Copper Coordination Research Articles

Copper(II) coordination to the intrinsically disordered region of SARS-CoV-2 Nsp1

The intrinsically disordered C-terminal peptide region of severe acute respiratory syndrome coronavirus 2 nonstructural protein-1 (Nsp1-CT) inhibits host protein synthesis by blocking messenger RNA (mRNA) access to the 40S ribosome entrance tunnel. Aqueous copper(II) ions bind to the disordered peptide with micromolar affinity, creating a possible strategy to restore protein synthesis during host infection. Electron paramagnetic resonance (EPR) and tryptophan fluorescence measurements on a 10-residue model of the disordered protein region (Nsp1-CT10), combined with advanced quantum mechanics calculations, suggest that the peptide binds to copper(II) as a multidentate ligand. Two optimized computational models of the copper(II)-peptide complexes were derived: One corresponding to pH 6.5 and the other describing the complex at pH 7.5 to 8.5. Simulated EPR spectra based on the calculated model structures are in good agreement with experimental spectra.

Post-synthetic Metalation on the Ionic TiO2 Surface to Enhance Metal-CO2 Interaction During Photochemical CO2 Reduction.

During the photochemical CO2 reduction reaction, CO2 adsorption on the catalyst's surface is a crucial step where the binding mode of the [metal-CO2] adduct directs the product selectivity and efficiency. Herein, an ionic TiO2 nanostructure stabilized by polyoxometalates (POM), ([POM]x@TiO2), is prepared and the sodium counter ions present on the surface to balance the POMs' charge are replaced with copper(II) ions, (Cux[POM]@TiO2). The microscopic and spectroscopic studies affirm the copper exchange without altering the TiO2 core and weak coordination of copper (II) ions to the POMs' surface. Band structure analysis suggests the photo-harvesting efficiency of the TiO2 core with the conduction band edge higher than the reduction potential of CuII/I and multi-electron CO2 reduction potentials. Photochemical CO2 reduction with Cux[POM]@TiO2 results in 30 μmol gcat. -1 CO (79 %) and 8 μmol gcat -1 of CH4 (21 %). Quasi-in-situ Raman study provides evidence in support of CO2 adsorption on the Cux[POM]@TiO2 surface. 13C and D2O labeling studies affirm the {Cu-[CO2]-} adduct formation. Despite the photo-harvesting ability of Nax[POM]@TiO2 itself, the poor CO2 adsorption ability of sodium ions highlights the crucial role of copper ion CO2 photo-reduction. Characterization of the {M-[η2-CO2]-} species via surface tuning validates the CO2 activation and photochemical reduction pathway proposed earlier.

Anti-Acanthamoeba metallopharmaceuticals: Amoebicidal activity and synergistic effect of copper(II)coordination compound.

Acanthamoeba spp. emerged as a clinically important pathogen related to amoebic keratitis. It is among the main causes of corneal transplantation and vision loss in ophthalmology. The treatment protocols have a low cure rate, high toxicity, and need for drug combination. Transition metal compounds have shown promising antiprotozoal effects. This study evaluates the amoebicidal activity of copper(II) coordination compounds in combination with chlorhexidine and the cytotoxicity to topical ocular application. These copper(II) coordination compounds were screened against Acanthamoeba castellanii trophozoites (ATCC 50492). The cytotoxicity on rabbit corneal cell line (ATCC-CCL 60) was performed. The compounds showed high amoebicidal potential, with inhibition of trophozoite viability above 80%. The Cp12 and Cp13 compounds showed Minimal Inhibitory Amoebicidal Concentration (MIAC) at 200µM and mean inhibitory concentration (IC50) values lower than 10µM. Against the cysts, Cp12 showed a reduction in viability (48%) in the longest incubation period. A synergistic effect for Cp12 with chlorhexidine was observed. The compounds have a dose-dependent effect against rabbit corneal cells. Compound Cp12 haspotential for future application in developing ophthalmic formulations against Acanthamoeba keratitis and its use in multipurpose solutions is highlighted.

Extending the Scope of the C-Functionalization of Cyclam via Copper(I)-Catalyzed Alkyne-Azide Cycloaddition to Bifunctional Chelators of Interest.

