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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]

[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]

Amino acid chirality plays an important role in conveying directionality and specificity to their supramolecular organization. However, the impact of enantiopure and racemic amino acids on the favorable packing and macroscopic properties of organic cocrystals with nonchiral coformers is poorly understood. Herein, we performed a systematic study of the effect of chirality on the macroscopic properties of acetylated alanine (AcA) single crystals and cocrystals with a nonchiral photo-sensitive bipyridine derivative (BPE). Cocrystallization with BPE produced a marked morphology transition that improved the supramolecular chirality, thermal stability and mechanical strength of AcA crystals. The distinct supramolecular packing modes were analyzed by X-ray crystallography. The highest rigidity was observed for BPE/ dl -AcA, while BPE/ d -AcA and BPE/ l -AcA crystals exhibited higher efficiency of photo-induced emission for fluorescent imprinting, as well as significantly higher piezoelectricity. This work provides a striking illustration that subtle differences in amino acid stereochemistry translate into tunable macroscopic properties of organic cocrystals for future applications in rigid solids, fluorescent imprinting, and energy harvesting. [ABSTRACT FROM AUTHOR]

Abstract An electrochromic device, capable of three-level color switching, has been envisaged by exploiting different color switching properties of Ethyl viologen (EV) and Poly (3-hexylthiophene) (P3HT) to make them switch in congruence with each other. The device, consisting of an EV/P3HT bilayer in poly-ethylene oxide matrix, appears magenta, blue or transparent under an appropriate bias. The unbiased device shows magenta colored appearance and turns transparent at a bias of 1 V when P3HT layer is used as anode. The device turns blue on increasing the bias to 1.4 V without changing the polarity. The mechanism of multilevel switching has been identified using UV–Vis and Raman spectroscopic investigations which reveal that the 1 V bias converts the P3HT into polarons and 1.4 V converts the EV dications (EV2+) into free radical. The electrochromic device demonstrates better color contrast (~ 50%) in both the optical domains. The fabricated device shows better switching speeds of ~ 1.5 s and good stability and coloration efficiency along with three-level color switching. However the reported device uses ITO coated glass as substrate, it can be used for all-organic flexible electrochromic device. Graphical abstract fx1 Highlights • Multistage electrochromic device by exploiting electrochromism of P3HT-viologen. • Enhancement in electrochromic performance parameters. • Electrolyte free electrochromic device designed for power efficient operation. • Paving way for all-organic flexible electrochromic device. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • One-pot synthesis of 6-oxo-7-aryl-6,7-dihydrochromenopyrano[2,3- b ]pyridines was described. • Guanidine hydrochloride as the organocatalyst was used. • Aromatic aldehydes containing various functional groups are well tolerated in the reaction. • Double heterocyclization was carried out in the reaction. Abstract A simple and efficient protocol has been developed for the construction of novel 6-oxo-7-aryl-6,7-dihydrochromenopyrano[2,3- b ]pyridine derivatives using one-pot, three-component cyclocondensation of 4-hydroxycoumarin, various aromatic aldehydes and 2-aminoprop-1-ene-1,1,3-tricarbonitrile using 10 mol % guanidine hydrochloride as the organocatalyst under solvent-free conditions at 90 °C for the first time. The significant features of this protocol are operational simplicity, provide good to high yields, avoidance of toxic solvents, straightforward work-up, no column chromatographic purification and atom-economy which is considered to be relatively environmentally benign. [ABSTRACT FROM AUTHOR]

A new symmetrical dinuclear complex of two tricarbonylrhenium(I) moieties, of formula [(CH 3 CN)(CO) 3 Re(4,4″-azobpy) Re(CO) 3 (CH 3 CN)](PF 6 ) 2 , with 4,4″-azobpy = 4,4″-azobis-(2,2′-bipyridine), has been synthesized and characterized by spectroscopic, electrochemical, spectroelectrochemical, photophysical and computational techniques. The bridging azo group in the bipyridyl ring decreases the emission quantum yield of the 3 MLCT lowest-lying excited state respect to similar Re(I) complexes and introduces a new emissive excited state with a longer lifetime, due to increased electronic delocalization in the bridging ligand. When reducing the azo group in CH 3 CN/H 2 O mixtures with sodium dithionite, the emission is enhanced by an order of magnitude. Therefore, this complex can be used as a “molecular switch” with electron and proton additions. Besides, changes in the absorption spectrum on addition of l -Cysteine can be applied for sensing aminoacids with reducing thiol groups. The electronic structures calculated by DFT methods agree reasonably well with experimental results. [ABSTRACT FROM AUTHOR]

