Heteroacene-quinone covalent organic framework for electrochemical direct air capture of CO2

Direct air capture of CO2 at meaningful scale remains one of the hardest engineering problems in climate mitigation. The dominant incumbent technology — amine-grafted solid sorbents and liquid amine scrubbers — requires thermal regeneration energy that erodes economics and produces significant parasitic losses. Electrochemical potential-swing approaches, where a material captures CO2 under a reducing bias and releases it under an oxidizing bias, have attracted intense research interest precisely because they decouple regeneration energy from heat, enable modular low-temperature operation, and can in principle run on stranded renewable electricity. Quinone-based organic materials sit at the center of this research front: they have well-characterized two-electron redox chemistry, tunable reduction potentials, and can be incorporated into porous frameworks that amplify accessible surface area. The invention disclosed here — a covalent organic framework built from heteroacene-quinone cores — is a lead composition asset in Lattice Graph's integrated packaging, storage and PFAS-treatment systems portfolio. It captures CO2 from ambient air by reductive/oxidative potential swing across a window of approximately -0.4 to -1.2 V versus reference, operating in a non-hydrogen-bond-donor electrolyte that suppresses competing side reactions. The timing matters acutely. A landmark anthraquinone-COF paper (DOI 10.1021/jacs.5c12304, published 2025) demonstrated that simple-quinone COFs can perform electrochemical DAC, which simultaneously validates the concept commercially and narrows the novelty space for any claim that reads on anthraquinone or benzoquinone alone. This asset responds directly to that pressure: the heteroacene-quinone cores — benzodithiophene-quinone, cyclopentadithiophene-quinone, benzodifuran-quinone, dithienosilole-quinone, and thienothiophene-quinone — represent a structural class that is chemically distinct from the prior art while preserving or improving the redox properties that make quinones effective for CO2 swing. The claim strategy layers composition (the specific heteroacene-quinone core selection), linker restrictions (non-TFP, non-beta-ketoenamine), operational conditions (non-HBD electrolyte, reductive/oxidative swing), and a carefully constructed set of negative limitations that carve clear whitespace around known prior art. The redox-swing quinone-COF field is advancing rapidly through 2025-2026; the race window for a defensible filing in heteroacene-quinone DAC is narrow and closing. What makes this a credible lead asset — rather than a purely defensive placeholder — is that the computational validation stack is real and multi-layered: GFN2-xTB redox calibration to estimate reduction potential placement, MACE-MP-0 structural relaxation of the binding geometry, Widom insertion grand canonical sampling for CO2 uptake estimation, and a Butler-Volmer-Langmuir cycle model that couples electrochemical kinetics to CO2 capture thermodynamics. These are not toy calculations; they constitute a physics-grounded prior that substantially de-risks experimental investment. The open validation gates are clearly identified: a full multilayer COF uptake model and experimental redox-cycled CO2 uptake on a framework-embedded heteroacene-quinone. That candor about what remains to be done is a feature, not a weakness — a buyer or licensee knows exactly where the next capital should go.

The engines did not fully agree here — the asset carries that uncertainty openly rather than overstating confidence.

