (UAE), and the Department of Physics at Queen’s University (Canada) and the Faculty of Mechanical Engineering and Design at Kaunas University of Technology (Lithuania). This multidisciplinary partnership enabled advanced material design, structural analysis, and photophysical characterisation, strengthening the overall scientific impact of the work.

Future Research Plans:
Future work can focus on tuning the molecular structure to achieve even longer-lived phosphorescence and higher oxygen sensitivity, as well as improving stability under real-world conditions. Expanding the library of XAN derivatives with different substituents may enable color-tunable RTP. Integrating these materials into device prototypes such as wearable sensors, smart packaging films, or flexible optical chips will help translate the technology into practical applications. Additionally, studying their performance in biological environments could open pathways for biomedical imaging and real-time oxygen mapping.

The link to the article:
https://doi.org/10.1016/j.mseb.2025.118997
https://www.sciencedirect.com/science/article/pii/S0921510725010219