Copper Phenanthroline Complexes Research Articles

Interaction of Phenanthroline-Containing Copper Complexes with Model Phospholipid Membranes

Medicinal Inorganic Chemistry has provided oncology with metallodrugs for cancer treatment, including several promising candidate drugs. In particular, copper(II) coordination compounds with phenanthroline stand out as potential anticancer agents. In this work, we used Differential Scanning Calorimetry and Electron Spin Resonance to investigate the interaction of the copper phenanthroline complexes [Cu(phen)]2+ and [Cu(L-dipeptide)(phenanthroline) (L-dipeptide: L-Ala-Gly and L-Ala-Phe)) with model lipid membranes (1,2-dipalmitoyl-sn-glycero-3-phosphocholine, DPPC, and 1,2-dipalmitoyl-sn-glycero-3-phospho-(1′-rac-glycerol) sodium salt, DPPG). Our results showed that the complexes interact with the membrane models, fluidizing them. The [Cu(phen)]2+ presented a different localization than the free ligand phen. The dipeptide modulated the localization of the complex in the membrane and the modifications induced in the physicochemical properties of the lipid vesicles. A stronger interaction with DPPG anionic membranes was observed, which mimic membranes with negatively charged surfaces, as found on several tumor cells.

Cellular targets of cytotoxic copper phenanthroline complexes: a multimodal imaging quantitative approach in single PC3 cells.

Metal complexes are emerging as promising alternatives to traditional platinum-based cancer treatments, offering reduced side effects. However, understanding their cellular uptake and distribution and quantify their presence at the single cell level remains challenging. Advanced imaging techniques, including transmission electron microscopy (TEM), synchrotron radiation X-ray fluorescence (SR-XRF) and energetic ion beam-based nuclear microscopy (STIM, scanning transmission ion microscopy; PIXE, particle-induced X-ray emission; EBS, elastic backscattering spectrometry), allow detailed high-resolution visualization of structure and morphology, high sensitivity for elemental detection with quantification within single cells, and the construction of three-dimensional (3D) models of metal distribution, positioning them as powerful tools for assessing the cellular uptake and compartmentalisation of complexes. Three Cu(II) complexes [Cu(phen)2(H2O)](NO3)2 (1), [Cu(Me2phen)2(NO3)]NO3 (2) and [Cu(amphen)2(H2O)](NO3)2 (3), (phen = 1,10-phenanthroline, Me2phen = 4,7-dimethyl-1,10-phen, amphen = 5-amino-phen) were investigated for Cu uptake and distribution in PC3 prostate cancer cells. All complexes show significant Cu-uptake regardless of media concentration. Cu-concentrations in cytoplasm and nucleus are similar between treatments. Complexes 1 and 3 concentrate Cu in the nuclear region and show a vesicle-like pattern around the nucleus, while 2 shows a dispersed cytoplasmic pattern with large vesicles. The 3D models confirm that Cu is not retained at the plasma membrane, with complex 1 targeting the nucleus and 2 remaining in the cytoplasm. These results highlight the importance of quantifying metal distribution and correlating it with structural changes to understand the relevance of the ligand in the mechanisms of cellular uptake and targeting, crucial for the development of effective metal-based cancer therapies.

Visible‐Light‐Mediated Copper(I)‐Catalyzed Regiospecific Amino‐Hydroxylation and Amino‐Alkoxylation of Vinyl Arenes

AbstractAminohydroxylation of alkene is an important method for synthesizing 1,2‐amino alcohols, which are found in natural products, pharmaceutically active compounds, and several marketed drugs. Herein, we report the development of visible‐light mediated copper‐catalyzed aminohydroxylation and aminoalkoxylation of alkenes. In contrast to expensive iridium, ruthenium, or organic‐dyes‐based photocatalysts, this protocol takes advantage of economical copper phenanthroline complex as a photocatalyst for the generation of N‐centred radical from N‐amino pyridinium salt. Furthermore, this protocol features mild reaction conditions, a broad substrate scope, and regiospecific.