We report the study of a series of Ru-bipyridine (Ru-Bpy) complexes to correlate their photophysical and electrochemical properties to their performance in [4 + 2] cycloadditions, as a model reaction for electron transfer catalysis. Redox potentials, absorption and emission spectra, quantum yields and DFT calculations are presented to understand the catalytic transformation. The study shows that complex [Ru(Bpy) 3 ](PF 6 ) 2 is the more active photocatalyst, giving complete conversion to the product after 2 h reaction under white light. Any substitution in the para position of the Bpy ring decreases the reaction conversion. The [4 + 2] cycloaddition can be performed with different substrates and dienes, using either acetonitrile or nitromethane as solvents. Mechanistic studies suggest that the active catalyst for the transformation is [Ru(Bpy) 3 ] 3+ and that the rate determining step is the oxidation of [Ru(Bpy) 3 ] 2+ to generate the corresponding Ru 3+ species. [ABSTRACT FROM AUTHOR]

Manganese carbonyl complexes have become popular homogeneous catalysts for carbon dioxide electro- or photoreduction since the beginning of the 2010s. This article presents a comprehensive survey of all the Mn carbonyl systems reported during the last decade as being active catalysts for CO 2 reduction, with a comparison of their activity, stability and selectivity under electroreduction and, for some of them, photoreduction conditions. The development of in situ spectroelectrochemical techniques, often backed by DFT calculations, has enabled gaining more insight into the associated catalytic mechanisms and reaction intermediates. Though manganese tricarbonyl compounds featuring a bipyridine derivative have been by far the most studied, alternative Mn coordination spheres have recently been explored, opening a way towards new families of potential catalysts for homogeneous and heterogeneous CO 2 reduction. [ABSTRACT FROM AUTHOR]

Two novel D-π-A-π-D structural 2,2 ′ -bipyridine derivatives based on different electron donors, namely aza-crown ether and triphenylamine groups were synthesized and characterized. One of which was characterized by single crystal X-ray diffraction determination. Their linear photophysical properties were systematically investigated in various solvents. The two-photon excited fluorescence were investigated. The two dyes both exhibited excellent one- and two-photon excited fluorescence as well as high quantum yield and large two-photon absorption cross-section ( δ ). Fluorescence microscopy imaging of them in NIH/3T3 cell line was studied. The result indicated that both of them exhibit excellent biological compatibility. [ABSTRACT FROM AUTHOR]

Six new lanthanide complexes [Ln(2-Br-5-MOBA) 3 (2,2′-DIPY)] 2 (Ln = Nd( 1 ), Eu( 2 ), Gd( 3 ), Tb( 4 ), Ho( 5 ), Er( 6 ); 2-Br-5-MOBA = 2-bromine-5-methoxybenzoate; 2,2′-DIPY = 2,2′-bipyridine) have been successfully synthesized and characterized. The complexes 1 – 5 are isostructural and nine-coordinated by the single-crystal X-ray diffraction analyses, while the complex 6 is eight-coordinated. The difference of crystal structure may be the result of the lanthanide contraction effect. The binuclear units were further assembled into 1D, 2D, 3D supramolecular structures by the π-π stacking and C H⋯O hydrogen bonding interactions. The thermal decomposition mechanism of complexes 1 – 6 was studied by TG analysis and further authenticated by TG/DSC-FTIR techniques. The solid-state luminescence properties of complexes 2 and 4 were investigated at room temperature. The results indicate that complexes 2 and 4 show characteristic emission of Eu 3+ ion and Tb 3+ ion, respectively. What's more, the title complexes have good antibacterial activities against Candida albicans . [ABSTRACT FROM AUTHOR]

The article describes the interaction of Y(III), Zr(IV), La(III), Ce(IV) and U(VI) with moxifloxacin hydrochloride and 2,2′-bipyridine. Characterization of complexes was made by elemental analyses, molar conductivity, magnetic moment measurements and spectral measurements e.g. IR, UV–Vis., 1 H NMR and mass as well as thermal analyses (TG and DTG). The molar conductivity shows that the complexes are electrolytes nature. Spectroscopic investigation of the solid complexes studied here indicate that moxifloxacin hydrochloride and 2,2′-bipyridine are coordinated to the metal ions in a neutral bidentate manner. After complete characterization, the chemical formulae of the complexes were established. The calculated bond length and force constant, F(U O), in the uranyl complex are 1.756 Å and 637.90 Nm −1 , respectively. Kinetic and thermodynamic parameters were determined using Coats–Redfern and Horowitz–Metzger equations. Establishment of hydrochloric acid that induce acute lung injury (ALI) in rats by intratracheal administration through damaging the alveolar epithelium and activation of the neutrophil and subsequent oxidative stress by increasing malondialdehyde (MDA), tumor necrosis factor (TNF-α) and neutrophil, which were confirmed by histopathological investigation while decreasing in antioxidant enzymes and lymphocytes. Whereas treatment with mixed-ligand metal complexes significantly decrease MDA, TNF-α and neutrophils and increase antioxidant and lymphocytes. [ABSTRACT FROM AUTHOR]

