7703-74-4Relevant academic research and scientific papers
Free Amino Acid Recognition: A Bisbinaphthyl-Based Fluorescent Probe with High Enantioselectivity
Zhu, Yuan-Yuan,Wu, Xue-Dan,Gu, Shuang-Xi,Pu, Lin
, p. 175 - 181 (2019)
A novel fluorescent probe based on a bisbinaphthyl structure has been designed and synthesized. This compound in combination with Zn(II) has exhibited highly enantioselective fluorescence enhancement with 13 common free amino acids. For example, its enantiomeric fluorescent enhancement ratios (ef or δIL/δID) in the presence of the following amino acids are extremely high: 177 for valine, 199 for methionine, 186 for phenylalanine, 118 for leucine, and 89 for alanine. The observed high enantioselectivity and the extent of the substrate scope are unprecedented in the fluorescent recognition of free amino acids. This fluorescent probe can be applied to determine the enantiomeric composition of the structurally diverse chiral amino acids. NMR and mass spectroscopic investigations have provided clues to elucidate the observed high enantioselectivity.
Transition metal complexes with sulfur ligands, 145 [1]. [Ru(NO)('pybuS4')]br, a complex with [Ru(NO)(NS4)] core, activated CH2 groups, and interionic interactions in the solid state ('pybuS4'2- = 2,6-Bis(2-mercapto-3,5-di-tert-butylphenylthio)dimethylpyridine(2-))
Sellmann, Dieter,Ha?u?inger, Daniel,Gottschalk-Gaudig, Torsten,Heinemann, Frank W.
, p. 723 - 729 (2000)
In the search for soluble and reactive ruthenium nitrosyl complexes, [Ru(NO)('pybuS4')]Br ([2]Br) was synthesized by template alkylation of NBu4[Ru(NO)('buS2')2] with py(CH2Br)2 ['pybuS4'2- = 2,6-bis(2-mercapto-3,5-di-tert-butyl-phenylthio)dimethylpyridine(2-); 'buS2'2- = 2-mercapto-3,5-di-tert-butylphenylthiolate(2-); py(CH2Br)2 = 2,6-bis(bromomethyl)pyridine]. The solid state structure of 2 has been determined by X-ray diffraction, which reveals a head-to-head O-O interaction between the linear Ru-NO entities. The ligand CH2 protons of [2]+ are activated and exchange with D+ under ambient conditions. The v(NO) band of [2]Br appears at 1841 cm-1 in the solid state (KBr or hostaflon mull) and is significantly blue-shifted in solution (1879 cm-1 in MeOH. 1886 cm-1 in DMF). A similar blue-shift (1866 cm-1 in KBr vs. 1888 cm-1 in MeOH) has been found for [Ru(NO)('pyS4')]Br ([1]Br) which contains the parent [Ru(NO)('pyS4')]+ cation ['pyS4'2- = 2,6-bis(2-mercaptophenylthio)dimethylpyridine(2-)]. These v(NO) shifts can be explained either by an interionic charge-transfer between the bromide anions and the nitrosyl complex cation or by O-O interactions between two NO ligands as found for solid-state [2]Br. These interactions are not found for [I]OTs which exhibits a v(NO) band at ca. 1890 cm-1 in the solid state (KBr, hostaflon) as well as in MeOH solution.
A one dimensional coordination polymer composed of antiferromagnetically coupled disk-like [Mn7] units
Yang, En-Che,Huang, Han-Sheng,Huang, Shao-Yun,Huang, Shi-Yi,Chang, Yu-Ying,Lee, Gene-Hsiang,Sheu, Hwo-Shuenn,Chang, Chung-Kai
, p. 6963 - 6969 (2018)
The synthesis, characterization by X-ray analysis and magnetic properties of a one dimensional coordination polymer {[Mn7(OH)2(dhap)2(N3)3(MeCN)4(ClO4)2]·2(MeCN)·2(ClO4)}∞ (1) are reported. The ligand dhapH4 in the complex is 2,6-bis[N,N-di(hydroxyethyl)aminomethyl]pyridine. This compound crystallizes in the monoclinic space group C2/c. Each [Mn7(OH)2(dhap)2(N3)3(MeCN)4(ClO4)2] unit (abbreviated by Mn7) is linked end-to-end by azido ligands to its neighboring units to form a one dimensional polymer. Magnetic susceptibility measurements indicate that the polymer is composed of S = 8 units with inter-Mn7-unit antiferromagnetic coupling. The Jahn-Teller axes of the Mn7 units are arranged in a zigzag manner along the polymer chain which induces spin canting at low temperatures. The slow magnetization relaxation at low temperatures was evidenced by observing out-of-phase signals in ac magnetic susceptibility measurements that give Ueff = 47.5 K and Δ0 = 2.7 × 10-13 s. This phenomenon also indicates that this one dimensional coordination polymer functions as a single-chain magnet (SCM).
