Xing Huang, Wei Xu · Accounts of Chemical Research · 2026
To synthesise a decade of design, synthesis, structure determination, charge transport, device, thermoelectric, superconductivity, and topological-phenomena evidence for benzenehexathiol-based conjugated coordination polymers.
The review’s argument is preserved as a navigable set of section summaries.
Explains BHT as a small hexadentate dithiolene ligand whose soft donor atoms, dense geometry, and redox noninnocence support high conductivity and variable stoichiometry.
Relevance: Core · 3 · 2. The Uniqueness of Benzenehexathiol · Scheme 1
Summarises conductivity, mobility, metallicity, measurement caveats, FET behaviour and thermoelectric tuning, anchored by Table 1.
Relevance: Core · 9 · 5. Record-Breaking Charge Transport · Table 1
Distils the Account's outlook into rational lattice design, film quality, device integration, stability, higher-Tc superconductivity and new low-symmetry benzene ligands.
Relevance: Core · 12 · 8. Conclusion and Perspective
Frames the historical shift from low-conductivity CPs and MOFs to intrinsically conductive conjugated frameworks based on planar ortho-donor ligands.
Relevance: Core · 2 · 1. Introduction
Positions BHT-based c-CPs as correlated and geometrically frustrated systems supporting superconductivity, topological candidates, and Kondo-lattice behaviour.
Relevance: Supporting · 11 · 6. A Platform for Quantum Phenomena · Figures 9-10
Describes the structural-characterisation problem for c-CPs and organises BHT frameworks into Kagome, lamellar, 3D copper sulfide, and bimetallic topologies.
Relevance: Core · 8 · 4. Structural Diversity · Figures 4-5
Reviews ligand synthesis, interfacial growth, precursor-controlled crystallinity, redox modulation, bimetallic conversion, and CVD as conceptual routes to higher-quality BHT-based c-CPs.
Relevance: Core · 4 · 3. Synthetic Innovations · Figures 1-3
Classification systems are attributed to this review and are not treated as a global material registry.
Scheme 1 and the design section organise BHT as a two-dimensional analogue of ethylenetetrathiolate that extends metal-dithiolene conjugation into multidimensional transport pathways.
Categories: 1D metal-ett chains · 2D BHT Kagome sheets · 3D BHT hybrid networks · bimetallic topologies
2 · 2. The Uniqueness of Benzenehexathiol · Scheme 1
The Account classifies conductive frameworks by planar pi-conjugated ligands with ortho donor groups whose overlap with metal orbitals enables electronic delocalisation; it argues softer donors strengthen hybridisation.
Categories: HHTP catecholates with -OH donors · HATP imino/amine systems with -NH donors · BHT dithiolene systems with -SH donors · selenol analogues with -SeH donors
2 · 1. Introduction · Scheme 1
The review uses BHT-based c-CPs to organise a set of exotic phases arising from dense electronic structure, geometric frustration and strong correlation.
Categories: unconventional superconductivity in Cu3BHT · topological insulator candidates such as Ni1.5BHT · Weyl semimetal candidates such as Ag3BHT · Kondo-lattice behaviour in CuAg4BHT · quantum spin liquid and strong-correlation contexts
2 · 1. Introduction
The review treats BHT redox noninnocence as a classification principle because ligand oxidation state determines metal stoichiometry, topology, morphology, magnetism and electronic structure.
Categories: NixBHT, x = 1.5 or 3 · CuxBHT, x = 3, 4 or 5.5 · AgxBHT, x = 3 or 5 · CuAgxBHT bimetallic derivatives
3 · 2. The Uniqueness of Benzenehexathiol
Figure 5 and Section 4 provide an explicit structural taxonomy linking topology to metal coordination, interlayer bonding and transport-relevant orbital pathways.
Categories: Cu3BHT non-van-der-Waals Kagome framework · Ag5BHT lamellar metal-dithiolene/Ag-S network · CuxBHT layered-to-3D copper sulfide networks · CuAg4BHT topology-preserved bimetallic derivative · CuAg2BHT oxidation-generated new topology
7 · 4. Structural Diversity · Figure 5
The Account distinguishes benchmarking measurements from intrinsic transport probes, warning that grain boundaries in films and pellets can obscure metallic behaviour.
