Spacer-Acceptor Synergy in Cyanide Detection: Leveraging Dual-Site Reactivity to Overcome Sensitivity-Range...

Area of Science:

• Supramolecular Chemistry
• Analytical Chemistry
• Materials Science

Background:

• Reaction-based chemosensors face a critical sensitivity-range trade-off, limiting precise detection of analytes like cyanide.
• Existing chemosensors struggle with simultaneous high sensitivity and a wide linear concentration range, hindering practical applications.
• Hazardous ion detection, particularly cyanide, requires robust and reliable sensing methodologies.

Purpose of the Study:

• To rationally design and develop novel donor-π-acceptor fluorescent probes to overcome the sensitivity-range limitation.
• To investigate the impact of π-spacer rigidity on the photophysical properties and sensing performance of fluorescent probes.
• To establish a generalizable strategy for engineering next-generation reaction-based chemosensors for environmental monitoring.

Main Methods:

• Synthesis of donor-π-acceptor fluorescent probes (TRMN and TπRMN) with triphenylamine donors, rhodanine acceptors, and differentiated π-spacers.
• Photophysical characterization of parent aldehydes and developed probes to understand spacer effects on nonradiative decay.
• Evaluation of cyanide recognition selectivity, sensitivity, and linear concentration range for both probes.

Main Results:

• Both TRMN and TπRMN demonstrated rapid (<20 s) and selective cyanide detection.
• Flexible-spacer TRMN showed high sensitivity (0.39 nM) but a narrow linear range (2-5.5 μM).
• Rigid-spacer TπRMN exhibited dual-site reactivity and an extended linear range (8-34 μM) with a 4.2 nM detection limit, suppressing nonradiative decay.
• Probes displayed solid-state fluorescence for latent fingerprint imaging.

Conclusions:

• Spacer-acceptor synergy engineering is a viable strategy to overcome the fundamental sensitivity-range trade-off in chemosensors.
• Rigid π-spacers enhance the linear range and suppress nonradiative decay, leading to improved chemosensor performance.
• The developed probes offer a comprehensive framework for next-generation reaction-based chemosensors applicable in environmental monitoring and forensic science.