The material class is a two-dimensional covalent organic framework whose redox-active subunit is a heteroacene-quinone — a fused-ring aromatic carbonyl system incorporating sulfur, oxygen, or silicon heteroatoms within the acene backbone. The representative core is a benzodithiophene-5,10-dione, a dithiophene-annulated benzoquinone where the sulfur atoms modulate the pi-electron density, lower the reorganization energy of the redox event, and shift the reduction potential relative to simple anthraquinone. The broader claim covers cyclopentadithiophene-quinone, benzodifuran-quinone, dithienosilole-quinone, and thienothiophene-quinone — each a structurally distinct heteroatom permutation that produces a chemically non-obvious variation in electronic properties. The COF architecture links these cores through non-TFP (non-triformylphloroglucinol), non-beta-ketoenamine chemistry, which is critical both for novelty over the dominant imine-COF prior art and for electrochemical stability: beta-ketoenamine frameworks are known to partially irreversibly tautomerize, which can degrade cyclic performance in potential-swing applications. The computational validation was performed at multiple levels of theory and physical model. Semiempirical GFN2-xTB calculations were used to calibrate the reduction potential placement of the heteroacene-quinone cores, providing a rapid but physically meaningful screen of which members of the core family sit within the accessible electrochemical window for DAC (-0.4 to -1.2 V versus reference). These calculations are well-benchmarked for organic redox-active molecules and give reliable qualitative trends in reduction potential shifts driven by heteroatom substitution. Structural relaxation of the CO2-bound state and the framework geometry was performed with the MACE-MP-0 universal machine-learning interatomic potential, which was trained on the Materials Project database and provides reasonable coverage of organic framework materials. Grand canonical Monte Carlo Widom insertion was used to estimate the CO2 uptake isotherms, providing a framework-level assessment of accessible porosity and binding affinity that a molecular-level DFT calculation alone cannot supply. The critical threshold that separates this asset from passive physisorption claims is explicit: CO2 binding energy below 25 kJ/mol is disclaimed, reframing the entire claim around the electrochemical-redox mechanism rather than physisorption. The dynamic stability picture requires honest characterization. A single machine-learning potential (MACE) was applied to the phonon assessment, returning a minimum frequency of -6.87 THz — an imaginary mode indicating that the idealized periodic structure as relaxed has a soft phonon at that geometry. CHGNet, ORB, and MatterSim were not applied, so there is no cross-potential consensus at this stage. This does not necessarily indicate that the material is physically unstable — imaginary modes in framework structures frequently arise from the softness of pore-breathing deformation modes or from an idealized unit cell that does not capture the actual torsional degrees of freedom of the linker chemistry — but it does mean that the full phonon stability picture is unresolved and should be revisited with additional potentials and, ultimately, DFT-level phonon calculations. The Butler-Volmer-Langmuir cycle model, a combined electrochemical-kinetic and Langmuir adsorption simulation, was used to predict the capture/release cycle performance as a function of overpotential, CO2 partial pressure, and sweep rate. This model integrates the thermodynamic uptake data from Widom insertion with a standard electrochemical kinetics framework to give a semi-quantitative prediction of capture efficiency and cycle energy under DAC-relevant partial pressures (approximately 420 ppm CO2 in air). The non-HBD electrolyte requirement in the operating conditions is not an arbitrary limitation: hydrogen-bond-donor solvents such as protic species competitively interact with the reduced quinone anion through protonation, diverting the redox couple away from CO2 binding and toward H2 evolution or simple protonation. The choice of non-HBD electrolyte is therefore a mechanistic requirement for the electrochemical CO2 swing to function as claimed.

The direct air capture market is pre-commercial but maturing rapidly. Current announced project capacity, government purchase agreements (U.S. DOE, the EU Innovation Fund, and bilateral carbon removal procurement programs), and voluntary carbon market demand put the addressable market for DAC technology licensing and project development at an estimated $5-10 billion over the next decade, with the understanding that these figures are estimates reflecting current policy commitments and announced capacity, not proven revenue. The key buyers are DAC project developers seeking technology licensing or co-development agreements, carbon removal buyers (sovereign and corporate) writing long-term purchase agreements that require a specific capture technology to be nominated, and large energy and industrial companies building internal DAC portfolios. The licensing logic for a composition-plus-device-use patent in this space is straightforward: a project developer who builds a commercial DAC installation using potential-swing quinone-COF electrodes would need a license to practice the composition claim, and the royalty structure would typically be tied to capacity (per-ton CO2 removed) or to electrode material supply. Electrochemical DAC has a specific economic advantage over thermal DAC that makes it attractive to a different buyer profile: it does not require a high-temperature steam or hot-gas regeneration loop, which means it can be sited at locations with abundant cheap electricity but no process heat — offshore wind farms, remote solar installations, stranded geothermal. This decoupling of regeneration energy from heat expands the viable deployment geography substantially. The O2-suppressing anodic engineering referenced in the commercial characterization is an important practical detail: ambient air contains approximately 21% O2, and reduced quinone anions are notoriously reactive toward molecular oxygen, which would otherwise scavenge the reduced species and oxidize it back before CO2 can bind. The claim's device-use scope, combined with the operating condition limitations (non-HBD electrolyte, specific voltage window), addresses this by defining the operational regime in which the material performs its intended function, which also makes the claim more enforceable against a clearly defined device configuration. Royalty income from a material-plus-device-use claim in an emerging technology with a narrow field — heteroacene-quinone COFs for electrochemical DAC — is modest per-project but potentially compounding as the DAC industry scales: a portfolio holder who controls the composition space for the next-generation core structures has long-duration optionality on a market that most analysts expect to grow by orders of magnitude if policy targets are met.