Cyclam, known for its potent chelation properties, is explored for diverse applications through selective N-functionalization, offering versatile ligands for catalysis, medical research, and materials science. The challenges arising from N-alkylation, which could decrease the coordination properties, are addressed by introducing a robust C-functionalization method. The facile two-step synthesis proposed here involves the click chemistry-based C-functionalization of a hydroxyethyl cyclam derivative using Cu(I)-catalyzed alkyne-azide cycloaddition (CuAAC). Boc-protecting groups prevent undesired copper coordination, resulting in compounds with a wide range of functionalities. The optimized synthesis conditions enable C-functional cyclams to be obtained easily and advantageously, with high application potential in the previously cited fields. The methodology has been extended to trehalose-based Siamese twin amphiphiles, enabling efficient gene delivery applications.

Realizing Ultrasensitive and Accurate Point-of-Care Profiling for ATP with a Triple-Mode Strategy Based on the ATP-Induced Reassembly of a Copper Coordination Polymer Nanoflower.

New strategies for accurate and reliable detection of adenosine triphosphate (ATP) with portable devices are significant for biochemical analysis, while most recently reported approaches cannot satisfy the detection accuracy and independent of large instruments simultaneously, which are unsuitable for fast, simple, and on-site ATP monitoring. Herein, a unique, convenient, and label-free point-of-care sensing strategy based on novel copper coordination polymer nanoflowers (CuCPNFs) was fabricated for multimode (UV-vis, photothermal, and RGB values) onsite ATP determination with high selectivity, sensitivity, and accuracy. The resulting CuCPNFs with a 3D hierarchical structure exhibit the ATP-triggered decomposition behavior because the competitive coordination between ATP and the copper ions of CuCPNFs can result in the formation of ATP-Cu, which reveals preeminent peroxidase mimics activity and can accelerate the oxidation of 3, 3', 5, 5'-tetramethylbenzidine (TMB) to form oxTMB. During this process, the detection system displayed not only color changes but also a strong NIR laser-driven photothermal effect. Thus, the photothermal and color signal variations are easily monitored by a portable thermometer and a smartphone. This multimode point-of-care platform can meet the requirements of onsite, without bulky equipment, accuracy, and reliability all at once, greatly enhancing its application in practice and paving a new way in ATP analysis.

Three-Fold Coordination of Copper in Sulfides: A Blockade for Hole Carrier Delocalization but a Driving Force for Ultralow Thermal Conductivity.

Copper-rich sulfides are very promising for energy conversion applications due to their environmental compatibility, cost effectiveness, and earth abundance. Based on a comparative analysis of the structural and transport properties of Cu3BiS3 with those of tetrahedrite (Cu12Sb4S13) and other Cu-rich sulfides, we highlight the role of the cationic coordination types and networks on the electrical and thermal properties. By precession-assisted 3D electron diffraction analysis, we find very high anisotropic thermal vibration of copper attributed to its 3-fold coordination, with an anisotropic atomic displacement parameter up to 0.09 Å2. Density functional theory calculations reveal that these Cu atoms are weakly bonded and give rise to low-energy Einstein-like vibrational modes that strongly scatter heat-carrying acoustic phonons, leading to ultralow thermal conductivity. Importantly, we demonstrate that the 3-fold coordination of copper in Cu3BiS3 and in other copper-rich sulfides constituted of interconnected CuS3 networks causes a hole blockade. This phenomenon hinders the possibility of optimizing the carrier concentration and electronic properties through mixed valency Cu+/Cu2+, differently from tetrahedrite and most other copper-rich chalcogenides, where the main interconnected Cu-S network is built of CuS4 tetrahedra. The comparison with various copper-rich sulfides demonstrates that seeking for frameworks characterized by the coexistence of tetrahedral and 3-fold coordinated copper is very attractive for the discovery of efficient thermoelectric copper-rich sulfides. Considering that lattice vibrations and carrier concentration are key factors for engineering transport phenomena (electronic, phonon, ionic, etc.) in copper-rich chalcogenides for various types of applications, our findings improve the guidelines for the design of materials enabling sustainable energy solutions with wide-ranging applications.

