26082-96-2Relevant academic research and scientific papers
Monooxygenation of an appended phenol in a model system of tyrosinase: Implications on the enzymatic reaction mechanism
Hamann, Jessica Nadine,Rolff, Malte,Tuczek, Felix
, p. 3251 - 3258 (2015)
A new tridentate N-donor ligand and its corresponding copper(i) complex have been synthesized to investigate the tyrosinase-like aromatic hydroxylation of an attached phenol. The results of the oxygenation reactions are compared to related systems having attached phenyl and catechol groups, respectively. The title complex is the first system mediating the monooxygenation of a phenol in the absence of an external base. This journal is
Triply bridged dinuclear ruthenium complexes bearing alkylbis(2-pyridylmethyl)amine in the mixed-valence state of Ru(ii)-Ru(iii)
Misawa-Suzuki,Matsuya,Watanabe,Nagao
, p. 16182 - 16189 (2018)
Triply halogeno and methoxido-bridged dinuclear ruthenium complexes bearing a tridentate ancillary ligand, alkylbis(2-pyridylmethyl)amine (alkyl, ethyl and benzyl), in the Ru(ii)-Ru(iii) mixed-valence state were synthesized by reduction reactions of the trichloridoruthenium(iii) complex, fac-[RuIIICl3(ebpma)], followed by chlorido-substitution and oxidation reactions in air. The conversion of the bridging ligands of the diruthenium complexes was also made possible through reduction of the dinuclear core. The electronic structures of the mixed-valence state were investigated by electron spin resonance (ESR), X-ray crystallography, electrochemical measurements and UV-vis-near infrared (NIR) spectroscopy. The mixed-valence state of all the triply bridged complexes was stable and classified as Class III.
Towards polymer diagnostic agents - Copolymers of N-(2-hydroxypropyl)- methacrylamide and bis(2-pyridylmethyl)-4-vinylbenzylamine: Synthesis, characterisation and Re(CO)3-labelling
Kunz, Peter C.,Brueckmann, Nadine E.,Spingler, Bernhard
, p. 394 - 399 (2007)
Diagnosis of early stage angiogenic tumours is fundamental for cancer therapy. In this study we present the synthesis and characterisation of functionalised HPMA-copolymers with optimal molecular weights that meet the demands of the enhanced permeability and retention (EPR) effect. Rhenium tricarbonyl complexes of the tripodal ligands bis(2-pyridylmethyl)benzylamine (1a) and bis(2-pyridylmethyl)-4-vinylbenzylamine (1b) were prepared and characterised by 1H NMR and IR spectroscopy, mass spectrometry and X-ray diffraction. Ligand 1b was copolymerised with N-(2-hydroxypropyl) methacrylamide (HPMA), and the resulting copolymer was treated with (nBu 4N)2[Re(CO)3Br3] to yield a Re(CO)3-labelled copolymer. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
New tridentate ligands of the type N-Alkyl-N,N-bis(2-pyridylmethyl)amine
Dick, Stefan,Weiss, Armin
, p. 188 - 192 (1997)
New tridentate ligands of the type N-alkyl-N,N-bis(2-pyridylmethyl)amine (alkyl = methyl, benzyl, adamantyl) have been synthesized by reaction of alkylamines with 2-(chlormethyl)pyridine in alkaline solution. These amines are preferably isolated and stored as perchlorates. The perchlorale of the methyl substituted ligand has been crystallized in two modifications that differ in the twisting of the aromatic rings and in the coordination of the perchlorate anions.
