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Solvatochromic covalent organic frameworks.

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New covalent organic frameworks (COFs) act as reversible sensors, changing color with humidity and solvent vapors. These porous materials offer ultrafast response times for advanced sensing applications.

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Area of Science:

  • Materials Science
  • Chemistry

Background:

  • Covalent organic frameworks (COFs) are tunable crystalline, porous materials.
  • Developing COFs with responsive electronic structures is an active research area.

Purpose of the Study:

  • To report the first COFs exhibiting reversible electronic structure changes based on atmospheric conditions.
  • To demonstrate COFs as solid-state supramolecular solvatochromic sensors.

Main Methods:

  • Synthesis of novel COFs.
  • Fabrication of vertically oriented COF films.
  • Testing sensor response to humidity and solvent vapors.
  • Characterization of electronic structure changes and response times.

Main Results:

  • The developed COFs show reversible electronic structure changes in response to atmospheric conditions.
  • These COFs function as solvatochromic sensors with color changes dependent on vapor concentration and polarity.
  • Ultrafast response times (<200 ms) were achieved due to accessible pores in vertically oriented films.
  • The sensors demonstrated high stability over 4000 cycles and outperformed commercial humidity sensors.

Conclusions:

  • COFs can be designed as effective solid-state supramolecular solvatochromic sensors.
  • Their tunable nature and rapid response open possibilities in sensing and optoelectronics.
  • These materials offer a promising platform for developing advanced vapor sensors.