Novel Trinuclear Copper(II) Complex: Crystal Structure at 100 K and Magnetic Properties of (R, S)-di[(6,7-dimethoxy-isoquinolin-1-yl)-(3,4-dimethoxy-phenyl)-methanolato]-tetra(2-hydroxybenzoato)-diaqua-tricopper dihydrate, [Cu3(C7H5O3)4(C20H20NO5)2(H2O)2]·2(H2O)

The crystal structure of [Cu3(C7H5O3)4(C20H20NO5)2(H2O)2]·2(H2O) (1) and analysis of temperature and field dependence of magnetic susceptibility is reported in this work. The structure of 1 is composed of trinuclear complex units and water molecules. The middle copper atom occupies the center of symmetry. N, O-bonded (6,7-dimethoxy-isoquinolin-1-yl)-(3,4-di­methoxy-phenyl)-methanolato ligands, 2-hydroxybenzoates with bridging carboxylic groups, and oxo-bridged water molecules connect the middle Cu(II) atom with the terminal copper atoms. Two 2-hydroxybenzoates coordinate the terminal copper atoms via one carboxylic oxygen and an O atom of the hydroxyl group. The analysis of copper coordination by bond-valence sum approach and relevant structural correlation is consistent with hexacoordinated Cu(II) centers. Cu···Cu separation is 3.0269(3) Å. The magnetism of 1 shows a strong ferromagnetic interaction between the neighboring metallic centers accompanied by very weak antiferromagnetic intermolecular interactions. The complex units are mutually held by π···π stack interactions of 2-hydroxybenzoates and hydrogen bonds.Graphical A new N,O bonded ligands, (R, S)-[(6,7-dimethoxy-isoquinolin-1-yl)-(3,4-dimethoxy-phenyl)-methanolate] coordinate the terminal atoms of the trinuclear copper(II) complex.

Synthesis, structural and computational study, DNA binding and cytotoxic activity of Cu(II) complexes of 6- and 7-chloro-2-oxo-1,2-dihydroquinoline-3-carbaldehyde-2-furoyl-hydrazones

Three new coordination complexes of Cu(II) ions made from two hydrazone ligands, 7-chloro-2-oxo-1,2-dihydroquinoline-3-carbaldehyde-2-furoyl-hydrazone (HL1) and 6-chloro-2-oxo-1,2-dihydroquinoline-3-carbaldehyde-2-furoyl-hydrazone (HL2) have been synthesized and fully characterized by spectroscopic techniques. Their crystal and molecular structures revealed distorted square pyramidal mononuclear complexes: [(L1)Cu(H2O)2](NO3)·3H2O, 1(NO3), [(L2)Cu(H2O)2](NO3)·2H2O·CH3OH, 2(NO3), and [(L2)Cu(NO3)(CH3OH)]·2CH3OH, 3, comprising the ligand (L1 and L2) in tridentate fashion (ONO) with two water molecules in 1+ and 2+, and a single methanol molecule and a nitrate ion in 3 in their respective copper coordination spheres. EPR spectra in frozen methanol revealed the occurrence of several species arising from different coordination environments. A detailed DFT investigation on the energetics of solvents exchange (H2O, MeOH, and DMSO) and simulation of the EPR parameters showed that the exchange processes occur easily in solution. The value gz indicated the occurrence of a dimeric aggregate for 2+. The new copper complexes exhibited a noticeable antiproliferative activity with IC50 values in the micromolar range against HCT-15, H157, BxPC3, PNS-1, and A431 cell lines and they were found to be 3-fold more effective than cisplatin against pancreatic PSN-1 cell lines. Cross-resistance tests on A2780 and LoVo cancer cell lines and the corresponding multidrug or oxaliplatin resistant sublines showed that complexes 1(NO3) and 2(NO3) were equally cytotoxic to sensitive and resistant cells, thus overcoming multidrug and oxaliplatin resistance.

New hydrophilic mesoporous copper (II) coordination polymers obtained from poly(ethylene terephthalate) (PET) waste for diesel removal in water

Two new hydrophilic mesoporous copper (II) coordination polymers were synthetized from poly(ethylene terephthalate) waste by the coordination reaction under solvothermal conditions in only 60 min with quantitative yields. Both polymers and their aroyl hydrazone derivates were fully characterized by NMR (1H,13C, and 1H-15N HMBC), vibrational analysis, XPS spectroscopy, and high-resolution mass spectrometry. The XPS analysis of the new polymers 3a and 3b evidenced the formation of the N → Cu and O → Cu coordination bonds and the high-resolution mass spectrometry corroborates the presence of copper atoms in their molecular structure. The textural properties of 3a and 3b were analyzed by physisorption revealing that both materials can be classified as mesoporous materials with a pore size distribution of around 14.98 nm. Furthermore, the mesoporous copper (II) coordination polymer 3a exhibits a linear behavior with a maximum adsorption capacity of 743 and 1553 mg g−1 at 0.10 and 0.20 g/L, respectively. The adsorption/desorption cycles of 3a reveal that the novel copper (II) coordination polymers obtained from poly(ethylene terephthalate) (PET) waste had a greater adsorption capacity (1553 mg g−1); showing that structural modification of this type of coordination polymers can be a remarkable tool to increase the adsorption properties through the chemical modification to more hydrophilic, porous and crystalline coordination polymers.

