2-phenylpyridine Research Articles

An Unconventional trans - exo -Selective Cyclization of Alkyne-Tethered Cyclohexadienones Initiated by Rhodium(III)-Catalyzed C–H Activation via Insertion Relay

Different from the established trans-endo-selective cyclization of alkyne-tethered electrophiles that involve an E/Z isomerization process, herein, the authors present a novel strategy to allow tra...

Synthesis and characterization of new yellow emitting mixed heteroleptic Ir(III) complexes with solution-processed phosphorescent organic light-emitting diodes

Two new yellow emitting heteroleptic Ir(III) complexes are designed and synthesized for solution-processed yellow phosphorescent organic light-emitting diodes (PHOLEDs) with the amide-bridge core as main ligand and 2-phenylpyridine (ppy) as the ancillary ligand, named as bis[5-(2-ethylhexyl)−8-(trifluoromethyl)benzo[c][1,5]naphthyrid in-6(5)one](phenylpyridine)iridium(III) (Ir-1) and bis[5-(2-ethylhexyl)benzo[c][1,5naphthyridin-6(5H)one](phenylpyridi ne)iridium(III) (Ir-2). Ir-1 and Ir-2 complexes emit bright yellow emission in dichloromethane solution at 298 K. The newly synthesized Ir(III) complexes reveals the higher quantum yields over 40% and relatively short triplet lifetimes (0.12–0.15 μs), both which warrant to both complexes highly electroluminescence active materials. Both Ir(III) complexes were utilized as emitters for yellow solution-process PHOLEDs and obtained better performance. In particular, maximum external quantum efficiency (EQEmax) and maximum current efficiency (CEmax) of of 13.38% and 39.54 cd A−1 with the CIE (x, y) coordinates of (0.45, 0.53) was achieved for Ir-1 based yellow device. Furthermore, PHOLEDs with Ir-2 as an emitter attained EQEmax of 11.71% and CEmax of 37.60 cd A−1 with good color purity.

Catalytic studies of cyclometalated gold(III) complexes and their related UiO-67 MOF

Cyclometalated gold(III) complexes Au(L)(OAcF)2 (L = phenylpyridine dicarboxylic diester (ppyde) or phenylpyridine dicarboxylic acid (ppydc)) have been prepared reacting Au(OAc)3 with corresponding phenyl pyridines (ppyde or ppydc) in trifluoroacetic acid (HOAcF) under microwave heating. Further treatment of Au(L)(OAcF)2 with aqua regia resulted in dichloro complexes Au(L)Cl2. Au-functionalized UiO-67 MOF has been synthesized by exchanging linkers of UiO-67 with Au(ppydc)Cl2, furnishing the MOF with (N^C)-cyclometalated Au(III) centers. The catalytic activities of the molecular cyclometalated complexes and the Au-incorporated MOF were studied in gold-catalyzed propargyl ester cyclopropanations. Almost all complexes and the MOF showed catalytic activity to the cyclopropanation product (up to 97% conversion), with a preference for the trans diastereoisomer (up to 14:86 d.r.). The recyclability of the most active molecular complex has also been investigated.

C–H···π(metal–ligand ring) interaction in a mesaconate bridged Cd(II) 1-D coordination polymer: structural elucidation, theoretical study, and photophysical properties

A Cd(II)-based one-dimensional coordination polymer (1-D CP), [Cd2(mes)2(4-phpy)4] (1), was prepared using mesaconic acid (H2mes) and 4-phenyl pyridine (4-phpy) mixed ligand system. Compound 1 has been characterized by elemental analysis, infrared spectroscopy, thermogravimetric analysis (TGA), powder X-ray diffraction (PXRD) pattern and single crystal X-ray diffraction (SCXRD) techniques. Structural elucidation reveals a 1-D chain which contains a 14-membered metal-ligand ring composed of two mes ligands and two Cd(II) centers. Further, the 1-D chains are assembled into a two-dimensional (2-D) supramolecular network by C–H···π(metal-ligand ring) interactions. The fluorescence lifetime of 1 shows a good range of average lifetime. The theoretical band gap has also been calculated by density functional theory (DFT) computations, which shows that 1 may possess semiconducting properties.

