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[Display omitted] The covalent bonding of a ruthenium bipyridine complex derivative with the aromatic network of single walled carbon nanotubes (SWNT) through a stepwise protocol is presented, thus yielding the sample SWNT-Ru. To do that, an-amino decorated phenanthroline is bonded to the nanotube by means of the diazonium chemistry protocol, providing anchoring points for discrete organometallic units as depicted by the solid characterization techniques employed. The hybrid material, able to emit upon excitation, is active in the visible light-driven photocatalytic oxidation of organic sulfides to sulfoxides. SWNT-Ru presents a wide scope being able to convert more than 10 substrates with different characteristics, including added-value chemicals, with a stable performance over more than 6 cycles without metal leaching and enhanced activity compared to related homogeneous complexes. A versatile character is also demonstrated since this hybrid catalyst follows both possible photooxidation mechanisms. [ABSTRACT FROM AUTHOR]

Two molecular structures of a complex C26H16Cl2N2Pd (1) with a benzene hemisolvate (1•0.5C6H6) and a complex C34H20Cl2N2Pd (2) revealed similar conformations: one side of the arylethynyl group is flat to the bipyridine plane while the other side of the arylethynyl group is highly twisted to the plane because rhomb-like dimer fragments are formed between respective two complexes through CH⋯π interactions. The Hirshfeld surface analysis indicates that the most important contributions for the crystal packing of 1 are from H⋯H (33.6%), C⋯H/H⋯C (28.3%), Cl⋯H/H⋯Cl (17.8%), and C⋯C (10.6%) interactions and those of 2 are from H⋯H (36.5%), C⋯H/H⋯C (26.0%), Cl⋯H/H⋯Cl (15.7%), and C⋯C (12.3%) interactions, indicating the remarkable CH⋯π and electron distribution of molecules by Cl ions. The benzene solvate molecule of 1•0.5C6H6 performs to fill the internal space instead of the naphthyl group. Detailed crystallographic and DFT studies were performed to understand the molecular structures and the corresponding supramolecular associations. [ABSTRACT FROM AUTHOR]

Bipyridine and related compounds are starting materials or precursors for a variety of valuable substances such as biologically active molecules, ligands for catalysts, photosensitizers, viologens, and supramolecular architectures. Thus, it is important to classify their synthesis methods and understand their characteristics. Representative examples include methods using homo and heterocoupling of pyridine derivatives in the presence of a catalyst. Because bipyridine compounds strongly coordinate with metal centers, a decrease in catalytic activity and yield is often observed in the reaction system. To address this issue, this review provides insights into advances over the last ~30 years in bipyridine synthesis using metal complexes under both homogeneous and heterogeneous conditions. Moreover, strategies for bipyridine synthesis involving sulfur and phosphorous compounds are examined. These alternative pathways offer promising avenues for overcoming the challenges associated with traditional catalysis methods, providing a more comprehensive understanding of the synthesis landscape. [ABSTRACT FROM AUTHOR]

Supramolecular peptide assemblies have been widely used for the development of biomedical, catalytical, and optical materials with chiral nanostructures in view of the intrinsic chirality of peptides. However, the assembly pathway and chiral transformation behavior of various peptides remain largely elusive especially for the transient assemblies under out‐of‐equilibrium conditions. Herein, the N‐fluorenylmethoxycarbonyl‐protected phenylalanine‐tyrosine dipeptide (Fmoc‐FY) was used as a peptide assembly platform, which showed that the assembly proceeds multistep evolution. The original spheres caused by liquid‐liquid phase separation (LLPS) can nucleate and elongate into the formation of right‐handed helices which were metastable and easily converted into microribbons. Interestingly, a bipyridine derivative can be introduced to effectively control the assembly pathway and induce the formation of thermodynamically stable right‐handed or left‐handed helices at different stoichiometric ratios. In addition, the chiral assembly can also be regulated by ultrasound or enzyme catalysis. This minimalistic system not only broadens the nucleation‐elongation mechanisms of protein aggregates but also promotes the controllable design and development of chiral biomaterials. [ABSTRACT FROM AUTHOR]

