Tautomeric sensing using a covalent organic framework
Inventors
Marder, Seth R. • Dichtel, William R. • JHULKI, Samik • Barlow, Stephen • Evans, Austin M.
Assignees
Georgia Tech Research Corp • Northwestern University
Publication Number
US-12366535-B2
Publication Date
2025-07-22
Expiration Date
2040-09-08
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Abstract
Disclosed herein are sensors including a covalent organic framework (COF). The COF includes tautomerically active subunits (TAS) capable of reversible iminol-to-ketoenamine tautomerism between a first tautomer and a second tautomer and linking groups. Methods of detecting analytes with the sensors are also disclosed.
Core Innovation
The invention discloses sensors comprising a covalent organic framework (COF) that includes tautomerically active subunits (TAS) capable of reversible iminol-to-ketoenamine tautomerism between two tautomeric forms. These forms have detectably distinct characteristics, enabling the COF to act as a sensor. The sensor may include an electromagnetic radiation source, detector, regeneration agent, heating element, or combinations thereof.
The problem addressed is the rarity of solid-state systems exhibiting distinct tautomeric properties sensitive to environmental changes. Traditional molecular probes rely on rapid tautomer interconversion influenced by the environment, but solid-state sensing using tautomerization is limited due to challenges in analyte accessibility to tautomeric sites, which restricts sensitivity and practical sensing applications.
The invention overcomes these limitations by incorporating TAS into COFs with high surface area and accessible pores, facilitating reversible tautomerization upon analyte exposure, such as humidity, resulting in detectable optical changes. The COFs exhibit fast, reversible responses to analytes with stability over months, enabling repeated use and practical sensing applications in a solid-state platform.
Claims Coverage
The patent includes two independent claims covering a sensor with a COF featuring a tautomerically active subunit and a method for detecting analytes with said COF. The main inventive features focus on the COF composition, reversible tautomerism, detectably distinct tautomeric characteristics, and regeneration capability.
Sensor comprising a COF with reversible tautomerism and regeneration means
A sensor comprising a covalent organic framework including (i) a tautomerically active subunit capable of reversible iminol-to-ketoenamine tautomerism between two tautomeric forms, (ii) a linking group, and (iii) a means for regenerating the tautomerically active subunit from one tautomer to the other and vice versa, where the tautomers have detectably distinct characteristics; the tautomerically active subunit is a dihydroxydialdehyde aryl.
Sensor optionally comprising radiation source, detector, regeneration agent, and/or heating element
The sensor may further include an electromagnetic radiation source, a detector, a regeneration agent, a heating element, or any combination of these components to facilitate sensing and regeneration.
Linking group selection and subunit substitution
The linking group may have various planar or spatial geometries (trigonal planar, tetragonal planar, hexagonal planar, tetrahedral, or octahedral). The tautomerically active subunit can be substituted or unsubstituted 2,5 dihydroxyterephthaldehyde (PDA-OH), and the linking group can be 1,3,5-tris(aminophenyl)benzene (TAPB).
COF as a thin film with rapid response
The COF can be formed as a thin film sensor exhibiting a response time less than 10 seconds.
Method for analyte detection using COF with tautomerism
A method that detects the presence of an analyte by contacting the sample with the COF sensor and detecting either of the two distinct tautomeric characteristics.
Regeneration of COF sensor
The method includes regenerating the COF sensor either passively or by contacting with a regeneration agent or by heating, allowing repeated detection cycles.
Colorimetric or spectroscopic detection
Detection can be colorimetric or performed by irradiating the COF with electromagnetic radiation and measuring a spectroscopic feature using a detector.
Analyte characteristics
The analyte suitable for detection has an ETN greater than 0.7 and/or a pKa less than 15.5, covering volatile analytes like water.
The claims collectively cover a COF-based sensor and method utilizing reversible tautomerism within the COF's tautomerically active subunits, featuring distinct tautomeric optical characteristics and regeneration capabilities, with provisions for incorporating detection devices, regeneration methods, and specifying analyte properties.
Stated Advantages
The COF sensor enables rapid response times to analytes, such as changes in relative humidity, with demonstrated response times less than 10 seconds.
The sensor shows reversible tautomeric switching allowing passive or active regeneration, enabling repeated use without degradation of sensing performance.
The COF sensors are stable for months or longer, supporting long-term sensing applications with consistent reproducibility.
The use of structurally regular, porous COFs enhances accessibility of tautomeric sites, improving sensitivity and magnitude of optical changes compared to amorphous analogues.
The optical changes induced by tautomerism allow for colorimetric detection visible to the naked eye or spectroscopic detection using suitable instruments.
Documented Applications
Detecting analytes including water (humidity sensing), toxins, explosives, metals, and volatile gases.
Use as humidity sensors employing COF thin films monitored by UV-Vis spectroscopy to detect changes in optical absorption.
Application in sensing analytes with specific chemical characteristics such as analytes having high hydrogen-bonding ability and appropriate acidity (ETN > 0.7, pKa < 15.5).
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