Metal Insertion Research Articles

Novel Method for the Production of Titanium Foams to Reduce Stress Shielding in Implants.

Titanium foams have potential applications in orthopedic and dental implants because of their low elastic modulus and good bone in-growth properties. In the present study, a novel method for the preparation of three-dimensional interconnected microporous titanium foams has been developed. This method is based on the insertion of a filler metal into the titanium metal by arc melting, followed by its removal by an electrochemical dealloying process for the development of foams. Complete removal of the filler metal by the electrochemical dealloying process was confirmed by an X-ray diffractometry (XRD) analysis, whereas scanning electron microscopy (SEM) analysis of the developed foams showed the development of interconnected porosity. Ti foams with different levels of porosities were successfully developed by varying the amount of the filler metal. Mechanical and thermal characterizations of the developed foams were carried out using compression testing and laser flash apparatus, respectively. The yield strength and elastic modulus of the developed foams were found to decrease by increasing the volume fraction of pores. The elastic modulus of the developed titanium foams (15.5-36 GPa) was found to be closer to that of human bones, whereas their yield strength (147-170 MPa) remained higher than that of human bones. It is therefore believed that the developed Ti foams can help in reducing the problem of stress shielding observed in orthopedic implants. The thermal diffusivity of the developed foams (4.3-0.69 mm2/s) was found to be very close to that of human dentine.

Investigation of reversible metal ion (Li+, Na+, Mg2+, Al3+) insertion in MoTe2 for rechargeable aqueous batteries.

In this work, we report the electrochemical reactivity of MoTe2 for various metal ions with special emphasis on Al3+ ion storage in aqueous electrolytes for the first time. A stable discharge capacity of 100 mA h g-1 over 250 cycles at a current density of 1 Ag-1 could be obtained for the Al3+ ion, whereas inferior storage capacities were shown for other metal ions.

Formation of a dinuclear zinc complex with open-ring hemiporphyrazine

A dinuclear zinc complex was synthesized by the reaction of an open-ring hemiporphyrazine containing two terminal phenyl groups with zinc acetate dihydrate. Single crystal X-ray analysis revealed that the complex consists of two five-coordinated zinc ions and two open-ring ligands. The two phenyl rings in the zinc complex were found to be directed towards the benzene-ring side of the isoindoline moieties, which was in contrast to the metal-free compound with the oppositely-directed phenyl groups. The effects of metal insertion on molecular and electronic structures were investigated both experimentally and theoretically.

Tandem C-S Coupling and Debrominative Cyclization Enables an Easy Access to β-Thiazole-Fused Porphyrins.

A catalyst-free synthetic approach to β-thiazole-fused 5,10,15,20-tetraarylporphyrins via a cascade reaction of nickel(II) or copper(II) 2-amido-3-bromo-5,10,15,20-tetraarylporphyrins and Lawesson's reagent is described. During the course of the reaction, 3-bromo-2-thioamido-5,10,15,20-tetraarylporphyrins formed in situ undergo debrominative cyclization in refluxing toluene to provide novel β-thiazole-fused porphyrin macrocycles in good yields. Furthermore, free-base and zinc(II) β-thiazole-fused porphyrins have also been constructed in excellent yields by using standard demetalation and zinc metal insertion procedures. The preliminary photophysical studies revealed a significant bathochromic shift in the electronic absorption and emission spectra of new porphyrins as compared to meso-tetraarylporphyrin precursors.

Femtosecond laser-engineered 3D microfluidic chips: Synthesis system sprouting highly efficient multiphase organic reactions

Recent developments in the utilization of microfluidic chips (MFCs) have shown their potential utility in multiphase organic synthesis by enabling efficient organic reactions in flow chemistry. However, MFCs technology has been wandering in the laboratory of small dose synthetic routes, which is limited to the level of "tiny" fluid flux. To address this issue, we herein report the first case of the chips with high-throughput 3D channels produced by femtosecond laser being used to create a time-saving, cost-effective and risk-free approach suitable for large-scale flow synthesis. Several multiphase reactions have been successfully prepared on demand in our designed flow synthesis system containing 3D MFCs: 1) benzyl alcohol was converted to benzaldehyde in 3 min with a yield of 97.50% by liquid-liquid two-phase transfer catalytic oxidation; 2) organozinc reagents and α-cyano carbonyl carbon compounds were synthesized by solid-liquid two-phase metal insertion reaction in 7 min, and the yield was up to 100%; 3) benzoic acid was synthesized by gas-liquid two-phase carboxylation reaction in 2.8 s with a yield of 96%. Significant gains in production rate result from the effective scaling of flow reactors from microliters per hour in MFCs to intermediate milliliters per minute without affecting mass transport performance. Meanwhile, our 3D MFCs show excellent mass and heat transfer efficiency in large-scale industrial units, breaking through the bottleneck in this field. As a result, it is possible to imagine the creation of a new, streamlined flow synthetic technique via MFCs for green multiphase organic synthesis.

