Br Bond Research Articles

Independent LUMO Reactivity in Mesoionic N‐Heterocyclic Thiones: Synthesis of a Stable Radical Anion

AbstractMesoionic compounds, with positive and negative charges, are expected to have dual‐site highest occupied molecular orbital (HOMO, donor) and lowest unoccupied molecular orbital (LUMO, acceptor) reactivity. Herein, we report a novel class of air‐stable mesoionic N‐heterocyclic thiones (mNHTs) synthesized from abnormal N‐heterocyclic carbenes (aNHCs). DFT studies revealed a highly polarized exocyclic thione moiety and computed Fukui function analysis suggests the dual‐site HOMO/LUMO reactivity of mNHTs predicting donor property at the negatively charged ‘S’ center while acceptor property at the cationic imidazole ring. The independent LUMO reactivity of the mNHT was realized by its chemical reduction to an elusive radical anion, which was characterized by a single crystal X‐raydiffraction study. Further, we explore the reactivity of radical anion for the activation of SO2 gas, C−Br bonds of aryl bromide and photocatalytic functionalization of C−X (X = F, Br) bonds. This work unlocks the independent LUMO reactivity of a mesoionic compound.

Reductive C(sp2)–Si Cross‐Couplings by Catalytic Sodium‐Bromine Exchange

The metal‐halogen exchange reaction constitutes one of the most important preparative routes towards polar organometallic reagents such as aryllithium or Grignard reagents. However, despite extensive developments over the past eight decades, this fundamental organometallic elementary step has only been exploited stoichiometrically. Against this background, we demonstrate that the sodium‐bromine exchange reaction can be implemented in a catalytic setting as a mean to activate C(sp2)–Br bonds in a transition metal‐free manner en route to the regioselective and general preparation of (hetero)aryl silanes. Simply treating structurally diverse (hetero)aryl bromides with N‐tert‐butyl‐N’‐silyldiazenes (tBu–N=N–Si) as silylating reagents and inexpensive sodium alkoxides as catalytic promoters yields a range of aromatic organosilicon compounds under ambient conditions. Mechanistic studies provide solid evidence for the involvement of tert‐butyl sodium as the C(sp2)–Br metalating agent.

Reductive C(sp2)–Si Cross‐Couplings by Catalytic Sodium‐Bromine Exchange

The metal‐halogen exchange reaction constitutes one of the most important preparative routes towards polar organometallic reagents such as aryllithium or Grignard reagents. However, despite extensive developments over the past eight decades, this fundamental organometallic elementary step has only been exploited stoichiometrically. Against this background, we demonstrate that the sodium‐bromine exchange reaction can be implemented in a catalytic setting as a mean to activate C(sp2)–Br bonds in a transition metal‐free manner en route to the regioselective and general preparation of (hetero)aryl silanes. Simply treating structurally diverse (hetero)aryl bromides with N‐tert‐butyl‐N’‐silyldiazenes (tBu–N=N–Si) as silylating reagents and inexpensive sodium alkoxides as catalytic promoters yields a range of aromatic organosilicon compounds under ambient conditions. Mechanistic studies provide solid evidence for the involvement of tert‐butyl sodium as the C(sp2)–Br metalating agent.

Metal‐Free, Light‐Catalyzed ATRP For the Synthesis of Functional PVDF‐Based Block Copolymers and Their Characterization

AbstractThe synthesis and characterization of poly(vinylidene fluoride) (PVDF)‐based block copolymers using a metal‐free light‐catalyzed atom transfer radical polymerization (ATRP) approach are described. A PVDF macroinitiator with C─Br bonds at both ends of the chain is synthesized, and an organic photoredox catalyst (OPRC) is used to control the process. The metal‐free process expands the possibilities for the synthesis and application of PVDF‐based block copolymers, as it allows the use of monomers that is previously incompatible with classical ATRP due to their interaction with metal catalysts. The synthesized block copolymers are characterized structurally and thermally as powder materials and in thin films. Fourier‐transform infrared spectroscopy (FT‐IR) analysis revealed that the crystalline phase of PVDF changes when thin films are formed. Specifically, the disappearance of the FT‐IR peaks related to the gamma phase and the presence of characteristic peaks related to the alpha and beta phases indicate that film formation rearranged the PVDF chains, leading to changes in their crystalline phases. These PVDF‐based block copolymers have unique properties, including high thermal stability, chemical resistance, and piezoelectricity, making them potential candidates for use in various fields, such as biomedical engineering, energy storage, and electronic devices.

