- 2,6-Pyridinedicarbohydrazide-Salicylal hydrazone-base derivative with High detection limit and binding Constant for emissive ion chemosensing in aqueous solution
-
A new tridentate luminescent molecule, N2,N6-bis(salicylidene)pyridine-2,6-dicarbohydrazide (BSPDH), was introduced and facilely eco-synthesized with high yield. It was then characterized through Fourier transform infrared, Hydrogen-
- Amini, Abbas,Behmadi, Hossein,Benson, Veronika,Cheng, Chun,Nazari, Marziyeh,Rahimi, Marjan,Samali, Bijan
-
-
Read Online
- Novel 2,6-disubstituted pyridine hydrazones: Synthesis, anticancer activity, docking studies and effects on caspase-3-mediated apoptosis
-
Novel pyridine-based dihydrazones (3a-l) were synthesized by the condensation of appropriate aldehydes and pyridine-2,6-dicarbohydrazide (2) which was obtained by the treatment of dimethyl pyridine-2,6-dicarboxylate (1) with hydrazine hydrate. Structures of all the synthesized compounds were supported by their FTIR, 1H NMR, 13C NMR and microanalytical data. The compounds were screened primarily for their antibacterial activities as well as anticancer activities. None of the synthesized compounds had important antibacterial activity. Among the compounds which were tested against human colon cancer cell line (HT-29), compounds 3f and 3k showed significant activity (IC50=6.78 μM for compound 3f, IC50=8.88 μM for compound 3k). In addition, compound 3g exhibited promising activity against Ishikawa human endometrial cancer cell line (ISH) with an IC50 value of 8.26 μM. At 10 μM, compounds 3f, 3k and 3g caused morphological changes of HT-29 and ISH cells and caspase-3 activation. In addition, these compounds were evaluated against NIH 3T3 mouse embriyonic fibroblast cell line and all synthesized compounds (3a-l) were found to be less toxic than paclitaxel. Moreover, possible inhibition mechanism of compound 3g was evaluated in silico against BRAF kinase enzyme.
- ?evik, ?zge,?enkarde?, Sevil,Abbak, Mürüvvet,Durak, As?m Tu?rul,Ekrek, Sedanur,Güniz Kü?ükgüzel, ?.,Kü?ükgüzel, ?lkay,Ka?katepe, Banu,Türe, Asl?
-
-
Read Online
- Synthesis and characterization of bis[N′-(4-carboxybenzylidene)]- pyridine-2,6-dicarbohydrazide: Colorimetric and fluorometric modulation in presence of F- ions
-
(Graph Presented) A novel organic compound bis[N′-(4- carboxybenzylidene)]-pyridine-2,6-dicarbohydrazide (L) was synthesized and characterized using spectroscopic and X-ray diffraction techniques. Tetrabutyl ammonium halides [(Bu)4N+X-] X = F, Cl, Br and I were allowed to react separately with a solution of L in DMSO (1 × 10-5 M). The solution of L turned to shining yellow colour in the presence of F- ion only. The binding properties have been studied using absorption, emission and 1H NMR titrations. Theoretical studies on compound L and compound L + X- (X = F, Cl and Br) in DMSO medium were carried out using density functional theory (DFT) at the B3LYP/6-31G(d,p)/6-31G+(d,p) level. The theoretical calculations agreed to the experimental results.
- Sinha, Priti,Srivastava, Ashish Kumar,Mishra, Lallan
-
-
Read Online
- Colorimetric sensing of anions in aqueous solution using a charge neutral, cleft-like, amidothiourea receptor: Tilting the balance between hydrogen bonding and deprotonation in anion recognition
-
The design, synthesis and physical evaluation of 1, a visible colorimetric 'naked eye' pyridyl based bis-amidothiourea sensor for anions, is described. This charge neutral sensor gives rise to significant changes in the absorption spectra upon interactions with several important biological anions such as AMP and ADP in 4: 1 DMSO-H2O solution, while ATP was not detected. These colorimetric changes are due to the formation, or the combination of hydrogen bonding complexes and/or deprotonation between these anions and 1.