Cooperative, Close and Remote Steric Effects on the Structural and Optical Properties of Copper(I) Bis‐Phenanthroline Complexes

AbstractThe synthesis as well as the structural, optical and computational characterization of seven new highly hindered homoleptic copper(I) phenanthroline complexes (namely C1–C7) is reported along with the comparison with the benchmark derivatives. Despite limited steric hindrance in direct proximity of the copper(I) coordination site, X‐ray structures show that the higher hindered derivatives of the series display a more optimal tetrahedral geometry with minimal D2 symmetry distortion. A novel remote control of the geometry, with steric hindrance away from the coordination site, leads to a favorable arrangement as demonstrated by structural and computational data. In addition, electrochemical and steady‐state and time‐resolved photophysical studies are presented which further support the beneficial effects on the ground‐state redox and excited‐state properties when both remote and close steric effects are exploited. Indeed, both an increase of the photoluminescence quantum yield and a prolongation of the excited state lifetime is observed for the highly‐substituted derivative C6 compared to benchmark counterparts on account of the reduced excited‐state flattening distortions imparted by the additional steric constraints.

On the importance of unconventional Cu⋯π interaction in tetrachloro-bis(1,10-phenanthroline)-dicopper(II) complex: Insights from experiment and theory

A copper-phenanthroline complex, namely [bis(μ2‑chloro)-dichloro-bis(1,10-phenanthroline)-di-copper(II)] has been synthesized and structurally characterized by single-crystal X-ray diffraction. The X-ray structure of the complex is stabilized through the hydrogen bond, π⋯π, and Cu⋯π interactions. The Cu⋯π interactions of the title complex along with two other complexes (retrieved from CSD) are analyzed in great detail through various theoretical calculations. Hirshfeld surface analysis and fingerprint plot quantify the non-covalent interactions. The interaction energies associated with intermolecular interactions have been calculated based on QTAIM (Quantum Theory of atoms in molecule). The analysis of topological parameters of charge density at (3, −1) bond critical points characterize the interactions as “closed-shell” interactions. The non-covalent interactions are further characterized by the Non-Covalent Interaction (NCI) plot index, Independent Gradient Module based on Hirshfeld partition of molecular density (IGMH), and Intrinsic Bond Strength Index for Weak interaction (IBSIW).

Copper phenanthroline for selective electrochemical CO2 reduction on carbon paper.

We report a series of structurally relevant copper phenanthroline complexes as pre-catalysts for highly selective electrocatalytic reduction of CO2 to C2 products using inexpensive carbon paper electrodes. The Cu complexes with non-substituted phenanthroline promote the production of ethylene with a high faradaic efficiency of 71.2%, while the one with pyridinium-functionalized ligands is more selective for ethanol. The C2 selectivity can be effectively tuned by increasing the number of coordinated phenanthrolines and remains high at a wide range of potentials.

Design and Synthesis of Paraphenylene-derived Figure-of-eight Rigid Macrocycles

Abstract Macrocycles are essential building blocks for supramolecular architectures. In this Highlight Review, recent progress in our laboratory is summarized regarding the development of paraphenylene-derived figure-of-eight rigid macrocycles. These molecules are derived from X-shaped cores including anthracene photodimer, tetraphenylethylene, and copper-phenanthroline complex, and exhibit attractive topological or fluorescent properties.

Hydroxyl Radical Generation by the H2O2/CuII/Phenanthroline System under Both Neutral and Alkaline Conditions: An EPR/Spin-Trapping Investigation