Trinuclear nickel (II) string complexes and copper (II) coordination polymer with pyrazine modulated unsymmetrical dipyridylamino ligand: Synthesis, structure and bioactivity properties with molecular docking

The unsymmetrical pyrazine-modulated ligand, N-(pyridine-2-yl)pyrazin-2-amine (Hppza) (1), its 1D straight-chain copper (II) coordination polymer [Cu2(Hppza)2∙(NO3)4]n (2) and trinuclear metal string [Ni3(µ3-ppza)4Cl2] (3) and [Ni3(µ3-ppza)4(NCS)2] (4) complexes have been successfully synthesized and structurally characterized. The free ligand Hppza (1) exhibits anti-syn conformation. In an asymmetric unit of 2, there are two kinds of Cu(II) atoms, both of which have elongated octahedral coordination geometry, and the copper(II) centers are linked by oxygen atoms of one nitrate anion. There are only minor differences in Ni…Ni bond lengths between pyrazine-modulated ligand complexes of [Ni3(μ3-ppza)4×2] (X = Cl− (3), NCS− (4)) and their unmodulated analogs, while the distances between the terminal nickel atoms and the axial ligands 3 and 4 are shorter. The results of magnetic susceptibility measurements showed an antiferromagnetic exchange constant (J) of about J = –199.2 cm–1 for 3 and J = –178.0 cm–1 for 4. The electrochemical properties of nickel strings of Hppza differ significantly from their unmodulated counterparts. The activities of ligands and their metal complexes against various proteins that are AChE (PDB ID: 4M0E), BChE (PDB ID: 5NN0), α-Gly (PDB ID: 1UAS), hCA I (PDB ID: 2CAB), and hCA II (PDB ID: 3DC3) were compared, and then the ADME/T properties of molecules were examined. Afterward, the interactions occurring in the docking calculation were examined in detail with the Protein-Ligand Interaction Profiler (PLIP) service. These complexes were inhibitors of BChE, hCA I and II, α-glycosidase and AChE enzymes for complex 3 and 5 with Ki values of 12.65 and 42.95 μM for hCA I, 3.64 and 15.84 μM for hCA II, 5.44 and 50.07 μM for BChE, 15.85 and 4.77 μM for α-glycosidase and 8.58 and 86.24 μM for AChE, respectively.

Determining Factors to Understand the External Quantum Efficiency Values: Study Carried Out with Copper(I)-I and 1,2-Bis(4-pyridyl)ethane Coordination Polymers as Downshifters in Photovoltaic Modules.

Downshifters refer to compounds with the capacity to absorb UV photons and transform them into visible light. The integration of such downshifters has the potential to improve the efficiency of commercial photovoltaic modules. Initially, costly lanthanide derivatives and organic fluorescent dyes were introduced, resulting in a heightened module efficiency. In a novel research direction guided by the same physicochemical principles, the utilization of copper(I) coordination compounds is proposed. This choice is motivated by its simpler and more economical synthesis, primarily due to copper being a more abundant and less toxic element. Our proposal involves employing 1,2-bis(4-pyridyl) ethane (bpe), an economically viable commercial ligand, in conjunction with CuI to synthesize coordination polymers: [CuI(bpe)]n(1), [Cu3I3(bpe)3]n(2), and [CuI(bpe)0.5]n(3). These polymers exhibit the ability to absorb UV photons and emit light within the green and orange spectra. To conduct external quantum efficiency studies, the compounds are dispersed on glass and then encapsulated with ethylene vinyl acetate through heating to 150 °C. Interestingly, during these procedural steps, the solvents and temperatures employed induce a phase transformation, which has been thoroughly examined through both experimental analysis and theoretical calculations. The outcomes of these studies reveal an enhancement in external quantum efficiency with [Cu3I3(bpe)3]n(2), at a cost significantly lower (between 340 and 350 times) than that associated with lanthanide DS complexes.