- Duke, Rebecca M.,O'Brien, John E.,McCabe, Thomas,Gunnlaugsson, Thorfinnur
-
-
Read Online
- 2,6-Bis[(2-hydr-oxy-3-methoxy-benzyl-idene)hydrazinocarbon-yl]pyridine monohydrate
-
In the title compound, C23H19N5O6·H2O, the two components are linked into complex chains by a combination of two independent O - H...O and two independent N - H...O hydrogen bonds. The complex chains are linked into a two-dimensional sheet network via π-π
- Li, Zhi-Feng,Wang, Ping,Zhang, Qian,Chen, Zao-Ming,Wang, Chun-Xiang
-
-
Read Online
- Synthesis, density functional theory calculations and luminescence of lanthanide complexes with 2,6-bis[(3-methoxybenzylidene)hydrazinocarbonyl] pyridine Schiff base ligand
-
A pyridine-diacylhydrazone Schiff base ligand, L?=?2,6-bis[(3-methoxy benzylidene)hydrazinocarbonyl]pyridine was prepared and characterized by single crystal X-ray diffraction. Lanthanide complexes, Ln–L, {[LnL(NO3)2]NO3.xH2O (Ln?=?La, Pr, Nd, Sm, Eu, Gd, Tb, Dy and Er)} were prepared and characterized by elemental analysis, molar conductance, thermal analysis (TGA/DTGA), mass spectrometry (MS), Fourier transform infra-red (FT-IR) and nuclear magnetic resonance (NMR) spectroscopy. Ln–L complexes are isostructural with four binding sites provided by two nitro groups along with four coordination sites for L. Density functional theory (DFT) calculations on L and its cationic [LnL(NO3)2]+ complexes were carried out at the B3LYP/6–31G(d) level of theory. The FT-IR vibrational wavenumbers were computed and compared with the experimentally values. The luminescence investigations of L and Ln–L indicated that Tb–L and Eu–L complexes showed the characteristic luminescence of Tb(III) and Eu(III) ions. Ln–L complexes show higher antioxidant activity than the parent L ligand.
- Taha, Ziyad A.,Ababneh, Taher S.,Hijazi, Ahmed K.,Abu-Salem, Qutaiba,Ajlouni, Abdulaziz M.,Ebwany, Shroq
-
-
Read Online
- Dicarbohydrazide based chemosensors for copper and cyanide ions: Via a displacement approach
-
Ligands attached to pyridine dicarbohydrazide were synthesized and characterized by NMR, FT-IR, elemental analysis, UV-visible spectroscopy, mass spectrophotometry, emission spectra and single crystal X-ray diffraction. These ligands were found to recognize copper ions over other metal ions and cyanide ions by a copper complex performing an in situ experiment with turn on-off-on behaviour over different anions in a CH3OH:H2O (9:1, v/v solution) medium. These ligands displayed a red shift in their absorption spectra and quenching in their emission spectra when exposed to copper ions via a PET mechanism and a further copper complex was applied for cyanide detection among the other anions. The 1:2, 1:3, 1:2 and 1:2 stoichiometric ratios of the ligands (L1-L4, respectively) with copper ions were calculated from a Job plot based on the UV-visible spectra. The S-V plot represents the linearity of the ligands with copper ions. The limits of detection (LOD) of copper ions along with the ligands (L1-L4) were calculated to be 0.12, 0.10, 0.097 and 0.098 μM using emission spectra, respectively. The binding affinities of the ligands with copper ions were determined by various characterization techniques such as FTIR, mass spectrophotometry and electrochemical and optical studies. Furthermore, an in situ experiment was performed for cyanide detection via a metal displacement approach. L1 and L4 with Cu2+ ions showed an affinity towards cyanide ions, with detection limits of 0.31 and 0.53 μM.
- Yadav, Neetu,Singh, Ashok Kumar
-
-
Read Online
- Fluorescent sensing of anions using a bis-quinoxaline amidothiourea based supramolecular cleft; an example of an anion-induced deprotonation event
-
The quinoxaline 1, possessing a 2,6-pyridyl-based amidothiourea moiety, with the view of forming a pre-organised molecular cleft, was developed as a fluorescent anion sensor. The sensing ability of 1 was evaluated in organic solution where both the ground and the excited state of 1 was affected upon recognition of anions such as acetate [as tetrabutylammonium salt (TBAAc) solution] at the amiodothiourea moieties in MeCN. The fluorescence of 1, with λmax at 477 nm, was, on all occasions quenched, upon anion recognition. Using TBAOH, we also show that the same anion-induced changes occurred; demonstrating that for this particular sensor, the anion-sensing takes place via a deprotonation mechanism. This anion-induced deprotonation event was further investigated by carrying out 1H NMR titrations on 1, using both AcO- and OH- in DMSO-d6.
