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Symmetrical (phthalocyaninato)copper(II) complexes Cu(Pc′) [Pc′ = Pc(15C5), Pc(opp-15C5)₂, Pc(adj-15C5)₂, Pc(15C5)₃; Pc = unsubstituted phthalocyaninate, Pc(15C5) = 2,3-(15-crown-5)phthalocyaninate, Pc(opp-15C5)₂ = 2,3,16,17-bis(15-crown-5)phthalocyaninate, Pc(adj-15C5)₂ = 2,3,9,10-bis(15-crown-5)phthalocyaninate, Pc(15C5)₃ = 2,3,9,10,16,17-tris(15-crown-5)phthalocyaninate] (2–5) have been prepared by the reaction of corresponding heteroleptic bis(phthalocyaninato)europium complexes Eu(Pc)(Pc′) [Pc′ = Pc(15C5), Pc(opp-15C5)₂, Pc(adj-15C5)₂, Pc(15C5)₃, Pc(15C5)₄; Pc = unsubstituted phthalocyaninate] with Cu(OAc)₂ in dry dmf at 100 °C. For the purpose of comparative studies, the symmetrical counterparts CuPc (1) and CuPc(15C5)₄ [Pc(15C5)₄ =2,3,9,10,16,17,24,25-tetrakis(15-crown-5)phthalocyaninate](7) have also been prepared. These monomeric complexes have been characterized by spectroscopic methods in addition to elemental analysis. Having a series of closely related phthalocyanines with a different number and/or disposition of 15-crown-5 groups at the peripheral positions, the effects of 15-crown-5 substituent number and molecular symmetry on the electronic absorption spectra, infra-red (IR) spectra, and supramolecular structure formation induced by K⁺ ions have been investigated. Systematic studies on the formation of dimeric supramolecular structures of the series of monomers 2–6 reveal and confirm the previously proposed two-step three-stage process of K⁺-induced dimerization of phthalocyanines with three or four 15-crown-5 moieties.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Orientierungssinn: Eine charakteristische geordnete Domäne eines 2:1-Sandwichkomplexes aus Phthalocyaninen und Tetraphenylporphyrin wurde durch STM in situ auf einer Au(111)-Oberfläche nachgewiesen. Demnach entstand die hochgeordnete Struktur dadurch, dass sich die Moleküle abwechselnd in zwei verschiedenen Orientierungen anordneten.

Three perylene-3,4;9,10-tetracarboxydiimide (PTCDI) compounds with two dodecyloxy or thiododecyl chains attached at the bay positions of the perylene ring, PTCDIs 1–3, were fabricated into nanoassemblies by a solution injection method. The morphologies of these self-assembled nanostructures were determined by transmission electronic microscopy (TEM), scanning electronic microscopy (SEM), and atomic force microscopy (AFM). PTCDI compound 1, with two dodecyloxy groups, forms long, flexible nanowires with an aspect ratio of over 200, while analogue 3, with two thiododecyl groups, self-assembles into spherical particles. In line with these results, PTCDI 2, with one dodecyloxy group and one thiododecyl group, forms nanorods with an aspect ratio of around 20. Electronic absorption and fluorescence spectroscopy results reveal the formation of H-aggregates in the nanostructures of these PTCDI compounds owing to the π–π interaction between the substituted perylene molecules and also suggest a decreasing π–π interaction in the order 1>2>3, which corresponds well with the morphology of the corresponding nanoassemblies. On the basis of DFT calculations, the effect of different substituents at the bay positions of the perylene ring on the π–π interaction between substituted perylene molecules and the morphology of self-assembled nanostructures is rationalized by the differing degree of twisting of the conjugated perylene system caused by the different substituents and the different bending of the alkoxy and thioalkyl groups with respect to the plane of the naphthalene.