The electronic structure of thiazolo[3,2- a ]pyridine and some of its derivatives are investigated theoretically using B3LYB/6-311G (d, p) method. The calculations show that all the studied compounds 1 – 5 are non-planar, as indicated from the dihedral angles. The electronic absorption spectra of the studied compounds are recorded in the UV–VIS region, in both DMF and Dioxane solvents. Assignments of the observed electronic transitions are facilitated via time-dependent density functional theory (TD-DFT) computations. Band maxima ( λ max ) and intensities of the spectra are found to have solvent dependence reflected as blue and red shifts. Electronic configurations contributing to each excited state are identified and the relevant MOs are characterized. The extent of delocalization and intermolecular charge transfer are estimated and discussed in terms of natural bond orbital (NBO) analysis and second order perturbation interactions between donor and acceptor MOs. The theoretical spectra computed at “A new hybrid exchange-correlation functional using the Coulomb-attenuating method (CAM-B3LYP),” at the 6-311G (d, p) bases set in gas phase and with the Polarizable Continuum Model (PCM) in Dioxane and DMF indicate a good agreement with the observed spectra. [ABSTRACT FROM AUTHOR]

Two bis -bromo substituted imidazo-[1,5- a ]-pyridine derivatives IMPY1 and IMPY2 were synthesized from a 2:1:2 mixture of ortho / meta -bromobenzaldehyde, 2-cyanopyridine and ammonium acetate. The compounds IMPY1 and IMPY2 exhibit blue fluorescence in both THF and methanol solution and their highly fluorescent nature is revealed by the quantum yields Φ F ranging from 9.3 to 10.4%. The crystal structure of the compounds are stabilized by various weak, non-classical hydrogen bonds viz. C−H⋯N, C−H⋯Br and C−H⋯π as well as type II interhalogen and C−Br⋯π halogen bonds. The supramolecular features and electronic property of these compounds have been thoroughly analyzed with the aid of DFT, TD-DFT and molecular electrostatic potential (MEP) analyses. [ABSTRACT FROM AUTHOR]

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]

A series of mercury(II) complexes, [Hg(N N)(SCN) 2 ] (N N is 4,4′-dimethyl-2,2′-bipyridine in 1 , 5,5′-dimethyl-2,2′-bipyridine in 2 , 6,6′-dimethyl-2,2′-bipyridine in 3 and 6-methyl-2,2′-bipyridine in 4 ), were prepared from the reactions of Hg(SCN) 2 with mentioned ligands in methanol. Suitable crystals of these complexes were obtained for X-ray diffraction measurement by methanol diffusion into a DMSO solution. The four complexes were thoroughly characterized by spectral methods (IR, UV–Vis, 13 C{ 1 H}NMR, 1 H NMR and luminescence), elemental analysis (CHNS) and single crystal X-ray diffraction. The X-ray structural analysis indicated that in the structures of these complexes, the mercury(II) cation is four-coordinated in a distorted tetrahedral configuration by two S atoms from two thiocyanate anions and two N atoms from one chelating 2,2′-bipyridine derivative ligand. Also, in these complexes intermolecular interactions, for example C H⋯N hydrogen bonds (in 1 – 4 ), C H⋯S hydrogen bonds (in 1 , 2 and 4 ), π … π interactions (in 2 – 4 ), Hg⋯N interactions (in 2 ) and S⋯S interactions (in 4 ), are effective in the stabilization of the crystal structures and the formation of the 3D supramolecular complexes. Furthermore, the luminescence spectra of the title complexes show that the intensity of their emission bands are stronger than the emission bands for the free bipyridine derivative ligands. [ABSTRACT FROM AUTHOR]

We previously reported a novel series of 1 H -pyrazolo[3,4- c ]pyridine derivatives and the identification of compound 4b as a highly potent GPR119 agonist. However, the advancement of preclinical evaluations of compound 4b is expected to be difficult because of the compound’s significantly poor aqueous solubility (0.71 μM at pH6.8). In this article, we describe the further optimization of compound 4b focusing on the improvement of its aqueous solubility. Optimization of the central spacer, left-hand aryl group and right-hand piperidine N -capping group led to the identification of a potent GPR119 agonist, 3 H -[1,2,3]triazolo[4,5- c ]pyridine derivative 32o , with improved solubility (15.9 μM at pH6.8). [ABSTRACT FROM AUTHOR]

