Synthesis and Characterization of Extended Bis(terpyridine)ruthenium Amino Acids

(Oligopyridine)ruthenium(II) complexes have been widely used in dye sensitized solar cells and other sophisticated optical devices due to their outstanding photophysical properties and their chemical stability. Herein, we describe the longitudinal extension of our previously reported bis(terpyridine)ruthenium(II) amino acid [Ru(tpy–NH₂)(tpy–COOH)]²⁺ (tpy = 4′‐substituted 2,2′:6′,2″‐terpyridine) by insertion of para‐phenylene spacers –C₆H₄– between the terpyridine and the functional groups. The influence of the para‐phenylene spacer on the absorption and emission properties is investigated using UV/Vis absorption and emission spectroscopy and is discussed within a qualitative molecular orbital picture.     

Monodentate and bridging behaviour of the sulfur‐containing ligand 4′‐[4‐(methylsulfanyl)phenyl]‐4,2′:6′,4′′‐terpyridine in two discrete zinc(II) complexes with acetylacetonate

The Zn complexes bis(acetylacetonato‐κ²O,O′)bis{4′‐[4‐(methylsulfanyl)phenyl]‐4,2′:6′,4′′‐terpyridine‐κN¹}zinc(II), [Zn(C₅H₇O₂)₂(C₂₂H₁₇N₃S)₂], (I), and {μ‐4′‐[4‐(methylsulfanyl)phenyl]‐4,2′:6′,4′′‐terpyridine‐κ²N¹:N^1′′}bis[bis(acetylacetonato‐κ²O,O′)zinc(II)], [Zn₂(C₅H₇O₂)₄(C₂₂H₁₇N₃S)], (II), are discrete entities with different nuclearities. Compound (I) consists of two centrosymmetrically related monodentate 4′‐[4‐(methylsulfanyl)phenyl]‐4,2′:6′,4′′‐terpyridine (L1) ligands binding to one Zn^II atom sitting on an inversion centre and two centrosymmetrically related chelating acetylacetonate (acac) groups which bind via carbonyl O‐atom donors, giving an N₂O₄ octahedral environment for Zn^II. Compound (II), however, consists of a bis‐monodentate L1 ligand bridging two Zn^II atoms from two different Zn(acac)₂ fragments. Intra‐ and intermolecular interactions are weak, mainly of the C—H...π and π–π types, mediating similar layered structures. In contrast to related structures in the literature, sulfur‐mediated nonbonding interactions in (II) do not seem to have any significant influence on the supramolecular structure.     

Ru–bis(pyridine)pyrazolate (bpp)‐Based Water‐Oxidation Catalysts Anchored on TiO2: The Importance of the Nature and Position of the Anchoring Group

Three distinct functionalisation strategies have been applied to the in,in‐[{Ru^II(trpy)}₂(μ‐bpp)(H₂O)₂]³⁺ (trpy=2,2′:6′,2′′‐terpyridine, bpp=bis(pyridine)pyrazolate) water‐oxidation catalyst framework to form new derivatives that can adsorb onto titania substrates. Modifications included the addition of sulfonate, carboxylate, and phosphonate anchoring groups to the terpyridine and bis(pyridyl)pyrazolate ligands. The complexes were characterised in solution by using 1D NMR, 2D NMR, and UV/Vis spectroscopic analysis and electrochemical techniques. The complexes were then anchored on TiO₂‐coated fluorinated tin oxide (FTO) films, and the reactivity of these new materials as water‐oxidation catalysts was tested electrochemically through controlled‐potential electrolysis (CPE) with oxygen evolution detected by headspace analysis with a Clark electrode. The results obtained highlight the importance of the catalyst orientation with respect to the titania surface in regard to its capacity to catalytically oxidize water to dioxygen.     