- Duke, Rebecca M.,Gunnlaugsson, Thorfinnur
-
-
Read Online
- Hydrazones in anion transporters: The detrimental effect of a second binding site
-
Synthetic anion transporters can be developed using anion receptors that are able to bind the anion and stabilize it in the lipophilic interior of a bilayer membrane, and they usually contain functional groups with acidic NHs, such as ureas, thioureas and squaramides. To assess the suitability of acylhydrazones as a new functional group for the preparation of anion transporters, we have studied a family of thioureas functionalized with these and related functional groups.1H NMR titrations and DFT calculations indicate that the thioureas bearing acylhydrazone groups behave as chloride receptors with two separate binding sites, of which the acylhydrazone binds weaker than the thiourea. Chloride transport studies show that the additional binding site has a detrimental effect on thiourea-based transporters, and this phenomenon is also observed for bis(thio)ureas with two separate binding sites. We propose that the presence of a second anion binding unit hinders the transport activity of the thiourea due to additional interactions with the phospholipids of the membrane. In agreement with this hypothesis, extensive molecular dynamics simulations suggest that the molecules will tend to be positioned in the water/lipid interface, driven by the interaction of the NHs of the thiourea and of the acylhydrazone groups with the POPC polar head groups and water molecules. Moreover, the interaction energies show that the poorest transporters have indeed the strongest interactions with the membrane phospholipids, inhibiting chloride transport. This detrimental effect of additional functional groups on transport activity should be considered when designing new ion transporters, unless these groups cooperatively promote anion recognition and transmembrane transport.
- Félix, Vítor,Halgreen, Lau,Marques, Igor,Martínez-Crespo, Luis,Soares, Márcio,Valkenier, Hennie
-
supporting information
p. 8324 - 8337
(2021/10/12)
-
- Chromogenic and fluorogenic "off-on-off" chemosensor for selective and sensitive detection of aluminum (Al3+) and bifluoride (HF2-) ions in solution and in living Hep G2 cells: Synthesis, experimental and theoretical studies
-
A simple pyridine-dicarbohydrazide based colorimetric and fluorometric chemosensor L was designed and synthesized for Al3+ ion sensing in organo aqueous solution. In the presence of Al3+ ions, probe L exhibited visible color changes and fluorescence enhancement (20-fold) due to Al3+ induced chelation-enhanced fluorescence (CHEF) effects. Chemosensor L revealed high selectivity toward Al3+ ions by "turn-on"fluorescence among the other competitive metal ions examined with a detection limit of 0.8 μM. Probe L was found to bind with Al3+ ions in a 1 : 2 (probe : metal) stoichiometric fashion, with an association constant (Ka) of 4.26 × 104 M-2. In addition, DFT and TDDFT calculations were carried out to recognize the binding nature and electronic properties of probe L and its Al-complex. Furthermore, the in situ prepared [L-Al] complex was able to detect HF2- anions via a metal displacement strategy. The bioimaging application of Al3+ and HF2- was implemented in living human liver cancer cells (Hep G2). This journal is
- Manna, Saikat Kumar,Mondal, Debasish,Mukhopadhyay, Subrata,Pal, Kunal,Pathak, Sudipta,Pramanik, Samit
-
p. 13259 - 13265
(2020/10/07)
-
- Novel cationic bis(acylhydrazones) as modulators of Epstein–Barr virus immune evasion acting through disruption of interaction between nucleolin and G-quadruplexes of EBNA1 mRNA
-
The oncogenic Epstein–Barr virus (EBV)evades the immune system through limiting the expression of its highly antigenic and essential genome maintenance protein, EBNA1, to the minimal level to ensure viral genome replication, thereby also minimizing the production of EBNA1-derived antigenic peptides. This regulation is based on inhibition of translation of the virally-encoded EBNA1 mRNA, and involves the interaction of host protein nucleolin (NCL)with G-quadruplex (G4)structures that form in the glycine–alanine repeat (GAr)-encoding sequence of the EBNA1 mRNA. Ligands that bind to these G4-RNA can prevent their interaction with NCL, leading to disinhibition of EBNA1 expression and antigen presentation, thereby interfering with the immune evasion of EBNA1 and therefore of EBV (M.J. Lista et al., Nature Commun., 2017, 8, 16043). In this work, we synthesized and studied a series of 20 cationic bis(acylhydrazone)derivatives designed as G4 ligands. The in vitro evaluation showed that most derivatives based on central pyridine (Py), naphthyridine (Naph)or phenanthroline (Phen)units were efficient G4 binders, in contrast to their pyrimidine (Pym)counterparts, which were poor G4 binders due to a significantly different molecular geometry. The influence of lateral heterocyclic units (N-substituted pyridinium or quinolinium residues)on G4-binding properties was also investigated. Two novel compounds, namely PyDH2 and PhenDH2, used at a 5 μM concentration, were able to significantly enhance EBNA1 expression in H1299 cells in a GAr-dependent manner, while being significantly less toxic than the prototype drug PhenDC3 (GI50 > 50 μM). Antigen presentation, RNA pull-down and proximity ligation assays confirmed that the effect of both drugs was related to the disruption of NCL–EBNA1 mRNA interaction and the subsequent promotion of GAr-restricted antigen presentation. Our work provides a novel modular scaffold for the development of G-quadruplex-targeting drugs acting through interference with G4–protein interaction.