A 2-D coordination polymer based on 3-(2-pyridyl)-5-(4-chlorophenyl)-1,2,4-triazine ligands and lead(II) bromide: synthesis, structure, luminescent properties, and application in organic light-emitting diodes

The combination of PbBr2 with 3-(2-pyridyl)-5-(4-chlorophenyl)-1,2,4-triazine (PCPT) results in a 2-D Pb(II) coordination polymer, denoted as [Pb9(PCPT)4Br18] n . This compound has been identified and studied through CHN analysis, FT-IR, and 1H NMR spectroscopy, in addition to detailed analysis using single-crystal X-ray diffraction techniques. Considering the primary and secondary Pb–N and Pb–Br bonds, Pb1 and Pb2 exhibit hemidirected pentagonal bipyramidal geometries, whereas Pb3, Pb4, and Pb5 demonstrate holodirected octahedral geometries. The 2-D structure transitions into a 3-D arrangement due to the presence of non-covalent C–H…Br and π…π stacking interactions. The interactions highlighted above enhance the structural stability and support the transfer of charge and energy between metal centers, positioning the polymer as a potential candidate for luminescence applications. Analysis of the electro-optical characteristics of this compound indicates its suitability as a luminescent material for incorporating into organic light-emitting diodes.

Structure of inorganic compounds halogen bonds in derivatives of 2,5-diiod-1,4-dimethylbenzene

The synthesis of 1,4-di(bromomethyl)-2,5-diiodo-benzene (1), diacetate of 2,5-diiodo–1,4-di(hydroxymethyl)benzene (2) and diiodide of 1,1’-[(2,5-diiodo-1,4-phenylene)bis(methylene)]dipyridinium (3) is described and their crystallographic data are given. All three crystal structures are characterized by the stacked packing of planar molecules and the presence of halogen bonds I–Br, I–O, and I–I, respectively. The number of halogen bonds is maximum in compound 1: two I–Br bonds for each halogen atom. Compounds 2 and 3 contain one halogen bond per halogen atom, but they are significantly shorter than in compound 1. All crystals were investigated by IR spectroscopy and synchronized thermal analysis. Compound 1, which has no ionic or hydrogen bonds, melts at a higher temperature than ionic compound 3 (218 and 200°C, respectively) due to the presence of a large number of intermolecular halogen bonds. Compound 2 melts at a lower temperature (151°C), which is characteristic of esters.

In Situ Synthesis of Br‐Rich CsPbBr3 Nanoplatelets: Enhanced Stability and High PLQY for Wide Color Gamut Displays

AbstractThis study presents the Br‐rich in situ synthesis of blue‐emitting 2D CsPbBr3 nanoplatelets (NPLs) with various Br/Pb ratios using ZnBr2 as a Br precursor to enhance Br ion adsorption significantly. This leads to effective passivation of surface defects, particularly Pb−Br bonds, by increasing the positive charge density around Pb atoms, thus creating a stable bonding environment and reducing defect formation. Consequently, the photoluminescence quantum yield (PLQY) improves from 31.15% for a Br/Pb ratio of 2 to 87.2% for a ratio of 6. NPLs with a Br/Pb ratio of 6 also exhibit longer lifetimes (16.69 ns) and slower bleach recovery dynamics, indicating fewer non‐radiative recombination pathways and effective exciton dynamics. Additionally, NPLs with the Br/Pb ratio of 6 demonstrated better thermal stability, with an activation energy of 124.3 meV, indicating stronger exciton binding. These NPLs also exhibited enhanced stability, with UV tolerance at 43.9% and water resistance at 23.8%, making them suitable for displays and lighting. Furthermore, Br‐passivated CsPbBr3 NPLs are used as blue emitters in prototype white LEDs, achieving a wide color gamut, 126.6% of the National Television Standards Committee and 94.5% of Rec. 2020, demonstrating their potential for high‐quality lighting and advanced display technologies.