Tuning Structural and Optical Properties of Porphyrin-based Hydrogen-Bonded Organic Frameworks by Metal Insertion.

Herein, a simple way of tuning the optical and structural properties of porphyrin-based hydrogen-bonded organic frameworks (HOFs) is reported. By inserting transition metal ions into the porphyrin cores of GTUB-5 (p-H8 -TPPA (5,10,15,20-Tetrakis[p-phenylphosphonic acid] HOF), the authors show that it is possible to generate HOFs with different band gaps, photoluminescence (PL) life times, and textural properties. The band gaps of the resulting HOFs (viz., Cu-, Ni-, Pd-, and Zn-GTUB-5) are measured by diffuse reflectance and PL spectroscopy, as well as calculated via DFT, and the PL lifetimes are measured. Across the series, the band gaps vary over a narrow range from 1.37 to 1.62 eV, while the PL lifetimes vary over a wide range from 2.3 to 83 ns. These differences ultimately arise from metal-induced structural changes, viz., changes in the metal-to-nitrogen distances, number of hydrogen bonds, and pore volumes. DFT reveals that the band gaps of Cu-, Zn-, and Pd- GTUB-5 are governed by highest occupied/lowest unoccupied crystal orbitals (HOCO/LUCO) composed of π- orbitals on the porphyrin linkers, while that of Ni-GTUB-5 is governed by a HOCO and LUCO composed of Ni dorbitals. Overall, our findings show that metal-insertion can be used to optimize HOFs for optoelectronics and small-molecule capture applications.

(Invited) Prussian Blue Analogues as Battery Materials

Prussian Blue Analogues (PBAs) have gathered renewed interest recently because of their unique electrochemical properties, several of which are highly desirable for energy storage1. These intriguing properties arise from the interaction of the crystal structure with inserting ions. The general electrochemical equation for the insertion of an alkali metal into a PBA is given by:AxPJ[RK(CN)6]1−y · wH2O + A+ + e− → Ax+1PJ[RK−1(CN)6]1−y · wH2Owhere A is an alkali-metal ion, and P and R are transition-metal ions octahedrally coordinated to six cyanide ligands via the nitrogen and carbon atom, respectively (Figure 1). The value y is the fraction of vacancies in the hexacyanoferrate complex ion (the primary lattice defect). Water can also be present, both as zeolitic and coordinated to deficiently bonded metal ions at vacancies. Figure 1: Schematic representation of the crystal structure of PBAs. The green and dark-blue atoms are transition-metal ions at the R site and P site, respectively. Gray atoms are carbon and light-blue atoms are nitrogen. In my talk, I will show how these exciting properties are linked to the structural diversity of PBAs2 and how their chemistry can be tuned to adapt their electrochemistry to a variety of energy storage applications3,4, with focus on K-ion batteries5–7. References Hurlbutt, K., Wheeler, S., Capone, I. & Pasta, M. Prussian Blue Analogs as Battery Materials. Joule vol. 2 1950–1960 (2018).Cattermull, J., Pasta, M. & Goodwin, A. L. Structural complexity in Prussian blue analogues. Materials Horizons 8, 3178–3186 (2021).Wheeler, S., Capone, I., Day, S., Tang, C. & Pasta, M. Low-Potential Prussian Blue Analogues for Sodium-Ion Batteries: Manganese Hexacyanochromate. Chemistry of Materials 31, 2619–2626 (2019).Hurlbutt, K., Giustino, F., Pasta, M. & Volonakis, G. Electronic Structure and Electron-Transport Properties of Three Metal Hexacyanoferrates. Chemistry of Materials 33, 7067–7074 (2021).Fiore, M. et al. Paving the Way toward Highly Efficient, High-Energy Potassium-Ion Batteries with Ionic Liquid Electrolytes. Chemistry of Materials 32, 7653–7661 (2020).Dhir, S., Wheeler, S., Capone, I. & Pasta, M. Outlook on K-Ion Batteries. Chem 6, 2442–2460 (2020).Cattermull, J. et al. Revealing the structural complexity of Prussian blue analogues: the case of K2Cu[Fe(CN)6]. ChemRxiv (2022) doi:10.26434/chemrxiv-2022-zr5nn. Figure 1

Moco Carrier and Binding Proteins.