Synthesis, characterisation and theoretical studies of a series of Iridium (III) heteroleptic complexes with Schiff base ligands

A series of Iridium (III) complexes of general formula [Ir(ppy)2(L)]0/+ (ppy = 2-phenyl pyridine, L = Schiff base) were synthesised from the dichloro bridged dimeric starting material, [(ppy)2Ir(μ-Cl)2Ir(ppy)2]. Three Schiff bases used as ligand were obtained from condensation of 2-amino phenol with benzaldehyde (L1), salicylaldehyde with 2-aminopyridine (L2) and pyridine 2-aldehyde with 2-aminopyridine (L3). All the complexes were characterised by IR, 1H NMR, electronic absorption spectroscopy and cyclic voltammetry studies. Molecular structure of two of these complexes were determined by single crystal X-ray structure analysis. Complexes displayed several weak absorptions in visible region in the range of 401–499 nm. TDDFT calculations on complexes revealed the ligand orbital dominance in both HOMO and LUMO orbitals and subsequent ligand centred transitions were observed in absorption spectra.

An Efficient Probe of Cyclometallated Phosphorescent Iridium Complex for Selective Detection of Cyanide.

A cyclometallated phosphorescent iridium-based probe to detect CN– was prepared through a cyanide alcoholize reaction based on the C^N type main ligand and N^N type ancillary ligand (2-phenyl pyridine and 1,10-phenanthroline-5-carboxaldehyde, respectively). The efficient probe exhibited good sensitivity in response to CN– in an CH3CN and H2O (95/5) mixture within a 1.23 μM detection limit. The response of PL is directly in line with the concentration of CN– from 0 to 2.0 equiv. The PL investigation of other reactive anions proved the great selectivity to CN–. Additionally, upon adding 1.0 equiv. of cyanide, the formation of cyanohydrin was correctly elucidated in 1H NMR, FT-IR, and mass spectra studies. The conspicuous results indicate that the iridium complex has the potential possibility of application in other biosystems related to CN–.

A cyclometalated trinuclear Ir(iii)/Pt(ii) complex as a luminescent probe for histidine-rich proteins.

Organometallic complexes have important application in the field of protein staining, with potential for use in proteomic analysis. The rational synthesis of a trinuclear luminescent organometallic complex with two platinum(ii) centres appended to the cyclometalated ligand of the iridium(iii) centre is reported here. Two di-2-picolylamine groups bonded to the cyclometalated phenyl pyridine moiety provide three coordinating sites to each platinum centre. The replacement of chloride in the fourth coordination site of two square planar platinum metal centres with the imidazole nitrogen or sulphur atom of histidine/cysteine is evident from the change in luminescence intensity upon binding these amino acids. The increase in luminescence emission intensity upon binding of histidine to the organometallic complex allowed it to be used as a protein staining agent. Reversibility of staining upon washing with imidazole enhances the possibility of its application in mass spectrometric analysis.

Structure‐activity relationships of fragment‐based inhibitors of Trichomonas vaginalis adenosine/guanosine preferring nucleoside ribohydrolase

Trichomoniasis is a sexually transmitted infection caused by the parasite, Trichomonas vaginalis. Infections are currently treated with 5‐nitroimidazole drugs, such as metronidazole and tinidazole. However, strains of the parasite with resistance to these drugs have emerged, indicating the need for new treatments with novel mechanisms. Since the parasite is unable to perform de novo synthesis of nucleobases, it must obtain them from its host using salvage pathway enzymes including adenosine/guanosine preferring nucleoside ribohydrolase (AGNH), an essential enzyme involved in the pyrimidine salvage pathway. We previously used fragment screening to identify ligand‐efficient fragment inhibitors of AGNH. Medicinal chemistry efforts were then focused on several fragment scaffolds including benzimidazoles and phenyl pyridines. IC50 values were determined using the same 1H NMR‐based activity assays as the fragment screens. The resulting structure‐activity relationships suggest that the fragment scaffolds interact primarily with the nucleobase regions of the active site rather than the ribose pocket. Collectively, the data define emerging structure‐activity relationships that suggest likely vectors and chemical modifications for improving inhibition potency while maintaining ligand efficiency. The data establishes a platform for ongoing medicinal chemistry development of compounds with nM potency that will provide the tools for in vitro target validation against both 5‐nitroimidazole‐sensitive and 5‐nitroimidazole‐resistant T. vaginalis strains.Support or Funding InformationResearch was supported by the National Institute of Allergy and Infectious Diseases of the National Institutes of Health under Award Number R15AI128585 to BJS and MAVP. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Copper(II) mediated C–H methylthiolation of 2-phenyl pyridines with dimethyl sulfoxide using an amino acid ligand