Efficient degradation of haloacetic acids by vacuum ultraviolet-activated peroxymonosulfate: Kinetics, mechanisms and theoretical calculations

Efficient degradation of haloacetic acids (HAAs) is crucial due to their potential risks. This study firstly proposed vacuum ultraviolet - activated peroxymonosulfate (VUV/PMS) to remove HAAs (i.e., monochloroacetic acid (MCAA), monobromoacetic acid (MBAA), dichloroacetic acid (DCAA), etc). VUV/PMS achieved 99.51 % MCAA and 63.29 % TOC removal within 10 min. Electron paramagnetic resonance (EPR), quenching and probe experiments demonstrated that •OH was responsible for MCAA degradation. MCAA degradation followed pathways of dehalogenation (major) and decarboxylation (minor). VUV/PMS showed application potential under various reaction parameters. Broad spectrum of VUV/PMS on various HAAs was further explored. Chlorinated HAAs (Cl-HAAs) were primarily degraded by oxidation reactions, while brominated HAAs (Br-HAAs) by direct VUV photolysis. The density functional theory-based calculations (DFT) revealed that reaction rates of HAAs correlated with the highest occupied molecular orbital (HOMO) and energy gap (ΔE), indicating that HAAs degradation depends on their chemical structures. The Fukui function (f0 values) and bond length showed vulnerability of the halogen atom in Cl-HAAs and C–Br bond in Br-HAAs. Overall, this study provides an in-depth perspective on the oxidation performance and mechanism of HAAs using VUV/PMS. It not only demonstrates a green and efficient method but also inspires new strategies for HAAs remediation.

Enhancement of Overall Kinetics by Se−Br Chemistry in Rechargeable Li−S Batteries

AbstractThe sluggish kinetics of lithium‐sulfur (Li−S) batteries severely impedes the application in extreme conditions. Bridging the sulfur cathode and lithium anode, the electrolyte plays a crucial role in regulating kinetic behaviors of Li−S batteries. Herein, we report a multifunctional electrolyte additive of phenyl selenium bromide (PhSeBr) to simultaneously exert positive influences on both electrodes and the electrolyte. For the cathode, an ideal conversion routine with lower energy barrier can be attained by the redox mediator and homogeneous catalyst derived from PhSeBr, thus improving the reaction kinetics and utilization of sulfur. Meanwhile, the presence of Se−Br bond helps to reconstruct a loose solvation sheath of lithium ions and a robust bilayer SEI with excellent ionic conductivity, which contributes to reducing the de‐solvation energy and simultaneously enhancing the interfacial kinetics. The Li−S battery with PhSeBr displays superior long cycling stability with a reversible capacity of 1164.7 mAh g−1 after 300 cycles at 0.5 C rate. And the pouch cell exhibits a maximum capacity of 845.3 mAh and a capacity retention of 94.8 % after 50 cycles. Excellent electrochemical properties are also obtained in extreme conditions of high sulfur loadings and low temperature of −20 °C. This work demonstrates the versatility and practicability of the special additive, striking out an efficient but simple method to design advanced Li−S batteries.

Theoretical Study on Photo‐Induced Copper Autoredox Construction of Chiral Amines

AbstractDensity functional theory (DFT) calculations were conducted to investigate the photo‐induced copper‐catalyzed C−N coupling reaction for the synthesis of chiral tertiary amines. The ligands′ effects on the metal center and the factors determining regioselectivity in chiral tertiary amine formation were examined. The computational results revealed that the oxidative quenching process involved in the photocatalytic redox cycle via CuI‐CuI*‐CuII‐CuIII transitions. Throughout the reaction, four key processes occurred: C−Br bond activation, ligand exchange, amide ion/Br ion exchange, and C−N coupling. Among these steps, alkyl radical generation through single electron transfer was identified as the rate‐determining step with an energy barrier of 13.9 kcal/mol. The chelating diphosphine ligand improved copper‘s reducibility and its capacity to activate the C−Br bond by charge transfer when exposed to visible light (CT). Copper's own redox process was facilitated by interactions between diphosphine and diamine ligands. Finally, when combined with oxygen, this catalyst system formed a chiral plane CuII‐O1‐N1‐N2‐N3 essential for enantioselective product formation.