Here, we present the preparation and characterization of two novel picrate salts. The 2,2′-bis(pyridinium)ketone picrate, DPK-PA (1), crystallizes in the triclinic system and centrosymmetric space group P 1 ¯ , with unit cell parameters a = 9.378(17) Å, b = 9.790(15) Å, c = 10.141(16) Å, α = 99.63(7)°, β = 99.09(8)°, and γ = 102.55(8)°, while the 4,4′-bis(tert-butyl)-2-pyridine-2-pyridinium picrate, BBBPY-PA (2), crystallizes in the non-centrosymmetric P212121 space group, orthorhombic unit cell parameters a = 6.3902(6) Å, b = 23.416(3) Å, and c = 16.7320(18) Å. Both crystal structures present an ion-pair in the asymmetric unit, one picrate anion, and one bipyridine derivative. In the DPK-PA (1) structure, the molecule of DPK presents one intramolecular N1-H ⋯ N H-bond that contributes to stabilizing the planar conformation of DPK. The absence of intramolecular H-bonding in the BBBPY-PA (2) can be explained by the steric hindrance of the tert-butyl group. For DPK-PA (1) and BBBPY-PA (2), the crystal packing is stabilized N–H ⋯ O strong hydrogen bonding interactions, which could be identified by the Hirshfeld surface analysis and fingerprint plots. The compounds were also studied by UV–Vis and infrared analyses, which may support the statement of the formation of new material. Finally, as an attempt to obtain a molecular system to act as a chemical sensor, we studied the fluorescence of both compounds, in solution and in solid state; however, no fluorescence was observed. [ABSTRACT FROM AUTHOR]

Starting from 3‐oxo‐N‐(3‐pyridyl)butanamide, as key intermediate, the title compounds were synthesized in good yields. Reaction of the pyridine‐carboxamide 1 with hydrazonoyl chlorides 3a,b and with triethyl orthoformate afforded the corresponding pyrazole‐carboxamides 6a,b, and the bis‐pyridine 7, respectively. Coupling of the pyridine‐carboxamide 1 with 3‐phenylpyrazole‐5‐diazonium chloride gave the hydrazone 10 which upon heating in pyridine afforded the pyrazolo[5,1‐c]‐1,2,4‐triazine derivative 11. Reaction of the pyridine‐carboxamide 1 with arylmethylenepropanedinitrile derivatives afforded 1,3′‐bipyridines 13a–c. Structure elucidation of the newly synthesized compounds was carried out using IR, NMR spectroscopy, and mass spectrometry. The extensive theoretical and experimental mechanical studies of the pyrazole derivative 6a were in accordance with its elemental analysis, FT‐IR, NMR, and MS spectral data. Moreover, computer analyses indicated that the pyridine derivatives 13a,b predominated over the pyran derivatives 14a,b as the adducts. In addition, the optimization of compounds utilized the HF/6‐31G(d) and DFT/B3LYP/6‐31G(d) basis sets. Furthermore, the physical descriptors of these compounds demonstrated their stability, and NMR correlation investigations were also carried out. [ABSTRACT FROM AUTHOR]

The supramolecular complex formation between donor (E)-bis(18-crown-6)azobenzene ((E)-1) and bis(ammoniopropyl) derivatives of bipyridine and dipyridylethylene acceptors (2, (E)-3) was studied in MeCN using steady-state absorption and fluorescence spectroscopy, fluorescence kinetics, and quantum-chemical (DFT, TDDFT, QDPT) calculations. The complexes are quite stable, but they undergo decomposition via substitution by alkali and alkaline-earth metal cations. The formation of 1:1 and 1:2 complexes between (E)-1 and alkali and alkaline-earth metal cations (Mn+) was confirmed. Spectral-kinetic parameters and stability constants were calculated. The determined stability constants are generally lower than those for bis(crown)stilbene complexes due to moderate electron-donor ability of azobenzene. The plot of fluorescence quantum yields of 1·(Mn+)2vs charge density of the metal cation shows two separate linear relations for unipositive and dipositive ions. The results of quantum-chemical calculations supported the conclusions derived from steady-state experiments. The most stable conformations of pseudocyclic complex (E)-1·2 and two metal complexes were found. The latter involve 4 or 6 molecules of acetonitrile per each complex: (E)-1·(Ca2+)2·(MeCN)4, (E)-1·(K+)2·(MeCN)6. Based upon quantum-chemical calculations of model species, the character of absorption bands of crowns and their complexes with actual energy conversion pathway are discussed. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: In recent years, the construction of stable multicomponent assembled structures on surfaces and the exploration of the assembled mechanism have become research hotspots. In this paper, the azobenzene‐carboxylic acid called (E)‐4',4"'‐(diazene‐1,2‐diyl) bis(([1,1'‐biphenyl]‐3,5‐dicarboxylic acid)) (H4DBBD) could self‐assemble into regular network structure at heptanoic acid/graphite via hydrogen bonding, and could be regulated into analogous kagomé network by coronene (COR) molecules. In addition, a series of bipyridine derivatives were further introduced to construct bi‐component systems with H4DBBD molecules, and successfully induced diversified structural transitions of H4DBBD on the graphite surface. Combined with scanning tunneling microscope (STM) and density functional theory (DFT) calculations, we have investigated the diversified structural transitions and analyzed the formation mechanism of the assembled systems. [ABSTRACT FROM AUTHOR]

