Tetrazole Complexes Research Articles

Transformation of Mononuclear Plutonium(III) Tetrazolate Complexes into Dinuclear Complexes in the Solid State.

The salt metathesis reaction of Na(pmtz)·H2O [pmtz- = 5-(pyrimidyl)tetrazolate] and PuBr3·nH2O in an aqueous media leads to the formation of the mononuclear compound [Pu(pmtz)3(H2O)3]·(3 + n) H2O (Pu1, n = ∼8) that is isotypic with the lanthanide compounds [Ln(pmtz)3(H2O)3]·(3 + n) H2O (Ln = Ce-Nd). Dissolution and recrystallization of Pu1 in water yields the dinuclear compound {[Pu(pmtz)2(H2O)3]2(μ-pmtz)}2(pmtz)2·14H2O (Pu2), which is isotypic with the lanthanide compounds {[Ln(pmtz)2(H2O)3]2(μ-pmtz)}2(pmtz)2·14H2O (Ln = Nd and Sm). Like their nine-coordinate ionic radii, the M-O and M-N bond lengths in Pu1/Pu2 and Nd1/Nd2, respectively, are within error of one another. The Laporte-forbidden 4f → 4f and 5f → 5f transitions are also assigned in the UV-vis-NIR spectra for these f-element tetrazolate coordination compounds.

Magnetic chitosan stabilized Cu(II)-tetrazole complex: an effective nanocatalyst for the synthesis of 3-imino-2-phenylisoindolin-1-one derivatives under ultrasound irradiation

In the present research, a recyclable catalyst has been prepared via a simple approach using chitosan as a linear polysaccharide. This paper reports the synthesis of novel copper(II) complex of 5-phenyl-1H-tetrazole immobilized on magnetic chitosan (MCS@PhTet@Cu(II)) as an effective catalyst. Transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), vibrating sample magnetometer (VSM), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), and inductively coupled plasma mass spectrometry (ICP-MS) techniques were applied for the characterization of the catalyst. The catalytic activity of MCS@PhTet@Cu(II) was evaluated in the ultrasound-assisted synthesis of 3-imino-2-phenylisoindolin-1-one derivatives via the reaction between benzoyl chloride and arylcyanamides in ethanol at ambient temperature. Utilizing a wide variety of arylcyanamides under mild conditions, no use of toxic organic solvents, moderate reaction time, high yields along with catalyst excellent reusability and easy separation of the products without any tedious separation techniques, made this method a novel and simple process. The resulting heterogeneous catalyst showed valuable advantages such as easier work-up, better stability, and greater separation ability using an external magnet. The catalyst showed high efficacy and recyclability even after five cycles with no significant loss of its efficacy. The present methodology provides a path for the preparation of structurally diverse heterocyclic compounds, which may exhibit important biological activity.

Role of the ancillary ligand in determining the antimicrobial activity of Pd(II) complexes with N^N^N-tridentate coligand

Two [PdN3L]PF6 complexes (L = 2,6-bis(1-ethyl-benzimidazol-2́-yl)pyridine (LBZ) and 4-(2-pyridyl)-2,2′:6′,2′'-terpyridine (LPY)) underwent catalyst-free 1,3-dipolar cycloaddition coupling with phenyl isothiocyanate at the room temperature giving the corresponding tetrazole–thiolato complexes. 1H NMR studies showed that the N1-isomer appeared first in the catalyst-free coupling, then gradually isomerized to the more stable tetrazole–thiolato isomer. The interconversion of N1-isomer into the S-isomer is accompanied by a decrease of the greater steric demand of the 5-membered ring. Tetrazolate complex of LBZ displayed higher antifungal activity (MIC ≤ 0.25 μg/mL) than the chloride analogue (MIC = 0.5–1.0 μg/mL) and the reference drug, Fluconazole (MIC = 0.125–8.0 μg/mL) against Candida albicans and Cryptococcus neoformans. The treated non-cancerous human embryonic kidney cells (HEK293) showed no cytotoxicity and no haemolysis release at the measured concentrations of the chloride complex of LBZ and tetrazolate complex of LPY.

