Copper Phenanthroline Research Articles

On the interplay of solvent and conformational effects in simulated excited-state dynamics of a copper phenanthroline photosensitizer.

Copper(i) bis-phenanthroline complexes represent Earth-abundant alternatives to ruthenium-based sensitizers for solar energy conversion and photocatalysis. Improved understanding of the solvent-mediated excited-state structural dynamics can help optimize their photoconversion efficiency. Through direct dynamics simulations in acetonitrile and excited-state minimum energy path calculations in vacuum, we uncover the mechanism of the photoinduced flattening motion of the prototypical system [Cu(dmphen)2]+ (dmphen = 2,9-dimethyl-1,10-phenanthroline). We find that the ligand distortion is a two-step process in acetonitrile. The fast component (∼110 fs) is due to spontaneous pseudo Jahn-Teller instability and is largely solvent independent, while the slow component (∼1.2 ps) arises from the mutual interplay between solvent molecules closely approaching the metal center and rotation of the methyl substituents. These results shed new light on the influence of a donor solvent such as acetonitrile and methyl substituents on the flattening dynamics of [Cu(dmphen)2]+.

Theoretical and Experimental Reactivity Predictors for the Electrocatalytic Activity of Copper Phenanthroline Derivatives for the Reduction of Dioxygen

We have systematically studied the catalytic activity of a series of substituted bisphenanthroline Cu complexes adsorbed on glassy carbon electrodes for the oxygen reduction reaction (ORR) in aqueous media. The aim of this work is to test reactivity descriptors for ORR previously proposed for MN4 complexes. As the active site is the Cu(I) center, the foot of the wave for O2 reduction on electrodes modified with Cu bisphenanthrolines appears at potentials very close to the [Cu(II)phen2]ad++ + e– ⇆ [Cu(I)phen2]ad+ redox process. Generally, the catalytic activity as (log i)E versus the ECu(II)/(I)° redox potentials follows a linear correlation with a slope close to +0.120 V/decade, where the activity increases as the ECu(II)/(I)° becomes more positive. This indicates that electron-withdrawing substituents on the ligand favor the reaction by shifting the ECu(II)/(I)° to more positive values, making the Cu center more noble. This shift in the ECu(II)/(I)° is essentially an electronic effect. However, another way to stabilize the Cu(I) state is by placing groups on the ligand that hinder the [Cu(II)square-planar]ad++/[Cu(I)tetrahedral]ad+ change. We have found that this steric effect seems to be more prominent than the electronic effects caused by electron-withdrawing groups and the increase in the catalytic activity for ORR is more pronounced.

Synthesis and characterization of self-assembled inorganic-organic hybrid arsenotungstates.

A series of 12 inorganic-organic hybrid 4f-substituted arsenotungstates decorated with 3d-based complexes along with acetate bridging, viz. {[Cu2(H2O)(1,10-phen)2(μ-CH3COO)2]4[Ln2(H2O)2(μ-CH3COO)2(α-AsW11O39)2]}2- (LnIII = Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu), have been synthesized. These compounds were isolated using a one-pot synthetic strategy with copper, lanthanoid, trilacunary arsenotungstate and 1,10-phenanthroline as precursors. They were characterized using various analytical techniques, such as single-crystal X-ray diffraction (SC-XRD), powder XRD (PXRD), Fourier transform IR (FT-IR) spectroscopy, UV-Vis spectroscopy and thermogravimetric analysis (TGA). In all these compounds, a dinuclear Ln2(ac)2 moiety is sandwiched between two monolacunary [AsW11O39]7- polyoxometalates (POMs), where the Ln2(ac)2 moiety is comprised of two acetate ligands in a μ-κO,O':κO fashion. Moreover, the anion is decorated by a copper-phenanthroline-acetate complex through a terminal O atom of the polyanion.

Substrate-Induced Motion between TM4 and TM7 of the Glutamate Transporter EAAT1 Revealed by Paired Cysteine Mutagenesis