An efficient gold [Au]‐catalyzed one‐pot synthesis has been developed for the construction of biologically interesting mono‐ and bipyridines by utilizing the commercially available cyclic ketones and propargylamine in a sealed tube. The formation of bipyridine derivative 21 a indicates that annulation followed by retro‐Diels–Alder reaction is occurring with norbornene system. However, keto‐derivatives containing bicyclo[2.2.2]octene system 25 indicate that retro‐Diels–Alder reaction is not facile. Compounds 32 a and 33 a were subjected to ring opening cross‐ metathesis to generate diversity and further functionalization of pyridine derivatives. [ABSTRACT FROM AUTHOR]

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The structural transformations of metal nanoclusters are typically quite complex processes involving the formation and breakage of several bonds, and thus are challenging to study. Herein, we report a case where two lacunary Keggin polyoxometallate templated silver single-pods [PW9O34@Ag51] (SD/Ag51b) fuse to a double-pod [(PW9O34)2@Ag72] by reacting with 4,4'-bipyridine (bipy) or 1,4-bis(4-pyridinylmethyl)piperazine (pi-bipy). Their crystal structures reveal the formation of a 2D 44-sql layer (SD/Ag72a) with bipy and a 3D pcu framework (SD/Ag72c) with pi-bipy. The PW9O349− retains its structure during the cluster fusion and cluster-based network formation. Although the two processes, stripping of an Ag-ligands interface followed by fusion, and polymerization, are difficult to envisage, electrospray ionization mass spectrometry provides enough evidences for such a proposal to be made. Through this example, we expect the structural transformation to become a powerful method for synthesizing silver nanoclusters and their infinite networks, and to evolve from trial-and-error to rational. Controlling the structural transformations of metal clusters is challenging. Here, the authors synthesize a silver nanocluster and study the structural changes that take place upon reaction with bipyridine derivatives. [ABSTRACT FROM AUTHOR]

In this work we show, using the example of a series of [Cu(Xantphos)(N^N)]+ complexes (N^N being substituted 5-phenyl-bipyridine) with different peripheral N^N ligands, that substituents distant from the main action zone can have a significant effect on the physicochemical properties of the system. By using the C≡C bond on the periphery of the coordination environment, three hybrid molecular systems with −Si(CH3)3, −Au(PR3), and −C2HN3(CH2)C10H7 fragments were produced. The Cu(I) complexes thus obtained demonstrate complicated emission behaviour, which was investigated by spectroscopic, electrochemical, and computational methods in order to understand the mechanism of energy transfer. It was found that the −Si(CH3)3 fragment connected to the peripheral C≡C bond changes luminescence to long-lived intra-ligand phosphorescence, in contrast to MLCT phosphorescence or TADF. The obtained results can be used for the design of new materials based on Cu(I) complexes with controlled optoelectronic properties on the molecular level, as well as for the production of hybrid systems. [ABSTRACT FROM AUTHOR]

In this current study, we have synthesized four europium(III) complexes utilizing a tri-fluorinated β-diketone moiety: 1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione (TFDH) with auxiliary ligand: 2,2′- bipyridine and its derivatives. FTIR, UV–Vis and luminescence spectroscopic characterizations were implemented for evaluation of the bonding and luminous characteristics in synthesized europium(III) complexes. Eight-coordination environment around Eu3+ ion has been demonstrated by 1H NMR spectral data. Photoluminescence (PL) study of these complexes has been carried out in powdered form. Characteristic red emitting behavior of Eu(III) ion was observed corresponds to the transition of 5D 0 →7F 2 in PL spectra of Eu(III) complexes. The CIE (Commission Internationale de l'Eclairage) chroma coordinates 1931 and CCT (Correlated Color Temperature) values were derived from the information obtained from the emission spectra. The Judd-Ofelt intensity parameters (Ω τ ) and excited state deactivation time ( τ ) in solid state have also been estimated. In the synthesized Eu(III) complexes, the europium ion was present in a highly polarizable ligand field, as demonstrated by the higher values of Ω 2. Values of band gap i.e. optical and electronic as well as the red luminous nature of prepared complexes showed up their utilization in display devices. [Display omitted] • Octa coordinated Eu(III) complexes were synthesized using 1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione and N -donor ancillary ligand. • Most intense peak at ∼612 nm relative to 5D 0.→7F 2 transition was responsible for the characteristic red emission of europium complexes. • Computational analyses were performed with the help of JOES, Avogadro interface and ORCA. • The band gap as well as the red luminous behavior suggests the utilization of Eu(III) complexes in lighting and display applications. [ABSTRACT FROM AUTHOR]