Nitrato briged dinuclear complexes of type [Cu 2 (L) 2 (bpy) 2 (NO 3 )](NO 3 )·4H 2 O, 1 and [Zn 2 (L) 2 (bpy) 2 (NO 3 )](NO 3 )·4H 2 O, 2 (L = deprotonated form of free ligand LH, [1-(2-hydroxyphenyl)-3-(9-anthracenyl) propenone; bpy = 2,2′bipyridine] are synthesized and characterized using a battery of physicochemical techniques and X-ray crystallography. A distorted square pyramidal geometry is assigned to them with N 2 O 3 coordination core around the metal ion. The co-ligand L binds the metal ions through its O , O' atoms in anti-syn mode. The metal centers in complexes 1 and 2 are separated via bridging nitrato group at a distance of 6.073 Å and 5.635 Å respectively. Their structures and absorption spectra are supported by the computational studies using density functional theory (DFT) and TD-DFT. Both complexes exhibit nuclease activity and cleave supercoiled (form I) DNA. The complex 1 preferentially binds major groove of DNA and follows an oxidative pathway whereas complex 2 binds with minor groove of DNA via hydrolytic pathway. Both complexes inhibit topoisomerase I relaxation activity with IC 50 values of 7 and 35 μM. Molecular docking studies support the groove binding and topoisomerase I binding of the complexes. The complex 1 showed a significant cytotoxicity against HeLa cell lines (a cervical cancer cell lines) in vitro with IC 50 value calculated as 2.9 ± 0.021 μM as compared to 28.2 ± 0. 044 μΜ for complex 2 . Complex 2 induces the cell apoptosis at a later-stage as compared to complex 1 . The cell apoptosis and topoisomerase inhibition by complexes enable them to be potential candidates as future anticancer drugs. [ABSTRACT FROM AUTHOR]

In the protein chemical synthesis via native chemical ligation (NCL) method with three peptide segments, the N-terminal cysteine residue of middle segment is generally protected by thiazolidine ring. In this paper, we show the novel method for thiazolidine ring opening using 2,2′-dipyridyl disulfide (DPDS). The N-terminal thiazolidine was converted into S -pyridylsulfenylated cysteine residue with DPDS under acidic conditions, and this N-terminally Cys peptide protected with disulfide was applicable to NCL reaction without purification and deprotection steps. DPDS treatment did not remove other Cys protecting groups generally used for regioselective disulfide bond formation reactions. These results indicate that this thiazolidine ring opening reaction is quite useful for the protein chemical synthesis with three-segment NCL strategy. [ABSTRACT FROM AUTHOR]

Herein, we report the synthesis of zirconium metal-organic frameworks by a mechanochemical route. The frameworks are obtained by the coordination of a zirconium cluster with the biphenyldicarboxylic acid linker to obtain UiO-67 or with the iso-structural 2,2′-bipyridine-5,5′-dicarboxylic acid to access to a functional MOF ( UiO-67-bpy ). In a second mechanochemical reaction, it has been possible to coordinate by post-synthetic modification a copper salt on each bipyridine site ( UiO-67-bpy-Cu ). Both materials exhibit crystallinity and porosity (up to 750 m 2 /g) showing the possibility to get access to elaborated materials in a cleaner way than the classical solvothermal route in DMF. [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]

Nowadays, the design and development of novel phosphorescent iridium(III) complexes for various optoelectronic applications is a well-recognized area of research. The fascinating photophysical properties of iridium(III) compounds are strongly influenced by the spin-orbit coupling exerted by the iridium(III) core, usually resulting in intense emissions with short excited-state lifetimes, which can be precisely controlled with the aid of molecular engineering of the chelating ligand. This review focuses on the recent developments and state of the art knowledge on phosphorescent iridium(III) compounds, especially on heteroleptic complexes derived from 2,3′-bipyridine class of cyclometalating and ancillary ligands, highlighting the excited state phenomenon behind their emission behavior. [ABSTRACT FROM AUTHOR]

We report the synthesis and properties of new ruthenium- p -cymene complexes [(η 6 - -cymene)Ru(L)Cl][Cl] prepared from tetracarboxylic acid ligands L = 3,3′,4,4′-tetracarboxylicacid-2,2′-bipyridine (3,3′,4,4′-H 4 tcbpy), their methyl and ethyl ester derivatives (R 4 tcbpy), 4,4′,5,5′-tetracarboxylicacid-2,2′-bipyridine (4,4′,5,5′-H 4 tcbpy), and 4,4′-di- n -nonyl bipyridine (4,4′-dnbpy). The complexes were fully characterized by NMR, IR, MS, elemental analysis, UV–vis spectroscopy, and cyclic voltammetry. The single-crystal structure of [(η 6 - p -cymene)Ru(4,4′,5,5′-H 4 tcbpy)Cl]Cl 2 shows a ‘piano stool’ geometry with Ru-C (2.177(2)-2.231(2) Å), Ru-N (2.0791–2.0801 Å) distances and an N-Ru-N bond angle (77.4°) similar to equivalents in the 4,4′-dicarboxylic acid sister complex. Compared to the latter and also the 4,4′-dnbpy derivative 3 , the UV–vis spectra show MLTC absorptions of the tetracarboxylates shifted to lower energy. The CVs show Ru(II/III) oxidation processes at 0.56–0.98 V ( vs Fc/Fc + ), depending on the ligand substitution. Changes in the electronic situation at the Ru centre reflected in the UV–vis and voltammetric data are correlated to HOMO levels calculated from photoelectron spectroscopy in air spectra recorded for all complexes. According to NMR experiments rapid ligand dissociation occurred when dissolving [(η 6 - p -cymene)Ru(3,3′,4,4′-Me 4 tcbpy)Cl]Cl 1b in DMF. In hot DMF decarboxylation led to the isolation of the 4′-dicarboxylic acid complex derivative. [ABSTRACT FROM AUTHOR]