- Reznichenko, Oksana,Quillévéré, Alicia,Martins, Rodrigo Prado,Loa?c, Nadège,Kang, Hang,Lista, María José,Beauvineau, Claire,González-García, Jorge,Guillot, Régis,Voisset, Cécile,Daskalogianni, Chrysoula,F?hraeus, Robin,Teulade-Fichou, Marie-Paule,Blondel, Marc,Granzhan, Anton
-
-
- NOVEL HYDRAZONE DERIVATIVES FOR PREVENTING OR TREATING EBV-RELATED CANCERS
-
The present invention relates to novel bis-hydrazone derivatives of formula (I): wherein Ar1 and Ar2 may be identical or different and are each independently selected from the group consisting of groups of formula (II) and (III): Ys
- -
-
Paragraph 0093
(2019/10/22)
-
- A highly sensitive pyridine-dicarbohydrazide based chemosensor for colorimetric recognition of Cu2+, AMP2-, F- and AcO- ions
-
A new pyridine-dicarbohydrazide based colorimetric chemosensor L1 is designed and synthesized for the detection of anions and cations. The chemosensor allows the 'naked-eye' recognition of toxic cation Cu2+ and biologically relevant anions AMP2-, F- and AcO- in DMSO/H2O (8/2, v/v) solution with a fast response time (~5 s). The selectivity, sensitivity and binding stoichiometry of L1 for the aforementioned ions are investigated using colorimetric, UV-Vis spectroscopic and 1H NMR studies. The binding mode is analyzed by UV-Vis and 1H NMR studies, which are supported by density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations. The optimized geometries indicate that the carbohydrazide moiety provides the binding site for the cation and anions. The HOMO-LUMO energy gap for the complex of AMP2- with L1 is least among all the complexes, possibly due to the charge-transfer effect. The detection limits of L1 for Cu2+ and AMP2- were determined to be 0.12 μM and 0.08 μM, respectively. Furthermore, the potential application of the sensor for the detection of fluoride ion in commercially available toothpaste was demonstrated successfully.
- Kumar, Rakesh,Jain, Harshita,Gahlyan, Parveen,Joshi, Ankita,Ramachandran
-
p. 8567 - 8576
(2018/06/08)
-
- Copper ion fluorescence sensor molecules, preparation method, and application in detection of copper ions
-
The invention discloses copper ion fluorescence sensor molecules, a preparation method, and application in detection of copper ions. The molecular chemical formula of a sensor is C29H35N7O4, and has the structure which is as shown in formula I; the preparation method of the copper ion fluorescence sensor molecules comprises the steps of taking 2,6-pyridinedicarboxylic acid as a raw material, chloridizing, performing hydrazinolysis and performing condensation reaction to obtain the sensor molecules. The prepared sensor molecules have high selectivity and sensitivity to the copper ions in a DMSOsolution, have obvious visual colorimetric response, and moreover, are not interfered with other cations. According to the preparation method, ion detection paper which is loaded with the sensor molecules is prepared and has the advantages of convenience in carrying, obvious phenomenon, rapid detection and the like. In addition, the fluorescence sensor molecules prepared by the preparation methodis simple in synthesis method and low in cost, and has a very good application prospect in the field of cationic detection.
- -
-
Page/Page column 7
(2019/08/26)
-
- Mono- and bis-dipicolinic acid heterocyclic derivatives - Thiosemicarbazides, triazoles, oxadiazoles and thiazolidinones as antifungal and antioxidant agents
-
A series of dipicolinic acid derivatives was synthesized and investigated for antimicrobial and antioxidant activity. Mono and bis derivatives of ethyl dipicolinate were utilized as starting materials for synthesis of mono- and bis-hydrazides. Thiosemicarbazides were obtained by reaction of hydrazides with isothiocyanates and cyclized into triazoles, thiadiazoles, oxadiazoles and thiazolidinones. Some of these products, especially those incorporating a thiazolidinone moiety in their structure, are excellent antioxidants, DPPH scavengers and antifungal agents.