Categories: pellet four-probe conductivity · thin-film four-probe conductivity · single-crystal four-probe devices · FET mobility · TRTS mobility · UPS and Seebeck metallicity indicators
9 · 5. Record-Breaking Charge Transport · Table 1
Review-defined families retain their representative materials and conduction descriptions.
Neutral and oxidised silver benzenehexathiol coordination networks with lamellar and 3D silver-sulfur topologies.
Conduction: Ag5BHT is reviewed as metallic or semiconducting depending on postsynthetic treatment, while Ag3BHT is a conductive topological candidate.
Representative materials: Ag5BHT · Ag3BHT
Nodes / linkers: Ag · benzenehexathiol · silver-sulfur networks
8 · 4. Structural Diversity · Figure 5
Conductive coordination frameworks based on larger triphenylene ligands such as HHTP, HATP and THT.
Conduction: Used as benchmark comparators; the Account argues BHT often gives denser frameworks and stronger donor coupling.
Representative materials: Cu1.5HHTP · Cu-CAT-1 · Ni1.5HATP · Fe1.5THT
Nodes / linkers: Cu · Ni · Fe · HHTP · HATP · THT
3 · 2. The Uniqueness of Benzenehexathiol
BHT-based copper-sulfur conjugated coordination polymers with stoichiometries including Cu3BHT, Cu4BHT and Cu5.5BHT.
Conduction: Dense Cu-S/BHT conjugation supports high conductivity, metallic transport in high-quality Cu3BHT, and thermoelectric tuning across Cu4BHT and Cu5.5BHT.
Representative materials: Cu3BHT · Cu4BHT · Cu5.5BHT
Nodes / linkers: Cu · benzenehexathiol · metal-bis(dithiolene)
8 · 4. Structural Diversity · Figure 5
Bimetallic BHT-based c-CPs generated by selective metal metathesis and oxidation transformations.
Conduction: Conductivities are lower than homometallic Cu3BHT, but the family is emphasised for Kondo-lattice and topology-tuning behaviour.
Representative materials: CuAg4BHT · CuAg2BHT
Nodes / linkers: Cu · Ag · benzenehexathiol · metal chalcogenide coordination networks
8 · 4. Structural Diversity · Figure 5
One-dimensional metal-dithiolene coordination polymers built from ethylenetetrathiolate linkers.
Conduction: High conductivity and thermoelectric performance are acknowledged, but poor crystallinity, counterion sensitivity and reproducibility limitations motivate the BHT analogue.
Representative materials: Ni-ett · poly(metal 1,1,2,2-ethenetetrathiolate)s
Nodes / linkers: Ni · other transition metals · ethylenetetrathiolate · metal-bis(dithiolene)
3 · 2. The Uniqueness of Benzenehexathiol · Scheme 1
Nickel benzenehexathiol coordination nanosheets formed from metal-bis(dithiolene) units.
Conduction: The oxidised form is used as an early high-conductivity BHT benchmark and as a predicted topological-insulator platform.
Representative materials: Ni1.5BHT
Nodes / linkers: Ni · benzenehexathiol · nickel bis(dithiolene)
4 · 3. Synthetic Innovations · Figure 2
Review-level synthesis principles remain separate from primary-study recipes.
Replace hazardous Birch-reduction routes with BBr3 deprotection through a stabilised boron-containing intermediate to obtain a cleaner BHT feedstock.
Claimed effects: Provides a purer and more reliable BHT source that the review links to large-crystal growth.
Controlling variables: protected precursor design · deprotection reagent · stability of intermediate · ligand purity
Representative materials: BHT · DHTTB
Caveat: The Account describes the route conceptually; primary synthesis conditions should be taken from the original ligand paper.
3 · 3. Synthetic Innovations · Figure 1
Use metal ion migration under oxidative conditions to substitute Cu into Ag5BHT and then further oxidise to a new bimetallic topology.
Claimed effects: Creates atomically precise CuAg4BHT and CuAg2BHT, enabling metal-ion tuning and correlated magnetic behaviour.
Controlling variables: parent Ag5BHT topology · Cu(NO3)2 treatment · oxidative conditions · subsequent oxidation
Representative materials: Ag5BHT · CuAg4BHT · CuAg2BHT
Caveat: Direct metal substitution is presented as challenging because c-CP bonding is strongly covalent rather than ionic.
