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1. From insulator to semiconductor: effect of host–guest interactions on charge transport in M-MOF-74 metal–organic frameworks

   https://doi.org/10.1039/d3tc04155g  

   Angel, Sydney M; Barnett, Nicholas S; Talin, A Alec; Foster, Michael E; Stavila, Vitalie; Allendorf, Mark D; So, Monica C (January 2024, Journal of Materials Chemistry C)

   Here, we report an air-free approach to infiltrate isostructural metal–organic frameworks (MOFs), M-MOF-74 (M = Cu, Mn, Zn, Mg), with conjugated acceptor 7,7,8,8-tetracyanoquinodimethane (TCNQ). The TCNQ@M-MOF-74 compounds exhibit a striking correlation between their bulk conductivities and the open d shell variants (Cu, Mn), arising from TCNQ p-doping of the MOFs. Importantly, conjugation of the guest molecule is a prerequisite for inducing electrical conductivity in these systems. 

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2. Charge-Transfer-Driven Electrical Conductivity in Single Crystals of Assembled Triphenylamine Bis-urea Macrocycles

   https://doi.org/10.1021/acs.jpcc.5c04522  

   Gbadamosi, Fahidat A; Islam, Md Faizul; Shaker, Abdulla E; Wijesekera, Gamage_Isuri P; Smith, Mark D; Winfred, J_S_Raaj Vellore; Wetthasinghe, Shehani T; Garashchuk, Sophya; Greytak, Andrew B; Shimizu, Linda S (August 2025, The Journal of Physical Chemistry C)

   Achieving tunable electrical conductivity in organic materials is a key challenge for the development of next-generation semiconductors. This study demonstrates a novel approach using triphenylamine (TPA) bis-urea macrocycles as supramolecular hosts for guest-induced modulation of charge-transfer (CT) properties. By encapsulating guests with varying reduction potentials, including 2,5-dichloro-1,4-benzoquinone (ClBQ), 2,1,3-benzothiadiazole (BTD), and malononitrile (MN), we observed significant changes in the electrical conductivity. Crystals of the 1(ClBQ)0.31 complex exhibited an electrical conductivity of ∼2.08 × 10–5 S cm–1, a 10,000-fold enhancement compared to the pristine host. This is attributed to efficient CT observed in spectroscopic analyses and is consistent with the computed small HOMO–LUMO gap (2.92 eV) in a model of the host–guest system. 1(MN)0.39 and 1(BTD)0.5 demonstrated moderate conductivities explained by the interplay of electronic coupling, reorganization energy, and energy gap. Lower ratios of guest inclusion decreased the electrical conductivity by 10-fold in 1(ClBQ)0.18, while 1(MN)0.25 and 1(BTD)0.41 were nonconductive (10–9 S cm–1). This work highlights the potential of metal-free, porous organic systems as tunable semiconductors, offering a pathway to innovative applications in organic electronics. 

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3. Host–Guest Interactions and Redox Activity in Layered Conductive Metal–Organic Frameworks

   https://doi.org/10.1021/acs.chemmater.0c01007  

   Stolz, Robert M.; Mahdavi-Shakib, Akbar; Frederick, Brian G.; Mirica, Katherine A. (July 2020, Chemistry of Materials)

   This paper describes the identification of specific host–guest interactions between basic gases (NH3, CD3CN, and pyridine) and four topologically similar 2-dimensional (2D) metal–organic frameworks (MOFs) comprising copper and nickel bis(diimine) and bis(dioxolene) linkages of triphenylene-based ligands using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance spectroscopy (EPR), and powder X-ray diffraction (PXRD). This contribution demonstrates that synthetic bottom-up control over surface chemistry of layered MOFs can be used to impart Lewis acidity or a mixture of Brønsted and Lewis acidities, through the choice of organic ligand and metal cation. This work also distinguishes differences in redox activity within this class of MOFs that contribute to their ability to promote electronic transduction of intermolecular interactions. Future design of structure–function relationships within multifunctional 2D MOFs will benefit from the insights this work provides. 

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4. Electrically Conducting Redox‐Complementary Dual‐Ligand 2D Graphitic MOF with Orthogonal Charge Transport Pathways

   https://doi.org/10.1002/aelm.202500319  

   Zhang, Shiyu; Zhang, Weikang; Yadav, Ashok; Ansari, Mohd_A_H; Cromer, Jonathan_L; Barroso, Jorge; McCarver, Gavin_A; Zhou, Wei; Saha, Sourav (August 2025, Advanced Electronic Materials)

   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. 

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5. High-throughput screening of hypothetical metal-organic frameworks for thermal conductivity

   https://doi.org/10.1038/s41524-022-00961-x  

   Islamov, Meiirbek; Babaei, Hasan; Anderson, Ryther; Sezginel, Kutay B.; Long, Jeffrey R.; McGaughey, Alan J. H.; Gomez-Gualdron, Diego A.; Wilmer, Christopher E. (January 2023, npj Computational Materials)

   Abstract Thermal energy management in metal-organic frameworks (MOFs) is an important, yet often neglected, challenge for many adsorption-based applications such as gas storage and separations. Despite its importance, there is insufficient understanding of the structure-property relationships governing thermal transport in MOFs. To provide a data-driven perspective into these relationships, here we perform large-scale computational screening of thermal conductivitykin MOFs, leveraging classical molecular dynamics simulations and 10,194 hypothetical MOFs created using the ToBaCCo 3.0 code. We found that high thermal conductivity in MOFs is favored by high densities (> 1.0 g cm⁻³), small pores (< 10 Å), and four-connected metal nodes. We also found that 36 MOFs exhibit ultra-low thermal conductivity (< 0.02 W m⁻¹ K⁻¹), which is primarily due to having extremely large pores (~65 Å). Furthermore, we discovered six hypothetical MOFs with very high thermal conductivity (> 10 W m⁻¹ K⁻¹), the structures of which we describe in additional detail. 

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