To maintain efficient synaptic communication, glutamate transporters reuptake glutamate from the synaptic cleft and prevent glutamate concentrations from reaching neurotoxic levels. The number of amino acid residues of the transmembrane (TM) domain 4b-4c loop of mammalian excitatory amino acid transporters (EAATs) is 50 amino acids more than that of the prokaryotic homolog. To investigate the spatial proximity and functional significance of residues in glutamate transporters, cysteine pairs were introduced at positions A243 of the TM4b-4c loop and T396 or A414 of TM7, respectively. The transport activity of double mutants A243C/T396C and A243C/A414C was inhibited by Cu(II) (1,10-phenanthroline)3 [copper phenanthroline (CuPh)] and cadmium ions, but the uptake activity of corresponding single mutants remained unchanged. Treatment with dithiothreitol after CuPh restored much of the transport activity. The inhibitory effects of CuPh and cadmium could only be detected when cysteine pairs are in the same polypeptide. Therefore, we suggest that the formation of these disulfide bonds occurs intramolecularly. Glutamate, potassium, and DL-threo-β-benzyloxyaspartate facilitated crosslinking in the A243C/T396C transporter and this suggests that the TM4b-4c loop and β-bridge region in TM7 were drawn into close proximity to each other in the inward- and outward-facing conformation of EAAT1. Thus, these data provide evidence that substrate-induced structural rearrangements occur between the TM4b-4c loop and TM7 during the transport cycle.

(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].

The Different Faces of Photoredox Catalysts: Visible-Light-Mediated Atom Transfer Radical Addition (ATRA) Reactions of Perfluoroalkyl Iodides with Styrenes and Phenylacetylenes

A photoredox-catalyzed procedure for the iodoperfluoroalkylation of styrenes and phenylacetylenes using readily available copper phenanthroline catalyst is reported. In contrast to commonly employed [Ru(bpy)3]Cl2, [Ru(phen)3]Cl2 or fac-Ir(ppy)3, [Cu(dap)2]Cl is capable to convert styrenes to the corresponding perfluoroalkyl tagged ethylbenzenes, pointing toward an additional role of the copper catalyst beyond photoinduced electron transfer. An inner sphere catalytic cycle involving Cu(III) intermediates or ligand abstraction from a [CuI]+ intermediate is proposed.

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.

Functional properties of dopamine transporter oligomers after copper linking.

Although it is universally accepted that dopamine transporters (DATs) exist in monomers, dimers and tetramers (i.e. dimers of dimers), it is not known whether the oligomeric organization of DAT is a prerequisite for its ability to take up dopamine (DA), or whether each DAT protomer, the subunit of quaternary structure, functions independently in terms of DA translocation. In this study, copper phenanthroline (CuP) was used to selectively target surface DAT: increasing concentrations of CuP gradually cross-linked natural DAT dimers in LLC-PK1 cells stably expressing hDAT and thereby reduced DA uptake functionality until all surface DATs were inactivated. DATs that were not cross-linked by CuP showed normal DA uptake with DA Km at ~ 0.5μM and DA efflux with basal and amphetamine-induced DA efflux as much as control values. The cocaine analog 2β-carbomethoxy-3β-[4-fluorophenyl]-tropane (CFT) was capable to bind to copper-cross-linked DATs, albeit with an affinity more than fivefold decreased (Kd of CFT=109nM after cross-linking vs 19nM before). A kinetic analysis is offered describing the changing amounts of dimers and monomers with increasing [CuP], allowing the estimation of dimer functional activity compared with a DAT monomer. Consonant with previous conclusions for serotonin transporter and NET that only one protomer of an oligomer is active at the time, the present data indicated a functional activity of the DAT dimer of 0.74 relative to a monomer.

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.

A Copper(II) Phenanthroline Metallopeptide That Targets and Disrupts Mitochondrial Function in Breast Cancer Stem Cells

AbstractThe breast cancer stem cell (CSC) and bulk breast cancer cell potency of a series of metallopeptides containing dichloro(1,10‐phenanthroline)copper(II) and various organelle‐targeting peptide sequences is reported. The mitochondria‐targeting metallopeptide 1 exploits the higher mitochondrial load in breast CSCs over the corresponding non‐CSCs and the vulnerability of breast CSCs to mitochondrial damage to potently and selectively kill breast CSCs. Strikingly, 1 reduces the formation and size of mammospheres to a greater extent than salinomycin, an established CSC‐potent agent. Mechanistic studies show that 1 enters CSC mitochondria, induces mitochondrial dysfunction, generates reactive oxygen species (ROS), activates JNK and p38 pathways, and prompts apoptosis. To the best of our knowledge, 1 is the first metallopeptide to selectivity kill breast CSCs in vitro.

A Copper(II) Phenanthroline Metallopeptide That Targets and Disrupts Mitochondrial Function in Breast Cancer Stem Cells.

