5453-67-8Relevant articles and documents
Catalytic Water Oxidation by a Molecular Ruthenium Complex: Unexpected Generation of a Single-Site Water Oxidation Catalyst
Rabten, Wangchuk,K?rk?s, Markus D.,?kermark, Torbj?rn,Chen, Hong,Liao, Rong-Zhen,Tinnis, Fredrik,Sun, Junliang,Siegbahn, Per E. M.,Andersson, Pher G.,?kermark, Bj?rn
, p. 4611 - 4620 (2015)
The increasing energy demand calls for the development of sustainable energy conversion processes. Here, the splitting of H2O to O2 and H2, or related fuels, constitutes an excellent example of solar-to-fuel conversion schemes. The critical component in such schemes has proven to be the catalyst responsible for mediating the four-electron oxidation of H2O to O2. Herein, we report on the unexpected formation of a single-site Ru complex from a ligand envisioned to accommodate two metal centers. Surprising N-N bond cleavage of the designed dinuclear ligand during metal complexation resulted in a single-site Ru complex carrying a carboxylate-amide motif. This ligand lowered the redox potential of the Ru complex sufficiently to permit H2O oxidation to be carried out by the mild one-electron oxidant [Ru(bpy)3]3+ (bpy = 2,2′-bipyridine). The work thus highlights that strongly electron-donating ligands are important elements in the design of novel, efficient H2O oxidation catalysts. (Chemical Equation Presented).
Phenyl and pyridyl Bis-Pyrazoles: Synthesis from the Bis(p-diketone) precursors and characterization by analytical and spectroscopic methods
Pons, Josefina,Chadghan, Arafa,Garcia-Anton, Jordi,Ros, Josep
, p. 178 - 181 (2010)
The bis(β.-diketone) compounds, 3,3'-(pyridine-2,6-diyl)bis(1- phenylpropane-1,3-dione) monohydrated (1a-H2O) and 3,3'-(pyridine-2,6-diyl)bis(1-(pyridin-2-yl)propane-1,3-dione) monohydrated (1b-H2O) were prepared by Claisen condensation of the appropriate ketone and dimethyl pyridine-2,6-dicarboxylate ester. Compounds 2,6-bis(5- phenyl-17Y-pyrazol-3-yl)pyridine dihydrated (2a-2H2O) and 2,6-bis(5-(pyridin-2-yl)-17Y-pyrazol-3-yl)pyridine monohydrated (2b-H 2O) were synthesized by reaction of the appropriate bis(β.-diketone) compounds and hydrazine monohydrate.
Correction to: Dipicolinic acid derivatives as inhibitors of new delhi metallo-β-lactamase-1 (Journal of Medicinal Chemistry (2017) 60 (7267-72830 DOI: 10.1021/acs.jmedchem.7b00407)
Chen, Allie Y.,Thomas, Pei W.,Stewart, Alesha C.,Bergstrom, Alexander,Cheng, Zishuo,Miller, Callie,Bethel, Christopher R.,Marshall, Steven H.,Credille, Cy V.,Riley, Christopher L.,Page, Richard C.,Bonomo, Robert A.,Crowder, Michael W.,Tierney, David L.,Fast, Walter,Cohen, Seth M.
, p. 6400 - 6400 (2018)
Page 7270. In Scheme 1, the compound numbers are mislabeled. Compound 11 should be compound 1, compound 12 should be 2, and compounds 13?30 should be 3?20. The mislabel of the compounds in the scheme does not affect the main text or the results of this paper. The corrected Scheme 1 is shown here. (Figure Presented).
Thermochemistry of a Cobalt Complex with Ionisable Pyrazole Protons
Wilken, Mona,Würtele, Christian,Kügler, Merle,Chrobak, Frank,Siewert, Inke
, p. 2339 - 2344 (2018)
Herein, we present the thermodynamic analysis of a cobalt complex with a new pentadentate N-donor ligand bearing four ionisable pyrazole protons in aqueous solution. A detailed analysis of the CoII complex [Co(L)(X)]+/2+ in the solid state revealed that the 6th ligand X at the metal centre depends on the cobalt source employed. Small anions such as Cl– and NO3– coordinate to the metal ion, while larger anions that are weaker hydrogen-bond acceptors are found in the second coordination sphere of the complex and instead a solvent molecule coordinates. However, in aqueous KCl solution, the sixth ligand is always chloride forming [Co(L)Cl]Cl, 1Cl. pH dependent species distribution studies revealed a pKa of 7.3(3) for the first ionisable pyrazole proton in the cobalt(II) complex and 6.0(3) in the cobalt(III) complex (methanol/H2O mixture). That is the oxidation state has a fairly minor influence on the pKa of the pyrazole proton. The CoIII/CoII redox pair of the complex with the fully protonated ligand exhibits a potential of 0.78 V vs. NHE. The BDFE of the hypothetical H-atom abstraction step of [CoII(L)Cl]+ forming [CoIII(LH–1)Cl]+ was determined to equal 336 kJ mol–1.