Spectroscopic and Molecular Docking Study of the Interaction between Neutral Re(I) Tetrazolate Complexes and Bovine Serum Albumin.

Re(I) complexes have potential in biomedical sciences as imaging agents, diagnostics and therapeutics. Thus, it is crucial to understand how Re(I) complexes interact with carrier proteins, like serum albumins. Here, two neutral Re(I) complexes were used (fac-[Re(CO)3 (1,10-phenanthroline)L], in which L is either 4-cyanophenyltetrazolate (1) or 4-methoxycarbonylphenyltetrazole ester (2), to study the interactions with bovine serum albumin (BSA). Spectroscopic measurements, calculations of thermodynamic and Förster resonance energy transfer parameters, as well as molecular modelling, were performed to study differential binding between BSA and complex 1 and 2. Induced-fit docking combined with quantum-polarised ligand docking were employed in what is believed to be a first for a Re(I) complex as a ligand for BSA. Our findings provide a basis for other molecular interaction studies and suggest that subtle functional group alterations at the terminal region of the Re(I) complex have a significant impact on the ability of this class of compounds to interact with BSA.

Colourless luminescent solar concentrators based on Iridium(III)-Phosphors

The first real examples of luminescent solar concentrators (LSCs) based on Ir(III) cyclometalates, are described herein. Two new Ir(III) tetrazole complexes, namely [Ir(ppy)2(iQTZ-PPG)]+ and [Ir(npy)2(iQTZ-PPG)]+, where (C^N) = ppy, 2 phenylpyridine or npy = 2-(naphthalen-2-yl)pyridine and iQTZ-PPG = 1-(2-(prop-2-yn-1-yl)-2H-tetrazol-5-yl)isoquinoline, were synthesized, fully characterized and tested as phosphors for colourless LSCs. Notably, increasing quantities (0.2–1.8 wt %) of the new Ir(III) based phosphors were dispersed in different acrylate polymers like poly(methyl methacrylate), PMMA, poly(benzyl methacrylate), PBzMA and poly(cyclohexyl methacrylate), PCHMA, leading to visible transparent polymeric films exhibiting excellent photostability and bright yellow to orange phosphorescent emissions. The performances as solar collectors of all the Ir(III)-doped polymers were investigated, providing results comparable, or superior, to those obtained from colourless LSC based on organic fluorophores. In fact, the best optical efficiency (ηopt up to 7%, combined to transmittance close to 80% at 390 nm) was displayed by the polymer film obtained from physical dispersion of [Ir(ppy)2(iQTZ-PPG)]+ (1.4 wt %) in PCHMA.

Selective anticancer activities of ruthenium(II)-tetrazole complexes and their mechanistic insights

Ruthenium-based metallotherapeutics is an interesting alternative for platinum complexes acting as anticancer agents after the entry of KP1019, NAMI-A, and TLD1339 in clinical trials. Herein, we have synthesized three new arene ruthenium(II)-tetrazole complexes viz. [Ru2(η6-p-cymene)2(2-pytz)2Cl2] (1), [Ru2(η6-p-cymene)2(3-pytz)Cl3] (2), [Ru2(η6-p-cymene)2(4-pytz)Cl3] (3) [2-pytzH = 2-pyridyl tetrazole; 3-pytzH = 3-pyridyl tetrazole; 4-pytzH = 4-pyridyl tetrazole] which have been characterized by different analytical techniques. To aid the understanding of the complex formation, reactions of the arene ruthenium(II) dimer with tetrazoles were investigated using the first principles-based Density Functional Theory (DFT) B3LYP method. Electronic structures, equilibrium geometries of the reactants and products with the first-order saddle points, reactions mechanism, the changes of enthalpy (∆H) and free energy (∆G), chemical stability, and reaction barriers of the complexes were computed using the B3LYP DFT approach. The in vitro cytotoxicity of these complexes was investigated by MTT assay on different cancer cell lines which reveal complex 2 as the most significant cytotoxic agent toward the HeLa cell line. The complexes have also shown a strong binding affinity towards CT-DNA and albumin proteins (HSA and BSA) as analyzed through spectroscopic techniques. Investigation of the mechanism of cell death by complex 2 was further performed by various staining techniques, flow cytometry, and gene expression analysis by RT-PCR. Inhibition of cell migration study has been also revealed the possibility of complex 2 to act as a prospective anti-metastatic agent.