- Molnar, Maja,Pavi?, Valentina,?arkanj, Bojan,?a?i?, Milan,Vukovi?, Dubravka,Klenkar, Jelena
-
-
- Highly sensitive and selective "naked eye" sensing of Cu(ii) by a novel amido-imine based receptor: A spectrophotometric and DFT study with practical application
-
We report the synthesis of a novel compound (E)-bis-N′-((1H-pyrrol-2-yl)methylene)-pyridine-2,6-carbohydrazide and its sensing ability to detect copper(ii) ion in aqueous medium by a sharp color change from yellow to brown, the sensing limit being 4.0 × 10-9 M. Theoretical modeling of the compound and its copper complex was performed. Practical utility was explored by successful paper strip response.
- Bhattacharyya, Arghyadeep,Ghosh, Soumen,Guchhait, Nikhil
-
p. 28194 - 28199
(2016/04/09)
-
- Synthesis and antibacterial activity evaluation of 2,6-bis(6-substituted-1, 2,4-triazolo[3,4-b][1,3,4]thiadiazol-3-yl)pyridine derivatives
-
The reaction of 5,5′-(pyridine-2,6-diyl)bis(4-amino-3-mercapto-1,2,4- triazole) with various carboxylic acid in phosphorus oxychloride yielded the corresponding 2,6-bis(6-substituted-1,2,4-triazolo[3,4-b][1,3,4]thiadiazol-3-yl) pyridine derivatives 6a-l. The structures of the newly synthesized compounds were confirmed by elemental analysis, 1H NMR and 13C NMR spectral, mass spectral, and Infrared spectral studies. All the synthesized target compounds have been investigated for their in vitro antibacterial activity, and the preliminary results revealed that the compounds 6b and 6k exhibited very promising activity against Escherichia coli and Pseudomonas aeruginosa. Springer Science+Business Media 2013.
- Xiao, Haihua,Li, Pingliang,Guo, Dongcai,Hu, Jinhui,Chai, Yuchao,He, Wei
-
p. 1941 - 1949
(2014/05/06)
-
- Synthesis and fluorescence properties of 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazol derivatives and their terbium complexes
-
Eight novel 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazol derivatives have been designed and synthesized, and their corresponding Tb3+ complexes were also prepared successfully. The fluorescence properties and fluorescence quantum yields of the target complexes were investigated, the results showed that the ligands were an efficient sensitizer for Tb3+ luminescence, and the target complexes exhibited characteristic fluorescence emissions of Tb3+ ion. The fluorescence intensity of the complex substituted by chlorine was stronger than that of other complexes. The substituents' nature has a great effect upon the electrochemical properties of the target complexes. The results showed that the introduction of the electron-withdrawing groups tended to decrease the oxidation potential and highest occupied molecular orbital energy levels of the target Tb3+ complexes; however, introduction of the electron-donating groups can increase the corresponding complexes' oxidation potential and highest occupied molecular orbital energy levels.
- Zhang, Wu,Chai, Yuchao,Li, Kangyun,Chen, Yanwen,Yan, Dong,Guo, Dongcai
-
p. 1113 - 1122
(2015/02/19)
-
- Efficient synthesis of some novel symmetrical and unsymmetrical pyridine bis-1,2,4-triazoles and bis-1,3,4-thiadiazoles
-
A series of novel bis-1,2,4-triazoles and bis-1,3,4-thiadiazoles bearing pyridine rings was synthesised, by multistep reaction sequences, in good to high yields. Reaction of pyridine-2,5-bis- and pyridine-2,6-bis-carbohydrazides with alkyl- or arylisothio
- Foroughifar, Naser,Mobinikhaledi, Akbar,Rafiee, Abdolhossein
-
p. 111 - 114
(2014/03/21)
-
- Synthesis, characterization and properties of 1,2,4-triazolo[3,4-b][1,3,4] thiadiazole derivatives and their europium complexes
-
Eight novel 1,2,4-triazolo[3,4-b][1,3,4]thiadiazole derivatives and their corresponding Eu(III) complexes were synthesized and characterized. From the spectral studies it has been concluded that the title Eu(III) complexes display six coordination. The investigation of the luminescence properties of the title complexes showed that the ligands favor energy transfers to the emitting energy level of europium ions. The title Eu(III) complexes exhibited characteristic emissions of europium ions, and possessed strong luminescence intensities, good fluorescence quantum yields, and the highest fluorescence quantum yield is up to 0.522. Furthermore, the luminescence intensity of the complex with chlorine-substituted group is the strongest than that of other complexes. The exploration of the electrochemical properties of the title complexes shows that the introduction of electron-donating groups can increase the HOMO energy levels, LUMO energy levels and the oxidation potential of the complexes, however, the result of introduction of electron-withdrawing groups was just opposite.