The molybdenum cofactor (Moco) is the active site prosthetic group found in numerous vitally important enzymes (Mo-enzymes), which predominantly catalyze 2 electron transfer reactions. Moco is synthesized by an evolutionary old and highly conserved multi-step pathway, whereby the metal insertion reaction is the ultimate reaction step here. Moco and its intermediates are highly sensitive towards oxidative damage and considering this, they are believed to be permanently protein bound during synthesis and also after Moco maturation. In plants, a cellular Moco transfer and storage system was identified, which comprises proteins that are capable of Moco binding and release but do not possess a Moco-dependent enzymatic activity. The first protein described that exhibited these properties was the Moco carrier protein (MCP) from the green alga Chlamydomonas reinhardtii. However, MCPs and similar proteins have meanwhile been described in various plant species. This review will summarize the current knowledge of the cellular Moco distribution system.

Theoretical study of 36Adz based alkaline earthides M+(36Adz)M− (M+ = Li & Na; M− = Be, Mg & Ca) with remarkable nonlinear optical response

The 36Adz complexant has been used to design and investigate another group of alkaline earthides, M+(36Adz)M−. Here, M+ represents the alkali metals i.e., Li & Na while M− represents alkaline earth metals i.e., Be, Mg & Ca. Basic pattern of arrangement of atoms in alkaline earthides includes the insertion of the alkali metal at the middle of hollow 36Adz cage and the space outside the cage is occupied by the alkaline earth metal. Natural bond orbitals are scrutinized, and calculation results show the alkaline earth metals as anions (negative charges on them). Highest occupied molecular orbitals are also analysed and the results of this analysis show that highest occupied molecular orbitals are present on alkaline earth metals. Both these characteristics confirm that the designed compounds are alkaline earthides. The same characteristic i.e., locale of excess electron, is further corroborated by the partial density of states spectra of the compounds. Moreover, extraordinarily higher first hyperpolarizabilities are shown by these compounds, the highest βo being shown (equal to 5.1 × 108 au) by Li+(36Adz)Mg−. These inordinately higher values of hyperpolarizability are ascribed to the distinctive feature of these compounds i.e., alkaline earth metals incorporate excess electron/bear negative charge. Furthermore, these complexes show very low transition energies (ΔE) and vertical ionization energy (VIE) values, ranging from 0.30 to 2.57 eV and 2.24 eV–2.51 eV, respectively. Such lower ΔE and VIE justify their larger values of hyperpolarizabilities. These results reveal that the alkaline earthides are a useful entry for high-performance NLO materials.

Function of Molybdenum Insertases.

For most organisms molybdenum is essential for life as it is found in the active site of various vitally important molybdenum dependent enzymes (Mo-enzymes). Here, molybdenum is bound to a pterin derivative called molybdopterin (MPT), thus forming the molybdenum cofactor (Moco). Synthesis of Moco involves the consecutive action of numerous enzymatic reaction steps, whereby molybdenum insertases (Mo-insertases) catalyze the final maturation step, i.e., the metal insertion reaction yielding Moco. This final maturation step is subdivided into two partial reactions, each catalyzed by a distinctive Mo-insertase domain. Initially, MPT is adenylylated by the Mo-insertase G-domain, yielding MPT-AMP which is used as substrate by the E-domain. This domain catalyzes the insertion of molybdate into the MPT dithiolene moiety, leading to the formation of Moco-AMP. Finally, the Moco-AMP phosphoanhydride bond is cleaved by the E-domain to liberate Moco from its synthesizing enzyme. Thus formed, Moco is physiologically active and may be incorporated into the different Mo-enzymes or bind to carrier proteins instead.

Assembly of a Heterometallic Cu(II)-Pd(II) Cage by Post-assembly Metal Insertion.

