UCLA researchers have developed a conductive, stimuli-responsive metal-organic framework (MOF) network that incorporates bismuth and hydroxy-functional ligands to create a chemiresistive sensing material capable of detecting gases (e.g. NO, NH₃) and volatile organic compounds, and that can also be integrated into textiles or personal protective equipment for radiation shielding.
Traditional coordination polymers or MOFs that are conductive tend to fall short in stability, sensitivity, or multifunctionality. Many existing materials either aren’t very responsive to environmental changes (humidity, gas exposure), or can’t be integrated into wearable formats. There is a need for materials that combine good electrical conductivity, stimuli responsiveness (e.g. structural changes with hydration), and versatile deployment in sensing and protective applications.
This invention describes a MOF/network built using bismuth plus ligands such as hexahydroxytriphenylene (HHTP) (or related triphenylene-ligands), where hydroxy moieties (not part of carboxyls) coordinate with bismuth forming Bi–O bonds. The network is both conductive and interconnected; it exists in different structural phases depending on environmental stimuli (e.g. hydration/dehydration), which alters its sensing behavior. It can detect gases at low ppm, respond to volatile organics, be incorporated into textiles for wearable formats, and even be used for radiation shielding, offering a blend of sensing and protection in one material.
Responsive to environmental changes: shows distinct structural phases under hydration vs dehydration, which can modulate sensing properties.
Sensitive gas detection at low concentrations (ppm levels) for multiple analytes including NO, NH₃, and VOCs.
Good electrical conductivity facilitating chemiresistive sensing at low driving voltages.
Versatility: integration into textiles / wearable formats, and potential for radiation shielding materials.
Multifunctionality: one material fulfills both sensing and protective (shielding) roles.
Gas sensors for environmental monitoring (air quality, industrial safety).
Wearable safety gear (gas masks, protective clothing) that monitor and protect.
Smart textiles for soldiers, first responders, or workers in hazardous environments.
Radiation shielding materials that also provide sensing (e.g. in nuclear or space applications).
Portable or embedded sensors for volatile organic compounds in manufacturing, labs, or indoor air quality monitoring.
US 2024/0199664 A1 — Conductive stimuli-responsive coordination network linked with bismuth Priority Date: Apr. 12, 2022; Publication Date: June 20, 2024. Conductive stimuli-responsive coordination network linked with bismuth (US20240199664A1) Google Patents
Aykanat A., Jones C. G., Cline E., Stolz R. M., Meng Z., Nelson H. M., Mirica K. A. Conductive stimuli-responsive coordination network linked with bismuth for chemiresistive gas sensing. ACS Applied Materials & Interfaces, 2021, 13(48), 60306-60318. DOI: 10.1021/acsami.1c14453 X-MOL
Aylin Aykanat, Zheng Meng, Katherine A. Mirica, others. Bimetallic Two-Dimensional Metal-Organic Frameworks for Chemiresistive Detection of Carbon Monoxide. Angewandte Chemie (Int. Ed.), 2021. DOI: 10.1002/anie.202113665 Google Scholar+1