The breast cancer stem cell (CSC) and bulk breast cancer cell potency of a series of metallopeptides containing dichloro(1,10-phenanthroline)copper(II) and various organelle-targeting peptide sequences is reported. The mitochondria-targeting metallopeptide 1 exploits the higher mitochondrial load in breast CSCs over the corresponding non-CSCs and the vulnerability of breast CSCs to mitochondrial damage to potently and selectively kill breast CSCs. Strikingly, 1 reduces the formation and size of mammospheres to a greater extent than salinomycin, an established CSC-potent agent. Mechanistic studies show that 1 enters CSC mitochondria, induces mitochondrial dysfunction, generates reactive oxygen species (ROS), activates JNK and p38 pathways, and prompts apoptosis. To the best of our knowledge, 1 is the first metallopeptide to selectivity kill breast CSCs in vitro.

Salicylate •Phenanthroline copper (II) complex induces apoptosis in triple-negative breast cancer cells.

In this study, we investigated anti-tumor activity and associated molecular mechanism of action of Salicylate ●Phenanthroline Copper (II) Complex in triple-negative breast cancer. Salicylate ●Phenanthroline Copper (II) Complex inhibited the growth of four breast cancer cell lines (MCF-7, T47D, MDA-MB-231 and BT-20) and induced apoptosis in a concentration-dependent manner. The effect was more profound in MDA-MB-231 and BT-20 triple-negative breast cancer cell lines. Western blot showed that the expression of the apoptosis-related protein Bcl-2, Bcl-xl and survivin was significantly reduced in MDA-MB-231 after treatment with Salicylate ●Phenanthroline Copper (II) Complex. In vivo, Salicylate ●Phenanthroline Copper (II) Complex administration significantly attenuated tumor growth of MDA-MB-231 xenografts, and the expression levels of Bcl-2, Bcl-xL and survivin were reduced as measured by immunohistochemical staining. These data suggest that Salicylate ●Phenanthroline Copper (II) Complex is a promising novel therapeutic drug for triple-negative breast cancer and warrants further study.

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.

Photophysics of a copper phenanthroline elucidated by trajectory and wavepacket-based quantum dynamics: a synergetic approach.

On-the-fly excited state molecular dynamics is a valuable method for studying non-equilibrium processes in excited states and is beginning to emerge as a mature approach much like its ground state counterparts. In contrast to quantum wavepacket dynamics methods, it negates the need for modelling potential energy surfaces, which usually confine nuclear motion within a reduced number of vibrational modes. In addition, on-the-fly molecular dynamics techniques are easily combined with the atomistic description of the solvents (through the QM/MM approach) making it possible to explicitly address the effect of the environment. Herein, we study the nonadiabatic relaxation of photoexcited [Cu(dmp)2]+ (dmp = 2,9-dimethyl-1,10-phenanthroline) using QM/MM Trajectory Surface Hopping (TSH). We show that the decay of the initially excited singlet state into the lowest singlet (S1) state occurs within 100 fs, in agreement with previous experiments, and is slightly influenced by the solvent. Using a principal component analysis (PCA), we also identify the dominant normal modes activated during the excited state decay, which are then used to design the vibronic Hamiltonian for quantum wavepacket dynamics simulations.

Pro-apoptotic and cytotoxic effects of enriched fraction of Elytranthe parasitica (L.) Danser against HepG2 Hepatocellular carcinoma.

BackgroundHepatocellular carcinoma (HCC), the most common type of liver cancer accounts for more than one million deaths worldwide. Current treatment modality for HCC is marginally effective. Plants belonging to Mistletoe family (Loranthaceae) have been used in chemotherapy for many years. The present study was aimed at exploring the anti-proliferative, pro-oxidant and pro-apoptotic potential of stem of Elytranthe parasitica (L.) Danser (EP), a parasitic shrub belonging to Loranthaceae.Methods Elytranthe parasitica (L.) Danser, a climbing parasitic shrub was investigated for its cytotoxic activity against HepG2, a hepatocellular carcinoma cell line by Sulforhodamine B (SRB) assay. Further, pro-oxidant activity of EP extract/fractions was studied using copper phenanthroline assay. To understand the mechanism of cell death, the pro-apoptotic effects of Hep-G2 cells treated with EP extract/fractions were visualized by dual staining using acridine orange and ethidium bromide, a morphological marker of apoptosis. Phytochemical profiling of EP was explored by estimating the phenol, flavonoid and tannin content in its various fractions and extract. The occurrence of gallic acid, a principal polyphenol in EP extract and fractions was detected and further quantified using HPTLC (High Performance Thin Layer Chromatography) fingerprinting.ResultActive fraction of Elytranthe parasitica, EP.DEE exhibited potent cytotoxic activity in a dose dependent manner against HepG2 hepatocellular carcinoma cell line with an IC50 of 56.7 ± 7.8 μg/mL. Dual staining with acridine orange and ethidium bromide revealed that HepG2 cells treated with EP active fractions underwent cell death chiefly by apoptosis. Highest phenol, flavonoid and tannin content were observed in active fractions, EP.EA (Ethyl acetate fraction) and EP.DEE (Diethyl ether fraction). Gallic acid was identified and quantified in EP extract and active fractions, EP.DEE and EP.EA.ConclusionOur findings indicate EP active fraction could be a promising contender in the treatment of hepatocellular carcinoma.