The location of the hole and acid proton in neutral nonprotonated and protonated mixed (phthalocyaninato)(porphyrinato) yttrium double-decker complexes, respectively, is studied on the basis of density functional theory (DFT) calculations on the molecular structures, molecular orbitals, atomic charges, and electronic absorption and infrared spectra of the neutral, reduced, and two possible protonated species of a mixed (phthalocyaninato)(porphyrinato) yttrium compound: [(Pc)Y(Por)], [(Pc)Y(Por)]⁻, [(HPc)Y(Por)], and [(Pc)Y(HPor)], respectively. When the neutral [(Pc)Y(Por)] is reduced to [(Pc)Y(Por)]⁻, the calculated results on the molecular structure, atomic charge, and electronic absorption and infrared spectra show that the added electron has more influence on the Pc ring than on its Por counterpart, suggesting that the location of the hole is on the Pc ring in neutral [(Pc)Y(Por)]. Nevertheless, comparison of the calculation results on the structure, orbital composition, charge distribution, and electronic absorption and infrared spectra between [(HPc)Y(Por)] and [(Pc)Y(HPor)] leads to the conclusion that the acid proton in the protonated mixed (phthalocyaninato)(porphyrinato) yttrium compound should be localized on the Por ring rather than the Pc ring, despite the localization of the hole on the Pc ring in [(Pc)Y(Por)]. This result is in line with the trend revealed by comparative studies of the X-ray single-crystal molecular structures between [M^III{Pc(α-OC₅H₁₁)₄}(TClPP)] and [M^IIIH{Pc(α-OC₅H₁₁)₄}(TClPP)] (H₂TClPP=5,10,15,20-tetrakis(4-chlorophenyl)porphyrin; M=Sm, Eu). The present work not only represents the first systemic DFT study on the structures and properties of mixed (phthalocyaninato)(porphyrinato) yttrium double-decker complexes, but more importantly sheds further light on the nature of protonated bis(tetrapyrrole) rare-earth complexes.

Mixed cyclization of 3-mono-, 4-mono-, or 4,5-di(porphyrinated) phthalonitrile compounds 2, 3, or 6 and unsubstituted phthalonitrile with the half-sandwich complex [Eu^III(acac)(Pc)] (Pc=phthalocyaninate, acac=acetylacetonate) as the template in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in n-pentanol afforded novel porphyrin-appended europium(III) bis(phthalocyaninato) complexes 7–9 in 30–40 % yield. These mixed tetrapyrrole triads and tetrad were spectroscopically and electrochemically characterized and their photophysical properties were also investigated with steady-state and transient spectroscopic methods. It has been found that the fluorescence of the porphyrin moiety is quenched effectively by the double-decker unit through an intramolecular photoinduced electron-transfer process, which takes place in several hundred femtoseconds, while the recombination of the charge-separated state occurs in several picoseconds. By using different phthalocyanines containing different numbers of porphyrin substituents at the peripheral or nonperipheral position(s) of the ligand, while the other unsubstituted phthalocyanine remains unchanged in these double-deckers, the effects of the number and the position of the porphyrin substituents on these photophysical processes were also examined.

Sense of direction: A characteristic well-ordered domain of a 2:1 sandwich complex consisting of phthalocyanines and tetraphenylporphyrin was observed on an Au(111) surface by STM in situ, indicating that a highly ordered array was formed by alternately arranging the molecules in two different orientations.

A series of heteroleptic and homoleptic bis(phthalocyaninato) lanthanide(III) complexes, namely M(Pc)[Pc(OPh)₈], M[Pc(OPh)₈]₂, Eu(Pc)[Pc(SPh)₈], and Eu[Pc(SPh)₈]₂ [M = Eu, Ho, Lu; Pc = unsubstituted phthalocyaninate; Pc(OPh)₈ = 2,3,9,10,16,17,23,24-octaphenoxyphthalocyaninate; Pc(SPh)₈ = 2,3,9,10,16,17,23,24-octathiophenoxyphthalocyaninate](1–8) have been prepared. The molecular structure of Eu[Pc(OPh)₈]₂ (4) has been determined by single-crystal X-ray diffraction analysis. All of the new sandwich compounds have been characterized with various spectroscopic methods. Their electrochemical characteristics show that the introduction of phenoxy or thiophenoxy groups onto the peripheral positions of the phthalocyaninato ligand makes the double-decker harder to oxidize and easier to reduce than the analogous compounds without the (thio)phenoxy group. Theoretical calculations, with the semi-empirical PM3 method, indicate that the change in the energy level of the frontier orbitals of these ligands induced by the electron-withdrawing substituents is responsible for these unusual electrochemical properties. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