A series of novel cyano-substituted bipyridine derivatives were obtained in good yields (45–72%) via the reaction of malononitrile dimer with isomeric azachalcones. For all synthesized compounds, spectral-fluorescent properties were carefully investigated, and correlation thereof with chemical structure was found. The developed approach represents a novel convenient method for the preparation of functionalized bipyridines containing unique combination of structural fragments. [ABSTRACT FROM AUTHOR]

This microreview summarizes the most frequently employed methods for the synthesis of cyano-substituted bipyridine derivatives over the past 5 years. Most of the approaches to the preparation of such compounds described in the literature are based on cross-coupling reactions, heterocyclization of pyridine-containing substrates, and various multicomponent processes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Investigating new types of β-diketonate based europium complexes. • Incorporation of Eu complexes into PMMA films to comprehensively investigate their long-term photoluminescence stability. • Eu-films were subjected to light, indoor, and dark storage conditions for a duration of 720 h. • the FAC-based europium complexes demonstrated good stability under light, indoor, and dark conditions. • β-diketonate ligands structure impact directly on the photostability of the Eu-films. In this work, two β-diketonate ligands: dibenzoylmethane (DBM) and Hexafluoroacetone (hfac) have been selected to synthesize a series of β-diketonate europium complexes based on bipyridine and terpyridine derivatives. These complexes were then incorporated into PMMA films to comprehensively investigate their thermal and long-term photoluminescence stability. Comparatively, Eu(hfac) 3 L 1-5 demonstrated higher heat resistance than Eu(DBM) 3 L 1-5 , as indicated by their respective initial decomposition temperatures. Various aspects including absorbance, excitation, and emission were examined in solution, powder, and within the PMMA-doped films. Notably, the complexes exhibited a remarkable red emission peak at 613nm and a high photoluminescence quantum yield. To assess their stability, the films were subjected to light, indoor, and dark storage conditions for 720h, with photoluminescence measurements recorded at both 0h and 720h. The results revealed that the hfac-based europium complexes (Eu(hfac) 3 L 1-5) demonstrated good stability under light, indoor, and dark conditions compared to the DBM-based europium complexes (Eu(DBM) 3 L 1-5). This study highlights the direct impact of the β-diketonate ligand structure on the stability of such complexes in films, thus showcasing their potential for future applications in stable optoelectronic devices. [ABSTRACT FROM AUTHOR]

The Cu(II) ion locates in a distorted octahedral geometry, defined by one O atom (O2) form one 6-phenylpyridine-2-carboxylate ligand and one N atom (N1) from 2,2'-bipyridine ligand at the axial positions (O2-Cu1-N1, 173.37(6)°), one O atom (O2') and two N atoms (N2, N2') form 6-phenylpyridine-2-carboxylate ligand, and one N atom (N1') from the 2,2'-bipyridine ligand in the equatorial plane. 8 Liu, S.-Y., Tian, J.-J., Zhu, L.-J., Tian, H.-T., Yang, M., Huang, K.-L., Xu, W.-T. 13 Wang, L.-H., Wang, Z.-J., Ouyang, J., Tai, X.-S. [Extracted from the article]