Cobalt(II) and cobalt(III) complexes with 4′‐(4‐cyanophenyl)‐2,2′:6′,2′′‐terpyridine

4′‐Cyanophenyl‐2,2′:6′,2′′‐terpyridine (cptpy) was employed as an N,N′,N′′‐tridentate ligand to synthesize the compounds bis[4′‐(4‐cyanophenyl)‐2,2′:6′,2′′‐terpyridine]cobalt(II) bis(tetrafluoridoborate) nitromethane solvate, [Co^II(C₂₂H₁₄N₄)₂](BF₄)₂·CH₃NO₂, (I), and bis[4′‐(4‐cyanophenyl)‐2,2′:6′,2′′‐terpyridine]cobalt(III) tris(tetrafluoridoborate) nitromethane sesquisolvate, [Co^III(C₂₂H₁₄N₄)₂](BF₄)₃·1.5CH₃NO₂, (II). In both complexes, the cobalt ions occupy a distorted octahedral geometry with two cptpy ligands in a meridional configuration. A greater distortion from octahedral geometry is observed in (I), which indicates a different steric consequence of the constrained ligand bite on the Co^II and Co^III ions. The crystal structure of (I) features an interlocked sheet motif, which differs from the one‐dimensional chain packing style present in (II). The lower dimensionality in (II) can be explained by the disturbance caused by the larger number of anions and solvent molecules involved in the crystal structure of (II). All atoms in (I) are on general positions, and the F atoms of one BF₄⁻ anion are disordered. In (II), one B atom is on an inversion center, necessitating disorder of the four attached F atoms, another B atom is on a twofold axis with ordered F atoms, and the C and N atoms of one nitromethane solvent molecule are on a twofold axis, causing disorder of the methyl H atoms. This relatively uncommon study of analogous Co^II and Co^III complexes provides a better understanding of the effects of different oxidation states on coordination geometry and crystal packing.     

Structural characterization of a hybrid terpyridine–pyrazine ligand and its one‐dimensional ZnII coordination polymer: a computational approach to conventional and nonconventional intermolecular interactions

The structures of a new hybrid terpyridine–pyrazine ligand, namely 4′‐[4‐(pyrazin‐2‐yl)phenyl]‐4,2′:6′,4′′‐terpyridine (L2), C₂₅H₁₇N₅, and its one‐dimensional coordination polymer catena‐poly[[bis(acetylacetonato‐κ²O,O′)zinc]‐μ‐4′‐[4‐(pyrazin‐2‐yl‐κN⁴)phenyl]‐4,2′:6′,4′′‐terpyridine‐κN¹], [Zn(C₅H₇O₂)₂(C₂₅H₁₇N₅)]_n or [Zn(acac)₂(L2)]_n (Hacac is acetylacetone), are reported. Packing interactions in both crystal structures are analyzed using Hirshfeld surface and enrichment ratio techniques. For the simpler structure of the monomeric ligand, further studies on the interaction hierarchy using the energy framework approach were made. The result was a complete picture of the intermolecular interaction landscape, which revealed some subtle details, for example, that some weak (at first sight negligible) C—H…N interactions in the structure of free L2 play a relevant role in the crystal stabilization.     

Enhanced third‐order nonlinear optical properties determined in thin films using the Z‐scan technique: bis(μ‐4,4′‐oxydibenzoato)bis[(4′‐phenyl‐2,2′:6′,2′′‐terpyridine)cobalt(II)]

π‐Conjugated organic materials exhibit high and tunable nonlinear optical (NLO) properties, and fast response times. 4′‐Phenyl‐2,2′:6′,2′′‐terpyridine (PTP) is an important N‐heterocyclic ligand involving π‐conjugated systems, however, studies concerning the third‐order NLO properties of terpyridine transition metal complexes are limited. The title binuclear terpyridine Co^II complex, bis(μ‐4,4′‐oxydibenzoato)‐κ³O,O′:O′′;κ³O′′:O,O′‐bis[(4′‐phenyl‐2,2′:6′,2′′‐terpyridine‐κ³N,N′,N′′)cobalt(II)], [Co₂(C₁₄H₈O₅)₂(C₂₁H₁₅N₃)₂], (1), has been synthesized under hydrothermal conditions. In the crystal structure, each Co^II cation is surrounded by three N atoms of a PTP ligand and three O atoms, two from a bidentate and one from a symmetry‐related monodentate 4,4′‐oxydibenzoate (ODA²⁻) ligand, completing a distorted octahedral coordination geometry. Neighbouring [Co(PTP)]²⁺ units are bridged by ODA²⁻ ligands to form a ring‐like structure. The third‐order nonlinear optical (NLO) properties of (1) and PTP were determined in thin films using the Z‐scan technique. The title compound shows a strong third‐order NLO saturable absorption (SA), while PTP exhibits a third‐order NLO reverse saturable absorption (RSA). The absorptive coefficient β of (1) is −37.3 × 10⁻⁷ m W⁻¹, which is larger than that (8.96 × 10⁻⁷ m W⁻¹) of PTP. The third‐order NLO susceptibility χ⁽³⁾ values are calculated as 6.01 × 10⁻⁸ e.s.u. for (1) and 1.44 × 10⁻⁸ e.s.u. for PTP.     

