Near IR-emitting DNA-probes exploiting stepwise energy transfer processes

Area of Science:

• Coordination Chemistry
• Supramolecular Chemistry
• Photophysics

Background:

• Lanthanide complexes are crucial for luminescence applications, but efficient near-infrared (NIR) emission remains a challenge.
• Energy transfer cascades offer a pathway to sensitize lanthanide emission across the UV-visible-NIR spectrum.
• Developing selective sensors for biomolecules like DNA is vital for diagnostics and research.

Purpose of the Study:

• To synthesize and characterize novel cyclen-based lanthanide complexes for NIR emission.
• To investigate the energy transfer dynamics within a coumarin-rhodamine-lanthanide cascade.
• To establish a luminescent DNA-sensing platform operating in the NIR region.

Main Methods:

• Synthesis of cyclen-based lanthanide complexes.
• Characterization using spectroscopic techniques (UV-Vis absorption, emission spectroscopy).
• Computational analysis using Density Functional Theory (DFT) for regioselectivity.
• Evaluation of DNA-sensing capabilities through luminescence modulation.

Main Results:

• Successful synthesis of two new cyclen-based NIR-emitting lanthanide complexes.
• Demonstration of an efficient energy transfer cascade from coumarin to rhodamine to lanthanide.
• Observation of large Stokes shifts due to the cascade mechanism.
• Selective switching off of one energy transfer pathway by double-stranded DNA.
• Successful luminescent DNA sensing in the NIR region.

Conclusions:

• The developed cyclen-based lanthanide complexes exhibit efficient NIR emission via an energy transfer cascade.
• The system allows for selective luminescent DNA sensing in the NIR region by exploiting DNA-induced modulation of energy transfer.
• DFT calculations provide insights into the regioselective functionalization of the cyclen scaffold.