Electro/Ni Dual‐Catalyzed Decarboxylative C(sp3)−C(sp2) Cross‐Coupling Reactions of Carboxylates and Aryl Bromide

AbstractPaired redox‐neutral electrolysis offers an attractive green platform for organic synthesis by avoiding sacrificial oxidants and reductants. Carboxylates are non‐toxic, stable, inexpensive, and widely available, making them ideal nucleophiles for C−C cross‐coupling reactions. Here, we report the electro/Ni dual‐catalyzed redox‐neutral decarboxylative C(sp3)−C(sp2) cross‐coupling reactions of pristine carboxylates with aryl bromides. At a cathode, a NiII(Ar)(Br) intermediate is formed through the activation of Ar−Br bond by a NiI‐bipyridine catalyst and subsequent reduction. At an anode, the carboxylates, including amino acid, benzyl carboxylic acid, and 2‐phenoxy propionic acid, undergo oxidative decarboxylation to form carbon‐based free radicals. The combination of NiII(Ar)(Br) intermediate and carbon radical results in the formation of C(sp3)−C(sp2) cross‐coupling products. The adaptation of this electrosynthesis method to flow synthesis and valuable molecule synthesis was demonstrated. The reaction mechanism was systematically studied through electrochemical voltammetry and density functional theory (DFT) computational studies. The relationships between the electrochemical properties of carboxylates and the reaction selectivity were revealed. The electro/Ni dual‐catalyzed cross‐coupling reactions described herein expand the chemical space of paired electrochemical C(sp3)−C(sp2) cross‐coupling and represent a promising method for the construction of the C(sp3)−C(sp2) bonds because of the ubiquitous carboxylate nucleophiles and the innate scalability and flexibility of electrochemical flow‐synthesis technology.

Electrochemical Hydroxylation of α‐Bromoacetophenones: Access to α‐Hydroxyacetophenones

AbstractHerein, a new method has been developed for the synthesis of various α‐hydroxyacetophenones via an electro‐oxidation process. It involves electrocatalytic hydroxylation via debromination of C(sp3)−Br bond. Here, simultaneous breaking of carbon‐bromine (C−Br) bond and formation of a new carbon‐oxygen (C−O) bond has been achieved through electrolysis of H2O using binary mixture of water and DMSO. The protocol features easy performance, oxidant and base‐free mild conditions and short reaction time.

Investigation on the phase transition, geometric and electronic properties of Bi-doped CsPbBr3 perovskites

Given the ongoing debate regarding the potential impact of Bi dopant on the phase transition of CsPbBr3, our study aims to provide a comprehensive understanding of this phenomenon. Through a multifaceted examination encompassing energetic states, geometric configurations, bonding interactions, and electronic structures, we find that the inclusion of Bi dopants alone does not directly induce the orthorhombic/tetragonal phase transition in CsPbBr3. However, we observe a obvious reduction in the energetic discrepancy between these two phases, indicating an indirect stimulation of the phase transition by Bi dopants. This accelerates the stimulations originating from external environment, which may be responsible for the experimentally observed phase transition. Moreover, our investigation confirms that Bi dopants selectively weakens the bonding interaction within the Pb/Bi octahedra of the CsPbBr3 lattice in an anisotropic manner. Specifically, we identify that the weakening of the out-of-plane Bi–Br bond strength arises from the diminished bonding interaction between the p orbital of Bi and the s orbital of Br. This phenomenon results in the elongation of the metal-halide octahedra, consequently relaxing lattice distortions and twists in undoped CsPbBr3 systems, particularly pronounced in orthorhombic phases. Consequently, both orthorhombic and tetragonal CsPbBr3 lattices tend to evolve towards similar geometric configurations. Our findings reveal the significant influence of Bi dopants on the phase dynamics of CsPbBr3, a factor often overlooked in previous investigations.

Red Light-Blue Light Chromoselective C(sp2)-X Bond Activation by Organic Helicenium-Based Photocatalysis.

Chromoselective bond activation has been achieved in organic helicenium (nPr-DMQA+)-based photoredox catalysis. Consequently, control over chromoselective C(sp2)-X bond activation in multihalogenated aromatics has been demonstrated. nPr-DMQA+ can only initiate the halogen atom transfer (XAT) pathway under red light irradiation to activate low-energy-accessible C(sp2)-I bonds. In contrast, blue light irradiation initiates consecutive photoinduced electron transfer (conPET) to activate more challenging C(sp2)-Br bonds. Comparative reaction outcomes have been demonstrated in the α-arylation of cyclic ketones with red and blue lights. Furthermore, red-light-mediated selective C(sp2)-I bonds have been activated in iodobromoarenes to keep the bromo functional handle untouched. Finally, the strength of the chromoselective catalysis has been highlighted with two-fold functionalization using both photo-to-transition metal and photo-to-photocatalyzed transformations.