Facile Self‐Assembly of Metallo‐Supramolecular Ring‐in‐Ring and Spiderweb Structures Using Multivalent Terpyridine Ligands

A series of metallo‐supramolecular ring‐in‐ring structures was generated by assembling Cd^II ions and the multivalent terpyridine ligands ( L^1‐3 ) composed of one 60°‐bent and two 120°‐bent bis(terpyridine)s with varying alkyl linker lengths. The mechanistic study for the self‐assembly process excluded an entropically templated pathway and showed that the intramolecularly complexed species is the key intermediate leading to ring‐in‐ring formation. The next‐generation superstructure, a spiderweb, was produced in quantitative yield using the elongated decakis(terpyridine) ligand ( L⁵ ).     

Coordination‐Driven Macrocyclization for Locking of Photo‐ and Thermal cis→trans Isomerization of Azobenzene

Both trans and cis isomers of azobenzene‐linked bis‐terpyridine ligand L1 were incorporated in rigid macrocycles linked by Fe^II(tpy)₂ (tpy: terpyridine) units. The complex of the longer trans‐ L1 is dinuclear [(trans‐ L1 )₂ ? Fe^II₂], whereas the complex of the shorter cis‐ L1 is mononuclear [cis‐ L1? Fe^II]. The complex cis‐ L1? Fe^II was not only thermally stable but also photochemically inactive. These results indicate a perfectly locked state of cis‐azobenzene. The stable macrocyclic structure of cis‐ L1? Fe^II causes locking of the isomerization. To the best of our knowledge, this is first example of dual locking of photo‐ and thermal isomerization of cis‐azobenzene.     

Superior Electron‐Transport Ability of π‐Conjugated Redox Molecular Wires Prepared by the Stepwise Coordination Method on a Surface

Electronic conductivity of molecular wires is a critical fundamental issue in molecular electronics. π‐Conjugated redox molecular wires with the superior long‐range electron‐transport ability could be constructed on a gold surface through the stepwise ligand–metal coordination method. The β^d value, indicating the degree of decrease in the electron‐transfer rate constant with distance along the molecular wire between the electrode and the redox active species at the terminal of the wire, were 0.008–0.07 Å^?1 and 0.002–0.004 Å^?1 for molecular wires of bis(terpyridine)iron and bis(terpyridine)cobalt complex oligomers, respectively. The influences on β^d by the chemical structure of molecular wires and the terminal redox units, temperature, electric field, and electrolyte concentration were clarified. The results indicate that facile sequential electron hopping between neighboring metal–complex units within the wire is responsible for the high electron‐transport ability.     

Substituent and Solvent Effects on the Electrochemical Properties and Intervalence Transfer in Asymmetric Mixed‐Valent Complexes Consisting of Cyclometalated Ruthenium and Ferrocene

Four heterodimetallic complexes [Ru(Fcdpb)(L)](PF₆) (Fcdpb=2‐deprotonated form of 1,3‐di(2‐pyridyl)‐5‐ferrocenylbenzene; L=2,6‐bis‐(N‐methylbenzimidazolyl)‐pyridine (Mebip), 2,2′:6′,2′′‐terpyridine (tpy), 4‐nitro‐2,2′:6′,2′′‐terpyridine (NO₂tpy), and trimethyl‐4,4′,4′′‐tricarboxylate‐2,2′:6′,2′′‐terpyridine (Me₃tctpy)) have been prepared. The electrochemical and spectroelectrochemical properties of these complexes have been examined in CH₂Cl₂, CH₃NO₂, CH₃CN, and acetone. These complexes display two consecutive redox couples owing to the stepwise oxidation of the ferrocene (Fc) and ruthenium units, respectively. The potential difference, ΔE_1/2 (E_1/2(Ru^II/III)?E_1/2(Fc^0/+)), decreased slightly with increasing solvent donocity. The mixed‐valent states of these complexes have been generated by electrolysis and the resulting intervalence charge‐transfer (IVCT) bands have been analyzed by Hush theory. Good linear relationships exist between the energy of the IVCT band, E_op, and ΔE_1/2 of four mixed‐valent complexes in a given solvent.     