- Yan, Dong,Xiang, Yu,Li, Kangyun,Chen, Yanwen,Yang, Zehui,Guo, Dongcai
-
p. 487 - 495
(2014/07/21)
-
- Recognition and sensing of biologically relevant anions in alcohol and mixed alcohol-aqueous solutions using charge neutral cleft-like glycol-derived pyridyl-amidothiourea receptors
-
In this paper, the synthesis and the spectroscopic investigation of new colorimetric receptors for anions 3-6, possessing a glycol chain at the 4-position of the pyridyl ring, and 1 and 2, which lack such a chain, and the X-ray crystal structure of 2 is presented. Structures 3-6 are able to bind to anions in competitive media, such as alcohol or in a mixture of methanol and water, where the anion recognition gives rise to changes in the absorption spectra, which is red-shifted, in 1:1 or 1:2 (sensor/anion) stoichiometry. The anion recognition for 1 and 2 was also investigated in organic solvents and in a 4:1 mixture of DMSO/H2O. The binding of 1 to anions such as acetate, phosphate, and fluoride was also evaluated using 1H NMR in DMSO-d6.
- Duke, Rebecca M.,McCabe, Thomas,Schmitt, Wolfgang,Gunnlaugsson, Thorfinnur
-
scheme or table
p. 3115 - 3126
(2012/05/20)
-
- Synthesis and antioxidant evaluation of Schiff bases derived from 2,6-pyridinedicarboxylic acid
-
A series of novel Schiff bases derived from dipicolinic acid was synthesized and evaluated for antioxidant and iron chelating activity. In most cases Schiff bases derived from di-hydrazide showed higher antioxidant activity than the ones derived from mono-hydrazide and some of them are very promising considering the fact of being better antioxidants than the standards used in the investigation. For iron chelating activity substituents had a greater impact on the activity than mono or di-hydrazide skeleton.
- Molnar, Maja,Cacic, Milan,Zrinusic, Sanja Zec
-
p. 401 - 410
(2012/10/18)
-
- Crystal structure of nonadentate tricompartmental ligand derived from pyridine-2,6-dicarboxylic acid: Spectroscopic, electrochemical and thermal investigations of its transition metal(II) complexes
-
The coordinating behavior of a new dihydrazone ligand, 2,6-bis[(3- methoxysalicylidene)hydrazinocarbonyl]pyridine towards manganese(II), cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) has been described. The metal complexes were characterize
- Vadavi, Ramesh S.,Shenoy, Rashmi V.,Badiger, Dayananda S.,Gudasi, Kalagouda B.,Devi, L. Gomathi,Nethaji, Munirathinam
-
experimental part
p. 348 - 355
(2011/08/03)
-
- Novel and efficient procedure for the preparation of two pyridine dicarboxylic acid derivatives
-
New strategies for the synthesis of two pyridine dicarboxylic acid derivatives namely; 4-(2-(2,6-dicarboxypyridin-4-yl)vinyl)pyridine-2,6- dicarboxylic acid and 2,6-bis(2-(2,6-dicarboxy-pyridin-4-yl)vinyl)pyridine have been described. New oxidant used is a good example of green chemistry technology and the synthesis procedure harvest a high-purity product at a high yield.