A novel protocol for the C–H methylthiolation of 2-phenyl pyridines using DMSO as the methylthio source and an amino acid ligand is described. This simple procedure requires neither an oxidant nor additional solvent. The developed protocol tolerates a wide range of functional groups including methyl, methoxy, fluoro, chloro, and in particular the formyl group. This new strategy is highly regioselective and provides aryl methyl sulfides from 2-phenyl pyridines in moderate to good yields.

Pyridinium p-DSSC dyes: An old acceptor learns new tricks

A family of six (five new) thiophenyl bridged triarylamine-donor based dyes with pyridine anchoring groups have been synthesized and studied as sensitizers for the p-type dye-sensitized solar cell (p-DSSC). They comprise bis-dicyano acceptor systems with a single pyridyl binder incorporated directly into the triarylamine (1), or separated by a phenyl group (2); a mono-dicyano with two phenyl pyridine binders (3); and respective homologues 4 to 6 with pyridinium acceptors. In all cases, compared to their dicyano counterparts, the pyridinium based dyes have higher extinction coefficients and smaller HOMO-LUMO gaps that give broader spectrum absorption. Thus, despite lower dye uptake, devices based on pyridiniums 4 and 6 have identical power conversion efficiencies (η) to the equivalent dicyano systems 1 and 3. However, the best performing device (η = 0.06%) is based on the known bis-acceptor dicyano system 2, as the large size and double positive charge of 5 leads to a substantial disadvantage in loading on NiO. Absorbed-photon-to-current efficiencies for 5 are competitive with or higher than those of 2, implying a better per dye performance consistent with the absorption profile, and DFT calculations suggesting better charge separation. Thus, pyridiniums may provide a new, and easily accessible high performance acceptor for p-DSSC dyes, but are likely better paired with anionic binding groups such as carboxylates.

Metal–ligand ring aromaticity in a 2D coordination polymer used as a photosensitive electronic device

14-Membered metal–ligand ring present in a photosensitive 2D coordination polymer, [Zn2(fum)2(4-phpy)4(H2O)2] (H2fum = fumaric acid and 4-phpy = 4-phenyl pyridine) shows aromatic character as evident by the nucleus-independent chemical shifts (NICS) calculation.

Cyclometalated Ir(III) Complexes Involving Functionalized Terpyridine-Based Ligands Exhibiting Aggregation-Induced Emission and Their Potential Applications in CO2 Detection

Synthesis of three novel terpyridine-based donor–acceptor (D-A) ligands (TP1, TP2, TP3) and cyclometalated iridium complexes [Ir(ppy)2TP1]+PF6– (C1), [Ir(ppy)2TP2]+PF6– (C2), and [Ir(ppy)2TP3]+PF6– (C3) [ppy = 2−phenyl pyridine] involving these were described. The ligands and complexes were characterized by spectroscopic studies (1H, 13C, 19F, 31P, ESI-MS, UV-vis, and fluorescence). Crucial role of intermolecular interactions in aggregation-caused quenching (ACQ; C2) and aggregation-induced emission (AIE; C3) was rationalized by X-ray single-crystal analyses. Vital role of restricted intramolecular rotation (RIR) in inducing AIE upon aggregation via π–π interactions in these complexes was scrutinized by various studies. Because of strong intramolecular charge transfer these D−A based AIEgens exhibited solvatochromism. Further, AIE property of the complexes C1 and C3 was exploited toward detection of CO2.

Copper(II) Catalyzed C–H Alkoxylation of 2‐Phenyl Pyridines with Aliphatic Diols

A very simple copper(II) catalyzed C–O coupling reaction of 2‐phenylpyridines and aliphatic diols was achieved by using a strategy of C–H functionalization. A series of aroxyl ethanols are easily obtained with the yields of 30–67 %. Various functional groups, as well as different length of aliphatic diols are well tolerated in the developed catalytic system. This new protocol featurs a simple reaction system, economical catalyst and good regioselectivity. In addition, a “one‐pot” synthesis of 2‐phenyl pyridines was developed.