Porous structures based on multi-metallic motifs are receiving growing interest, but their general preparation still remains a challenge. Here, we report the self-assembly and structure of a CuII metal-organic cage (MOC) that is functionalized with free bis(pyrazolyl)methane sites. The homometallic Cu4L4 cage is isolated as a water-stable crystalline solid, and its formation is dependent on metal-ligand stoichiometry and the pre-organization of the Cu2 paddlewheel. We show by X-ray diffraction and SEM-EDX that PdII chloride can be quantitatively inserted into the free chelating sites of the MOC to yield a [Cu4(L(PdCl2))4] structure. Moreover, the solvent employed in the metalation dictates the solid-state isomerism of the heterometallic cage─a further handle to control the MOC's structural diversity and permanent porosity.

Potential Application of Photosensitizers With High-Z Elements for Synergic Cancer Therapy

The presence of heavy elements in photosensitizers (PS) strongly influences their electronic and photophysical properties, and hence, conjugation of PS with a suitable element is regarded as a potential strategy to improve their photodynamic properties. Moreover, PS conjugated to metal ion or metal complex and heavy atoms such as halogen have attracted considerable attention as promising agents for multimodal or synergistic cancer therapy. These tetrapyrrole compounds depending on the type and nature of the inorganic elements have been explored for photodynamic therapy (PDT), chemotherapy, X-ray photon activation therapy (PAT), and radiotherapy. Particularly, the combination of metal-based PS and X-ray irradiation has been investigated as a promising novel approach for treating deep-seated tumors, which in the case of PDT is a major limitation due to low light penetration in tissue. This review will summarize the present status of evidence on the effect of insertion of metal or halogen on the photophysical properties of PS and the effectiveness of various metal and halogenated PS investigated for PDT, chemotherapy, and PAT as mono and/or combination therapy.

Porphyrin as a versatile visible-light-activatable organic/metal hybrid photoremovable protecting group

Photoremovable protecting groups (PPGs) represent one of the main contemporary implementations of photochemistry in diverse fields of research and practical applications. For the past half century, organic and metal-complex PPGs were considered mutually exclusive classes, each of which provided unique sets of physical and chemical properties thanks to their distinctive structures. Here, we introduce the meso-methylporphyrin group as a prototype hybrid-class PPG that unites traditionally exclusive elements of organic and metal-complex PPGs within a single structure. We show that the porphyrin scaffold allows extensive modularity by functional separation of the metal-binding chromophore and up to four sites of leaving group release. The insertion of metal ions can be used to tune their spectroscopic, photochemical, and biological properties. We provide a detailed description of the photoreaction mechanism studied by steady-state and transient absorption spectroscopies and quantum-chemical calculations. Our approach applied herein could facilitate access to a hitherto untapped chemical space of potential PPG scaffolds.

Framework of metal insertion in the projection domain for image quality optimization in interventional computed tomography.

Purpose: This work aims to develop a framework to accurately and efficiently simulate metallic objects used during interventional oncology (IO) procedures and their artifacts in computed tomography (CT) images of different body regions. Approach: A metal insertion framework based on an existing lesion insertion tool was developed. Noise and beam hardening models were incorporated into the model and validated by comparing images of real and artificially inserted metallic rods of known material composition and dimensions. The framework was further validated by inserting ablation probes into a water phantom and comparing image appearance to scans of real probes at matching locations in the phantom. Finally, a comprehensive library of metallic probes used in our IO practice was generated and a graphical user interface was built to efficiently insert any number of probes at arbitrary positions in patient CT data, including projection and image domain insertions. Results: Metallic rod experiments demonstrated that noise and beam hardening were properly modeled. Phantom and patient data with virtually inserted probes demonstrated similar artifact appearance and magnitude compared with real probes. The developed user interface resulted in accurately co-registered virtual probes both with and without accompanying artifacts from projection and image domain insertions, respectively. Conclusions: The developed metal insertion framework successfully replicates metallic object and artifact appearance with projection domain insertions and provides corresponding artifact-free images with the metallic object in the identical location through image domain insertion. This framework has potential to generate robust training libraries for deep learning algorithms and facilitate image quality optimization in interventional CT.