The copper–phenanthroline complex CuI(Phen)2 was the first artificial nuclease studied in biology. The mechanism responsible for this activity involves CuII(Phen)2 and H2O2. Even if H2O2/Cu systems have been extensively studied in biology and oxidative chemistry, most of these studies were carried out at physiological pH only, and little information is available on the generation of radicals by the H2O2/CuII-Phen system. In the context of paper pulp bleaching to improve the bleaching ability of H2O2, this system has been investigated, mostly at alkaline pH, and more recently at near-neutral pH in the case of dyed cellulosic fibers. Hence, this paper aims at studying the production of radicals with the H2O2/CuII-Phen system at near-neutral and alkaline pHs. Using the EPR/spin-trapping method, HO• formation was monitored to understand the mechanisms involved. DMPO was used as a spin-trap to form DMPO–OH in the presence of HO•, and two HO• scavengers were compared to identify the origin of the observed DMPO–OH adduct, as nucleophilic addition of water onto DMPO leads to the same adduct. H2O2 decomposition was enhanced by the addition of CuII–Phen (and only slightly by addition of CuSO4), reaching a level similar to the Fenton reagent at near-neutral pH. This evidences the role of Phen, which improves the effect of CuII by tuning the electronic structure and structural properties of the corresponding CuII complexes.

Synthesis and characterization of nanoclusters: Inorganic-organic hybrid copper and cobalt containing arsenotungstates(III) with lone pair on heteroatom incorporating bidentate N-donating ligands

Three inorganic-organic hybrid nanoclusters of copper and cobalt containing arsenotungstates with lone pair on heteroatom have been synthesized under mild reactions conditions. All the compounds have been characterized by single crystal X-ray diffraction, Fourier transform infrared, UV/visible spectroscopy, thermogravimetric and field emission scanning electron microscopic (FE-SEM) analysis. The compound [NaRb{Cu(phen) (H 2 O) 2 Cl} 2 ][{Cu(phen)(H 2 O)} 2 {Cu(phen) (H 2 O)Cl} 2 {Cu 2 As 2 W 19 O 67 (H 2 O)] (1a) is a sandwiched type arsenotungstate with two copper atoms in square planar environment in the belt region. The polyanion- 1 is decorated by four copper phenanthroline complexes through a terminal oxygen atom of the polyanion. In addition, two other cobalt containing inorganic-organic hybrid lone pair containing arsenotungstates(III) with 1,10-phenanthroline [NaRbCo(phen) 3 ][{Co(phen)(H 2 O) 3 }CoAs 2 W 20 O 67 (H 2 O) 3 ] (2a) and 2,2’-bipyridine[Na 3 RbCo(2,2-bipy) 3 ][CoAs 2 W 20 O 67 (H 2 O) 3 ] (3a) has also been synthesized under mild conditions. The polyanion ( 2 ) is a mono cobalt substituted sandwiched type structure that is decorated by a cobalt phenanthroline complex attached to the polyanion through a terminal oxygen atom. Meanwhile the other complex ( 3 ) is also a monocobalt substituted sandwiched type structure which contains a cobalt 2,2’-bipyridine complex in the cationic part. Polyanion- 1 shows intermolecular π-π stacking interaction between the phenanthroline ligand in the cationic part and one that is attached directly to the polyanion. The compounds are also characterized by FE-SEM analysis and the compound 3a shows ultra- smooth cuboids with grain size in the range of 1 to several micrometer though some very small irregular particles with the size of a few micrometer were also observed.

(Keynote) The Versatility of Mesoscopic Solar Cells

In our work on solid-state dye-sensitized solar cells (ssDSSC) we have recently shown that copper phenanthroline complexes can act as an efficient hole transporting material. We prepared ssDSCs with a novel organic dye WS-72 and [Cu(tmby)2]2+/+as redox system and achieved record power conversion efficiencies for ssDSCs of 11.7% [1]. With this redox system DSSCs give also excellent performance under ambient light conditions [2]. Our best DSC efficiency of 13.1% for a liquid Cu-complex electrolyte is achieved by the discovery that the PEDOT based counter electrode can be directly contacted with the dye/TiO2photoelectrode [3]. Thus, there is no space between the two electrodes minimizing diffusion limitations and fill factors up to 0.8 is achieved. In our work on perovskite solar cells (PSC) we have achieved efficiencies above 20% with a mixed composition of iodide/bromide and methyl ammonium/formamidinium [4]. With the use of SnO2 compact underlayers as electron acceptor contacts we have constructed planar perovskite solar cells with a hysteresis free efficiency above 20% [5,6]. The strategy of cation mixing of the perovskite film was taken further by including the Cs in a so-called ‘triple cation’ composition, i.e. Cs/FA/Ma as well as Rb in a quadruple cation mixture [7,8]. Larger grains grown in a monolithic manner are observed and reproducibility and device stability are improved. For example, above 22% efficiency has been obtained with an outstanding open-circuit voltage of 1.24 V at a band gap of 1.63 eV entailing one of the smallest loss-in-potential of 0.39 V measured for any solar cell material. With regards to lifetime testing, we have shown a promising stability at 85 oC for 500 h under full solar illumination and maximum power point tracking (95% of the initial performance was retained). Recently, we have also commented on the standardization of PSC aging tests [9].