Retinoid X receptor alpha (RXRα) is an important therapeutic target of cancer. Recently, small molecules (e.g., XS-060 and its derivatives), which can significantly induce RXRα-dependent mitotic arrest by inhibiting p RXRα-PLK1 interaction, have been demonstrated as excellent anticancer agents. To further obtain novel RXR-targeted antimitotic agents with excellent bioactivity and drug-like properties, we herein synthesized two new series of bipyridine amide derivatives with XS-060 as the lead compound. In the reporter gene assay, most synthesized compounds showed antagonistic activity against RXRα. The most active compound, bipyridine amide B9 (BPA-B9) , showed better activity than XS-060 , with excellent RXRα-binding affinity (K D = 39.29 ± 1.12 nM) and anti-proliferative activity against MDA-MB-231 (IC 50 = 16 nM, SI > 3). Besides, a docking study revealed a proper fitting of BPA-B9 into the coactivator binding site of RXRα, rationalizing its potent antagonistic effect on RXRα transactivation. Further, the mechanism studies revealed that the anticancer activity of BPA-B9 was dependent on its cellular RXRα-targeted mechanism, such as inhibiting p RXRα-PLK1 interaction and inducing RXRα-dependent mitotic arrest. Besides, BPA-B9 displayed better pharmacokinetics than the lead XS-060. Further, animal assays indicated BPA-B9 had significant anticancer efficacy in vivo with no considerable side effects. Together, our study reveals a novel RXRα ligand BPA-B9 targeting the p RXRα-PLK1 interaction, with great potential as a promising anticancer drug candidate for further development. [Display omitted] • New bipyridine amide derivatives are synthesized as novel RXRα modulators. • Compound B9 is an excellent RXRα binder (K D = 39 nM) and selective RXRα antogonist. • B9 induces RXRα-dependent cell cycle arrest and apoptosis by hindering pRXRα-PLK1 interaction. • B9 displays more better pharmacokinetic properties than the lead XS-060. • B9 effectively inhibits tumor growth in a mice MDA-MB-231 xenograft model. [ABSTRACT FROM AUTHOR]

• Heterogenization of ru through polydopamine and bipyridine on carbon black. • Functionalized carbon Ru-catalysts active in the oxidative cleavage of oleic acid. • Total conversion and 95% of yields after 7 h of stirring at room temperature. • High catalytic activity of carbon black-polydopamine-Ru up to 5 recycling tests. Macroporous oxidized carbon black (CBO) have been functionalized with 4,4′-diamino-2,2′-bipyridine (NH 2 -bpy) and polydopamine (PDA) allowing the complexation of Ru for the catalytic valorization of oleic acid through its oxidative cleavage. This reaction produces azelaic and pelargonic acids which are highly demanded in pharmacology. Conventional bpy is a well-known chelating agent for Ru and the aim of this work is directed to assess its suitability along with polydopamine in building a stable catalyst in the oxidative cleavage reaction. NH 2 -bpy was covalently bonded to COOH groups on CBO surface by amidation through an acylation and cross-linking(NHS/EDC). On its side, dopamine was self-polymerized in contact with CBO. The success of the deposition of NH 2 -bpy and PDA was confirmed by FTIR, TGA, and N 2 physisorption, while Ru complexation was determined by ICP and XPS analyses. Among the three catalysts, the catalyst based on PDA was the most promising one, reaching a complete conversion of oleic acid with yields of pelargonic and azelaic acids around 95%. Although hot-filtration tests confirmed the presence of Ru species in the reaction medium, the PDA catalyst remained active even after five runs. Actually, post-catalysis characterization of the solid revealed that catechol groups of PDA re-adsorb Ru species once the reaction ends thereby ensuring the reusability of the heterogeneous catalyst. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Ru(II)-picolinate photosensitizer bearing four phosphonate groups was synthesized. • Replacement of bipyridine with picolinate red-shifted the MLCT transition. • Rupic @Pt-TiO 2 showed higher activity than Rubpy @Pt-TiO 2 under red light irradiation. To utilize a wider region of the solar spectrum for solar-fuel production, we newly synthesized a heteroleptic Ru(II)-picolinate complex, [Ru(H 4 dpbpy) 2 (pic)]+ (Rupic ; H 4 dpbpy = H 4 dpbpy = 2,2′-bipyridine-4,4′-diphosphonic acid, Hpic = picolinic acid) as a red light-absorbing molecular photosensitizer. Rupic exhibited metal-to-ligand charge-transfer (MLCT) absorption and emission (λ abs and λ em = 491 and 711 nm, respectively) over a longer wavelength region than that observed with the bipyridine derivative [Ru(H 4 dpbpy) 2 (bpy)]2+ (Rubpy , bpy = 2,2′-bipyridine). The Ru(III)/Ru(II) redox potential of Rupic (E ox = +1.07 vs NHE) was approximately 0.27 V more negative than that of Rubpy , owing to the weaker ligand field strength of pic than that of bpy. Moreover, as expected, owing to the red-light absorption ability of Rupic, the photocatalytic H 2 evolution reaction activity of the Rupic -sensitized Pt-TiO 2 nanoparticles (apparent quantum yield, AQY ∼ 3 %) under red light illumination (λ = 625 ± 35 nm) was significantly higher than that of its Rubpy -sensitized analog (AQY ∼ 0.5 %). These results indicate the superior photosensitizing performance of the Ru(II)-picolinate complex for H 2 production under sunlight illumination. [ABSTRACT FROM AUTHOR]