The half-sandwich rare-earth complexes [M^III(acac)(TClPP)] (M=Sm, Eu, Y; TClPP=meso-tetrakis(4-chlorophenyl)porphyrinate; acac=acetylacetonate), generated in situ from [M(acac)₃]⋅n H₂O and H₂(TClPP), were treated with 1,8,15,22-tetrakis(3-pentyloxy)phthalocyanine [H₂{Pc(α-OC₅H₁₁)₄}] (Pc=phthalocyaninate) under reflux in n-octanol to yield both the neutral nonprotonated and protonated (phthalocyaninato)(porphyrinato) rare-earth double-decker complexes, [M^III{Pc(α-OC₅H₁₁)₄}(TClPP)] (1–3) and [M^IIIH{Pc(α-OC₅H₁₁)₄}(TClPP)] (4–6), respectively. In contrast, reaction of [Y^III(acac)(TClPP)] with 1,4,8,11,15,18,22,25-octakis(1-butyloxy)phthalocyanine [H₂Pc(α-OC₄H₉)₈] gave only the protonated double-decker complex [Y^IIIH{Pc(α-OC₄H₉)₈}(TClPP)] (7). These observations clearly show the importance of the number and positions of substituents on the phthalocyanine ligand in controlling the nature of the (phthalocyaninato)(porphyrinato) rare-earth double-deckers obtained. In particular, α-alkoxylation of the phthalocyanine ligand is found to stabilize the protonated form, a fact supported by molecular-orbital calculations. A combination of mass spectrometry, NMR, UV-visible, near-IR, MCD, and IR spectroscopy, and X-ray diffraction analyses, facilitated the differentiation of the newly prepared neutral nonprotonated and protonated double-decker complexes. The crystal structure of the protonated form has been determined for the first time.

Three heteroleptic tris(phthalocyaninato) rare-earth triple-decker complexes [(Pc)M(Pc)M{Pc(α-OC₅H₁₁)₄}] [M = Sm, Gd, Lu; Pc = phthalocyaninate; Pc(α-OC₅H₁₁)₄ = 1,8,15,22-tetrakis(3-pentyloxy)phthalocyaninate] have been prepared as racemic mixtures by treating [M{Pc(α-OC₅H₁₁)₄}(acac)], generated in situ, with the bis(phthalocyaninato) rare-earth double-decker complex [M(Pc)₂] in refluxing n-octanol. The molecular structures of the gadolinium and lutetium complexes have been determined by single-crystal X-ray diffraction analysis, both of which adopt the asymmetrical structure [(Pc)M(Pc)M{Pc(α-OC₅H₁₁)₄}]. The outer Pc and Pc(α-OC₅H₁₁)₄ rings are significantly domed, while the inner Pc ring is essentially planar. The ring-to-ring separation between the two adjacent Pc rings, as defined by the two N₄ mean planes, diminishes from [(Pc)Gd(Pc)Gd{Pc(α-OC₅H₁₁)₄}] to [(Pc)Lu(Pc)Lu{Pc(α-OC₅H₁₁)₄}] as a result of the smaller Lu^III ion. The decreased molecular symmetry for these complexes has also been revealed by the NMR spectra of the samarium and lutetium analogs, in which four sets of signals appear for the inner Pc ring protons due to the special disposition of the neighboring Pc(α-OC₅H₁₁)₄ ring. Electrochemical studies have revealed four one-electron oxidations and up to five one-electron reductions for these complexes. The dependence of the phthalocyanine Q band as well as the first and second oxidation potentials on the size of the metal center indicates that substantial π-π interactions are present in these compounds. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Reaction of heteroleptic bis(phthalocyaninato) lanthanide compounds [(Pc)M{Pc(OC₈H₁₇)₈}] [H₂Pc=unsubstituted phthalocyanine; H₂Pc(OC₈H₁₇)₈=2,3,9,10,16,17,23,24-octakis(octyloxy)phthalocyanine] with monomeric complexes [(Pc)M(acac)] (Hacac=acetylacetone), both of which generated in situ, led to the isolation of heteroleptic phthalocyaninato-[2,3,9,10,16,17,23,24-octakis(octyloxy)phthalocyaninato] lanthainde(III) triple-decker complexes [(Pc)M{Pc(OC₈H₁₇)₈}] (M=Gd–Lu) (1–8) as the sole product. Heterodinuclear analogues [(Pc)Lu{Pc(OC₈H₁₇)₈}M(Pc)] (M=Gd–Yb) (9–15) were obtained in a similar manner from the reaction of [(Pc)M{Pc(OC₈H₁₇)₈}] (M=Gd–Yb) and [(Pc)Lu(acac)]. The molecular structures of the herterodinuclear compound [(Pc)Lu{Pc(OC₈H₁₇)₈}Er(Pc)] (13) and its homodinuclear counterparts [(Pc)M{Pc(OC₈H₁₇)₈}M(Pc)] (M=Er, Lu) (5, 8) have been determined by X-ray diffraction analysis; these structures exhibit a symmetrical molecular structure with one inner planar Pc(OC₈H₁₇)₈ ligand and two outer domed Pc ligands. In addition to various spectroscopic analyses, the electrochemistry of these compounds has also been studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods, revealing the gradually enhanced π–π interactions among the phthalocyanine rings in the triple-deckers along with the lanthanide contraction.