In-situ Raman/SERS studies of molecular adsorption/reaction behaviors at well-defined electrochemical interfaces are important for understanding the fundamentals of electrochemical processes. However, it is still a great challenge to perform such studies on model single-crystal surfaces as the smooth surface cannot support surface plasmon resonance (SPR). In this work, shell-isolated nanoparticle-enhanced Raman spectroscopy was combined with an electrochemical method (EC-SHINERS) to study the adsorption and redox transformation of a resonant molecule viologen HS-8V8H at Au(hkl) single-crystal electrodes. Changes in the molecular structure with potential were identified on different single-crystal surfaces, which explained the transformation process of viologen from V 2 + state to V + and then V 0 . Facet-dependent SERS enhancement was also observed, which results from the different imaginary part of the dielectric function on Au(111), Au(100) and Au(110), and is supported by the FEM simulations. Furthermore, a nonlinear resonant Raman process has been directly observed in our experiments, which is consistent with the simulation results. These findings increase our understanding of the electrochemical behavior of molecules in model systems. [ABSTRACT FROM AUTHOR]

Reaction of 6-methoxy-2,2′-bipyridine (bpy 6OMe ) with the electron-rich platinum(II) complex [Pt(Me) 2 (DMSO) 2 ] gave the rollover cyclometalated complex [Pt(κ 2 -N,C-bpy 6OMe -H) (Me) (DMSO)] under mild conditions. The occurrence of rollover cyclometalation was demonstrated by single crystal X-ray diffraction structure determination. In contrast, reaction of bpy 6OMe with [Pt(Ph) 2 (DMSO) 2 ] and [Pt(Cl) 2 (DMSO) 2 ] under mild conditions gave only adduct species of the type [Pt(X) 2 (bpy 6OMe )] (X = Ph, Cl). Under harsher conditions, activation of a C H bond in the methoxy substituent yielded the terdentate cyclometalated complex [Pt (κ 3 -N,N,C-bpy 6OMe -H)Cl]. Finally, reaction of Pd(II) and Au(III) derivatives invariably gave adduct species, with the exception of the dimeric complex [Pd(κ 2 -N,C-bpy 6OMe -H) (OAc)] 2 , which, however, was not isolated in pure form. The reactivity of bpy 6OMe , as emerged from this study, was compared with that of the corresponding disubstituted ligand 6,6′-dimethoxy-2,2′-bipyridine, previously studied by us. [ABSTRACT FROM AUTHOR]

Six series of novel 4-(2-fluorophenoxy)-3,3′-bipyridine derivatives conjugated with aza-aryl formamide/amine scaffords were designed and synthesized through a structure-based molecular hybridization approach. The target compounds were evaluated for c-Met kinase inhibitory activities and cytotoxicity against four cancer cell lines (HT-29, A549, MKN-45 and MDA-MB-231) in vitro . Most compounds exhibited moderate to excellent potency, and the most promising candidate 26c (c-Met kinase IC 50 = 8.2 nM) showed a 4.7-fold increase in cytotoxicity against c-Met-addicted MKN-45 cell line in vitro (IC 50 = 3 nM), superior to that of Foretinib (IC 50 = 23 nM). The preliminary structure–activity relationship indicated that a 1 H -benzo [e] [1,3,4]thiadiazine-3-carboxamide-4,4-dioxide moiety as linker contributed to the antitumor potency. [ABSTRACT FROM AUTHOR]

Electronic structures of ruthenium complexes [Ru(bpy) 2 (L)] 2+ were studied by DFT calculations, where bpy is 2,2′-bipyridine and L's are its derivatives. They are parent ( 1 ) and five complexes with L = 4,4′-dimethyl-2,2′-bipyridine ( 2 ), 6,6′-dimethyl-2,2′-bipyridine ( 3 ), biquinoline ( 4 ), 5-nitro-1,10-phenanthroline ( 5 ) and two acetonitrile molecules ( 6 ). These complexes were characterized by ESI-MS, 1 H NMR, UV–vis spectroscopy and elementary analysis. The crystal structures of 3· (PF 6 ) 2 , 4· (PF 6 ) 2 , 5· (PF 6 ) 2 and 6· (PF 6 ) 2 were also determined. Spin densities were analyzed to characterize the excited triplet states in those complexes. It was found that the complexes have three triplet (called here 3 MLCT, 3 MC 1 and 3 MC 2 ) states. The 3 MC 1 and 3 MC 2 states have elongated Ru N bonds and large spin densities on Ru 2+ . Those states are stable and would lead to the nonradiative relaxation to the ground state. In particular, those of 3 , 5 and 6 are very stable, which results in their poor quantum yields ( Φ < 0.01) of the emissions. In contrast, both 1 and 2 showed the 3 MLCT states. Energy gaps between triplet and ground states were compared with energies corresponding to wavelengths of emission spectra of 1 – 5 . Good agreement between the calculated and the experimental energies was found. Moreover, dual emission which depends on the excitation wavelength was observed in complex 4 . [ABSTRACT FROM AUTHOR]