framework-anchored redox-swing DAC with O2-suppressing anodic engineering

heteroacene-quinone core + non-TFP/non-beta-ketoenamine linker; simple quinones disclaimed

The most natural acquirers or licensees for this asset fall into two groups. The first is industrial DAC project developers and technology companies that are building or licensing electrochemical DAC systems — entities such as Verdox, Air Company, or the growing number of startups developing non-thermal carbon capture approaches who need IP protection for their electrode material choices as they move toward commercial scale. For these buyers, a composition-plus-use patent on a structurally novel class of redox-active COF electrodes is directly on the critical path of their technology platform, and licensing or acquisition at the pre-experimental stage would be the most capital-efficient way to secure the IP before the field advances. The second group is large chemical and materials companies — specialty chemical producers, advanced materials divisions of energy majors — that are building DAC materials portfolios either for internal deployment or for licensing to project developers. For these buyers, the heteroacene-quinone COF asset fits within a broader electrochemical DAC materials position, particularly if combined with other assets in the integrated packaging, storage and PFAS-treatment systems portfolio that address adjacent parts of the value chain. Carbon removal buyers — corporate and sovereign entities writing long-term offtake agreements — are indirect buyers who influence acquisition by creating demand pull for specific technology classes. If a major carbon removal buyer specifies electrochemical DAC as a preferred technology pathway, that specification directly increases the strategic value of composition IP in the quinone-COF space. Government research agencies (DOE Office of Fossil Energy, ARPA-E) are also relevant as potential collaborative partners who could fund the experimental validation work in exchange for co-development rights, lowering the capital requirement for the asset holder to reach the experimental proof-of-concept gate.

The primary risk for this asset is speed: the redox-swing quinone-COF field is advancing through 2025-2026 at a pace that creates a genuine race condition between the filing and experimental demonstration on one side and independent academic or competitive publication on the other. A publication or competing patent filing on benzodithiophene-quinone or dithienosilole-quinone COFs for electrochemical DAC by another group before this asset reaches experimental demonstration and publication would materially narrow the claim scope or create prior art that prosecution must navigate. The single-potential phonon result (imaginary mode from MACE, no cross-potential consensus) is a secondary technical risk: if additional potentials or DFT calculation were to confirm structural instability of the representative core-linker combination as an extended periodic solid, the material would need to be reformulated or the claim narrowed to specific core/linker combinations that are confirmed stable. This is a soluble problem — the heteroacene core series is large enough to find stable members — but it requires computational and ultimately experimental effort. The roadmap to de-risk is straightforward in principle. The immediate priority is completing the multilayer COF uptake model and resolving the phonon stability question across multiple potentials, which are both computational tasks executable at the cost of compute time. The experimental demonstration — synthesis of a representative heteroacene-quinone COF and measurement of redox-cycled CO2 uptake — is the highest-value de-risking step and the one that would most directly support a licensing conversation. The narrow FTO position means that the experimental work and any publication arising from it should be coordinated with the patent filing strategy to avoid creating intervening prior art or statutory bars. A buyer who acquires this asset and funds the experimental demonstration within a 12-18 month window has a reasonable probability of establishing a defensible first-mover IP position in the heteroacene-quinone COF DAC space before the field fully consolidates.