- Guoliang,Ming
-
experimental part
p. 449 - 452
(2012/02/01)
-
- Synthesis and antimicrobial evaluation of 1,3,4-oxadiazole-2-thione from some pyridine carboxylic acids
-
The 5-(2-pyridyl)-1,3,4-oxadiazole-2-thione (4a) and the bis-5-(2,6-pyridyl)-1,3,4-oxadiazole-2-thione (4b) have been synthesized from the corresponding 2-pyridine carboxylic acid (picolinic acid) (1a) and 2,5-pyridine dicarboxylic acid (1b) by similar method. The esterification of the acids with ethyl and methyl alcohols gave the corresponding esters 2a and 2b. The hydrazides 3a and 3b were obtained in good yields. The 1,3,4-oxadiazoles 4a and 4b were formed by treatment of the corresponding hydrazides with CS 2 and KOH. The intermediates and the final products were characterized with IR, UV, 1H and 13C NMR and MS. The hydrazides 3a and 3b, the final products and the commercially available 5-(4-pyridyl)-1,3,4-oxadiazole-2-thione (5) were tested in vitro against the following micro organisms: Escherichia coli ATCC 25924, Pseudomonas aeruginosa ATCC 27853, Enterococcus faecalis ATTC 29212, Staphylococcus aureus ATCC 25923 and Pseudomonas fluorescens ATCC 17552 and compared with the known antibiotics Cephalosporin (cefotaxim) and Gentamycin. The results have shown that the synthesized compounds have appreciable effects. The bis-5-(2,6-pyridyl)-1,3,4- oxadiazole-2-thione (4b) had the highest effect upon all the tested microorganisms in general and on the gram-negative bacteria Pseudomonas fluorescens in particular, where its effect exceeded that of the well known Cephalosporin (cefotaxim).
- Benhammadi, Samia,Othman, Adil A.,Derdour, Aicha,Mami, Anas
-
p. 5535 - 5542
(2012/07/30)
-
- Self-assembled polymetallic square grids ([2 × 2] M4, [3 × 3] M9) and trigonal bipyramidal clusters (M5) - Structural and magnetic properties
-
New self-assembled grids and clusters are reported, with square [2 × 2] M4 (M = Mn(ii)4, Cu(ii)4), trigonal-bipyramidal Mn(ii)5, and square [3 × 3] M9 (M = Mn(ii), Cu(ii)) examples. These are based on a series of ditopic and tritopic hydrazone ligands involving pyridine, pyrimidine and imidazole end groups. In all cases the metal centres are bridged by hydrazone oxygen atoms with large (>125°) bridge angles, leading to antiferromagnetic exchange for all the Mn systems (J = -2 to -5 cm-1), which results in S = 0 (Mn4), and S = 5/2 (Mn5, Mn9) ground states. The copper systems have a 90° alternation of the Jahn-Teller axes within the Cu4 and Cu8 grid rings (Cu9), which leads to magnetic orbital orthogonality, and dominant ferromagnetic coupling. For the Cu9 grid antiferromagnetic exchange between the ring and the central copper leads to a S = 7/2 ground state, while for the Cu4 grids S = 4/2 ground states are observed. The magnetic data have been treated using isotropic exchange models in the cases of the Cu4 and Cu9 grids, and the Mn5 clusters. However due to the enormity of a fully isotropic calculation a simplified model is used for the Mn9 grid, in which the outer Mn8 ring is treated as the equivalent of an isolated magnetic chain, with no coupling to the central metal ion. The Royal Society of Chemistry 2006.
- Dawe, Louise N.,Abedin, Tareque S. M.,Kelly, Timothy L.,Thompson, Laurence K.,Miller, David O.,Zhao, Liang,Wilson, Claire,Leech, Michael A.,Howard, Judith A. K.
-
p. 2645 - 2659
(2007/10/03)
-
- A homoleptic, self-assembled [2 × 2] square Cu4 complex exhibiting intramolecular ferromagnetic exchange
-
A carboxylic acid-substituted picolinic hydrazone ligand (pcoap) forms a homoleptic [2 × 2] tetranuclear Cu(II)4 complex with four six-coordinate Cu(II) centers bridged by μ-O alkoxide groups in a square grid structure. The terminal carboxylic groups complete the six-coordinate structures at each copper centre, capping off external coordination positions, with two functioning as carboxylates, and two in neutral carboxylic acid form. Despite very large Cu-O-Cu bridge angles (139.2-140.6°), and short Cu-Cu distances (3.97-4.05 A), which would normally be expected to propagate antiferromagnetic exchange interactions within the grid, strictly orthogonal bridging connections between the metal centers lead to intramolecular ferromagnetic exchange (J = 7.2(3) cm-1), and an S = 4/2 magnetic ground state.
- Xu, Zhiqiang,Thompson, Laurence K.,Miller, David O.