Herein, we presented an in-situ hydrothermall y synthesized photoluminescent zinc(II) coordination polymer (Zn–CP), namely [Zn 2 (tzeba) 2 (bpy)] n 1 , in which H 2 tzeba = 3-(1-tetrazol-ethyl)benzoic acid, bpy = 4,4′-bipyridine. Compound 1 exhibits ligand-centered photoluminescence (PL) and displays interesting dual emissions based on the excitation of different chromophores from the mixed organic ligands. The PL colors of 1 could be tuned from blue-to-cyan-to-green directly by varying the excitation wavelengths. The PL mechanism has been investigated by the density of states (DOS) and density functional theory (DFT) calculations. [ABSTRACT FROM AUTHOR]

The synthesis, the NMR characterization and the crystal structure of 6-Chloro 4,4′-dimethyl 2,2′-bipyridine and of the reaction intermediate 4,4′-Dimethyl 2,2′-bipyridine N-Oxide are here reported. The target compound crystallizes in the orthorhombic system while the intermediate is monoclinic. In both structures, the molecules are linked by weak interactions. The structure of the reaction intermediate N-oxide is characterized by a dihedral angle between the two phenyl rings of 161.77° while the other is almost planar with a dihedral angle of 179.15°. The crystal packing was investigated, also with the aid of Hirshfeld surface analysis. In the N-oxide reaction intermediate the packing is governed by CH–O interactions, while in the product the packing is simply driven by minimizing the voids and thus maximizing the density, with a prevalence of H•••H and C•••H contacts, as indicated by fingerprint decomposition analysis. [ABSTRACT FROM AUTHOR]

An operationally simple visible light mediated intramolecular cyclization of benzimidazole to 2-amino benzimidazole hybrid. The disclosed procedure is rapid and the convenient synthesis of benzimidazole–amine hybrids from easily available substituted cyclic, acyclic amines, and benzimidazole under neat conditions in the presence of catalyst tris(2,2-bipyridine)ruthenium(II) chloride. Indubitably this methodology gives a facile and straightforward pathway to construct benzimidazole–amine hybrid derivatives in an eco-friendly fashion. The reaction proved to be economical interims of product yield, low loading of catalyst under solvent free condition. The solvent free method has supreme importance in industrial research. The scope and efficiency of this new green method is significantly better than the existing methods. [ABSTRACT FROM AUTHOR]

The synthesis of 4,4′-dibenzodifuran-2,2′-bipyridine derivatives as ligands of organic ruthenium dyes for DSSC applications is described. Two new heteroleptic ruthenium complexes have been prepared and compared with commercially available N719 and Z907 dyes, using dip dyeing and flow dyeing methods in large area testing cells prepared for industrial purposes. The newly synthesized dyes revealed higher solar-to-electric energy conversion efficiency ( η ), measured at the AM1.5G conditions, up to 21% compared to N719 and up to 46% compared to Z907 , and external quantum efficiency of 53%. These results can be explained by enhanced light-harvesting of the benzodifuran moiety of the dyes that is related to photocurrent. [ABSTRACT FROM AUTHOR]

A new family of eight ruthenium(II)-cyclopentadienyl bipyridine derivatives, bearing nitrogen, sulfur, phosphorous and carbonyl sigma bonded coligands, has been synthesized. Compounds bearing nitrogen bonded coligands were found to be unstable in aqueous solution, while the others presented appropriate stabilities for the biologic assays and pursued for determination of IC 50 values in ovarian (A2780) and breast (MCF7 and MDAMB231) human cancer cell lines. These studies were also carried out for the [ 5 : HSA] and [ 6 : HSA] adducts (HSA = human serum albumin) and a better performance was found for the first case. Spectroscopic, electrochemical studies by cyclic voltammetry and density functional theory calculations allowed us to get some understanding on the electronic flow directions within the molecules and to find a possible clue concerning the structural features of coligands that can activate bipyridyl ligands toward an increased cytotoxic effect. X-ray structure analysis of compound [Ru(η 5 -C 5 H 5 )(bipy)(PPh 3 )][PF 6 ] ( 7 ; bipy = bipyridine) showed crystallization on C2/c space group with two enantiomers of the [Ru(η 5 -C 5 H 5 )(bipy)(PPh 3 )] + cation complex in the racemic crystal packing. [ABSTRACT FROM AUTHOR]