Luminescent Charge‐Neutral Copper(I) Phenanthroline Complexes with Isocyanoborate Ligand

Copper(I) complexes with thermal activated delayed fluorescence (TADF) have attracted considerable attention for the development of emissive materials in organic light‐emitting devices. However, many emissive CuI complexes are cationic emitters and cannot be vacuum‐sublimed, a process used for device fabrication. This has limited their applications in devices. In this work we have developed a series of emissive charge‐neutral CuI complexes with the general formula [Cu(2,9‐Me2phen)(CNR){CNB(C6F5)3}] [R = 2,6‐Me2C6H3, 2,6‐iPr2C6H3, 2,4,6‐Cl3C6H2, 2,4,6‐Br3C6H2, 3,5‐(CF3)2C6H3, 4‐SF5C6H4] through the incorporation of a strong π‐accepting anionic isocyanoborate ligand. All the complexes have been structurally characterized and their photophysical properties have been studied.

Computational Investigations on IR, UV-VIS and NMR Spectra of Copper(II) Phenanthroline Complexes with DFT Method

Iki Cu(II) kompleksleri uzerine hesapsal arastirmalar yapildi. Literaturde, bu kompleksler hakkinda herhangi bir bilgi yada spektral sonuclar yoktur. Bu calismada, hibrit DFT fonksiyonellerinden biri olan B3LYP soz konusu komplekslerin hesaplarinda kullanildi. Soz konusu komplekslerin optimize yapilari hesaplandi ve IR, UV-VIS ve NMR spektrumlari hesaplandi ve detayli bir sekilde incelendi. Ilaveten, dogrusal olmayan optik ozellikler, molekuler elektrostatik potansiyel (MEP) haritalari, MEP konturlari ve tek dolu molekuler orbitalleri analiz edildi. Ligand ve metal atom arasindaki etkilesim enerjileri, olusum entalpileri ve Gibbs serbest enerjisi arastirildi. Geometrik yapi ve yapisal parametreler hesapsal tekniklerle belirlendi ve komplekslerin yapilari spektral analizler ile desteklendi. Soz konusu komplekslerin en aktif bolgeleri MEP haritalari ve MEP kontorlari ile belirlendi.

Competitive reactions among glutathione, cisplatin and copper-phenanthroline complexes

A large number of cancers are treated with cisplatin (CDDP). However, its use is limited by drug resistance, which is often related to intracellular levels of thiol-containing molecules such as glutathione (GSH). The role of GSH in cisplatin-resistant cancer cells is still unclear. GSH may form adducts with CDDP which results in the deactivation of the drug, and, actually, a high intracellular level of GSH was observed in some cisplatin-resistant cancers. To overcome drug resistance, CDDP is often administered in combination with one or more drugs to exploit a possible synergistic effect. In previous studies, we observed that the sensitivity to CDDP of leukemic and ovarian cisplatin-resistant cancer cells was restored in the presence of [Cu(phen)2(H2O)](ClO4)2 (C0) (phen is 1,10-phenathroline). In order to clarify the possible interactions between GSH and CDDP, the reactivity and competitive reactions among CDDP, C0 and GSH in binary and ternary mixtures were studied. The investigation was extended also to [Cu(phen)(H2O)2(ClO4)2] (C10) and GSSG, the oxidized form of GSH. It was observed that CDDP was able to react with the studied copper complexes and with GSH or GSSG. However, in mixtures containing CDDP, GSH or GSSG and C0 or C10, only copper-glutathione complexes were detected, while no platinum-glutathione adducts were found.