Ir−Sn Tetrazole Complexes with Proton‐Responsive P−OH Groups and an Ir−Ir Tetrazole Complex for CO2 Hydrogenation

AbstractBimetallic catalytic systems, especially heterogeneous bimetallic catalytic systems, have been shown to be effective catalysts for CO2 hydrogenation as a result of synergistic effects. Here‐in we report the synthesis of bimetallic Ir−Ir, Ir−Sn and a novel five‐membered heteroatomic Ir−Sn tetrazole complex. These complexes were obtained as a result of the heterolysis of P−S bond in the ligands during complexation. These complexes were evaluated for catalytic activity in homogeneous CO2 hydrogenation where they displayed excellent catalytic activity generating formate selectively. The mechanism of action for the Ir−Sn catalysts for CO2 hydrogenation indicates metal−metal bond breakage prior to formation of catalytically active species. However, this metal−metal bond breakage did not result in the decomposition of the catalysts. In addition, these bimetallic complexes were observed to effectively hydrogenate CO2 directly, or hydrogenate bicarbonate ions formed in solution during the catalytic cycle. For Ir−Ir catalyst, only one metal center was found to be directly involved in CO2 hydrogenation with the second iridium center primarily responsible as an electron source

Carbazolyl-bis(triazole) and Carbazolyl-bis(tetrazole) Complexes of Palladium(II) and Platinum(II)

The synthesis of several carbazole-bis(triazole) (CzTrR ) and carbazole-bis(tetrazole) (CzTR ) ligands (5a–d and 6a–d, respectively, where R=Me (a), i –Pr (b), Bz (c) and CH2-2,4,6-C6H2Me3 (d)) is reported. Reaction of these ligands with PdCl2 in refluxing acetonitrile affords the complete series of square planar complexes, Pd(CzTrR)Cl (7a–d) and Pd(CzTR)Cl (8a–d). The analogous platinum complexes are prepared by deprotonation of ligand carbazole nitrogen under nitrogen followed by reaction with Pt(COD)Cl2 to give Pt(CzTrR)Cl (9b, 9d) and Pt(CzTR)Cl (10b, 10d). The X-ray structure of several ligands (5b, 5c, 6c) and their metal complexes (8b, 8d, 9b) are reported. Complexes 7–10d were examined by cyclic voltammetry and DFT calculations to shed light on their electronic structures. The Pd and Pt complexes of the same ligand (CzTr: 7d, 9d; CzT: 8d, 10d) showed very similar oxidation potentials suggesting the lowest oxidation is ligand based. In contrast, oxidations of the tetrazole complexes 7d and 9d were notably more difficult than the triazole complexes 8d and 10d. Both of these observations are supported by DFT calculations that indicate the HOMO is essentially carbazole π-bonding in character.