Activation of Co(I) State in a Cobalt-Dithiolato Catalyst for Selective and Efficient CO2 Reduction to CO
Dey, Subal,Ahmed, Md Estak,Dey, Abhishek
, p. 5939 - 5947 (2018)
Reduction of CO2 holds the key to solving two major challenges taunting the society - clean energy and clean environment. There is an urgent need for the development of efficient non-noble metal-based catalysts that can reduce CO2 selectively and efficiently. Unfortunately, activation and reduction of CO2 can only be achieved by highly reduced metal centers jeopardizing the energy efficiency of the process. A carbon monoxide dehydrogenase inspired Co complex bearing a dithiolato ligand can reduce CO2, in wet acetonitrile, to CO with ～95% selectivity over a wide potential range and 1559 s-1 rate with a remarkably low overpotential of 70 mV. Unlike most of the transition-metal-based systems that require reduction of the metal to its formal zerovalent state for CO2 reduction, this catalyst can reduce CO2 in its formal +1 state making it substantially more energy efficient than any system known to show similar reactivity. While covalent donation from one thiolate increases electron density at the Co(I) center enabling it to activate CO2, protonation of the bound thiolate, in the presence of H2O as a proton source, plays a crucial role in lowering overpotential (thermodynamics) and ensuring facile proton transfer to the bound CO2 ensuring facile (kinetics) reactivity. A very covalent Co(III)-C bond in a Co(III)-COOH intermediate is at the heart of selective protonation of the oxygen atoms to result in CO as the exclusive product of the reduction.
Synthesis, characterization and X-ray crystal structures of cyclam derivatives. Part VI. Proton binding studies of a pyridine-strapped 5,12-dioxocyclam based macrobicycle
Meyer, Michel,Fremond, Laurent,Tabard, Alain,Espinosa, Enrique,Vollmer, Guy Yves,Guilard, Roger,Dory, Yves
, p. 99 - 108 (2005)
The 14-membered cyclic diamide 1,4,8,11-tetraazacyclotetradecane-5,12-dione (5,12-dioxocyclam) can be considered as a trans-autodiprotected tetraazamacrocycle and provides a convenient starting material for the preparation of macrobicyclic receptors. As an example, the secondary amine nitrogen atoms located at the 1 and 8 positions were cross-bridged with a 1,3-pyridyl strap, affording the constrained ansa-dioxocyclam ligand 1,9,12,18,22-pentaazatricyclo[7.6.6.13,7]docosa-3,5,7(22)-triene-13, 19-dione (L1). The proton binding properties of this cage-type compound, which possesses a hemispherical cavity, were fully investigated by spectroscopic (IR, NMR, UV, MALDI-TOF MS), quantum chemical, and potentiometric methods. While both bridgehead tertiary amines have their free lone pairs oriented inside the cavity, intramolecular hydrogen bonding was found to play a key role in determining the structural features of the free base and its protonated forms. L1 behaves as a diprotic base in water with log K011 = 8.94(1) and log K012 = 2.32(9), but most interestingly shows slow proton-transfer rates on the NMR timescale.
Seven coordinate Co(ii) and six coordinate Ni(ii) complexes of an aromatic macrocyclic triamide ligand as paraCEST agents for MRI
Pradhan, Rabindra N.,Chakraborty, Subhayan,Bharti, Pratibha,Kumar, Janesh,Ghosh, Arindam,Singh, Akhilesh K.
, p. 8899 - 8910 (2019)
We are reporting Co(ii) and Ni(ii) complexes of a pyridine containing aromatic macrocyclic triamide ligand, 3,6,9,15-tetraazabicyclo(9.3.1)pentadeca-1(15),11,13-triene-3,6,9-triacetamide (TPTA), as paramagnetic chemical exchange saturation transfer (paraCEST) MRI contrast agents. The synthesis and characterization of TPTA and its complexes are reported. The solution chemistry and solid-state structure of Co(ii) and Ni(ii) complexes are studied. Crystallographic data show that the [Co(TPTA)]·Cl2·2H2O complex (seven-coordinate, all four N atoms of ring and three amide O atoms) has a distorted pentagonal bipyramidal geometry, however the [Ni(TPTA)Cl]·Cl·0.25H2O complex (six-coordinate, all four N atoms of the ring, one amide O and one chloride ion) adopts a distorted octahedral geometry. Notably the two pendent amide arms are not coordinated in the [Ni(TPTA)Cl]+ complex and one chloride ion fulfils its sixth coordination. The CEST effect of [Co(TPTA)]2+ and [Ni(TPTA)Cl]+ amide protons is observed at 57 ppm and 78 ppm downfield of the bulk water proton respectively in a buffer solution containing 20 mM N-(2-hydroxyethyl)piperazine-N′-ethanesulfonic acid and 100 mM NaCl at pH 7.4 at 37 °C on a 9.4 T NMR spectrometer. The effects of CEST intensity and exchange rate constant with variation of pH of the solution were studied. The CEST effect and exchange rate constant for the amide protons of the [Co(TPTA)]2+ complex have been monitored in HEPES buffer, fetal bovine serum (FBS), rabbit serum and 4% agarose gel (w/w). The stability of the [Co(TPTA)]2+ complex in aqueous solution towards oxidation was verified by cyclic voltammetry measurement. The stability of [Co(TPTA)]2+ has further been monitored in the presence of biologically relevant ions including HPO42-, CO32-, and Zn2+ and under acidic conditions.