Copper(II)-phenanthroline hybrid material as efficient catalyst for the multicomponent synthesis of 1,2,3-triazoles via sequential azide formation/1,3-dipolar cycloaddition

A copper(II)-phenanthroline hybrid material based on the SBA-15 architecture was prepared using a two-step synthesis through co-condensation of 5-[N,N-bis-3-(triethoxysilyl)propyl]ureyl-1,10-phenanthroline with tetraethoxysilane, followed by coordination of Cu(OAc)2. The obtained hybrid material, Cu(II)phen@SBA-15, was fully characterized, at each stage of the preparation, by means of bulk and molecular techniques to assess both textural and structural catalyst features using XRD, XPS, EPR, HRTEM, SEM, solid-state NMR UV–vis and IR analytical tools. The characterization results altogether confirmed the structural integrity of the mesoporous host and the successful anchoring of the copper-phenanthroline complex as discrete mononuclear Cu(II)L species. The catalytic performances of Cu(II)phen@SBA-15 were evaluated in the aqueous 1,3-dipolar cycloaddition of azides with alkynes using a multicomponent one-pot synthesis where organic azides were produced in situ from organic bromide (or aryl diazonium salts or epoxides), providing for safer synthetic technologies. The catalyst proved to be highly active under mild reaction conditions (0.5mol%, 70°C) over a broad range of substrates, providing 1,4-disubstituted-1,2,3-triazoles in high yields.

Photoinduced structural distortions and singlet-triplet intersystem crossing in Cu(i) MLCT excited states monitored by optically gated fluorescence spectroscopy.

Copper(i) phenanthroline complexes represent viable earth-abundant alternatives to the ubiquitous Ru(ii) tris-bipyridine photosensitizers owing to their similar metal-to-ligand charge transfer (MLCT) properties. A well-established complication of Cu(i) phenanthroline complexes is that they can undergo significant photo-induced structural rearrangements, leading to excited states that are highly susceptible to exciplex formation and short-lived. In this work, a comprehensive analysis of the photo-induced structural distortions and singlet-triplet intersystem crossing dynamics of a series of four sterically encumbered Cu(i) phenanthroline chromophores has been conducted, namely, [Cu(dsbp)2]+ (dsbp = 2,9-di-sec-butyl-1,10-phenanthroline), [Cu(dsbtmp)2]+ (dsbtmp = 2,9-di-sec-butyl-3,4,7,8-tetramethyl-1,10-phenanthroline), [Cu(dipp)2]+ (dipp = 2,9-di-isopropyl-1,10-phenanthroline), and [Cu(diptmp)2]+ (diptmp = 2,9-di-isopropyl-3,4,7,8-tetramethyl-1,10-phenanthroline). Upconverted fluorescence decay kinetics were measured at wavelengths along the blue side of the photoluminescence spectrum. The experimental results displayed strong wavelength dependence of the singlet emission, with rapid sub-picosecond decay dominating at higher energies. At lower emission energies, increasing contribution of a longer decay component was revealed. This wavelength dependence is a signature of the excited state structural rearrangement of the phenanthroline ligands which concomitantly lower the excited state energy. The obtained time constants were in excellent agreement with those measured in the complementary ultrafast transient absorption experiments. The sub-picosecond component (prompt fluorescence) is associated with the photo-induced structural rearrangement that lowers the energy of the singlet excited state. The longer decay component represents the lifetime of the S1 excited state, and thus the time-scale of singlet-triplet intersystem crossing. Lastly, the observed dual emission was further characterized by constructing picosecond time-resolved emission spectra from the measured kinetic data. These qualitative luminescence spectra capture the resulting emission from both the S1 initial state and the S1 flattened state, providing further insight into the energy-lowering excited state distortion across the series.