6 · 3. Synthetic Innovations · Figure 3
React vaporised BHT with copper oxide layers so the oxide is consumed to form patterned Cu3BHT films compatible with device integration.
Claimed effects: Promising route to uniform and lithographically patterned films with crystallinity comparable to interfacial synthesis.
Controlling variables: BHT volatility · thiol thermal sensitivity · oxide prepatterning · reaction reversibility · coordination kinetics
Representative materials: Cu3BHT
Caveat: The review explicitly states direct CVD to device-quality BHT-based c-CP films remains challenging.
8 · 3. Synthetic Innovations
React aqueous metal precursors with BHT in an immiscible organic phase at the interface so nucleation is slowed and growth is directed to existing nuclei.
Claimed effects: Improves ordered domains, enables films and crystals, and under optimised conditions supports Cu3BHT single crystals over 10 micrometres.
Controlling variables: solubility contrast · immiscible solvent interface · temperature · ligand concentration · metal concentration
Representative materials: Ni1.5BHT · Cu3BHT · Ag5BHT
Caveat: Initial Cu3BHT films had only moderate crystallinity; the review attributes improvement to temperature and concentration optimisation.
5 · 3. Synthetic Innovations · Figure 3
Use copper precursors such as tetrakis(acetonitrile)copper(I) tetrafluoroborate or Cu2O to stabilise intermediates, introduce reversibility, and improve crystallinity.
Claimed effects: Provides alternative routes to highly crystalline Cu4BHT and Cu5.5BHT and links precursor choice to structural evolution.
Controlling variables: metal precursor identity · coordinating ligand on precursor · heterogeneous particle-solution interface · reaction reversibility
Representative materials: Cu4BHT · Cu5.5BHT
Caveat: Strategy-level extraction only; individual precursor recipes and stoichiometries remain primary-study details.
6 · 3. Synthetic Innovations · Figure 3
Exploit BHT redox noninnocence so oxidation state changes control framework stoichiometry, electronic structure and conversion between CuxBHT phases.
Claimed effects: Transforms Cu5.5BHT into Cu4BHT or Cu3BHT and tunes band structure, conductivity and thermoelectric performance.
Controlling variables: oxidant amount · ligand oxidation state · metal-to-ligand stoichiometry · postsynthetic treatment
Representative materials: Cu5.5BHT · Cu4BHT · Cu3BHT · Ag5BHT
Caveat: Postsynthetic changes can strongly alter transport; benchmark comparisons must specify phase and treatment.
6 · 3. Synthetic Innovations · Figure 3
These are the review authors’ synthesis, not newly measured results.
BHT redox noninnocence is presented as central to unusual stoichiometries, metal valence changes, charge-carrier density and structure/electronic-property tuning.
Evidence basis: multi_reference
Caveat: The chapter should distinguish this design principle from any individual mechanistic proof in a primary paper.
3 · 2. The Uniqueness of Benzenehexathiol
Conventional CPs and MOFs were limited in electronics by poor intrinsic conductivity from common insulating SBUs; conjugated CPs and c-MOFs provided an intrinsic-conductivity design route.
Evidence basis: multi_reference
Caveat: The review summarises the field broadly rather than adjudicating each early conductive MOF example.
2 · 1. Introduction
Cu3BHT metallicity is supported by review-summarised DFT, UPS Fermi edge evidence, negative temperature dependence in high-quality samples, and single-crystal RRR greater than 10.
Evidence basis: multi_reference
Caveat: Earlier films can look semiconducting-like because grain boundaries and defects introduce hopping contributions.
9 · 5. Record-Breaking Charge Transport · Figure 6
CVD is promising for direct patterned device growth, but the review cautions that BHT volatility and thiol thermal sensitivity still constrain film quality and growth windows.
Evidence basis: single_reference
Caveat: Use this as an outlook and processing caveat rather than a mature device-fabrication consensus.
8 · 3. Synthetic Innovations
Interfacial synthesis is interpreted as a way to slow nucleation and improve ordered-domain growth in BHT c-CPs, including films, nanocrystal arrays and micrometre-scale Cu3BHT crystals.
Evidence basis: multi_reference
Caveat: Crystallinity still depends on optimisation of temperature, solubility and precursor concentration.