Five new organometallic Ru(II) compounds (VI−X) with the general formula [Ru(η 6 -arene)( N , N )Cl]PF 6 , where arene- N , N correspond to methylisoeugenol-bipyridine (VI); anethole-bipyridine (VII); methylisoeugenol-ethylenediamine (VIII); anethole-ethylenediamine (IX) and methylisoeugenol-1,2-diaminobenzene (X), have been synthesized, fully characterized and biologically evaluated in vitro . The reaction conditions based on the reduction of [Ru(1,5-COD)Cl 2 ] n in situ with methyleugenol and estragole, which are natural ligands, induced an alkene isomerization on the allylic substituent of coordinated arenes. The Ru(II)-arene bond formation and isomerization of the C C bond on the allyl substituent was confirmed using 1 H NMR spectroscopy; this result was validated for compound VIII by X-ray diffraction. An XRD analysis revealed the presence of both enantiomers of the complex in the single-crystal. Compounds IX and X exhibited a better cytotoxic activity in vitro than carboplatin, which is a commercial drug, against three human tumor cell lines (MCF-7, PC-3 and HT-29). [ABSTRACT FROM AUTHOR]

A mild heterogeneous oxidizing agent, cupric bromide has been utilized for the oxidative aromatization of Hantzsch 1,4-dihydropyridines to the corresponding pyridine derivatives in excellent yields with the isolation of products by simple work-up procedure. [ABSTRACT FROM AUTHOR]

The compounds MoO2Cl2L (L = 2,2′-bipyridine (bipy) (1); 4,4′-di-tert-butyl-2,2′-bipyridine (di- t Bu-bipy) (2)), [MoO2Cl2(H2O)2]·(diglyme)2 (3), MoO2Cl2 (4), MoO2(CH3)2L (L = bipy (5); di- t Bu-bipy (6)), [MoO3(bipy)] n (7), {[MoO3(bipy)][MoO3(H2O)]} n (8), [Mo8O22(OH)4(di- t Bu-bipy)4] (9) and MoO3 (10) were tested as phosphoester bond hydrolysis promoters in aqueous media. Sodium para-nitrophenylphosphate (pNPP) was used as a model substrate for the phosphoester bond hydrolysis reaction, which was performed at 55 °C, using D2O as solvent and 100 or 10 mol% of the chosen promoter. The progression of all the reactions was monitored by 1H NMR spectroscopy. All studied systems promote phosphoester bond hydrolysis. The best performance was obtained with MoO2Cl2L compounds (1–4) and with the inorganic–organic hybrid {[MoO3(bipy)][MoO3(H2O)]} n (8). The studied compounds originate either homogeneous or solid/liquid biphasic systems. For the biphasic systems (1, 2, 5–9), the solid phase was recovered at the end of the reaction and characterized by FT-IR spectroscopy. [ABSTRACT FROM AUTHOR]

Highlights: [•] Four azobipyridines were synthesized. [•] Based on the DFT modeling the structures of these compounds were proposed. [•] The vibrational characteristics of the azo-bond were reported. [•] The role of substitution position of the methyl group was discussed. [ABSTRACT FROM AUTHOR]

Highlights: [•] Synthesis and characterization of two novel 6′-phenyl-2,2′-bipyridine ligands (L1, L2) and their CdL1,2 I2 complexes are presented. [•] Single crystal study indicated that Cd(II) ion is in a distorted tetrahedral structure. [•] Linear absorption and single-photon exited fluorescence properties have been investigated. [•] The results showed that the complex 2 has the longest fluorescence lifetime. [•] Linear absorption spectral features are studied by TD-DFT methods. [Copyright &y& Elsevier]

Abstract: Three classes of fused bipyridine heterocycles were designed, synthesized and evaluated for their antimycobacterial activities. The method for preparation of fused bipyridine derivatives is straight and efficient. The primary antimycobacterial screening reveals that mono-indolizine mono-salts are displaying potency superior to the second-line antitubercular drugs Cycloserine and Pyrimethamine and, equal as the first line anti-TB Ethambutol. The data from Cycle-2 screening assay (MIC, MBC, LORA, intracellular (macrophage) drug screening, and MTT cell proliferation) confirm the promising anti-TB results from Cycle-1 for mono-indolizine mono-salts. These data indicate that mono-indolizine mono-salt 6d is a potent compound against both replicating and non-replicating Mycobacterium tuberculosis, is active against both extracellular and intracellular organisms, has a bacteriostatic mechanism of action and has basically no toxicity. We see no influence concerning the anti-TB activity of the fused-pyridine substituents. [Copyright &y& Elsevier]

Abstract: Coordination chemistry of 2,2′-bipyridine bearing an ortho-substituted phenyl group at the 6-position, i.e., 6-(o-X-phenyl)-2,2′-bipyridine (MeO-L: X = OMe; Me2N-L: X = NMe2) with [Ru(ttpy)Cl3] (ttpy = 4′-(4-tolyl)-2,2′;6′,2″-terpyridine) was investigated. The reaction of MeO-L and [Ru(ttpy)Cl3] in the presence of N-methylmorpholine afforded demethylated, O-coordinated complex [Ru(O-L)(ttpy)]+ (O-L: X = O) as well as the cyclometalated, C-coordinated complex [Ru(MeO-L)(ttpy)]+. On the other hand, reaction of Me2N-L and [Ru(ttpy)Cl3] in the presence of N-methylmorpholine afforded only N-coordinated complex [Ru(Me2N-L)(ttpy)]2+. The crystal structures, spectroscopic and redox properties were examined supplemented by DFT calculations. The spectroscopic and redox properties of RuN are more or less similar to those of [Ru(ttpy)Cl3]. On the other hand, the properties of RuC and RuO are mutually similar but significantly different from those of RuN. The anionic ligand in RuC and RuO raises the HOMO energy as compared to the neutral ligand in RuN, which is manifested in negatively shifted redox potentials, particularly the oxidation potentials, and thus, the red shift in the visible absorption band. Relevance of these complexes to sensitizers for dye-sensitized solar cells is briefly discussed. [Copyright &y& Elsevier]