Synthesis and Characterization of Palladium (II) Complexes Containing Mixed Ligands with Pyrrolidine Dithiocarbamate and Phosphines

This work includes preparation and characterization of new four mono nuclear complexes of palladium metal ion result from treating palladium chloride with ammonium pyrrolidine dithiocarbamate (PDTC), tertiary phosphines(dppe, dppp) and 2-phenyl pyridine (Hppy) in different molar ratios. All complexes have been characterized by spectroscopic methods{IR, UV-Vis, 1HNMR} spectroscopy, in addition to elemental analysis (C.H.N) and conductivity measurement. pyrrolidine dithiocarbamate‎ ligand behaves like bidentate in the complexes [Pd(PDTC)(dppe)]Cl and [Pd(PDTC)(ppy)] but it behaves as mono dentate in the complexes [Pd(PDTC)2(dppp)] and [Pd(PDTC)2(dppe)], while tertiary phosphines and 2-phenyl pyridine behave like bidentate ligand.

Metal‐free cross‐dehydrogenative coupling approach for C‐H bond functionalization of 2‐phenyl pyridine derivatives in water

AbstractWe have developed a simple K2S2O8‐mediated C‐H bond functionalization of 2‐phenyl pyridines (C‐2 position) with ethers involving C(sp2)‐C(sp3) cross‐dehydrogenative coupling. The reaction does not require metal catalysts nor visible light and operates under mild conditions. Furthermore, the protocol is easily scalable and extendable to a wide range of pyridine derivatives.

Efficient solution-processed yellow/orange phosphorescent OLEDs based on heteroleptic Ir(Ⅲ) complexes with 2-(9,9-diethylfluorene-2-yl)pyridine main ligand and various ancillary ligands

Abstract Efficient solution-processible yellow/orange emissive phosphors are highly required in solution-processed phosphorescent organic light-emitting diodes (s-PhOLEDs). With respect to phenyl pyridine (ppy)-type Ir(III) complexes, 2-(9,9-diethylfluoren-2-yl)pyridine (Flpy)-type Ir(III) complexes have huge potential in yellow/orange s-PhOLEDs due to their extended conjugation and excellent solubility in common organic solvents. Herein, a new series of phosphorescent Ir(III) complexes, i.e. Ir(Flpy)2pic-N O, Ir(Flpy-CF3)2pic-N O, Ir(Flpy-CF3)2dbm and Ir(Flpy-CF3)2acac, based on Flpy main ligand and picolinic N-oxide (pic-N O), acetylacetone (acac), and dibenzoyl methane (dbm) ancillary ligands are synthesized. The photophysical, electrochemical, and electroluminescent (EL) properties of these phosphorescent Ir(III) complexes are investigated in details. By introducing the CF3 group in Flpy ligand and varying the ancillary ligands, the emission spectra of these phosphorescent complexes are tuned in a large range with EL emission peaks from 544 nm to 588 nm. The s-PhOLEDs employing these phosphors show promising EL performance with maximum external quantum efficiency (EQE) from 15.4% to 23.7% and high power efficiency from 61.9 l m W−1 to 80.4 l m W−1. These highly efficient phosphorescent Ir(III) complexes may serve as ideal chromaticity components in solution-processed full-color displays and lighting devices.

Synthesis, crystal structure and magnetic property of a new Co(II) complex based on 4-phenyl pyridine and 5-sulfoisophthalic acid anion

ABSTRACTA new cobalt complex [Co3(SIP)2(4-PP)8(H2O)6]·4H2O·2(4-PP) (1) with 5-sulfoisophthalic acid sodium (NaH2SIP) and 4-phenyl pyridine (4-PP) as ligands has been synthesized in the mixed solvents of ethanol and water. It crystallized in monoclinic, space group P21/c, with a = 20.9642(9) Å, b = 15.6091(5) Å, c = 20.0126(8) Å, α = 90.00°, β = 115.493(6)°, γ = 90.00°, V = 5911.2(4) Å3, Z = 2, Dc = 1.346 g/cm−3, F(000) = 2494, the final GOOF = 1.038, Rint = 0.0258 and wR2 = 0.1793. The complex (1) was characterized by single-crystal X-ray diffraction, magnetic susceptibility and IR spectroscopy analyses. Single-crystal X-ray diffraction shows that complex (1) is trinuclear based on cobalt units. Magnetic susceptibility measurement indicates that complex (1) shows an antiferromagnetic coupling between the Co(II) ions.