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

Copper Phenanthroline as a Fast and High-Performance Redox Mediator for Dye-Sensitized Solar Cells

The most commonly used redox mediators in dye-sensitized solar cells (DSCs), iodide/triiodide and cobalt trisbipyridine ([Co(bpy)3]2+/3+), were successfully replaced by bis(2,9-dimethyl-1,10-phenanthroline)copper(I/II) ([Cu(dmp)2]1+/2+). The use of the copper complex based electrolyte led to an exceptionally high photovoltaic performance of 8.3% for LEG4-sensitized TiO2 solar cells, with a remarkably high open-circuit potential of above 1.0 V at 1000 W m–2 under AM1.5G conditions. The copper complex based redox electrolyte has higher diffusion coefficients and is considerably faster in dye regeneration than comparable cobalt trisbipyridine based electrolytes. A driving force for dye regeneration of only 0.2 eV is sufficient to obtain unit yield, pointing to new possibilities for improvement in DSC efficiencies. The interaction of the excited dye with components of the electrolyte was monitored using steady-state emission measurements and time-correlated single-photon counting (TC-SPC). Our results indicat...

Disulfide Cross-linking of a Multidrug and Toxic Compound Extrusion Transporter Impacts Multidrug Efflux

Multidrug and toxic compound extrusion (MATE) transporters contribute to multidrug resistance by extruding different drugs across cell membranes. The MATE transporters alternate between their extracellular and intracellular facing conformations to propel drug export, but how these structural changes occur is unclear. Here we combine site-specific cross-linking and functional studies to probe the movement of transmembrane helices in NorM from Neiserria gonorrheae (NorM-NG), a MATE transporter with known extracellular facing structure. We generated an active, cysteine-less NorM-NG and conducted pairwise cysteine mutagenesis on this variant. We found that copper phenanthroline catalyzed disulfide bond formation within five cysteine pairs and increased the electrophoretic mobility of the corresponding mutants. Furthermore, copper phenanthroline abolished the activity of the five paired cysteine mutants, suggesting that these substituted amino acids come in spatial proximity during transport, and the proximity changes are functionally indispensable. Our data also implied that the substrate-binding transmembrane helices move up to 10 Å in NorM-NG during transport and afforded distance restraints for modeling the intracellular facing transporter, thereby casting new light on the underlying mechanism.

SBA-15 Immobilized Phenanthroline–Copper(I) Complex as a Recyclable Efficient Catalyst for N-Arylation of Amides and N–H Heterocycles with Aryl Halides

5-(N,N-bis-3-(triethoxysilyl) propyl) ureyl-1,10-phenanthroline was prepared and successively grafted onto mesoporous silica of SBA-15 to get SBA-15 anchored ligand which was then reacted with Cu(I) to get SBA-15 anchored complex as the heterogeneous copper catalyst. This catalyst was characterized by FT-IR, XRD, CHN, AAS, TGA, EDAX, BET, SEM and TEM. The activities of the catalyst were tested in C–N cross-coupling of amides and N–H heterocycle compounds with aryl halides. The catalyst showed high catalytic activities for these cross-coupling reactions providing good to excellent yields of desired products. Moreover, the catalyst can be easily recovered by simple filtration and reused several times without significant loss of its catalytic activity.

A Macrocyclic Phenanthroline–Copper Complex with Less Steric Hindrance: Synthesis, Structure, and Application to the Synthesis of a [2]Rotaxane

Abstract We synthesized a macrocyclic 2,9-dialkyl-1,10-phenanthroline–Cu complex (9) from 1,10-phenanthroline. Compound 9 existed as a dinuclear complex in solid state. In solution, however, the compound existed as a mononuclear complex. Compound 9 mediated the Glaser reaction of an alkyne with a bulky blocking group and the formation of a [2]rotaxane was observed. The reactivity of the 2,9-dialkyl-1,10-phenanthroline–Cu complex (9) was lower than that of a diaryl analogue.