[Display omitted] • Luminescence quenching of the excited 3MLCT by molecular oxygen. • Photosensitized generation of singlet oxygen by heteroleptic ruthenium (II) complexes. • Energy transfer versus charge transfer in the quenching process. • Effect of the partial charge transfer on the efficiency of singlet oxygen production. The photophysical properties of some synthesized heteroleptic polypyridyl ruthenium(II) complexes of the form [Ru(bpy) 2 L](PF 6) 2 where L = 2,2′-bipyridine, 4,4′-dimethoxy-2,2′-bipyridine, 1,10-phenanthroline, 4,4′-dimethyl-2,2′-bipyridine, 4,7-diphenyl-1,10-phenanthroline and 3,4,7,8-tetramethyl-1,10-phenanthroline, are investigated in acetonitrile. The excited state lifetime of the metal to ligand charge transfer (3MLCT) states of these complex ions are found to be ligand dependent and were found to be in the range 0.56 μs to 1.5 μs. Oxygen quenching of the excited states rate constants, k q , were found to be in the range 1.50–2.24 × 109 M−1s−1. Singlet oxygen quantum yield values, Φ Δ , are found to vary from 0.40 to 0.60 and the efficiency, f Δ T , with which excited singlet oxygen, O 2 (1Δ g), is thereby produced was found to be in the range 0.55–0.85. Treatment of the data with charge transfer and non-charge transfer pathways using Schmidt's model shows that partial charge transfer parameter was in the range of 0.18 to 0.58. It has also been found that f Δ T decreases and oxygen quenching rate constants, k q , increases as p CT increases. [ABSTRACT FROM AUTHOR]

[Display omitted] • Electronic aspects of Cu(I) and Cu(II) metal complexes. • Intricate mechanisms of helicate formation and chiral separation. • Generation of reactive oxygen species (ROS) from copper complexes. • Oxygen reduction and water oxidation mediated by copper complexes. • Charge injection onto TiO 2 by copper complexes and ultrafast rearrangement of copper complexes structures. Copper complexes are highly versatile species that find promising uses in broad fields such as catalysis, drug design, and bioinorganic applications. However, copper complexes display a rich chemical behavior in solution due to their oxidation-state dependent geometrical rearrangements that make it daunting to the inexperienced. This review summarizes the advances in the synthesis of copper complexes containing phenanthroline- and bipyridine-like ligands covering from the electronic aspects of Cu(I) and Cu(II) metal ions to the intricate mechanisms of helicate formation and generation of reactive oxygen species (ROS). To illustrate the complexity of Cu complexes and strategies to address it, we will focus on three main aspects of their chemistry: 1) their electronic/geometric structure relationships, 2) the formation and behavior of helicates, and 3) oxygen reaction chemistry with copper complexes. In the first case, g values from EPR spectroscopy are discussed as a powerful method to elucidate the molecular structure of different copper complexes using crystal field approximations and the R parameter. Also, we correlate these with the geometries and the electronic properties observed for different copper species. In the second case, we cover structural changes observed in helicates from the synthesis of tetracoordinate ligands to trimetallic species. We consider relevant equilibria in the helicates, and we discuss the chiral separation of diastereosimers and their properties. In addition, we summarize oxygen reduction by copper(I) complexes and the oxygen adducts determined for hydroxyl and peroxyl radicals in different solvents. Their water oxidation chemistry and the concept of "autoreduction" that many copper complexes have is addressed. Lastly, we revised photoinduced charge transfer activates the electron transfer mechanisms proposed for copper complexes onto support TiO 2 receiving charge injection from copper photosensitizers for use in solar cells. We describe the generation of reactive oxygen species and their detection by EPR. While the reader may find different challenges in their research on coordination chemistry, these three illustrations provide solid examples of how ligand field theory, crystal structure, and spin characterization are used to solve concrete problems posed by Cu chemistry. We hope this review will help jumpstart the novice chemist into the fascinating chemistry of Cu complexes and provide new discussion and conceptual tools to more advanced researchers. [ABSTRACT FROM AUTHOR]