High-Efficiency Dye-Sensitized Solar Cells with Molecular Copper Phenanthroline As Solid Hole Conductor

Until recently, there have been no viable alternatives for Spiro-OMeTAD as a hole-transport material (HTM) for dye-sensitized solar cells (DSSC).1 In this study we show that copper phenanthroline complexes in the solid phase can act as efficient molecular hole conductors in DSSCs. Normally, DSSCs utilize a liquid redox electrolyte, but there are significant advantages in replacing it by a solid state hole transport material (HTM): The use of an HTM prevents dye desorption, electrolyte leakage and evaporation problems, as well as making series connection between cells much easier.2 The photovoltaic performance of solid state-DSSCs is, however, usually much lower than its liquid counterparts.3 Here we present a new HTM alternative: bis(2,9-dimethyl-1,10-phenanthroline)copper(I/II) (Cu(dmp)2). This copper complex has a straightforward synthetic route from low cost starting materials. We prepared solid-state DSSCs with the organic dye LEG44 and Cu(dmp)2 as HTM with a power conversion efficiency of 8.2% under 1000 W m-2AM1.5G illumination, having an open-circuit potential higher than 1.0 V. The successful application of a copper complex-based HTM paves the way for low-cost and efficient hybrid solar cells, as well as other optoelectronic devices. This type of material is anticipated to have large impact on current DSC and MSC research. (1) Bach, U.; Lupo, D.; Comte, P.; Moser, J. E.; Weissortel, F.; Salbeck, J.; Spreitzer, H.; Gratzel, M. Nature 1998, 395, 583. (2) Hagfeldt, A.; Boschloo, G.; Sun, L.; Kloo, L.; Pettersson, H. Chem. Rev. 2010, 110, 6595. (3) Bai, Y.; Yu, Q.; Cai, N.; Wang, Y.; Zhang, M.; Wang, P. Chem. Commun. 2011, 47, 4376. (4) Yang, L.; Xu, B.; Bi, D.; Tian, H.; Boschloo, G.; Sun, L.; Hagfeldt, A.; Johansson, E. M. J. J. Am. Chem. Soc. 2013, 135, 7378. Figure 1

Amperometric determination of sulfide ion by glassy carbon electrode modified with multiwall carbon nanotubes and copper (II) phenanthroline complex

Abstract Electrocatalytic oxidation of sulfide ion on a glassy carbon electrode (GCE) modified with multiwall carbon nanotubes (MWCNTs) and a copper (II) complex was investigated. The Cu(II) complex was used due to the reversibility of the Cu(II)/Cu(III) redox couple. The MWCNTs are evaluated as a transducer, stabilizer and immobilization matrix for the construction of amperometric sensor based on Cu(II) complex adsorbed on MWCNTs immobilized on the surface of GCE. The modified GCE was applied to the selective amperometric detection of sulfide at a potential of 0.47 V (vs. Ag/AgCl) at pH 8.0. The calibration graph was linear in the concentration range of 5 µM–400 µM; while the limit of detection was 1.2 µM, the sensitivity was 34 nA µM−1. The interference effects of SO3 2−, SO4 2−, S2O3 2−, S4O6 2−, Cysteine, and Cystein were negligible at the concentration ratios more than 40 times. The modified electrode is more stable with time and more easily restorable than unmodified electrode surface. Also, modified electrode permits detection of sulfide ion by its oxidation at lower anodic potentials.

Ferrocenyl methylene units and copper(ii) phenanthroline complex units anchored on branched poly(ethyleneimine) – DNA binding, antimicrobial and anticancer activity

Polymer conjugates ([Cu(phen)2–(Fc-BPEI)]Cl2) were synthesized and characterized by spectroscopic and analytical techniques:in vitroantimicrobial and anticancer studies.