Homoleptic bis(phthalocyaninato) rare-earth double-deckers complexes [M^III{Pc(α-OC₅H₁₁)₄}₂] (M=Eu, Y, Lu; Pc(α-OC₅H₁₁)₄=1,8,15,22-tetrakis(3-pentyloxy)phthalocyaninate) have been prepared by treating the metal-free phthalocyanine H₂Pc(α-OC₅H₁₁)₄ with the corresponding M(acac)₃⋅nH₂O (acac=acetylacetonate) in refluxing n-octanol. Due to the C_4h symmetry of the Pc(α-OC₅H₁₁)₄ ligand and the double-decker structure, all the reactions give a mixture of two stereoisomers with C_4h and D₄ symmetry. The former isomer, which is a major product, can be partially separated by recrystallization due to its higher crystallinity. The molecular structure of the major isomer of the Y analogue has been determined by single-crystal X-ray diffraction analysis. The metal center is eight-coordinate bound to the isoindole nitrogen atoms of the two phthalocyaninato ligands, forming a distorted square antiprism. Such an arrangement leads to an interesting “pinwheel” structure when viewed along the C₄ axis, which assumes a very unusual S₈ symmetry. The major isomers of all these double-deckers have also been characterized with a wide range of spectroscopic methods. A systematic investigation of their electronic absorption and electrochemical data reveals that the π–π interaction between the two Pc(α-OC₅H₁₁)₄ rings is weaker than that for the corresponding unsubstituted or β-substituted bis(phthalocyaninato) analogues.

Two series of mixed phthalocyaninato and porphyrinato rare earth(III) triple-decker complexes [M₂(Pc)(TClPP)₂] (1a−10a) and [M₂(Pc)₂(TClPP)] (1b−11b) [M = Y, La−Er except Ce and Pm; Pc = phthalocyaninate; TClPP = tetrakis(4-chlorophenyl)porphyrinate] have been prepared by treating the half-sandwich complexes [M(TClPP)(acac)] (acac = acetylacetonate), generated in situ from [M(acac)₃]·nH₂O and H₂(TClPP), with Li₂(Pc). All the triple-decker complexes have been characterized by a wide range of spectroscopic and electrochemical methods. The molecular structures of [M₂(Pc)(TClPP)₂] (M = Y, Ho) have also been determined, and show a symmetrical disposition of ligands, with two outer domed TClPP and one inner Pc rings. A systematic investigation of the optical and electrochemical data of these complexes has revealed the nature of the HOMO and LUMO, as well as the origin of the electronic absorptions of these triple-decker complexes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