Highly selective hydroxylation of alkanes catalyzed by (μ-oxo)bis(μ- carboxylato)-bridged diiron(iii) complexes: Involvement of mononuclear iron(iii) species in catalysis
Visvaganesan, Kusalendiran,Suresh, Eringathodi,Palaniandavar, Mallayan
, p. 3814 - 3823 (2009)
A few diiron(iii) complexes [Fe2(O)(OAc)2(L1) 2](ClO4)21, [Fe2(O)(OBz) 2(L1)2](ClO4)22, [Fe 2(O)(OAc)2(L2)2](ClO4)23 and [Fe2(O)(OBz)2(L2)2](ClO4) 24, where L1 = N,N-bis(pyrid-2-ylmethyl)-iso-butylamine, L2 = N,N-bis(pyrid-2-ylmethyl)benzylamine, AcO = acetate and BzO = benzoate, have been isolated and characterized by means of elemental analysis and spectral and electrochemical methods. The molecular structures of the complexes 2 and 4 have been determined by single-crystal X-ray diffraction analysis and they possess a distorted bioctahedral geometry in which each iron atom is coordinated to the oxygen atom of the μ-oxo bridge, two oxygen atoms of the μ-benzoato bridges and three nitrogen atoms of L1 and L2 ligands capping the two ends of the diiron(iii) cluster. The ESI-MS spectral data of the complexes reveal that the complexes remain intact in dichloromethane (DCM) solution. Upon adding one equivalent of Et3N to a mixture of one equivalent of the diiron(iii) complexes and excess of m-chloroperbenzoic acid (m-CPBA) in DCM, an intense absorption band (λmax, 670-700 nm) appears, which corresponds to the species [Fe2(O)(OAc)(m-CPBA)(L)2]2+ (ESI-MS, m/z 466) suggested as the intermediate involved in the oxygenation reactions. All the present complexes show efficient alkane hydroxylation with 300-400 turn over numbers and good selectivities for cyclohexane (A/K, 10-14) and adamantane (3°/2°, 9-11). Interestingly, the formation of monoiron(iii) species has been discerned in the alkane hydroxylation reactions beyond ～50 turnovers. The mononuclear 1: 1 iron(iii) complexes of L1 and L2 ligands generated in situ are also found to catalyze the oxygenation reactions with high selectivity and efficiency for cyclohexane (A/K, 10-14). Upon their reaction with m-CPBA in DCM, a characteristic absorption band (λmax, 600 nm, εmax, 355 M-1 cm-1) appears and decays at room temperature. This spectral feature is consistent with the mononuclear high-valent iron-oxo species suggested as an intermediate in the oxygenation reactions.
Synthesis and structural characterisation of Palladium(ii) complexes with N,N′,N-tridentate N′-substituted N,N-Di(2-picolyl)amines and their application to methyl methacrylate polymerisation
Kim, Sunghoon,Kim, Dongil,Song, Yujin,Lee, Ha-Jin,Lee, Hyosun
, p. 953 - 961 (2014/07/07)
The reaction of [Pd(CH3CN)2Cl2] with N′-substituted N,N-di(2-picolyl)amine-based ancillary ligands, for example N,N-di(2-picolyl)cyclohexylmethylamine (L1), N,N-di(2-picolyl)benzylamine (L2), N,N-di(2-picolyl)aniline (L3), and 1,4-bis[bis(2-pyridylmethyl)aminomethyl] benzene (L4), in the presence of NaClO4 in ethanol yields a new series of [(NN′N)PdCl]X (X≤ClO4, Cl) complexes, i.e. mononuclear [LnPdCl]ClO4 (Ln≤L1, L2, L 3) and binuclear [L4Pd2Cl2]Cl 2. X-Ray crystallographic analysis determined that the Pd atom in complexes [(NN′N)PdCl]X showed a slightly distorted square-planar geometry involving three nitrogen atoms and a chlorido ligand. Moreover, the unit cell included a ClO4-or Cl-anion as the counterion. The complex [L1PdCl]ClO4 showed the highest catalytic activity for the polymerisation of methyl methacrylate in the presence of modified methylaluminoxane at 60°C among the mononuclear PdII complexes. Specifically, the activity of binuclear [L4Pd2Cl 2]Cl2 was 2-fold higher than the corresponding mononuclear [L2PdCl]ClO4 per active palladium metal centre. CSIRO 2014.
Solvent induced cooperativity of Zn(ii) complexes cleaving a phosphate diester RNA analog in methanol
Mohamed, Mark F.,Sánchez-Lombardo, Irma,Neverov, Alexei A.,Brown, R. Stan
experimental part, p. 631 - 639 (2012/02/05)
The kinetics of cyclization of 2-hydroxypropyl p-nitrophenyl phosphate (1) promoted by two mononuclear Zn(ii) catalytic complexes of bis(2-pyridylmethyl) benzylamine (4) and bis(2-methyl 6-pyridylmethyl)benzylamine (5) in methanol were studied under sspH-controlled conditions (where sspH refers to [H +] activity in methanol). Potentiometric titrations of the ligands in the absence and presence of Zn2+ and a non-reactive model for 1 (2-hydroxylpropyl isopropyl phosphate (HPIPP, 6)) indicate that the phosphate is bound tightly to the 4:Zn(ii) and 5:Zn(ii) complexes as L:Zn(ii):6-, and that each of these undergoes an additional ionization to produce L:Zn(ii):6-:(-OCH3) or a bound deprotonated form of the phosphate, L:Zn(ii):62-. Kinetic studies as a function of [L:Zn(ii)] indicate that the rate is linear in [L:Zn(ii)] at concentrations well above those required for complete binding of the substrate. Plots of the second order rate constants (defined as the gradient of the rate constant vs. [complex] plot) vs.sspH in methanol are bell-shaped with rate maxima of 23 dm mol-1 s-1 and 146 dm mol-1 s-1 for 4:Zn(ii) and 5:Zn(ii), respectively, at their sspH maxima of 10.5 and 10. A mechanism is proposed that involves binding of one molecule of complex to the phosphate to yield a poorly reactive 1:1 complex, which associates with a second molecule of complex to produce a transient cooperative 2:1 complex within which the cyclization of 1 is rapid. The observations support an effect of the reduced polarity solvent that encourages the cooperative association of phosphate and two independent mononuclear complexes to give a reactive entity.