Abstract: Two novel 6-phenyl-2,2′-bipyridine derivatives based on aza-crown ether groups were synthesized and characterized, one of which was characterized by single crystal X-ray diffraction determination. Their linear photophysical properties were systematically investigated in various solvents. The nonlinear photophysical properties were investigated by two-photon induced fluorescence method. Both dyes exhibited large two-photon absorption cross-section (δ 2PA ). The cytotoxicity of the dyes was evaluated in HepG2 cell line to assess the potential application for biomedical imaging. Two-photon fluorescence microscopy (TPFM) imaging of two dyes in HepG2 cell line was demonstrated, which indicated that introduction of the hydrophilic aza-crown ether facilitates biological compatibility of dyes. [Copyright &y& Elsevier]

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]

Abstract: A new fluorescent bipyridine derivative 1-(2-amino-5-formylphenyl)-2-[2-amino-5-[(E)-2-[6-(6-methylpyridin-2-yl)pyridin-2-yl]vinyl]phenyl]ethane-N,N,N′,N′-tetraacetic acid (abbreviated as BPYTA) has been synthesized and characterized, which can be dissolved in water. Then its optical properties have been studied. When Zn2+ ion is added into BPYTA solution, the fluorescence intensity has a linear relationship with the concentration of Zn2+ ion. Meanwhile, BPYTA has little response to the existence of many other metal ions, especially Cd2+ ion. Thus, BPYTA has potential application in determining trace Zn2+ ion in water. [Copyright &y& Elsevier]

Abstract: Two new compounds containing chiral cations and anions, [M(bpy)3][VO(O2)(ox)(bpy)]2⋅7H2O (M =Fe, Ni; bpy =2,2′-bipyridine; ox =oxalato(2–)) have been prepared and characterized by elemental analysis, vibrational spectra in the solid state, and by 51V NMR and electronic spectroscopy in solution. The compounds are isostructural and racemic. The crystal structure contains two kinds of alternating (homochiral) triple layers: (i) the layer formed by Δ-[M(bpy)3]2+ cations intercalated between two layers of A-[VO(O2)(ox)(bpy)]−, and (ii) the layer formed by Λ-[M(bpy)3]2+ cations intercalated between two layers of B-[VO(O2)(ox)(bpy)]− (A- and B-denote different enantiomers of anions). [Copyright &y& Elsevier]

Abstract: Two organic co-crystals namely, 4,4′-bipyridine-bis(N-phenylanthranilic acid) (1) and 4,4′-bipyridinium bis(3-carboxypyridine-2-carboxylate) (2) have been synthesized and studied by FT-IR, TGA/DTA, and single crystal XRD studies. The crystal system of co-crystal 1 is triclinic with space group P1 and Z =4 and that of co-crystal 2 is monoclinic with space group P21/n and Z =2. Intermolecular hydrogen bonds, ON, with graph set designator (10) play a vital role in the formation of the co-crystal 1. Intramolecular hydrogen bond S(6) is also present in 1 and there is no π–π interaction. Whereas in co-crystal 2, the intermolecular hydrogen bonds NN with graph set designator (12), OO with graph set designator D, and the π–π interactions together play a major role in stabilizing the structure. [Copyright &y& Elsevier]

Nucleophilic substitutions involving [Ru(η2-bipy)2(η2-bipy–Cl2)]2+2PF6 − (bipy=2,2′-bipyridine; bipy–Cl2=4,4′-dichloro-2,2′-bipyridine) and NaSH or LiS(p-tol) (p-tol=4-CH3–C6H4), carried out in tetrahydrofuran at 115 °C, lead to [Ru(η2-bipy)2(η2-bipy–(SH)2)]2+2PF6 − or [Ru(η2-bipy)2{η2-bipy–(S(p-tol))2}]2+2PF6 −, respectively. Treatment of [Ru(η2-bipy)2(η2-bipy–Cl2)]2+2PF6 − with NaCN in methanol at 55 °C leads to [Ru(η2-bipy)2{η2-bipy–(OCH3)2}]2+2PF6 −. The complexes [Ru(η2-bipy)2(η2-bipy–X2)]2+2PF6 −, with X=Cl and OCH3, were structurally characterized by single crystal X-ray diffraction. Some spectroscopic features of the products are presented. [Copyright &y& Elsevier]