Single-step insertion of M-Nx moieties in commercial carbon for sustainable bifunctional electrocatalysis: Mapping insertion capacity, mass loss, and carbon reconstruction

Atomically dispersed earth-abundant metals in N-doped carbon (M-N-Cs) have emerged as a new class of electroactive materials that can match not only the performance of the precious metals but can catalyze both the cathodic and the anodic reactions due to their bifunctional behaviour. This inspires the development of simpler strategies for scale-up production since the existing ones rely on precursors whose commercial viability is not yet ascertained. Herein, we demonstrate the insertion prospects of M-Nx (M = Fe, Co, Ni) moieties, the electrocatalytic centers in the M-N-Cs, into commercial carbon to establish that a single-step heating of the inexpensive precursors is sufficient to generate bifunctional electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) with efficiencies that bypass the majority of the known catalysts. Further importantly, we quantify both the ORR and OER trends and the metal insertion limits for each metal while maintaining an atomic dispersion, without the formation of surface migration-induced clustering, because such clustering is inevitable in the existing processes to necessitate an extra acid-leaching step to remove them. We further quantify and explain for each metal a negative mass balance originating from anomalous mass loss of both metal and carbon content, and a massive reconstruction of the carbon backbone catalyzed by the very metal, an event documented for the first time though it ought to be associated with other M-N-C syntheses too. The study establishes an incredibly simple and inexpensive strategy for the realization of M-N-Cs and outlines the parameters to be considered during mass-production.

Electric field-induced modification of Dzyaloshinskii-Moriya interaction in Fe/Mg0(001) with heavy metal insertions

The effect of external electric field on the Dzyaloshinskii-Moriya interaction (DMI) in Fe/M/MgO(001) (M=Os, Ir, Pt, Au) is investigated by means of first principles full-potential linearized augmented plane wave (FLAPW)-based Density Functional Theory method. We find that, apart from the Au layer insertion, the sign of the DMI is altered by the introduction of the heavy metal, such that the magnetic chirality in Fe/M/MgO(001) is inverted from that of Fe/MgO(001). The magnitudes of DMI in the Fe/Os/MgO and Fe/Ir/MgO are enhanced by 5 - 7 times compared to that without the heavy metal insertion. The increase of the DMI can be attributed to the strength of spin-orbit coupling of the heavy metal layer, implied by the asymmetry of the orbital moments of the heavy metals within the spin spiral structures. When an external electric field is applied, no significant modification to the DMI can be observed. Our work suggests that additional heavy metal layer might be necessary for a fine control of DMI, and hence of the overall magnetic domain-related properties, by external gate voltages.

Photodynamic activity of novel cationic porphyrins conjugated to graphene quantum dots against Staphylococcus aureus

Novel 5-(pyridyl)-10-15-20-tris(4-bromophenyl) porphyrin (complex 1), indium metal derivative (complex 2), and quaternized derivative (complex 3) were synthesized and conjugated to graphene quantum dots (GQDs). The conjugation of the porphyrins to GQDs was through [Formula: see text]-[Formula: see text] stacking. Herein, the [Formula: see text]-[Formula: see text] stacking approach was used to avoid covalent conjugation which might compromise the intrinsic chemical and physical properties. The photodynamic activities of the proposed nanomaterials were assessed towards Staphylococcus aureus cell obliteration. The photophysical properties of the prepared complexes were also studied prior to the application. Moreover, a decrease in fluorescence lifetimes was observed upon metalation of complex 1. As anticipated, singlet oxygen quantum yield ([Formula: see text] increased notably upon heavy metal (indium) insertion and upon composite formation. Antimicrobial photodynamic therapy comparative studies were done on quaternized and unquaternized indium porphyrins conjugated to GQDs. Complex 3-GQDs exhibited the highest antibacterial activities compared to other complexes, and this was attributed to the high [Formula: see text] which plays an imperative role in photodynamic therapy applications.

Infrared Multiple Photon Dissociation Spectroscopy Confirms Reversible Water Activation in Mn+(H2O)n, n ≤ 8.

Controlled activation of water molecules is the key to efficient water splitting. Hydrated singly charged manganese ions Mn+(H2O)n exhibit a size-dependent insertion reaction, which is probed by infrared multiple photon dissociation spectroscopy (IRMPD) and FT-ICR mass spectrometry. The noninserted isomer of Mn+(H2O)4 is formed directly in the laser vaporization ion source, while its inserted counterpart HMnOH+(H2O)3 is selectively prepared by gentle removal of water molecules from larger clusters. The IRMPD spectra in the O–H stretch region of both systems are markedly different, and correlate very well with quantum chemical calculations of the respective species at the CCSD(T)/aug-cc-pVDZ//BHandHLYP/aug-cc-pVDZ level of theory. The calculated potential energy surface for water loss from HMnOH+(H2O)3 shows that this cluster ion is metastable. During IRMPD, the system rearranges back to the noninserted Mn+(H2O)3 structure, indicating that the inserted structure requires stabilization by hydration. The studied system serves as an atomically defined single-atom redox-center for reversible metal insertion into the O–H bond, a key step in metal-centered water activation.