Alkyl tetrazoles as diimine (“diim”) ligands for fac-[Re(diim)(CO)3(L)]-type complexes. Synthesis, characterization and preliminary studies of the interaction with bovine serum albumin

Herein, we report a new family of luminescent Re(I) complexes with general formula fac-[Re(diim)(CO)3L]0/+ in which the role of the diimine-type chelating ligand (diim) is played by alkylated tetrazoles. In particular, the design of the new complexes involved the choice of molecular scaffolds based on 2-pyridyl tetrazole (PTZ) and 2-quinolyl tetrazole (QTZ) which were decorated with various alkyl residues at N-2 position of the pentatomic ring, thereby endowing the resulting alkyl tetrazoles PTZ-R and QTZ-R with the proper “bpy-like” coordination attitude. As the “third” ligand (L), pyridine (pyr) or the 5-phenyl tetrazolato anion (Tph)− were selected, leading to cationic species such as fac-[Re(CO)3(PTZ-R)(pyr)]+, fac-[Re(CO)3(QTZ-R)(pyr)]+ and to the neutrally charged “fully tetrazole” complex fac-[Re(CO)3(QTZ-Me)(Tph)]. All the new complexes were identified by ESI-MS spectrometry and fully characterized by IR, 1H and 13C NMR spectroscopy. The findings that were suggested from the interpretation of the spectroscopic data were further confirmed by X-ray crystallography, with the analysis of the molecular structures of the cationic complexes fac-[Re(CO)3(PTZ-Me)(pyr)][PF6] and fac-[Re(CO)3(QTZ-Me)(pyr)][PF6]. Following the in-depth investigation of their photophysical properties, the new luminescent Re(I) tetrazole -based complexes were studied for any possible interaction with Bovine Serum Albumin (BSA). The results obtained from this preliminary screening highlighted that, along the series of the Re(I) tetrazole complexes, the QTZ-R based cationic derivatives fac-[Re(CO)3(QTZ-Me)(pyr)]+, fac-[Re(CO)3(QTZ-tBu)(pyr)]+, as well as the neutrally charged and “fully tetrazole” complex fac-[Re(CO)3(QTZ-Me)(Tph)], displayed the highest affinity to BSA.

Chiral-at-Metal: Iridium(III) Tetrazole Complexes With Proton-Responsive P-OH Groups for CO2 Hydrogenation.

A rise in atmospheric CO2 levels, following years of burning fossil fuels, has brought about increase in global temperatures and climate change due to the greenhouse effect. As such, recent efforts in addressing this problem have been directed to the use of CO2 as a non-expensive and non-toxic single carbon, C1, source for making chemical products. Herein, we report on the use of tetrazolyl complexes as catalyst precursors for hydrogenation of CO2. Specifically, tetrazolyl compounds bearing P–S bonds have been synthesized with the view of using these as P∧N bidentate tetrazolyl ligands (1–3) that can coordinate to iridium(III), thereby forming heteroatomic five-member complexes. Interestingly, reacting the P,N′-bidentate tetrazolyl ligands with [Ir(C5Me5)Cl2]2 led to serendipitous isolation of chiral-at-metal iridium(III) half-sandwich complexes (7–9) instead. Complexes 7–9 were obtained via prior formation of non-chiral iridium(III) half-sandwich complexes (4–6). The complexes undergo prior P–S bond heterolysis of the precursor ligands, which then ultimately results in new half-sandwich iridium(III) complexes featuring monodentate phosphine co-ligands with proton-responsive P-OH groups. Conditions necessary to significantly affect the rate of P–S bond heterolysis in the precursor ligand and the subsequent coordination to iridium have been reported. The complexes served as catalyst precursors and exhibited activity in CO2 and bicarbonate hydrogenation in excellent catalytic activity, at low catalyst loadings (1 μmol or 0.07 mol% with respect to base), producing concentrated formate solutions (ca 180 mM) exclusively. Catalyst precursors with proton-responsive P-OH groups were found to influence catalytic activity when present as racemates, while ease of dissociation of the ligand from the iridium center was observed to influence activity in spite of the presence of electron-donating ligands. A test for homogeneity indicated that hydrogenation of CO2 proceeded by homogeneous means. Subsequently, the mechanism of the reaction by the iridium(III) catalyst precursors was studied using 1H NMR techniques. This revealed that a chiral-at-metal iridium hydride species generated in situ served as the active catalyst.