5 · 3. Synthetic Innovations · Figure 2
The review positions BHT-based c-CPs as a platform for exotic quantum phases because dense d-pi conjugation, Kagome geometry and strong correlations support superconducting, topological and Kondo-lattice states.
Evidence basis: multi_reference
Caveat: Several phases are theoretical candidates or require further experimental confirmation; keep claimed and predicted states distinct.
12 · 6. A Platform for Quantum Phenomena · Figure 10
The authors identify rotation electron diffraction combined with PXRD refinement as a decisive method for structural determination of c-CPs that are too small or overlapped for conventional SCXRD/PXRD alone.
Evidence basis: single_reference
Caveat: This claim is about structural-characterisation strategy, not direct charge-transport measurement.
8 · 4. Structural Diversity · Figure 4
Redox modulation is presented as a general lever for in situ and postsynthetic structure evolution, enabling precise CuxBHT phase control and bimetallic transformations.
Evidence basis: multi_reference
Caveat: The review emphasises conceptual control; detailed transformation pathways require the cited primary articles.
6 · 3. Synthetic Innovations · Figure 3
The review argues that pellets and polycrystalline films are useful benchmarks but single-crystal devices are required to reveal intrinsic metallic transport in Cu3BHT.
Evidence basis: multi_reference
Caveat: Benchmark values from Table 1 should not be compared without noting morphology and method.
10 · 5. Record-Breaking Charge Transport · Figure 6
The authors interpret soft thiol and selenol donors as increasing metal-ligand covalency and charge delocalisation relative to oxygen and nitrogen donors, helping explain high BHT conductivities.
Evidence basis: multi_reference
Caveat: This is a review-level design interpretation and should be checked against primary electronic-structure and transport studies for quantitative comparison.
2 · 1. Introduction
The CuxBHT series is used to argue that ligand redox chemistry and stoichiometry can tune band structure, Seebeck response and thermoelectric performance.
Evidence basis: single_reference
Caveat: Record thermoelectric values remain secondary here and need primary-source confirmation for quantitative use.
10 · 5. Record-Breaking Charge Transport · Figure 8
Every row remains visibly secondary and links to a primary dossier only where the mapping is verified.
| Material | Property | Reported value | Context and quality | Primary evidence | Review source |
|---|---|---|---|---|---|
| SecondaryAg5BHT | electrical conductivity | 0.073 S.cm-1 | 4-probe pellet after LiBHEt3 treatment Text · Exact Reported | research_0735 | 6 · 3. Synthetic Innovations |
| SecondaryAg5BHT | electrical conductivity | 250 S.cm-1 | 4-probe film Table · Exact Reported | research_0735 | 9 · 5. Record-Breaking Charge Transport · Table 1 |
| SecondaryCu3BHT | electrical conductivity | 1000 S.cm-1 | 4-probe crystal, out-of-plane Table · Exact Reported | research_0113 | 9 · 5. Record-Breaking Charge Transport · Table 1 |
| SecondaryCu3BHT | electron mobility | 116 cm2.V-1.s-1 | FET mobility, electron channel Table · Exact Reported | research_0006 | 9 · 5. Record-Breaking Charge Transport · Table 1 |
| SecondaryCu3BHT | hole mobility | 99 cm2.V-1.s-1 | FET mobility, hole channel Table · Exact Reported | research_0006 | 9 · 5. Record-Breaking Charge Transport · Table 1 |
| SecondaryCu3BHT | electrical conductivity | 1580 S.cm-1 | 4-probe film Table · Exact Reported | research_0006 | 9 · 5. Record-Breaking Charge Transport · Table 1 |
| SecondaryCu3BHT | electrical conductivity | 2500 S.cm-1 | 4-probe film Table · Exact Reported | No verified corpus mapping | 9 · 5. Record-Breaking Charge Transport · Table 1 |
| SecondaryCu3BHT | charge-carrier mobility | 400 cm2.V-1.s-1 | TRTS mobility, quasi-equilibrium band-like Drude regime Table · Rounded Reported | research_0249 | 10 · 5. Record-Breaking Charge Transport · Table 1 |
| SecondaryCu4BHT | electrical conductivity | 270 S.cm-1 | 4-probe pellet Table · Exact Reported | No verified corpus mapping | 9 · 5. Record-Breaking Charge Transport · Table 1 |
| SecondaryCu5.5BHT | electrical conductivity | 220 S.cm-1 | 4-probe pellet Table · Exact Reported | No verified corpus mapping | 9 · 5. Record-Breaking Charge Transport · Table 1 |
| SecondaryCu5.5BHT | thermoelectric figure of merit | ZT = 0.12 at 390 K | p-type CP thermoelectric performance at 390 K Text · Exact Reported | No verified corpus mapping | 10 · 5. Record-Breaking Charge Transport · Figure 8 |
| SecondaryCuAg4BHT | electrical conductivity | 3 S.cm-1 | 4-probe pellet Table · Exact Reported | No verified corpus mapping | 9 · 5. Record-Breaking Charge Transport · Table 1 |
| SecondaryFe1.5THT | charge-carrier mobility | 211 cm2.V-1.s-1 | TRTS mobility Table · Exact Reported | research_0001 | 9 · 5. Record-Breaking Charge Transport · Table 1 |
| SecondaryNi1.5BHT | electrical conductivity | 160 S.cm-1 | 4-probe film, oxidized form Table · Exact Reported | No verified corpus mapping | 9 · 5. Record-Breaking Charge Transport · Table 1 |
Open questions are presented as review-author priorities, not conclusions from the primary database.