Dual ions enable vanadium oxide hydration with superior Zn2+ storage for aqueous zinc-ion batteries

The monovalent alkali metal ion K + , alkaline earth metal ion Mg 2+ and water molecules are inserted into the interlayer of V 2 O 5 by a simple one-step hydrothermal method (KMgV 2 O 5 ·nH 2 O denoted as KMgVOH) and the sample is used as the cathode material for ARZIBs with an outstanding specific capacity (423 mAh·g −1 at 0.1 A·g −1 ) and the capacity can still reach 222 mAh·g −1 after a long cycle with a large current density. • K + and Mg 2+ are inserted into the VOH layer to tune its structure. • Mg 2+ can increase the specific capacity of VOH and K + can boost the stability of V-O layer connection. • The synergistic effect of bimetallic ions greatly improves the electrochemical performance of VOH. Because of many advantages, aqueous rechargeable zinc-ion batteries (ZIBs) have become the best alternative energy storage device to lithium-ion batteries (LIBs). Current studies have shown that the insertion of metal ions can adjust the layer spacing of hydrated vanadium oxide (V 2 O 5 ·nH 2 O, denoted as VOH) and improve their electrochemical performance. However, the specific role of different metal ions has not been studied. Here, we have synthesized a bimetallic ion intercalation VOH, in which a one-valent metal K + and a divalent alkaline earth metal Mg 2+ are simultaneously inserted into the VOH interlayer by a one-step hydrothermal method, denoted as KMgVOH. In this material, Mg 2+ can increase the layer spacing of VOH, expand the ion transport channel and improve the specific capacity of the battery. Meanwhile, K + can make the connection between V-O layers closer and stabilize the structure of the material. The interaction of the two ions greatly improves the electrochemical performance of VOH. This KMgVOH cathode delivers an unprecedented high specific capacity of 423 mAh·g −1 at 0.1 A·g −1 , and the capacity can still reach 222 mAh·g −1 after a long cycle. This improvement for vanadium-based materials provides a new idea for zinc ion storage.

Octakis(dodecyl)phthalocyanines: Influence of Peripheral versus Non-Peripheral Substitution on Synthetic Routes, Spectroscopy and Electrochemical Behaviour.

Non-peripherally octakis-substituted phthalocyanines (npPc’s), MPc(C12H25)8 with M = 2H (3) or Zn (4), as well as peripherally octakis-substituted phthalocyanines (pPc’s) with M = Zn (6), Mg (7) and 2H (8), were synthesized by cyclotetramerization of 3,6- (2) or 4,5-bis(dodecyl)phthalonitrile (5), template cyclotetramerization of precursor phthalonitriles in the presence of Zn or Mg, metal insertion into metal-free phthalocyanines, and removal of Mg or Zn from the phthalocyaninato coordination cavity. The more effective synthetic route towards pPc 8 was demetalation of 7. npPc’s were more soluble than pPc’s. The Q-band λmax of npPc’s was red-shifted with ca. 18 nm, compared to that of pPc’s. X-ray photoelectron spectroscopy (XPS) differentiated between N–H, Nmeso and Ncore nitrogen atoms for metal-free phthalocyanines. Binding energies were ca. 399.6, 398.2 and 397.7 eV respectively. X-ray photoelectron spectroscopy (XPS) also showed zinc phthalocyanines 4 and 6 have four equivalent Nmeso and four equivalent N–Zn core nitrogens. In contrast, the Mg phthalocyanine 7 has two sets of core N atoms. One set involves two Ncore atoms strongly coordinated to Mg, while the other encompasses the two remaining Ncore atoms that are weakly associated with Mg. pPc’s 6, 7, and 8 have cyclic voltammetry features consistent with dimerization to form [Pc][Pc+] intermediates upon oxidation but npPc’s 3 and 4 do not. Metalation of metal-free pPc’s and npPc’s shifted all redox potentials to lower values.