Crystallographic and computational study of a network composed of [ZnCl4]2− anions and triply protonated 4′‐functionalized terpyridine cations

We report herein the synthesis, crystallographic analysis and a study of the noncovalent interactions observed in the new 4′‐substituted terpyridine‐based derivative bis[4′‐(isoquinolin‐2‐ium‐4‐yl)‐2,2′:6′,2′′‐terpyridine‐1,1′′‐diium] tris[tetrachloridozincate(II)] monohydrate, (C₂₄H₁₉N₄)₂[ZnCl₄]₃·H₂O or (ITPH₃)₂[ZnCl₄]₃·H₂O, where (ITPH₃)³⁺ is the triply protonated cation derived from 4′‐(isoquinolin‐4‐yl)‐2,2′:6′,2′′‐terpyridine (ITP) [Granifo et al. (2016). Acta Cryst. C 72 , 932–938]. The (ITPH₃)³⁺ cation presents a number of interesting similarities and differences compared with its neutral ITP relative, mainly in the role fulfilled in the packing arrangement by the profuse set of D —H…A [D (donor) = C, N or O; A (acceptor) = O or Cl], π–π and anion…π noncovalent interactions present. We discuss these interactions in two different complementary ways, viz. using a point‐to‐point approach in the light of Bader's theory of Atoms In Molecules (AIM), analyzing the individual significance of each interaction, and in a more `global' analysis, making use of the Hirshfeld surfaces and the associated enrichment ratio (ER) approach, evaluating the surprisingly large co‐operative effect of the superabundant weaker contacts.     

Reversible Assembly of Microgels by Metallo‐Supramolecular Chemistry

The combination of supramolecular chemistry and soft colloids as microgels represents an ambitious way to develop multi‐versatile colloidal assemblies. Hereafter, terpyridine‐functionalized poly(N‐isopropylacrylamide) (PNiPAM) microgel building blocks are shown to undergo an assemble–freeze–disassemble process. The microgel assemblies, which are controlled by monitoring the attractive and repulsive potentials between the soft colloidal particles, are then frozen by forming inter‐particle metal–terpyridine bis‐complexes upon addition of the metallic cation (such as Fe^II, Co^II). By oxidation of the metal–terpyridine bis‐complex links, the aggregates open up, which is due to the complex dissociation releasing the connected particles in the form of single microgels. We extended our work to the development of 1D filaments and 2D membranes materials made of soft particles connected via supramolecular chemistry.     

Remarkable Tuning of the Coordination and Photophysical Properties of Lanthanide Ions in a Series of Tetrazole‐Based Complexes

A series of seven new tetrazole‐based ligands (L1, L3–L8) containing terpyridine or bipyridine chromophores suited to the formation of luminescent complexes of lanthanides have been synthesized. All ligands were prepared from the respective carbonitriles by thermal cycloaddition of sodium azide. The crystal structures of the homoleptic terpyridine–tetrazolate complexes [Ln(Li)₂]NHEt₃ (Ln=Nd, Eu, Tb for i=1, 2; Ln=Eu for i=3, 4) and of the monoaquo bypyridine–tetrazolate complex [Eu(H₂O)(L7)₂]NHEt₃ were determined. The tetradentate bipyridine–tetrazolate ligand forms nonhelical complexes that can contain a water molecule coordinated to the metal. Conversely, the pentadentate terpyridine–tetrazolate ligands wrap around the metal, thereby preventing solvent coordination and forming chiral double‐helical complexes similarly to the analogue terpyridine–carboxylate. Proton NMR spectroscopy studies show that the solid‐state structures of these complexes are retained in solution and indicate the kinetic stability of the hydrophobic complexes of terpyridine–tetrazolates. UV spectroscopy results suggest that terpyridine–tetrazolate complexes have a similar stability to their carboxylate analogues, which is sufficient for their isolation in aerobic conditions. The replacement of the carboxylate group with tetrazolate extends the absorption window of the corresponding terpyridine‐ (≈20 nm) and bipyridine‐based (25 nm) complexes towards the visible region (up to 440 nm). Moreover, the substitution of the terpyridine–tetrazolate system with different groups in the ligand series L3–L6 has a very important effect on both absorption spectra and luminescence efficiency of their lanthanide complexes. The tetrazole‐based ligands L1 and L3–L8 sensitize efficiently the luminescent emission of lanthanide ions in the visible and near‐IR regions with quantum yields ranging from 5 to 53 % for Eu^III complexes, 6 to 35 % for Tb^III complexes, and 0.1 to 0.3 % for Nd^III complexes, which is among the highest reported for a neodymium complex. The luminescence efficiency could be related to the energy of the ligand triplet states, which are strongly correlated to the ligand structures.     