The review argues that new benzene-based ligands with low symmetry, stronger donors and greater flexibility are needed to advance conductivity, mobility and exotic phases.
Proposed direction: Design low-symmetry benzene ligands and BHT analogues that systematically vary donor strength and lattice geometry.
13 · 8. Conclusion and Perspective
Precise carrier-density control via mixed-valence metals or ligand oxidation is needed for transport tuning and FET performance.
Proposed direction: Engineer mixed-valence and ligand-redox doping strategies that can tune carrier density without degrading mobility or crystallinity.
12 · 8. Conclusion and Perspective
Direct CVD of BHT-based c-CPs to device-quality films remains limited by BHT volatility and thiol thermal sensitivity.
Proposed direction: Develop CVD strategies that enhance reaction reversibility and coordination kinetics while preserving ligand integrity.
8 · 3. Synthetic Innovations
Large-area, thickness-controlled and defect-free films remain needed to probe 2D physics and enable integration.
Proposed direction: Improve film-growth methods that control thickness, crystallinity, defect density and large-area uniformity.
12 · 8. Conclusion and Perspective
Translation from materials to devices requires fabrication compatibility, environmental robustness and long-term operational stability.
Proposed direction: Assess compatibility with existing fabrication technologies and improve film stability under realistic device conditions.
12 · 8. Conclusion and Perspective
Higher-Tc superconductivity and new superconducting phases in c-CPs remain grand challenges.
Proposed direction: Advance ligand design, d-pi coupling control and external-field tuning to raise Tc or discover new superconducting phases.
13 · 8. Conclusion and Perspective
Current c-CP crystals are micrometre-scale, limiting device fabrication and defect-free characterisation.
Proposed direction: Develop growth strategies for larger single crystals suitable for device fabrication and neutron scattering or other defect-sensitive probes.
12 · 8. Conclusion and Perspective
Mappings show which printed review references have a verified counterpart in the frozen primary corpus.