Control of peroxyoxalate chemiluminescence by nitrogen-containing ligand quenching: Turning off and on by ligand-metal ion host-guest interactions
Maruyama, Takayuki,Fujie, Yasuyuki,Oya, Noriyuki,Hosaka, Eisuke,Kanazawa, Aki,Tanaka, Daisuke,Hattori, Yoshiyuki,Motoyoshiya, Jiro
experimental part, p. 6927 - 6933 (2011/10/02)
The control of peroxyoxalate chemiluminescence (PO-CL) by the coordination of nitrogen-containing ligands and metal cations was investigated. Turning the CL off and on was done by PO-CL using 15-monoazacrown-5-tethered anthracene and alkali metal ions. CL quenching and regeneration was also observed in the separated molecular system of 15-monoazacrown-5 and the fluorophores. CL quenching by a number of ligands bearing dipicolylamino groups was evaluated by these PO-CL reactions and found to be closely related to their oxidation potentials, which is dependent on the Weller rate law for electron exchange and this provides strong support for the existence of the CIEEL PO-CL process. When Zn2+ or Cu2+ are added to the PO-CL system quenched by the ligand, N-[2-(2,2′-dipicolylamino)ethyl]aniline, CL was turned on because the electron donating ability of the ligands was modulated. This was controlled by the coordination of the studied metal ions and, therefore, this system results in CL because of host-guest interactions.
Toluene and Ethylbenzene aliphatic C-H bond oxidations initiated by a dicopper(II)-μ-1,2-Peroxo complex
Lucas, Heather R.,Li, Lei,Narducci Sarjeant, Amy A.,Vance, Michael A.,Solomon, Edward I.,Karlin, Kenneth D.
experimental part, p. 3230 - 3245 (2009/07/30)
With an anisole-containing polypyridylamine potential tetradentate ligand °L, a μ-1,2-peroxodicopper(II) complex [{°LCuII}2(O22-)]2+ forms from the r eaction of the mononuclear compound [Cu1(°L)(MeCN)]B(C6F 5)4 (°LCu1) with O2 in noncoordinating solvents at -80°C. Thermal decay of this peroxo complex in the presence of toluene or ethylbenzene leads to rarelyseen C-H activation chemistry; benzaldehyde and acetophenone/1-phenylet hanol mixtures, respectively, are formed. Experiments with 18O2 confirm that the oxygen source in the products is molecular O2 and deuterium labeling experiments indicate kH/kD = 7.5 2-reaction of [Cu1(BZL)(CH 2CN)]+ (BZLCu1) leads to a dicopper(III)-bis- μ-oxo species [{BzLCuIII}2(μ-O2-)2]2+ at -80°C, and from such solutions, very similar toluene oxygenation chemistry occurs. Ligand BZL is a tridentate chelate, possessing the same moiety found in °L, but without the anisole O-atom donor. In these contexts, the nature of the oxidant species in or derived from [{°LCu II}2(O2 2-)]2+ is discussed and likely mechanisms of reaction initiated by toluene H-atom abstraction chemistry are detailed. To confirm the structural formulations of the dioxygen-adducts, UV-vis and resonance Raman spectroscopic studies have been carried out and these results are reported and compared to previously described systems including [{CuII (PyL)}2(O2)]2+ ( PyL ) TMPA ) tris(2-methylpyridyl) amine). Using (L)Cu1, CO-binding properties (i.e., C-O values) along with electrochemical property comparisons, the relative donor abilities of °L, BZL, and PyL are assessed.
Synthesis, spectroscopic characterization and hydroxylation of Mn(II) complexes with bis(2-pyridylmethyl)benzylamine
Li, Jun-Feng,Chen, Qiu-Yun
experimental part, p. 25 - 28 (2009/05/31)
Two new Mn(II) complexes of bis(2-pyridylmethyl)benzylamine (bpa) were synthesized and characterized by elemental analyses, IR and UV-visible spectroscopies, thermal analyses and ES-MS. These complexes are stable in air with the formula of [(pba)2/s