Bis[S‐6‐(2,2:6′,2′′‐terpyridin‐4′‐yloxy)hexyl thioacetate]manganese(II) bis(hexafluorophosphate)

The structure of a manganese(II) complex of terpyridine functionalized with acetylsulfanyl‐terminated hexyloxy chains, [Mn(C₂₃H₂₅N₃O₂S)₂](PF₆)₂, is described. This type of complex is of interest in the study of single‐molecule transport properties in open‐shell systems. The manganese coordination environment is distorted octahedral but, importantly, with no larger deviations from the idealized geometry than those observed for other metal–terpyridine complexes. The Mn—N bond lengths range from 2.192 (2) to 2.272 (3) Å. The title compound crystallizes with the cation and anions all on general positions, with the hexafluorophosphate anions exhibiting orientational disorder. When compared with other bis‐terpyridine complexes, this structure demonstrates that manganese(II) is no more prone to undergo low‐symmetry distortions than systems with ligand field stabilization energy contributions.     

A Combined Experimental and Computational Study of Linear Ruthenium(II) Coordination Oligomers with End‐Capping Organic Redox Sites: Insight into the Light Absorption and Charge Delocalization

Two series of linear ruthenium coordination oligomers, [(Ntpy)Ru_n(tppz)_n?1(tpy)]²ⁿ⁺ (mono‐Ntpy series, n=1–3) and [(Ntpy)₂Ru_n(tppz)_n?1]²ⁿ⁺ (bis‐Ntpy series, n=1–3) have been prepared, where Ntpy is the capping ligand 4′‐di‐p‐anisylamino‐2,2′:6′,2′′‐terpyridine, tppz is tetra‐2‐pyridylpyrazine, and tpy is 2,2′:6′,2′′‐terpyridine. The electrochemical measurements evidence oxidation events from both the amine segments and the metal centers and reduction waves from tppz and the capping ligands. Both series complexes display much enhanced light absorption with respect to model complexes without terminal amine units. Density functional theory (DFT) calculations have been performed on both series and time‐dependent DFT (TD‐DFT) calculations have been performed on the bis‐Ntpy‐series compounds (n=1–4) to characterize their electronic structures and excited states and predict the electronic properties of long‐chain polymers. Upon one‐electron oxidation, the mono‐Ntpy‐series monoruthenium and diruthenium complexes display N⁺‐localized transitions and metal‐to‐nitrogen charge‐transfer (MNCT) transitions in the near‐infrared (NIR) region. DFT and TD‐DFT computations on the one‐electron‐oxidized forms of the mono‐Ntpy‐series compounds (n=1–4) provide insight into the nature of the MNCT transitions and the degree of charge delocalization.     

Side‐chain terpyridine polymers through atom transfer radical polymerization and their ruthenium complexes

Polymers containing side‐chain terpyridine ligands of well‐defined architectures and controllable molecular weights and molecular weight distributions are reported. These polymers were synthesized by the atom transfer radical polymerization (ATRP) of a newly synthesized terpyridine monomer with three functional initiators. The obtained polymers were characterized with ¹H NMR and gel permeation chromatography techniques. The efficiency of the ATRP technique and the overall control of the molecular characteristics of the polymers were demonstrated by a kinetic study of the polymerization reaction. Subsequently, the ruthenium(III)/ruthenium(II) complexation chemistry was employed for the attachment of bis(dodecyloxy)‐functionalized terpyridine moieties onto each side 2,2′:6′,2″‐terpyridine unit of the main polymeric backbone. Thus, the grafting approach was successfully combined with the metal–ligand coordination chemistry for the preparation of highly soluble polymeric complexes. The resulting complexes were fully characterized by means of ¹H NMR, gel permeation chromatography, and ultraviolet–visible spectroscopy. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4838–4848, 2005     