Use of Cotton Textiles Coated by Ir(III) Tetrazole Complexes within Ceramic Silica Nanophases for Photo-Induced Self-Marker and Antibacterial Application.

This study was aimed at the production and characterization of coated cotton textiles with luminescent ceramic nanophases doped with cationic Ir(III) tetrazole complexes. We confirmed that SiO2 nanoparticles (NPs) do not affect the phosphorescent properties of the complexes that maintain their emission (610 and 490 nm). For the first time we transferred the luminescence feature from nanosol to textile surface, highlighting the advantages of using nanosilica as an encapsulating and stabilizing matrix. The optimized Ir@SiO2 suspensions were homogenously applied onto the cotton surface by dip-pad-dry-cure technique, as proved by the 2p-fluorescence microscope analysis. Once we verified the self-marker properties of the Ir(III) complex, we observed an excellent washing fastness of the coating with a very limited release. SiO2 in the washing water was quantified at maximum around 1.5 wt% and Ir below the inductively coupled plasma optical emission spectrometry (ICP-OES) detection limit of 1 ppm. A Franz cell test was used to evaluate any possible ex-vivo uptake of Ir@SiO2 nanoparticles across human skin tissues, showing that epidermis and dermis stop over 99% of Ir, implying a reduced impact on human health. The light-induced antimicrobial potential of the Ir@SiO2 were assessed toward both Gram(−) and Gram(+) bacteria. The results encouraged further developments of such functional textiles coated by self-markers and antibacterial active nanophases.

Influence of the Mechanism of the Initial Stages of the Ligand Decomposition on the Initiating Ability of Cobalt(III) Ammine Tetrazolate Complexes

The results of quantum chemical calculations for isolated molecules of pentaammine-(5-cyano-2H-tetrazolato-N2)cobalt(III) perchlorate, pentaammine-(5-nitrotetrazolato-N2)cobalt(III) perchlorate, tetraammine-cis-bis(5-nitro-2H-tetrazolato-N2)cobalt(III) perchlorate, and tetraammine-cis-bis(1-methyl-5-aminotetrazolo-N3,N4)cobalt(III) perchlorate, as well as of the products of their possible initial decomposition stage were presented. The energetics and pathways of such reactions were determined. For the first time with the use of quantum chemical calculations it was shown that the decomposition of cobalt amminates can start with destruction of the tetrazole ligand and elimination of molecular nitrogen, rather than with dissociation of the coordinated ammonia molecule from the inner sphere of the cobalt(III) complex. The activation and dissociation energies of these processes were determined.

Copper-assisted desulfurization of 1-R-tetrazole-5-thiols under complexation

The interaction of 1-R-tetrazole-5-thiols with copper(II) chloride in solution was found to yield crystalline tetrazole complexes [CuCl2L2]n (L is 1-R-tetrazole, R = Me, Et, Bu) and [CuCl2L2]n·nMeCN (L is 1-phenyltetrazole). The observed transformation of 1-R-tetrazole-5-thiols into 1-R-tetrazoles presents the first examples of desulfurization of tetrazole-5-thiols under complexation. A possible pathway of desulfurization of 1-R-tetrazole-5-thiols is proposed. It includes initial oxidation of tetrazole-5-thiols by copper(II) ions into bis(tetrazol-5-yl)disulfanes, followed by copper-assisted oxidation by air oxygen. Obtained complexes [CuCl2L2]n and [CuCl2L2]n·nMeCN were found to be coordination polymers, 2D and 1D, respectively. In all them, 1-R-tetrazoles act as monodentate ligands coordinated to the metal via the tetrazole ring N4 atom, whereas chlorine atoms provide bidentate bridging coordination to generate polymeric structure.