The electrochemical characteristics of a series of heteroleptic tris(phthalocyaninato) complexes with identical rare earths or mixed rare earths (Pc)M(OOPc)M(OOPc) [M = Eu...Lu, Y; H₂Pc = unsubstituted phthalocyanine, H₂(OOPc) = 3,4,12,13,21,22,30,31-octakis(octyloxy)phthalocyanine] and (Pc)Eu(OOPc)Er(OOPc) have been recorded and studied comparatively by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in CH₂Cl₂ containing 0.1 M tetrabutylammonium perchlorate (TBAP). Up to five quasi-reversible one-electron oxidations and four one-electron reductions have been revealed. The half-wave potentials of the first, second and fifth oxidations depend on the size of the metal center, but the fifth changes in the opposite direction to that of the first two. Moreover, the difference in redox potentials of the first oxidation and first reduction for (Pc)M(OOPc)M(OOPc), 0.85−0.98 V, also decreases linearly along with decreasing rare earth ion radius, clearly showing the rare earth ion size effect and indicating enhanced π−π interactions in the triple-deckers connected by smaller lanthanides. This order follows the red-shift seen in the lowest energy band of triple-decker compounds. The electronic differences between the lanthanides and yttrium are more apparent for triple-decker sandwich complexes than for the analogous double-deckers. By comparing triple-decker, double-decker and mononuclear [Zn^II] complexes containing the OOPc ligand, the HOMO−LUMO gap has been shown to contract approximately linearly with the number of stacked phthalocyanine ligands. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

The electrochemistry of homoleptic substituted phthalocyaninato rare earth double-decker complexes M(TBPc)₂ and M(OOPc)₂ [M = Y, La...Lu except Pm; H₂TBPc = 3(4),12(13),21(22),30(31)-tetra-tert-butylphthalocyanine, H₂OOPc = 3,4,12,13,21,22,30,31-octakis(octyloxy)phthalocyanine] has been comparatively studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in CH₂Cl₂ containing 0.1 M tetra-n-butylammonium perchlorate (TBAP). Two quasi-reversible one-electron oxidations and three or four quasi-reversible one-electron reductions have been revealed for these neutral double-deckers of two series of substituted complexes, respectively. For comparison, unsubstituted bis(phthalocyaninato) rare earth analogues M(Pc)₂ (M = Y, La...Lu except Pm; H₂Pc = phthalocyanine) have also been electrochemically investigated. Two quasi-reversible one-electron oxidations and up to five quasi-reversible one-electron reductions have been revealed for these neutral double-decker compounds. The three bis(phthalocyaninato)cerium compounds display one cerium-centered redox wave between the first ligand-based oxidation and reduction. The half-wave potentials of the first and second oxidations and first reduction for double-deckers of the tervalent rare earths depend on the size of the metal center. The difference between the redox potentials of the second and third reductions for M^III(Pc)₂, which represents the potential difference between the first oxidation and first reduction of [M^III(Pc)₂]⁻, lies in the range 1.08−1.37 V and also gradually diminishes along with the lanthanide contraction, indicating enhanced π−π interactions in the double-deckers connected by the smaller, lanthanides. This corresponds well with the red-shift of the lowest energy band observed in the electronic absorption spectra of reduced double-decker [M^III(Pc′)₂]⁻ (Pc′ = Pc, TBPc, OOPc). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

A series of eleven heteroleptic bis(phthalocyaninato) rare earth double-deckers [M^III(pc){pc(α-OC₅H₁₁)₄}] 1–11 (M=Y, SmLu; pc=phthalocyaninato; pc(α-OC₅H₁₁)₄=1,8,15,22-tetrakis(1-ethylpropoxy)phthalocyaninato) were prepared as racemic mixtures by [M^III(pc)(acac)]-induced (acac=acetylacetonato) cyclic tetramerization of 3-(1-ethylpropoxy)phthalonitrile in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in refluxing pentanol. These compounds could also be prepared by treating [M^III(pc)(acac)] with the metal-free phthalocyanine H₂{pc(α-OC₅H₁₁)₄} in refluxing octanol. The whole series of double-decker complexes 1–11 were characterized by elemental analysis and various spectroscopic methods. The molecular structures of the Sm, Eu, and Er complexes 1, 2, and 8, respectively, were also determined by single-crystal X-ray diffraction analysis. The effects of the rare earth ion size on the reaction yield, molecular structure, and spectroscopic and electrochemical properties of these complexes were systematically examined.