Mononuclear Nickel(II) and Copper(II) Coordination Compounds with Ligands Based on Acetyl(benzoyl)acetone S-Methylisothiosemicarbazones and 8-Quinolinecarboxaldehyde. Synthesis and Crystal Structure

Mononuclear Nickel(II) and Copper(II) Coordination Compounds with Ligands Based on Acetyl(benzoyl)acetone S-Methylisothiosemicarbazones and 8-Quinolinecarboxaldehyde. Synthesis and Crystal Structure

Chiral Copper(I) Halide Clusters and Coordination Chain Exhibiting Photoluminescence and Circularly Polarized Luminescence

Chiral Copper(I) Halide Clusters and Coordination Chain Exhibiting Photoluminescence and Circularly Polarized Luminescence

Crystal structure and characterization of a new one-dimensional copper(II) coordination polymer containing a 4-amino-benzoic acid ligand.

A CuII coordination polymer, catena-poly[[[aqua-copper(II)]-bis-(μ-4-amino-benz-o-ato)-κ2 N:O;κ2 O:N] monohydrate], {[Cu(pABA)2(H2O)]·H2O}n (pABA = p-amino-benzoate, C7H4NO2 -), was synthesized and characterized. It exhibits a one-dimensional chain structure extended into a three-dimensional supra-molecular assembly through hydrogen bonds and π-π inter-actions. While the twinned crystal shows a metrically ortho-rhom-bic lattice and an apparent space group Pbcm, the true symmetry is monoclinic (space group P2/c), with disordered Cu atoms and mixed roles of water mol-ecules (aqua ligand/crystallization water). The luminescence spectrum of the complex shows an emission at 345 nm, cf. 349 nm for pABAH.

Morphology Control of Self-Assembled Copper Coordination Polymers for Glucose Assays.

Low-cost analytical assays enable accessible detection of clinically and environmentally important analytes; however, common enzyme-based assays suffer from high production and storage costs. Catalytically active synthetic materials serve as replacements for natural enzymes, but development of cost-effective, highly efficient synthetic strategies remains a challenge. Here, we utilized a facile synthesis for copper bipyridine coordination polymers (CuBpyCPs) and investigated structure-function relationships to achieve optimal catalytic properties for a glucose assay. We demonstrated the manipulation of CuBpyCP morphology, resulting in nanoscale petal-like structures and microscale high-index faceted structures, and identified three pure crystal morphologies exhibiting a comparable catalytic activity (Km = 0.3-0.5 mM) to horseradish peroxidase.

Self-assembled hydrated copper coordination compounds as ionic conductors for room temperature solid-state batteries

As the core component of solid-state batteries, neither current inorganic solid-state electrolytes nor solid polymer electrolytes can simultaneously possess satisfactory ionic conductivity, electrode compatibility and processability. By incorporating efficient Li+ diffusion channels found in inorganic solid-state electrolytes and polar functional groups present in solid polymer electrolytes, it is conceivable to design inorganic-organic hybrid solid-state electrolytes to achieve true fusion and synergy in performance. Herein, we demonstrate that traditional metal coordination compounds can serve as exceptional Li+ ion conductors at room temperature through rational structural design. Specifically, we synthesize copper maleate hydrate nanoflakes via bottom-up self-assembly featuring highly-ordered 1D channels that are interconnected by Cu2+/Cu+ nodes and maleic acid ligands, alongside rich COO− groups and structural water within the channels. Benefiting from the combination of ion-hopping and coupling-dissociation mechanisms, Li+ ions can preferably transport through these channels rapidly. Thus, the Li+-implanted copper maleate hydrate solid-state electrolytes shows remarkable ionic conductivity (1.17 × 10−4 S cm−1 at room temperature), high Li+ transference number (0.77), and a 4.7 V-wide operating window. More impressively, Li+-implanted copper maleate hydrate solid-state electrolytes are demonstrated to have exceptional compatibility with both cathode and Li anode, enabling long-term stability of more than 800 cycles. This work brings new insight on exploring superior room-temperature ionic conductors based on metal coordination compounds.

Synthesis of New Zinc and Copper Coordination Polymers Derived from Bis (Triazole) Ligands

Recent research has focused on molecules with different aromatic nitrogen-containing moieties coupled to a biphenyl core, as an effective approach for the assembly of coordination polymers. This study presents the synthesis and characterization of new ligands based on 1,1′-(3,3′-dimethoxy-[1,1′-biphenyl]-4,4′-diyl)bis(4-butyl-1H-1,2,3-triazole) (L1) and 1,1′-(3,3′-dimethoxy-[1,1′-biphenyl]-4,4′-diyl)bis(4-phenyl-1H-1,2,3-triazole) (L2) and their coordination polymers with Cu(II) and Zn(II). An unexpected coordination polymer with Cu(I) starting from Cu(II) was obtained in the case of the L2 ligand. The ligands and metal complexes underwent thorough characterization, including X-ray diffraction, NMR-, FTIR-, MS-spectrometry, and EPR, XPS, and TG-DTG analyses. While the ligand L2 generated a linear Cu(I) polymer, the ligand L1 formed a zigzag polymer with both copper and zinc.