Phosphonated chelates for nuclear imaging
Abada, Sabah,Lecointre, Alexandre,Christine, Cline,Ehret-Sabatier, Laurence,Saupe, Falk,Orend, Gertraud,Brasse, David,Ouadi, Ali,Hussenet, Thomas,Laquerrire, Patrice,Elhabiri, Mourad,Charbonnire, Loc J.
, p. 9601 - 9620 (2014)
A series of bis-, tris- and tetra-phosphonated pyridine ligands is presented. In view of their potential use as chelates for radiopharmaceutical applications, the physico-chemical properties of the ligands and of their Co(ii), Ni(ii), Cu(ii), and Zn(ii) complexes were studied by means of potentiometry and UV-Vis absorption spectroscopy. The pKa values of the ligands and of the complexes, as well as the stability constants for the formation of the complexes, are presented. The kinetic aspects of the formation of Cu(ii) complexes and of their dissociation in acidic media were studied by means of stopped flow experiments, and the stability of the Cu(ii) complex toward reduction to Cu(i) was investigated by cyclic voltammetry and by titration with different reducing agents. The different thermodynamic and kinetic aspects of the polyphosphonated ligands were compared with regard to the impact of the number of phosphonic acid functions. Considering the very promising properties for complexation, preliminary SPECT/CT imaging experiments were carried out on mice with 99mTc using the bis- and tetra-phosphonated ligands L2 and L1. Finally, a bifunctional version of chelate L1, L, was used to label MTn12, a rat monoclonal antibody with both specificity and relatively high affinity for murine tenascin-C. The labeling was monitored by MALDI/MS spectrometry and the affinity of the labeled antibody was checked by immunostaining experiments. After chelation with 99mTc, the 99mTc-L-MTn12 antibody was injected into a transgenic mouse with breast cancer and the biodistribution of the labeled antibody was followed by SPECT/CT imaging.
Synthesis of an hexadentate tricyclic tetraazadiacetic ligand as precursor for MRI contrast enhancement agents
Dioury, Fabienne,Ferroud, Clotilde,Guy, Alain,Port, Marc
, p. 7573 - 7579 (2009)
A tricyclic tetraazadiacetic compound, which is a rigidified derivative of cyclo-PCTA12 ligand with an oxo-ethylene bridge replacing an ethylene one, was prepared. The synthetic route involved the macrocyclization between an activated amido-disulfonamide and the 2,6-bis(bromomethyl)pyridine. The acetate side chains were grafted on the macrocyclic backbone to lead to the highly rigid tricyclic ligand in 34% overall yield in four steps from the linear amido-disulfonamide precursor. The corresponding Gd(III) and Mn(II) complexes were then prepared in order to evaluate their potential as contrast agent for MRI.
Synthesis of macrocyclic inclusion complexes using olefin metathesis
Ng, Po Ling,Lambert, John N.
, p. 1749 - 1750 (1999)
The ruthenium-catalysed synthesis of a macrocyclic chelate is described. The reaction proceeds at room temperature using 5% catalyst to afford 4 in 80% isolated yield.
COMPOUND, AMMONIA DETECTION MATERIAL CONTAINING THE SAME AND METHOD FOR PRODUCING THE SAME, AND METHOD FOR DETECTING AMMONIA USING THE SAME
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Paragraph 0046; 0059-0060, (2021/09/27)
PROBLEM TO BE SOLVED: To provide a novel compound that can detect the existence of ammonia with high sensitivity, an ammonia detection material including the same, and the like. SOLUTION: The present disclosure provides a compound represented by general formula (1). In the general formula (1), each R1 independently represent a hydrogen atom or R, each R independently represent an optionally branched, C8-35 alkyl group, alkyloxy group or alkylsilyloxy group, each Ar independently represent a substituent and/or an aromatic ring optionally having a hetero atom in a ring, each L independently represent -CR2=CR2-, -C≡C- or a single bond, each R2 independently represent a hydrogen atom or a C1-5 alkyl group, X- is any counter anion, each k independently represent an integer of 1-5, and m is an integer of 0-4. SELECTED DRAWING: Figure 2 COPYRIGHT: (C)2021,JPOandINPIT