Mixed phthalocyaninato tetrakis(4-pyridyl)porphyrinato rare earth triple-decker complexes M₂(TPyP)₂(Pc) [M = La (1), Eu (2)] have been prepared by condensation between M(TPyP)acac generated in situ and M(Pc)₂. Their symmetrical structure (TPyP)M(Pc)M(TPyP) was verified by ¹H NMR (1D and 2D) spectra in CDCl₃ solutions. The electronic absorption spectra of these two compounds were recorded in the UV/Vis and near-IR region. A weak absorption in the near-IR region at 860 and 942 nm for 1 and 2, respectively, was observed as the lowest energy band and is attributed to the electronic transition from HOMO to LUMO for these mono(phthalocyaninato) bis(porphyrinato) rare earth complexes. Their electrochemical properties were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Analysis of the relationship between the optical and redox properties of M₂(TPyP)₂(Pc) reveals that the HOMO and LUMO of M₂(TPyP)₂(Pc) have both porphyrin and phthalocyanine character. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

A series of 14 heteroleptic rare earth sandwich complexes [M^III(nc)(oep)] (M=Y, La–Lu except Ce and Pm; nc=2,3-naphthalocyaninate; oep=octaethylporphyrinate) have been prepared by a one-pot procedure from the corresponding [M(acac)₃]⋅nH₂O (acac=acetylacetonate), metal-free porphyrin H₂(oep), and naphthalonitrile in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in n-octanol. The molecular structures of four of these complexes (M=Sm, Gd, Y, Lu) are isostructural, exhibiting a slightly distorted square antiprismatic geometry with two domed ligands. The interplanar distance decreases from 2.823 to 2.646 Å along the series as a result of lanthanide contraction. The whole series of complexes have also been characterized spectroscopically. All the electronic absorptions, except the two B-bands due to nc and the oep rings, are metal-dependent, indicating that there are substantial π–π interactions. The hole or the unpaired electron in these double-deckers is delocalized over both macrocyclic ligands, as evidenced by the co-appearance of the IR marker bands for the nc^.− (1315–1325 cm⁻¹) and oep^.− (1510–1531 cm⁻¹) π radical ions. Three one-electron oxidation couples and up to three one-electron reduction couples have been revealed by electrochemical methods. All the potentials are linearly dependent on the size of the metal center. The changes in absorption spectra during the first electro-oxidation and reduction of the La^III, Eu^III, and Y^III double-deckers have also been studied spectroelectrochemically. The spectral data recorded for [M^III(nc)(oep)]⁻ (M=Y, La–Lu except Ce and Pm) reduced chemically with hydrazine hydrate are in accord with those obtained by spectroelectrochemical methods. The first heteroleptic naphthalocyaninate-containing triple-deckers [M^III₂(nc)(oep)₂] (M=Nd, Eu) have also been prepared by a raise-by-one-story method by using [M^III(nc)(oep)] (M=Nd, Eu), [M(acac)₃]⋅nH₂O (M=Nd, Eu), and H₂(oep) as starting materials. The compounds adopt a symmetrical triple-decker structure with two outer oep rings and one inner nc ring, which has been confirmed by ¹H NMR spectroscopy and X-ray structural determination of the Nd complex. Both compounds give a near-IR absorption at 1021 nm (for M=Nd) or 1101 nm (for M=Eu), which has rarely been observed for neutral (or hole-free) triple-decker complexes and can be ascribed to the lowest-energy Q′(0, 0) transition. Similarly to the double-decker analogues, these triple-decker complexes undergo a series of one-electron transfer processes with a relatively small potential gap (1.1–1.2 V) between the first oxidation and the first reduction.