A systematic look at structural diversity of metal phosphonates

AbstractHerein, we report the synthesis of three new copper phosphonate frameworks using a tetrahedral‐shaped organic building block, methane tetra‐p‐phenylphosphonic acid (H8‐MTPPA), and three different N‐ancillary ligands terpyridine (terpy), 2,2’‐bipyridine (2,2’‐bpy), phenanthroline (phen) to optimize the ligand binding modes on copper coordination sphere to generate molecular secondary building units (SBUs) in metal organophosphonates. We report the crystal structures of rod‐shaped one‐dimensional zig‐zag chain structure, [{Cu(terpy)}(H6‐MTPPA)(H2O)]⋅2H2O, three‐dimensional framework, [{Cu5(2,2’‐bpy)2}(H2‐MTPPA)(H4‐MTPPA)], and one‐dimensional structure [{Cu2(phen)2}(H4‐MTPPA)]⋅4H2O. Magnetic analysis of three‐dimensional copper phosphonate framework, namely [{Cu5(2,2’‐bpy)2}(H2‐MTPPA)(H4‐MTPPA)], showed paramagnetic behavior. Crystal structures were characterized by single crystal X‐ray diffraction, FT‐IR, and thermogravimetric analysis (TGA).

Copper Coordination Dynamics: Synthesis and Structural Insights Utilizing DFT, Hirshfeld, and Antimicrobial Analysis

In this work, two copper coordination compounds, ([Cu(phen)(L)(OH)(NO3)]NO3–) (ML1) and ([Cu(L)4(H2O)2)](NO3–)2) (ML2), have been synthesized and characterized (SC-XRD). ML1 is a long polymeric chain with a stable distorted octahedral geometry that is assembled from ligands such as 1,10-phenanthroline (Phen), 2-amino-5-methyl-1,3,4-thiadiazole (L), hydroxide (OH), and nitrate (NO3–). In contrast, ML2 is made up of water molecules and L ligands, forming the usual octahedral geometry. Furthermore, in the crystal structures of ML1 and ML2, the nitrate anion is essential for the formation of distinct supramolecular clusters. To confirm the structural integrity, we applied Hirshfeld surface analysis and Density Functional Theory (DFT) computations. We also evaluated the antibacterial efficacy of these compounds computationally and experimentally, which confirmed their potential to serve as potent inhibitors of drug-resistant microbial infections.

Coordination of copper within a crystalline carbon nitride and its catalytic reduction of CO2.

Inherently disordered structures of carbon nitrides have hindered an atomic level tunability and understanding of their catalytic reactivity. Starting from a crystalline carbon nitride, poly(triazine imide) or PTI/LiCl, the coordination of copper cations to its intralayer N-triazine groups was investigated using molten salt reactions. The reaction of PTI/LiCl within CuCl or eutectic KCl/CuCl2 molten salt mixtures at 280 to 450 °C could be used to yield three partially disordered and ordered structures, wherein the Cu cations are found to coordinate within the intralayer cavities. Local structural differences and the copper content, i.e., whether full or partial occupancy of the intralayer cavity occurs, were found to be dependent on the reaction temperature and Cu-containing salt. Crystallites of Cu-coordinated PTI were also found to electrophoretically deposit from aqueous particle suspensions onto either graphite or FTO electrodes. As a result, electrocatalytic current densities for the reduction of CO2 and H2O reached as high as ∼10 to 50 mA cm-2, and remained stable for >2 days. Selectivity for the reduction of CO2 to CO vs. H2 increases for thinner crystals as well as for when two Cu cations coordinate within the intralayer cavities of PTI. Mechanistic calculations have also revealed the electrocatalytic activity for CO2 reduction requires a smaller thermodynamic driving force with two neighboring Cu atoms per cavity as compared to a single Cu atom. These results thus establish a useful synthetic pathway to metal-coordination in a crystalline carbon nitride and show great potential for mediating stable CO2 reduction at sizable current densities.