Insight into self-assembly of malonate-based copper(II) phenanthroline complexes: Syntheses, crystal structures and properties

One-pot reactions of Cu(ClO4)2·6H2O, phenanthroline (phen), malonic acid (H2mal) and NaOH in molar ratio 1:1:1:2 (mmol) in 40mL H2O/MeOH afforded two novel complexes [Cu2(phen)2(H2O)3(mal)(ClO4)](ClO4) ([4]ClO4) and [Cu6(phen)6(H2O)2(mal)4(ClO4)2](ClO4)2 ([5](ClO4)2) besides three known complexes [Cu(phen)2(H2O)](ClO4)2 ([1](ClO4)2), [Cu(phen)(H2O)(mal)]·1.5H2O ([2]·1.5H2O) and [Cu3(phen)3(H2O)2(mal)3]·11H2O ([3]·11H2O). Complexes [2]·1.5H2O, [3]·11H2O, [4]ClO4 and [5](ClO4)2 commonly have a basic building motif of a general formulation [Cu(phen)(mal)X]n with the Cu square-pyramidally coordinated by phen molecule, (mal−) anion and an apical X group (X=H2O, ClO4−, [Cu(phen)(H2O)(mal)], n=0, +1). [3]·11H2O is built up of the hydrogen-bonded [Cu3(phen)3(H2O)2(mal)3] trimers and (H2O)11 clusters, while [4]ClO4 and [5](ClO4)2 feature 1D 1∞ {[Cu2(phen)2(H2O)3(mal)](ClO4)2/2}+ chain and hexanuclear [Cu6(phen)6(H2O)2(mal)4(ClO4)2]2+ complex cations, respectively. Self-assembly routes to the malonate-based Cu(II) phenanthroline complexes were well established on the basis of the [Cu(phen)(H2O)(mal)] complex molecule. Both acentric polar complexes [3]·11H2O and [4]ClO4 represent the first two examples of metal malonato complexes with ferroelectric property with a remnant polarization (Pr) of ca. 0.045 and 0.2002μCcm−2, coercive field (Ec) of ca. 0.70 and 1.79kVcm−1, and saturation of the spontaneous polarization (Ps) at ca. 0.39 and 0.248μCcm−2, respectively. The magnetic properties of [4]ClO4 and [5](ClO4)2 follow Curie–Weiss law χm=C/(T−Θ) with the Curie constant C=0.480(2), 0.587(7)cm3mol−1K and Weiss constant Θ=0.32(1), 0.61(2)K, respectively. The weak ferromagnetic behaviors can be well analyzed using dinuclear Cu2 and V-shaped trinuclear Cu3 models, respectively, and best-fittings gives J=6.2(6)cm1 for equatorial–equatorial syn–anti μ-COO groups.

Solvent-Induced Luminescence Quenching: Static and Time-Resolved X-Ray Absorption Spectroscopy of a Copper(I) Phenanthroline Complex

We present a static and picosecond X-ray absorption study at the Cu K-edge of bis(2,9-dimethyl-1,10-phenanthroline)copper(I) ([Cu(dmp)2](+); dmp = 2,9-dimethyl-1,10-phenanthroline) dissolved in acetonitrile and dichloromethane. The steady-state photoluminescence spectra in dichloromethane and acetonitrile are also presented and show a shift to longer wavelengths for the latter, which points to a stronger stabilization of the excited complex. The fine structure features of the static and transient X-ray spectra allow an unambiguous assignment of the electronic and geometric structure of the molecule in both its ground and excited (3)MLCT states. Importantly, the transient spectra are remarkably similar for both solvents, and the spectral changes can be rationalized using the optimized ground- and excited-state structures of the complex. The proposed assignment of the lifetime shortening of the excited state in donor solvents (acetonitrile) to a metal-centered exciplex is not corroborated here. Molecular dynamics simulations confirm the lack of complexation; however, in both solvents the molecules come close to the metal but undergo rapid exchange with the bulk. The shortening of the lifetime of the title complex and nine additional related complexes can be rationalized by the decrease in the (3)MLCT energy. Deviations from this trend may be explained by means of the effects of the dihedral angle between the ligand planes, the solvent, and the (3)MLCT-(1)MLCT energy gap.