Merry K. Smith

Self-Organized Frameworks on Textiles (SOFT): Conductive Fabrics for Simultaneous Sensing, Capture, and Filtration of Gases

Wearable electronics have the potential to advance personalized health care, alleviate disability, enhance communication, and improve homeland security. Development of multifunctional electronic textiles (e-textiles) with the capacity to interact with the local environment is a promising strategy for achieving electronic transduction of physical and chemical information. This paper describes a simple and rapid approach for fabricating multifunctional e-textiles by integrating conductive two-dimensional (2D) metal-organic frameworks (MOFs) into fabrics through direct solution-phase self-assembly from simple molecular building blocks. These e-textiles display reliable conductivity, enhanced porosity, flexibility, and stability to washing. The functional utility of these integrated systems is demonstrated in the context of chemiresistive gas sensing, uptake, and filtration. The self-organized frameworks on textiles (SOFT)-devices detect and differentiate important gaseous analytes (NO, H2S, and H2O) at ppm levels and maintain their chemiresistive function in the presence of humidity (5000 ppm, 18% RH). With sub-ppm theoretical limits of detection (LOD for NO = 0.16 ppm and for H2S = 0.23 ppm), these constitute the best textile-supported H2S and NO detectors reported and the best MOF-based chemiresistive sensors for these analytes. In addition to sensing, these devices are capable of capturing and filtering analytes.

Drawing Sensors with Ball-Milled Blends of Metal-Organic Frameworks and Graphite

The synthetically tunable properties and intrinsic porosity of conductive metal-organic frameworks (MOFs) make them promising materials for transducing selective interactions with gaseous analytes in an electrically addressable platform. Consequently, conductive MOFs are valuable functional materials with high potential utility in chemical detection. The implementation of these materials, however, is limited by the available methods for device incorporation due to their poor solubility and moderate electrical conductivity. This manuscript describes a straightforward method for the integration of moderately conductive MOFs into chemiresistive sensors by mechanical abrasion. To improve electrical contacts, blends of MOFs with graphite were generated using a solvent-free ball-milling procedure. While most bulk powders of pure conductive MOFs were difficult to integrate into devices directly via mechanical abrasion, the compressed solid-state MOF/graphite blends were easily abraded onto the surface of paper substrates equipped with gold electrodes to generate functional sensors. This method was used to prepare an array of chemiresistors, from four conductive MOFs, capable of detecting and differentiating NH₃, H₂S and NO at parts-per-million concentrations.

Rational synthesis of bis(hexyloxy)-tetra(hydroxy)-triphenylenes and their derivatives

A straightforward, reliable, and scalable synthesis of rationally designed, mixed-substituent triphenylene derivatives from ortho-terphenyl precursors is described. Three isomers of bis(hexyloxy)-tetrahydroxy triphenylenes were synthesized and functionalized with monomethyl di(ethylene glycol) chains to provide new amphiphilic, mixed substituent triphenylenes. Oxidative triphenylene annulation, tetra-ol formation, and subsequent functionalization were supported by significant changes in phase and melting point, and confirmed by mass spectrometry, differential scanning calorimetry, and UV/Vis, 1H, and 13C NMR spectroscopies. The thermal phase properties of amphiphilic mixed-substituent triphenylene derivatives were found to vary between the different isomers, demonstrating how small changes in substitution pattern can result in significant differences in mesogenic behavior. The controlled synthetic route to de novo designed triphenylene derivatives is dependable, wide in scope, and can be applied to the synthesis of a vast array of other mixed-substituent triphenylene derivatives, thus enabling the preparation of libraries of novel triphenylene and triphenylene-containing materials.