Synthesis, characterization and application of Fe3O4@SiO2 nanoparticles supported palladium(II) complex as a magnetically catalyst for the reduction of 2,4-dinitrophenylhydrazine, 4-nitrophenol and chromium(VI): A combined theoretical (DFT) and experimental study

In the present work, a new catalytic system based on palladium(II)-tetrazole complex immobilized on silica-coated Fe3O4 (Fe3O4@SiO2) nanoparticles ([Fe3O4@SiO2-Tet-Pd(II)]) is introduced. In the first stage, the geometry optimization and calculations of structural and electronic properties of molecular system 5-phenyl-1H-tetrazole-Pd (II) complex have been carried out at UB3LYP/6-31G∗/LANL2DZ level of theory. Then, the [Fe3O4@SiO2-Tet-Pd(II)] was prepared via immobilizing 5-phenyl-1H-tetrazole as a suitable ligand on the surface of Fe3O4@SiO2 as a support. The [Fe3O4@SiO2-Tet-Pd(II)] as a novel magnetically catalyst was characterized by XRD, FT-IR, FE-SEM, EDS, TG-DTA and VSM. This heterogeneous catalytic system demonstrated high activity in the reduction of 2,4-dinitrophenylhydrazine (2,4-DNPH), 4-nitrophenol (4-NP) and Cr(VI) in the present of NaBH4 as the reduction agent at room temperature and was reusable five times with no obvious decrease of catalytic activity.

Encapsulation of cationic iridium(iii) tetrazole complexes into a silica matrix: synthesis, characterization and optical properties

We designed a multi-scale process, and obtained luminescent powders with preserved optical properties from molecular scale to microscale.

The coordination- and photochemistry of copper(i) complexes: variation of N^N ligands from imidazole to tetrazole.

The prediction of coordination modes is of high importance when structure-property relationships are discussed. Herein, the coordination chemistry of copper(i) with pyridine-amines with a varying number of coordinating N-atoms, namely pyridine-benzimidazole, -triazole and -tetrazole, or their deprotonated analogues, and different phosphines was systematically studied and the photoluminescence properties of all synthesized complexes examined and related to DFT data. Each complex was characterized by single-crystal X-ray analysis and elemental analysis, and a set of prediction rules derived for the coordination chemistry of copper(i) with these ligands. A mononuclear cationic coordination motif was found for PPh3 or DPEPhos with all N^N ligands, which exhibits blue to green luminescence of MLCT character d(Cu) → π*(pyridine-amine ligand) with quantum yields up to 46%. With the deprotonated N^N ligands, mononuclear neutral complexes were only expected with DPEPhos. The emission's nature of this complex type is strongly dependent on the electronic effects of the N^N ligand and was characterized as (ML + IL)CT transition. In contrast to the high quantum yields up to 78% for the tetrazolate complexes (as reported before), the triazolate and imidazolate based complexes show much lower emission efficiencies below 10%. Besides the mononuclear copper(i) complexes, cluster-type complexes were obtained, which show moderate luminescence in the blue to green region of the visible spectrum (469-505 nm).

Luminescent studies of binuclear ternary europium(III) pyridineoxide tetrazolate complexes containing bis-phosphine oxide as auxiliary co-ligands.

A new class of antenna chromophores so called 'tetrazolates' have not been explored much for lanthanide luminescencent complexes. However, we have already published several articles considering pyridineoxide tetrazolates as sensitizer with lanthanide ions. Although this class of antenna attracted much less attention because of its poor photoluminescence quantum yields (tris-pyridineoxide tetrazolate europium complex=13% in solution) we tried and successfully achieved to improve the photoluminescence quantum yields for this particular antenna molecule by replacing coordinated water from the inner coordination sphere of europium ion by introducing phosphine oxides as additional chromophore. In the present article the two bis-phosphine oxides attach two molecules of tris-pyridineoxide tetrazolate europium(III) complex which leads to the improvement of the overall molar absorption coefficients as well as photo-physical properties of the complexes. We found more than two-fold increase (31% in solution) in photoluminescence quantum yield with one of the coordinated phosphine oxides comparing with that of tris-pyridineoxide tetrazolate europium(III) complex.