Although a theoretically extensive number of hydrophobic eutectic mixtures suitable for solvent extraction are obtainable, to date reported mixtures rely on a limited number of chelating groups, namely phosphine oxide, carboxylic acid, and ketones. Herein, a new family of Type V Deep Eutectic Solvents (DES) based on the polypyridyl ligand 1,10-phenanthroline (phen) is presented with the aim of facilitating the extrapolation of the disclosed findings to other potential systems based on phen or bipyridine derivatives. The hydrophobic eutectic solvent composed of the natural phenolic extract thymol with phen exhibits a solid-liquid phase diagram with a useable liquidus compositional range on the thymol-rich side. The physical properties of the mixture are dependent on the presence of solutes liable to change the nature of the existing hydrogen-bonded network, most notably through the protonation of phen. The metal chelating ability of phen are retained when included as a DES component. Quantitative extraction of various transition metals cations (Cd(II), Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)) as well as the platinum group metal Pd(II) was obtained across a range of solvent compositions. The extraction of Li(I), Mn(II), Co(II) and Ni(II) was further studied as a function of the aqueous phase pH, with the extent of metal partition decreasing with the protonation of phen at pH values below 1.0. Building upon the luminescent properties of phen, the eutectic solvent was further applied as a simultaneous pre-concentration and quantification medium for Fe(II/III), allowing for the facile UV–vis detection of Fe up to 12 μg L−1. [Display omitted] • Characterisation of hydrophobic eutectic solvents based on 1,10-phenanthroline (phen) and natural phenolic compounds. • Excellent metal extraction capabilities for transition metals. • Protonation of phen under acidic conditions reduces metal partition and alters the properties of the eutectic solvent. • Pre-concentration and detection of Fe(II/III) to μg L−1 levels was achieved in the thymol+phen system. [ABSTRACT FROM AUTHOR]

Metal-ligand axial coordination of zinc(II) phthalocyanines is an efficient strategy for regulation of structures and properties. In this work, we designed and prepared four unsubstituted zinc(II) phthalocyanine (ZnPc) dimer-based supramolecular complexes (1 – 4) via axtial coordination with bipyridine derivatives. Single crystal X-ray analysis revealed that the four novel complexes were dimeric (i.e. ZnPc-ligand-ZnPc), with H-shape for 1 , saddle-like for 2 , and Z-shapes for 3 and 4. It's interesting that a pair of saddle-like dimers of 2 crossed each other to form an interlocked tetramer structure. Furthermore, 3 and 4 were dense stacking because of their semirigid ligands, which significantly enhanced the intermolecular interactions. Intriguingly, in the crystal structure of 4 , the naphthalimide ring of the ligand embedded into two neighboring phthalocyanine macrocycles, resulting in a slipped sandwich structure of ZnPc-naphthalimide-ZnPc with double π···π interactions. More importantly, the strong intermolecular interactions led to very broad absorption spectra in vis-NIR region, quenched fluorescence, and highly efficient photothermal effect. Upon irradiation, 3 and 4 could reach up to 85.7 °C and 89.2 °C, respectively, enabling them to serve as outstanding photothermal conversion materials used for photothermal imaging and therapy. [Display omitted] • ZnPc coordinated with bipyridine derivatives to form four crystal complexes 1 – 4. • Two saddle-like dimers of 2 crossed each other to generate an interlocked tetramer. • The crystal of 4 showed a slipped sandwich structure of ZnPc-naphthalimide-ZnPc. • Stronger molecular interactions of 3 and 4 led to highly efficient photothermal activity. • The photothermal temperature of 3 and 4 reached 85.7 °C and 89.2 °C, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • Bipyridine was derivatized with polycyclic aromatic hydrocarbons. • Theoretical data indicated mixed local and intramolecular charge-transfer states. • Emission spectra of bipyridine derivatives showed dependence on solvent polarity. • Hybridized local and charge transfer states dominate in polar solvents. Photophysical studies of 4′-methyl-2,2′-bipyridine derivatized with the polycyclic aromatic hydrocarbons (PAHs) anthracene (mbpy-anth), naphthalene (mbpy-naph), and pyrene (mbpy-pyr) were acquired in different solvents. While the absorption spectra were not affected by the solvent nature, the emission ones showed red shifts with increase polarity consistent with an intramolecular charge-transfer (ICT) character. Theoretical calculations found a dominant "Hole" → "Particle" contribution for the first five transitions involving local excited-state (LE) and ICT transitions, with the latter being dominant at higher wavelengths (S 0 → 1CT). The fluorescence solvatochromic data suggested a hybridized local and charge transfer (HLCT) state for the mbpy-R compounds with the CT contribution prevailing in high polar solvents; a result that was corroborated by the monoexponential decay lifetimes. The Stokes shifts difference between heptane and dimethylsulphoxide, the most and least polar solvents used in this work, was calculated as 1315, 2969, and 808 cm−1 for mbpy-naph, mbpy-anth, and mbpy-pyr, respectively. The increase of the solvent polarity results in a red shift and a broadening of the emission and excitation bands for mbpy-anth and mbpy-naph with the spectra of the latter being the most affected. For mbpy-pyr, on the contrary, the emission spectra were narrower than the excitation ones indicating the L a transitions lie at lower energy than the L b. For this species, the results indicated an effective mixing of LE and CT states in the moderately polar solvents being in accordance with the observed single exponential decay which is likely related to one hybridized state. [ABSTRACT FROM AUTHOR]