Thermosensitive and Switchable Terpyridine‐Functionalized Metallo‐Supramolecular Poly(N‐isopropylacrylamide)

Metallo‐supramolecular polymers offer attractive possibilities to combine the properties of polymers with the characteristics offered by the metal–ligand coordination. Here we present for the first time the combination of metal‐bis(terpyridine) complexes and lower critical solution temperature (LCST) polymers that can be switched by addressing either the thermosensitive polymer or the metal complex. We describe a new strategy for the synthesis of poly(N‐isopropylacrylamide) (PNIPAM) end functionalized with a terpyridine moiety, which is further used for the preparation of Fe^II and Zn^II‐bis(terpyridine PNIPAM). The comparison of the LCST behavior of the uncomplexed ligands and their metal complexes that bear different counter ions is included. Furthermore, the switchability of the synthesized Fe^II system is demonstrated by a decomplexation reaction followed by the characterization of the uncomplexed ligand.

     

Oxygen Evolution Catalyzed by a Mononuclear Ruthenium Complex Bearing Pendant SO3− Groups

Rational molecular design of catalytic systems capable of smooth O? O bond formation is critical to the development of efficient catalysts for water oxidation. A new ruthenium complex was developed, which bears pendant SO₃^? groups in the secondary coordination sphere: [Ru(terpy)(bpyms)(OH₂)] (terpy=2,2′:6′,2′′‐terpyridine, bpyms=2,2′‐bipyridine‐5,5′‐bis(methanesulfonate)). Water oxidation driven by a Ce⁴⁺ oxidant is distinctly accelerated upon introduction of the pendant SO₃^? groups in comparisons to the parent catalyst, [Ru(terpy)(bpy)(OH₂)]²⁺ (bpy=2,2′‐bipyridine). Spectroscopic, electrochemical, and crystallographic investigations concluded that the pendant SO₃^? groups promote the formation of an O? O bond via the secondary coordination sphere on the catalyst, whereas the influence of the pendant SO₃^? groups on the electronic structure of the [Ru(terpy)(bpy)(OH₂)]²⁺ core is negligible. The results of this work indicate that modification of the secondary coordination sphere is a valuable strategy for the design of water oxidation catalysts.     

Mono‐ and bis‐tolylterpyridine iridium(III) complexes

The first structure report of trichlorido[4′‐(p‐tolyl)‐2,2′:6′,2′′‐terpyridine]iridium(III) dimethyl sulfoxide solvate, [IrCl₃(C₂₂H₁₇N₃)]·C₂H₆OS, (I), is presented, along with a higher‐symmetry setting of previously reported bis[4′‐(p‐tolyl)‐2,2′:6′,2′′‐terpyridine]iridium(III) tris(hexafluoridophosphate) acetonitrile disolvate, [Ir(C₂₂H₁₇N₃)₂](PF₆)₃·2C₂H₃N, (II) [Yoshikawa, Yamabe, Kanehisa, Kai, Takashima & Tsukahara (2007). Eur. J. Inorg. Chem. pp. 1911–1919]. For (I), the data were collected with synchrotron radiation and the dimethyl sulfoxide solvent molecule is disordered over three positions, one of which is an inversion center. The previously reported structure of (II) is presented in the more appropriate C2/c space group. The iridium complex and one PF₆⁻ anion lie on twofold axes in this structure, making half of the molecule unique.     

Construction of a Hexameric Zn(II)‐metallomacrocycle and its Photo‐ and Electroluminescence Properties: [Zn6(O‐hexyl‐3,5‐bis(2,2′:6′,2″‐terpyridine)phenol)6(BF4)12]

Summary: An O‐hexyl‐3,5‐bis(terpyridine)phenol ligand has been synthesized and transformed into a hexagonal Zn(II)‐metallomacrocycle by a facile self‐assembly procedure capitalizing on terpyridine‐Zn(II)‐terpyridine connectivity. The structural composition was confirmed by NMR and mass spectral techniques; photo‐ and electroluminescence properties were also investigated. The OLED device shows green electroluminescent emission at 515 nm with a maximum luminance of 39 cd · m⁻² and maximum efficiency of 0.16 cd · A⁻¹.

Structure and electroluminescent properties of the metallomacrocycle investigated.