| Reference | Study | Role and context | Corpus mapping |
|---|---|---|---|
| Ref. 12015 | A two-dimensional pi-d conjugated coordination polymer with extremely high electrical conductivity and ambipolar transport behaviour | transport_benchmark · thin_film_device · historical_framingFirst Cu3BHT thin-film report used for conductivity, FET mobility, UPS and early metallicity discussion. | research_0006 |
| Ref. 22018 | Highly Conducting Neutral Coordination Polymer with Infinite Two-Dimensional Silver-Sulfur Networks | transport_benchmark · structure_topology · synthesis_strategySilver-sulfur BHT network used for conductivity, redox conversion, interfacial synthesis, RED structure and lamellar topology. | research_0735 |
| Ref. 32018 | Superconductivity in a Copper(II)-Based Coordination Polymer with Perfect Kagome Structure | transport_benchmark · quantum_phenomena · structure_topologyKey Cu3BHT superconductivity and high-conductivity film reference; used in Table 1 and Figures 4, 6, and 9. | Unmapped |
| Ref. 42020 | Highly Conducting Organic-Inorganic Hybrid Copper Sulfides CuxC6S6 (x = 4 or 5.5): Ligand-Based Oxidation-Induced Chemical and Electronic Structure Modulation | transport_benchmark · redox_modulation · thermoelectricPrimary source for CuxBHT redox-controlled stoichiometry, conductivity and thermoelectric tuning. | Unmapped |
| Ref. 52024 | Synthesis and structure of a non-van-der-Waals two-dimensional coordination polymer with superconductivity | single_crystal_device · structure_topology · transport_benchmarkSingle-crystal Cu3BHT study used for RED structure, out-of-plane conductivity and intrinsic metallic transport. | research_0113 |
| Ref. 132013 | pi-Conjugated Nickel Bis(dithiolene) Complex Nanosheet | historical_framing · transport_benchmark · interfacial_synthesisEarly Ni1.5BHT nanosheet example used for interfacial synthesis history and Table 1 conductivity. | Unmapped |
| Ref. 142025 | Unveiling high-mobility hot carriers in a two-dimensional conjugated coordination polymer | mobility_benchmark · transport_mechanismTRTS study used for high mobility and carrier-dynamics claims in Cu3BHT. | research_0249 |
| Ref. 222018 | High-mobility band-like charge transport in a semiconducting two-dimensional metal-organic framework | mobility_benchmark · comparator_materialComparator high-mobility triphenylenehexathiol framework in Table 1. | research_0001 |
| Ref. 252022 | Highly Conductive Organic-Inorganic Hybrid Silver Sulfide with 3D Silver-Sulfur Networks Constructed from Benzenehexathiol: Structural Topology Regulation via Ligand Oxidation | structure_topology · quantum_phenomena · transport_benchmarkAg3BHT study used for conductivity, 3D silver-sulfur topology and Weyl-semimetal candidacy discussion. | Unmapped |
| Ref. 262021 | Strongly correlated superconductivity in a copper-based metal-organic framework with a perfect kagome lattice | quantum_phenomena · superconductivityUsed for strongly correlated and unconventional superconductivity interpretation in Cu3BHT. | Unmapped |
| Ref. 282022 | Construction of conducting bimetallic organic metal chalcogenides via selective metal metathesis and oxidation transformation | bimetallic_design · quantum_phenomena · transport_benchmarkBimetallic metathesis/oxidation source used for CuAg4BHT, CuAg2BHT, conductivity and Kondo-lattice interpretation. | Unmapped |
| Ref. 342022 | Facile synthesis, precise species control and chemical transformation of highly conducting organic metal chalcogenides CuxBHT (BHT = benzenehexathiol; x = 3, 4, and 5.5) | redox_modulation · synthesis_strategy · structure_topologyUsed for oxidation-driven CuxBHT transformation and precursor/kinetic control. | Unmapped |
| Ref. 352025 | Charge Transport and Carrier Polarity Tuning by Electrolyte Gating in Nickel Benzenehexathiol Coordination Nanosheets | electrochemical_modulation · device_contextUsed in the review as an example of tunable NixBHT stoichiometry and carrier polarity control. | Unmapped |
| Ref. 382023 | Semiconducting Conjugated Coordination Polymer with High Charge Mobility Enabled by "4 + 2" Phenyl Ligands | ligand_design · synthesis_strategyUsed for BHT analogue ligand design and BBr3 route applicability. | research_0256 |
| Ref. 392023 | Chemical Vapor Deposition and High-Resolution Patterning of a Highly Conductive Two-Dimensional Coordination Polymer Film | thin_film_processing · device_integrationCVD and patterning reference for device-quality BHT-based c-CP films. | research_0034 |
| Ref. 112012 | New Porous Crystals of Extended Metal-Catecholates | historical_framing · comparator_materialComparator HHTP/catecholate c-MOF used to frame the broader field before BHT. | Unmapped |
| Ref. 122014 | High Electrical Conductivity in Ni3(2,3,6,7,10,11-hexaiminotriphenylene)2, a Semiconducting Metal-Organic Graphene Analogue | historical_framing · transport_benchmark · comparator_materialComparator HATP conductive MOF used in design discussion and Table 1. | Unmapped |
| Ref. 232013 | Prediction of a Two-Dimensional Organic Topological Insulator | topological_candidate · quantum_phenomenaTheory reference for Ni1.5BHT topological-insulator prediction. | Unmapped |