Bromine substituent position of tetraphenylethylene-based luminogens effect on enhanced AIE and reversible mechanofluorochromic properties by halogen bonding

The halogen atoms have been exploited for designing highly efficient aggregation-induced emission (AIE) materials in recent years, whereas the development of halogenated AIEgen has been greatly limited by the unclear inherent mechanism. In this paper, a series of 1,1,2,2-tetrakis (4-(phenyl ethynyl) phenyl) ethene (TPPE) derivatives with bromine (Br) substituents in different positions were synthesized and their unique photophysical behaviors based on the anti-heavy atom effect were investigated. The brominated TPPE derivatives possessed higher fluorescence quantum yield (ФF) than that of TPPE, resulting from the formation of intermolecular Br-based bonds. Single crystal analysis and theoretical calculations revealed that changing the positions of the Br substituents could induce the formation of different intermolecular interactions. The Br-based bonds efficiently restricted the intermolecular motion, in which the Br⋯Br bond made a decisive factor in determining the highly efficient fluorescence. TPPE derivatives displayed obvious mechanofluorochromic (MFC) properties. PXRD and SEM results demonstrated that the crystal-to-amorphous transition attributed to the reversibility of MFC properties. This work provides a straightforward and practical method to achieve highly efficient AIE-active materials with higher contrast MFC properties via introducing the halogen atoms.

Optimizing the d-band center of sub-nanometer Pd–Pt alloy clusters for improved photocatalytic dehalogenation of polyhalogenated biphenyls

The efficient removal of highly toxic polyhalogenated biphenyls is rather challenging, mainly due to the difficulties in splitting C-X (X = Cl or Br) bond with high bond energy, as well as the transfer of active hydrogen species during the reduction dehalogenation process. In this work, sub-nanometer Pd–Pt alloy clusters (ca. 1 nm) supported on defect-containing TiO2(B) nanosheets (PdPt/TB), on absorption of visible light illumination (λ > 400 nm), were prepared and served as an efficient photocatalysts for dehalogenation of polyhalogenated biphenyls with H2O as the hydrogen source. An optimal sample (Pd0.7Pt0.3/TB) shows the highest photocatalytic dehalogenation efficiency for 3,3′,4,4′-trtrachlorobiphenyl (PCB77) within 30 mins, which is 12.5, 3.5 and 3 times higher than that of Pt1/TB, Pd1/TB, and Pd0.7 + Pt0.3/TB samples, respectively. Besides, 4,4′-dibromobiphenyl (PBB15) was also completely removed within 10 mins by using Pd0.7Pt0.3/TB photocatalyst, demonstrating its potential applications. Experiments and d-band theory calculations revealed that the introduction of Pt can regulate the d-band center of Pd to strength the interaction between active hydrogen with alloy and promote the transfer of hydrogen species. Meanwhile, Pd–Pt alloy is conducive to activate the C-X bond of polyhalogenated biphenyls. Finally, a mechanism based on Pd–Pt alloy clusters synergistic interaction is proposed at the molecular level. This work demonstrates the successful synthesis of sub-nanometer Pd–Pt alloy nanoclusters and elucidates the effect of interaction among Pd, Pt and supports, providing an efficient method for the removal of polyhalogenated compounds by photocatalytic technology.

Blue‐Light‐Excitable Red‐to‐Near Infrared Photoluminescence in 0D Antimony(III) Bromide Hybrids for Supplemental Lighting

AbstractAntimony (III)‐containing halide hybrids possess a distinctive stereoactivity with a 5s2 lone pair, which further induces significant structural distortions upon light excitation. Herein disordered dis‐[TPPen]2SbBr5 (TPPen = triphenylpentylphosphonium) and ordered ord‐[TPPen]2SbBr5, have been synthesized and exhibit self‐trapped excitons (STEs) emissions in the red‐to‐near infrared (NIR) range. Benefiting from a high distortion degree of STEs confined within the [SbBr5]2− unit and the pronounced alterations in the Sb─Br bond lengths upon blue‐light excitation, dis‐[TPPen]2SbBr5 achieves a greater level of excited state distortion and a larger Stokes shift than those of ord‐[TPPen]2SbBr5. The fabrication of blue light excited NIR light‐emitting device based on dis‐[TPPen]2SbBr5 demonstrates the prospective application in night vision supplemental lighting and non‐destructive examination. This work provides valuable molecular design strategies for the NIR luminescent materials in hybrid metal halides.