PH-Switchability and Second-Order Nonlinear Optical Properties of Monocyclopentadienylruthenium(II)/iron(II) Tetrazoles/Tetrazolates: Synthesis, Characterization, and Time-Dependent Density Functional Theory Calculations.

Tetrazole/tetrazolate monocyclopentadienyliron(II) and ruthenium(II) compounds of general formulas [(η5-C5H5)M(dppe)(N4(H)CC6H4NO2)][PF6]/[(η5-C5H5)M(dppe)(N4CC6H4NO2)] were investigated for their pH-switching second-order nonlinear optical (SONLO) properties. Compounds [(η5-C5H5)M(dppe)(N4CC6H4NO2)] (M = Fe, Ru) and compound [(η5-C5H5)Ru(dppe)(N4(H)CC6H4NO2)][PF6] were fully characterized by (1H-, 13C-, 31P-) NMR, cyclic voltammetry, and elemental analysis, and compounds [(η5-C5H5)Fe(dppe)(N4CC6H4NO2)] and [(η5-C5H5)Ru(dppe)(N4(H)CC6H4NO2)][PF6] were further characterized by single-crystal X-ray diffraction; the synthesis of [(η5-C5H5)Fe(dppe)(N4(H)CC6H4NO2)][PF6] was unsuccessful. Time-dependent density functional theory calculations were performed using PBE0 and CAM-B3LYP functionals to evaluate the first hyperpolarizability (βtot) of the tetrazole/tetrazolate complexes and for a detailed analysis of the experimental data. Both functionals predict (i) high first hyperpolarizabilities for the tetrazolate complexes [(η5-C5H5)M(dppe)(N4CC6H4NO2)], with βtot[Ru] ≈ 1.2βtot[Fe], and (ii) a 3-fold reduction in βtot[Ru] upon protonation, in complex [(η5-C5H5)Ru(dppe)(N4(H)CC6H4NO2)]+, forecasting [(η5-C5H5)Ru(dppe)(N4CC6H4NO2)]/[(η5-C5H5)Ru(dppe)(N4(H)CC6H4NO2)]+ complexes as on/off, pH-switchable SONLO forms.

Ruthenium Tetrazole Based Electroluminescent Device: Key Role of Counter Ions for Light Emission Properties

Light-emitting electrochemical cells (LECs), thanks to their simple device structure and the tunable emission wavelength of the light-emitting layer, are emerging as a class of electrochemical device candidate for the development of next-generation solid-state lighting. The possibility to tune on-demand the energy levels of Ruthenium(II) polypyridyl complexes, makes them ideal candidates as light-emitting layer. However, the optimization of the latter is not trivial and several issues, such as charge injection and electron and hole transport, have still to be solved to enhance the LEC performances. Here, we demonstrate how the exploitation of small counter anion (BF4-) enhances the light emission performance of ruthenium tetrazole complexes in light-emitting diodes. In comparison with neutral ruthenium tetrazole complexes, cationic Ru tetrazole ones, containing BF4- ion, show a reduction of turn-on voltage from7 to 5 V, at high luminous efficiency (1.49 cd/A) and applied voltage of 12 V, and a twofold improvement of the luminance. Moreover, complexes containing BF4- counter ion show better stability of luminance over time than other complexes without counter ion.

Frontispiece: Lanthanide Tetrazolate Complexes Combining Single‐Molecule Magnet and Luminescence Properties: The Effect of the Replacement of Tetrazolate N3 by β‐Diketonate Ligands on the Anisotropy Energy Barrier

Frontispiece: Lanthanide Tetrazolate Complexes Combining Single‐Molecule Magnet and Luminescence Properties: The Effect of the Replacement of Tetrazolate N₃ by β‐Diketonate Ligands on the Anisotropy Energy Barrier