An official website of the United States government
Abstract Due to their diverse potential in advanced electronics and energy technologies, electrically conducting metal‐organic frameworks (MOFs) are drawing significant attention. Although hexagonal 2D MOFs generally display impressive electrical conductivity because of their dual in‐plane (through bonds) and out‐of‐plane (through π‐stacked ligands) charge transport pathways, notable differences between these two orthogonal conduction routes cause anisotropic conductivity and lower bulk conductivity. To address this issue, we have developed the first redox‐complementary dual‐ligand 2D MOF Cu3(HHTP)(HHTQ), featuring a π‐donor hexahydroxytriphenylene (HHTP) ligand and a π‐acceptor hexahydroxytricycloquinazoline (HHTQ) ligand located at alternate corners of the hexagons, which form either parallel HHTP and HHTQ stacks (AA stacking) or alternating HHTP/HHTQ stacks (AB stacking) along the c‐axis. Regardless of the stacking pattern, Cu3(HHTP)(HHTQ) supports more effective out‐of‐plane conduction through either separate π‐donor and π‐acceptor stacks or alternating π‐donor/acceptor stacks, while promoting in‐plane conduction through the pushpull‐like heteroleptic coordination network. As a result, Cu3(HHTP)(HHTQ) exhibits higher bulk conductivity (0.12 S/m at 295 K) than single‐ligand MOFs Cu3(HHTP)2(7.3 × 10−2S/m) and Cu3(HHTQ)2(5.9 × 10−4S/m). This work introduces a new design approach to improve the bulk electrical conductivity of 2D MOFs by supporting charge transport in both in‐ and out‐of‐plane direcations.
more »
« less
This content will become publicly available on January 14, 2026
Mechanistic Insight into the Formation and Deposition of Conductive, Layered Metal–Organic Framework Nanocrystals
This paper describes the use of the layered conductive metal−organic framework (MOF) (nickel)3-(hexahydroxytriphenylene) 2 [Ni3(HHTP)2] as a model system for understanding the process of self-assembly within this class of materials. We confirm and quantify experimentally the role of the oxidant in the synthetic process. Monitoring the deposition of Ni3(HHTP)2 with in situ infrared spectroscopy revealed that MOF formation is characterized by an initial induction period, followed by linear growth with respect to time. The presence and identity of oxidizing agents is critical for the coordination-driven self-assembly of these materials and impacts both the length of the induction period and the observed rate of MOF growth. A large excess of hydrogen peroxide results in a 2× increase in the observed deposition rate (9.6 ± 6.8 × 10−4 vs 5.0 ± 2.8 × 10−4 min−1) over standard reaction conditions, but leads to the formation of large, irregularly shaped particles. Slower deposition rates in the presence of oxygen favor the formation of uniformly sized nanorods (98 ± 38 × 25 ± 6 nm). These quantitative insights into the mechanism of HHTP-based MOF formation provide valuable information about the fundamental aspects of coordination and polymerization that are critical for nanoscale crystal engineering of structure−property relationships in this class of materials.
more »
« less
- Award ID(s):
- 1945218
- PAR ID:
- 10614541
- Publisher / Repository:
- ACS Nano
- Date Published:
- Journal Name:
- ACS Nano
- Volume:
- 19
- Issue:
- 1
- ISSN:
- 1936-0851
- Page Range / eLocation ID:
- 1383 to 1395
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract Currently, there is considerable interest in developing advanced rechargeable batteries that boast efficient distribution of electricity and economic feasibility for use in large-scale energy storage systems. Rechargeable aqueous zinc batteries are promising alternatives to lithium-ion batteries in terms of rate performance, cost, and safety. In this investigation, we employ Cu3(HHTP)2, a two-dimensional (2D) conductive metal-organic framework (MOF) with large one-dimensional channels, as a zinc battery cathode. Owing to its unique structure, hydrated Zn2+ions which are inserted directly into the host structure, Cu3(HHTP)2, allow high diffusion rate and low interfacial resistance which enable the Cu3(HHTP)2cathode to follow the intercalation pseudocapacitance mechanism. Cu3(HHTP)2exhibits a high reversible capacity of 228 mAh g−1at 50 mA g−1. At a high current density of 4000 mA g−1(~18 C), 75.0% of the initial capacity is maintained after 500 cycles. These results provide key insights into high-performance, 2D conductive MOF designs for battery electrodes.more » « less
-
This paper describes the scalable fabrication of smart electronic textiles (e-textiles) capable of simultaneous sensing, filtration, and detoxification of sulfur dioxide (SO2). The templated method converts pre-deposited copper metal into copper hydroxide, followed by conversion into a copper-based hexahydroxytriphenylene metal-organic framework (MOF) (Cu3(HHTP)2), to afford a large-area (10 × 10 cm2) conductive coating (sheet resistance = 0.1–0.3 MΩ). The resulting e-textiles achieve sensing (theoretical limit of detection [LOD] of 0.43 ppm), filtration (adsorption uptake of 1.9 and 0.83 mmol g−1 for MOF powder and MOF/textile, respectively, at 1 bar and 298 K), and detoxification (redox conversion of SO2 gas into solid sulfate) due to the selective material-analyte interactions. This scalable method for generating e-textiles is a promising approach for the fabrication of smart membrane materials with multifunctional performance characteristics.more » « less
-
A library of thio- and selenourea derivatives is used to adjust the kinetics of PbE (E = S, Se) nanocrystal formation across a 1000-fold range ( k r = 10 −1 to 10 −4 s −1 ), at several temperatures (80–120 °C), under a standard set of conditions (Pb : E = 1.2 : 1, [Pb(oleate) 2 ] = 10.8 mM, [chalcogenourea] = 9.0 mM). An induction delay ( t ind ) is observed prior to the onset of nanocrystal absorption during which PbE solute is observed using in situ X-ray total scattering. Density functional theory models fit to the X-ray pair distribution function (PDF) support a Pb 2 (μ 2 -S) 2 (Pb(O 2 CR) 2 ) 2 structure. Absorption spectra of aliquots reveal a continuous increase in the number of nanocrystals over more than half of the total reaction time at low temperatures. A strong correlation between the width of the nucleation phase and reaction temperature is observed that does not correlate with the polydispersity. These findings are antithetical to the critical concentration dependence of nucleation that underpins the La Mer hypothesis and demonstrates that the duration of the nucleation period has a minor influence on the size distribution. The results can be explained by growth kinetics that are size dependent, more rapid at high temperature, and self limiting at low temperatures.more » « less
-
A ditopic nitrogen ligand (E)-N′-(pyridin-4-ylmethylene)isonicotinohydrazide (L) containing both divergent pyridyl coordination sites and a hydrogen-bonding hydrazide–hydrazone moiety was synthesized. The Co(NCS)2-mediated self-assembly of L has resulted in the synthesis of a novel 3-dimensional (3D) supramolecular framework (1) that features both coordination and hydrogen bonding interactions. X-ray structural analysis reveals the formation and coordination mode of 1 in the solid state. The rational utilization of coordination bonds and hydrogen bonding interactions is confirmed and responsible for constructing the 3D materials. Catalytic studies using 1 in the presence of an activator are performed for the hydroboration and hydrosilylation reactions of ketones and aldehydes, and the results are compared with previously reported cobalt-based polymeric catalysts.more » « less