Green, solventless debromination of C70Br10 To C70 with CsI

A smooth, solventless and solid state debromination of C70Br10 can be achieved in a CsI matrix with quantitative restoration of the pristine C70 in quantitative yields. The debromination kinetics was studied with FT-IR spectroscopy and according to the pseudofirst order kinetics law, the rate constant was found in the range 3.6–5.2 × 10−5 s−1. The compound C70Br10 was studied with TGA and its thermal decomposition by DSC analysis. From the DSC data both the activation energy for the thermal decomposition of C70Br10 was determined as well as its enthalpy of formation, which has led to some considerations on the relative weakness of C–Br bonds in brominated fullerenes compounds. The debromination mechanism is discussed in terms of unimolecular elimination reaction (E1) in a concerted mechanism which leads to the restoration of the pristine C70 fullerene.

Introducing Iodide Ligands on IrAu12 Cluster Enhances Phosphorescence Efficiency and Photoredox Activity

AbstractThe effects of halide ligands on the photoluminescence (PL) and photoredox properties were examined on [IrAu12(dppe)5X2]+ (1X; X=Cl, Br, I; dppe=1,2‐bis(diphenylphosphino)ethane). The PL quantum yield was enhanced in the order of 1Cl (67 %)<1Br (75 %)<1I (77 %). The lifetime of the photoexcited state was shortened in the order of 1Cl>1Br>1I due to the acceleration of radiative relaxation by the heavy atom effect in 1I. Despite the shortest PL lifetime, cluster 1I exhibited the highest conversion in the photocatalytic [2+2] cycloaddition of bisenone. The PL from 1Cl and 1Br was quenched by adding Lewis acid Li+, required for activation of bisenone, whereas that from 1I remained unaffected. Theoretical calculations showed that the Au−Cl and Au−Br bonds of 1Cl and 1Br were weakened by interaction with Li+, while the Au−I bond of 1I was not. Clusters 1Cl and 1Br underwent halide exchange with isocyanide in the presence of Li+, whereas 1I did not. These results suggested that the photoredox activity of 1Cl and 1Br was suppressed by the Li+‐induced nonradiative quenching of the photoexcited state. This study highlights the unexpected importance of halide ligands in the design of efficient cluster photocatalysts.

Competition between Cu-Br semi-coordinate bond and C-H∙∙∙Br, C-H∙∙∙S and S∙∙∙S interactions; new two thioalkylazothiophenol (SNS) copper (II) dimers [Cu(L)(µ-Br)

Two new copper dimers [Cu(L)(µ-Br)]2, HL = 2(RS)C6H4N = NC(COCH3)-SC6H5, where R = CH3 (1), C6H5 (2) were synthesized and characterized using a variety of physicochemical methods, including single crystal X-ray diffraction. The molecular structures of the two binuclear copper(II) complexes show that Cu∙∙∙Cu inter-nuclei distances are 3.662 \\AA and 3.392 \\AA in 1 and 2, respectively. Structural analysis of the two dimers supported by QTAIM analysis of electron density indicates the presence of competition between Cu∙∙∙Br semi-coordinate bond and CH∙∙∙Br and CH∙∙∙S hydrogen bonding interactions and S∙∙∙S chalcogen bonding interactions. In complex 1, CH∙∙∙Br and CH∙∙∙S hydrogen bonding interactions exist, in contrast, they are absent in 2. Cu∙∙∙Br semi-coordinate bonds are stronger in 2 as indicated by Cu∙∙∙Br bond distances; Cu∙∙∙Br bond distances are 2.955 and 2.858 Å in 1 and 2.746 Å in 2. There are two weaker S∙∙∙S interactions in 2 and one stronger interaction in 1 as indicated by S∙∙∙S interatomic distances. The two copper dimers and their ligands exhibited good anticancer efficacy against breast (MCF-7), lung (HCT115), and colon human (A549) cancer cell lines. Complex 1 demonstrated strong cancer cell death compared to complex 2. Additionally, the complexes exhibited higher activity than the ligands. Dimer 2 exhibits two quasi-reversible one-electron reduction waves at −0.05 V and −0.37 V. The comproportionating constant for forming the Cu(I/II) mixed-valence complex was 2.57 × 105. The absence of Intervalence transfer (IT) bands in the electronic absorption spectrum for the mixed-valence complex suggested that a single unpaired electron is localized on one copper center.