Synthesis, characterisation, evaluation of antimicrobial & antifungal activity of novel pyrazolopyrimidine & pyrazolopyridine derivatives

A new series of substituted PyrazoloPyrimidine & Pyrazolopyridine were designed to meet the structural requirement of antimicrobial ,Analgesic & antifungal drugs which has been known to possess a broad spectrum of biological activities such as analgesic,antimicrobial antifungal etc .(1) The therapeutic importance of these rings prompted us to develop selective molecules. The starting material of 1-{1-phenyl-3-(substituted phenyl)-1H-pyrazol-4-yl}-3-phenyl-1-propen-3-one (Chalcone) (3a-c) prepared from by claisen schmidt reaction from respective 1-phenyl-3-(substituted phenyl)-1H-pyrazoles-4-carboxaldehyde (Vilsmeier-Haack Reaction) ( 2a-c). 1-{1-phenyl-3-(substituted phenyl)-1H-pyrazol-4-yl}-3-phenyl-1-propen-3-one (Chalcone) (3a-c) further treated with thiourea ,3amino-s-triazole,ethylcyanoacetate, cynothioacetamideto produced 1,2,3,4 tetrahydropyrimidine (4 a-c),triazolopyrimidine (5 a,b),cynophenylpyridine(6 a-c) & phenyl pyridine thione derivatives.The structures of newly Synthesised compounds were characterized by spectral data & studied for their antimicrobial & Antifungal activities. Compounds 4a, 4c, 5a, 6c, 7c showed high antimicrobial activity using disc diffusion method with reference to using Amoxicillin as standard drug active active against Bacillus substillus, staphylococcus aureus, Proteus vulgaris.and pseudomonas.Similary compound 4c&7c showed maximum antifungal activity against fungal species candida albicans

Structural Mimics of Phenyl Pyridine (ppy) - Substituted, Phosphorescent Cyclometalated Homo and Heteroleptic Iridium(III) Complexes for Organic Light Emitting Diodes - An Overview.

Today organic light emitting diodes are a topic of significant academic and industrial research interest. OLED technology is used in commercially available displays, and efforts have been directed to improve this technology. Design and synthesis of phosphorescent based transition metals are capable of harvesting both singlet and triplet excitons and achieve 100 % internal quantum efficiency is an active area of research. Among all the transition metals, iridium is considered a prime candidate for OLEDs due to its prominent photophysical characteristics. In the present review, we have concentrated on the Iridium based homo and heteroleptic complexes that have dissimilar substitutions on phenylpyridine ligands, different ancillary ligands and the effect of substitution on HOMO/LUMO energies and a brief discussion and correlation on the photophysical, electrochemical and device performances of the different complexes have been reviewed for organic light emitting diodes.

Expeditious microwave-assisted synthesis and bio-evaluation of novel bis (trifluoromethyl) phenyl-triazole-pyridine hybrid analogues by the click chemistry approach

A series of novel 1,2,3-triazole-2,4-bis(trifluoromethyl) phenyl pyridine hybrids 7a–n were efficiently synthesized by the click chemistry approach. The precursor 6-(3,5-bis(trifluoromethyl)phenyl)pyridin-3-ol 3 was obtained by palladium catalyzed cross coupling between 6-bromo-3-pyridinol (2) and (3,5-bis (trifluoromethyl) phenyl) boronic acid (1) in a microwave under nitrogen conditions, which was further alkylated with propargyl bromide 4 in DMF in the presence of K2CO3 and a catalytic amount of TBAI to get 5. All products obtained in each step were well characterized by various spectral studies and found consistent with expected structure. The triazole derivatives 7a–n were evaluated against human bacterial pathogens, namely, Escherichia coli, Salmonella typhimurium and Staphylococcus aureus and fungal strains Aspergillus niger, Fusarium solani and Penicillium notatum for in vitro activity. Among them, 7e and 7m emerged as potential compounds comparable with the standard drug Ciprofloxacin against tested bacteria, and it is worthwhile to notice that compound 7k emerged more potent than the standard Griseofulvin against fungi.