Two new octa-coordinated ternary europium(III) complexes of the type [Eu(btfa) 3 (Br 2 -bpy)] (Eu-1) and [Eu(btfa) 3 (PhE 2 -bpy)] (Eu-2) (where btfa = 4,4,4-trifluoro-1-phenyl-1,3-butanedione, Br 2 -bpy = 5,5′-dibromo-2,2′-bipyridine, PhE 2 -bpy 5,5′-bis(phenylethynyl)-2,2′-bipyridine) together with a previously reported complex [Eu(btfa) 3 (bpy)] (Eu-3) have been synthesized. The complexes have been characterized by analytical and spectroscopic methods. The photophysical properties of the complexes have also been analyzed both experimentally and theoretically. The contribution of each ligand to the sensitized Eu(III) photoluminescence (PL) has been analyzed and is discussed. An energy transfer (ET) mechanism is proposed and discussed for the sensitized Eu(III) emission using experimental and theoretical data. The Eu(III) complex incorporating the parent bpy showed impressive performance as a double-emitting layer (EML) red organic light emitting diodes (R-OLEDs). [Display omitted] • Ancillary ligand PhE 2 -bpy was obtained by the reaction of Br 2 -bpy & phenylacetylene. • Photoluminescent europium complexes (Eu-1 –E u-3) were synthesized and characterized. • Complexes were investigated by detailed photophysical measurements. • Energy transfer mechanism is proposed using experimental and theoretical data. • A red emitting OLED was fabricated using Eu-3 complex with EQE = 2.14% & B = 428 cd/m. [ABSTRACT FROM AUTHOR]

A europium(III) hybrid material Eu(tta)3bpdc-SiO2@mTiO2 (Htta = 2-thenoyltrifluoroacetone, H2bpdc = 2,2′-bipyridine-3,3′-dicarboxylic acid) was successfully designed and synthesized by the covalent grafting complex Eu(tta)3bpdc to SiO2@mTiO2 core–shell nanosphere. The FT-IR, PXRD, XPS, TEM, HRTEM, SAED, TGA and PL were performed to characterize these materials. The results indicate that core–shell nanosphere structure and anatase crystallites of SiO2@mTiO2 are retained well after grafting the europium complex. Hybrid material Eu(tta)3bpdc-SiO2@mTiO2 displays uniform nanosphere structure, bright red color and long lifetime, which can serve as a multicolor emission material modulated by using Al3+ ions via the cation exchange approach under a single-wavelength excitation. To the best of our knowledge, this work is the first multicolor emissive sensor for Al3+ ions based on the lanthanide hybrid material. [ABSTRACT FROM AUTHOR]

Primary tumor targeting is the dominant approach in drug development, while metastasis is the leading cause of cancer death. Therefore, in addition to the cytotoxic activity of a series of Ru(II) polypyridyl complexes of the type [Ru(dip)2L]2+ (dip: 4,7-diphenyl-1,10-phenanthroline while L = dip; bpy: 2,2′-bipyridine; bpy-SC: bipyridine derivative bearing a semicarbazone 2-formylopyridine moiety; dpq, dpq(CH3)2, dpb: quinoxaline derivatives) their ability to inhibit cell detachment was investigated. In vitro studies performed on lung cancer A549 cells showed that they accumulate in cells very well and exhibit moderate cytotoxicity with IC50 ranging from 4 to 13 µM. Three of the studied compounds that have dip, bpy-SC, or dpb ligands after treatment of the cells with a non-toxic dose (<1/2IC50) enhanced their adhesion properties demonstrated by lower detachment in the trypsin resistance assay. The same complexes inhibited both MMP-2 and MMP-9 enzyme activities with IC50 ranging from 2 to 12 µM; however, the MMP-9 inhibition was stronger. More detailed studies for [Ru(dip)2(bpy-SC)]2+, which induced the greatest increase in cell adhesion, revealed that it is predominately accumulated in the cytoskeletal fraction of A549 cells. Moreover, cells treated with this compound showed the localization of MMP-9 to a greater extent also in the cytoskeleton. Taken together, our results indicate the possibility of a reduction of metastatic cells escaping from the primary lesion to the surrounding tissue by prevention of their detachment and by influencing the activity of MMP-2 and MMP-9. [ABSTRACT FROM AUTHOR]