-
p. 2462 - 2466
(2007/10/03)
-
- New electron-transporting materials for light emittind diodes: 1,3,4-oxadiazole-pyridine and 1,3,4-oxadiazole-pyrimidine hybrids
-
We described the synthesis of three new isomeric 1,3,4-oxadiazole-pyridine hybrids, namely: 2,6-, 3,5- and 2,4-bis[2-(4-tert-butylphenyl)-1,3,4-oxadiazol-5-yl]pyridine, (PDPy-2,6, PDPy-3,5 and PDPy-2,4, respectively) and a 1,3,4-oxadiazole-pyrimidine hybrid, namely: 2,5-bis[2-(4-tert-butylphenyl)-1,3,4-oxadiazol-5-yl]pyrimidine (PDPmDP). The X-ray crystal structures are reported for PDPy-2,4 and the known phenylene analogue 1,3-bis[2-(4-tert-butylphenyl)-1,3,4-oxadiazol-5-yl]benzene (OXD-7) as a 1:1 toluene solvate. The packing motif for molecules of both PDPy-2,4 and OXD-7 is that of discrete layers with the mean planes of all the molecules in the crystals parallel to within 6 deg. We have fabricated light-emitting diodes (LEDs) using poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) doped with rubrene as the emissive material, with and withuot a thermally evaporated electron conducting/hole blocking (ECHB) layer of PDPy-2,6, PDPy-3,5 and PDPy-2,4, PDPmDP and OXD-7, in the device configuration ITO/MEH-PPV(Ru)/ECHB layer/Al. Electroluminescence spectra indicate that light is emitted only from the MEH-PPV layer. The bilayer LEDs are considerably more efficient that single layer devices, e.g. the external quantum efficiences of devices incorporating PDPy-2,6, PDPy-3,5 and OXD-7 are 0.14, 0.04 and 0.06 percent at 40 mAm-2, respectively , cf. 0.007 percent for the reference single-layer MEH-PPV(Ru) device. There is no clear correlation between experomental EQE values and the PM3 calculated LUMO levels of the materials.
- Wang, Changsheng,Jung, Gun-Young,Batsanov, Andrei S.,Bryce, Martin R.,Petty, Michael C.
-
p. 173 - 180
(2007/10/03)
-
- Heterocyclic Amplifiers of Phleomycin. VIII Mono- and Bis-(5'-substituted 1',3',4'-thiadiazol-2'-yl)pyridines and Mono(5'-substituted 1',3',4'-thiadiazol-2'-ylmethyl)pyridines
-
A series of mono- and bis-(5'-substituted 1',3',4'-thiadiazol-2'-yl)pyridines with strongly basic side chains, e.g., 3,5-bispyridine (1), and (5'-substituted 1',3',4'-thiadiazol-2'-ylmethyl)pyridines have been prepared for evaluation as amplifiers of phleomycin.Five of this six bis(5'-substituted 1',3',4'-thiadiazol-2'-yl)pyridines were themselves antibacterial under the test conditions, but compounds (1) and the mono (5'-substituted 1',3',4'-thiadiazol-2'-yl)-pyridines and -methylpyridines displayed moderate two-to-three-star activity.
- Barlin, Gordon B.
-
p. 1491 - 1497
(2007/10/02)
-
- Magnetic and Spectral Studies on Binuclear Complexes of Iron(II), Cobalt(II) and Copper(II) with a Heptadentate Schiff Base Ligand
-
Homo-binuclear complexes of Fe(II), Co(II) and Cu(II) possessing the general formulae where M = Fe, Co or Cu; H2L = bis-(o-hydroxyacetophenone)-2,6-dipicolinoyl dihydrazone (adphH4); X = Cl, Br, NO3 or NCS and n = 2 or 3 have been synthesised.The ligand acts as a dibasic heptadentate schiff base.The complexes have been characterised on the basis of elemental analyses, conductance, magnetic susceptibility, infrared and electronic spectral data.The studies reveal that the two metal ions are present in different environments (one is present in an octahedral field whereas the other is in the five-coordinated environment) except for the Cu(II) complex where both the Cu(II) ions are in octahedral field.
- Arora, D. L.,Lal, Keemti,Gupta, S. P.,Sahni, S. K.
-
p. 980 - 982
(2007/10/02)
-
- Synthesis and Characterisation of Co(II), Ni(II) and Cu(II) Complexes of a Tridentate Macrocyclic Ligand
-
A novel tridentate macrocyclic ligand is synthesised by the reaction of 2,6-dipicolinic acid hydrazide and acetylacetone.Complexes of the macrocyclic ligand with Co(II), Ni(II) and Cu(II) have been isolated.These complexes have been characterised to be five-coordinated trigonal bipyramidal complexes on the basis of analyses, conductance, magnetic, electronic and infrared spectral studies.The IR studies reveal that the ligand coordinates through pyridine nitrogen, the amido nitrogen and the amino groups react with acac to form a ring giving rise to a 12-membered macrocyclic ligand system.
- Rana, V. B.,Teotia, M. P.
-
p. 267 - 268
(2007/10/02)
-