A Photoswitchable Heteroditopic Ion-Pair Receptor
Kokan, Zoran,Chmielewski, Micha? J.
, p. 16010 - 16014 (2018)
Designing light-switchable heteroditopic receptors is challenging because it necessitates simultaneous (de)activation of two separate binding sites. Herein, we present the first photoswitchable heteroditopic ion-pair receptor in which both cation and anion binding sites are simultaneously and reversibly switched OFF and ON by a single photoswitch. Our receptor is simple, low molecular weight, and readily synthesized from commercially available precursors. Single-crystal X-ray structures and NMR spectroscopic titrations support ion-pair binding to the receptor both in the solid state and in solution, with strong positive cooperativity between the cation and anion binding. The receptor can be completely switched OFF by UV light-triggered photoisomerization of an acylhydrazone C=N double bond and remains kinetically stable in the deactivated form due to an intramolecular hydrogen bond. Its re-activation could be achieved by light irradiation or, more effectively, by fast acid-catalyzed back-isomerization. Our simple photoswitchable ion-pair receptor may serve as a blueprint for the design of new generations of switchable receptors, transporters, soft materials, and self-assembled systems, where incorporation of a functional heteroditopic ON/OFF photoswitch has been challenging up to now.
Ligand symmetry significantly affects spin crossover behaviour in isomeric [Fe(pybox)2]2+complexes
Wang, Run-Guo,Meng, Yin-Shan,Gao, Fang-Fang,Gao, Wan-Qing,Liu, Chun-Hua,Li, Anyang,Liu, Tao,Zhu, Yuan-Yuan
, p. 3369 - 3378 (2021)
The understanding of the correlation between the spin-state behaviour and the structural features in transition-metal complexes is of pronounced importance to the design of spin crossover compounds with high performance. However, the study of the influence of ligand symmetry on the spin crossover properties is still limited due to the shortage of suitable structural systems. Herein we report the magneto-structural correlations of three mononuclear Fe(ii) isomers with respect to their ligand symmetry. In this work, two phenyl-substitutedmesoandoptically purepybox ligands were employed to constructmeso(1),optically pure(2), andracemic(3) ligand types of [Fe(pybox)2]2+complexes. Their magnetic susceptibilities were measuredviatemperature-dependent paramagnetic1H NMR spectroscopy. We fitted the midpoint temperatures of the transition (T1/2) of 260 K for1(ClO4), 247 K for2(ClO4), and 281 K for3(ClO4). The influence of structural symmetry on spin crossover was rationalized through density functional theory calculations. The optimized structures of [Fe(pybox)2]2+complex cations show that the geometric distortion of the central FeN6coordination sphere is mainly caused by the steric congestions between adjacent phenyl substituents. In these compounds, there is a distinct correlation that more steric congestions produce larger coordination distortion and favor the electron configuration in the high-spin state, which reflects in the increase ofT1/2. Additionally, the influence of the counter anion and lattice solvent on themesoseries compounds was inspected. It is revealed that multiple factors dominate the spin-state behaviour in the solid state. This work provides deep insight into the effect of ligand symmetry on the spin transition behaviour in spin crossover compounds. It demonstrates that molecular symmetry should be considered in the design of spin crossover compounds.
Synthesis and photophysical properties of a highly luminescent EuIII-containing hybrid thin film
Liu, Xue,Bouwman, Elisabeth
, p. 25 - 29 (2016)
A luminescent thin film, Eu@glass, has been prepared on the surface of glass substrates from a silylated diamidopyridyl ligand L and the complex [Eu(dbm)3(H2O)2] (Hdbm?=?dibenzoylmethane) via a sol–gel method. The Eu@glass exhibits intense red photoluminescence under the irradiation of near UV light with a quantum yield of 26%. Compared to the compound [Eu(dbm)3(H2O)2], the photoluminescence intensity of Eu@glass is dramatically enhanced, and the emission lifetime of EuIII(0.517?ms) is more than an order of magnitude longer.
Complexes of 2,6-bis[N-(2′-pyridylmethyl)carbamyl]pyridme: Formation of mononuclear complexes, and self-assembly of double helical dinuclear and tetranuclear copper(II) and trinuclear nickel(II) complexes
Alcock, Nathaniel W.,Clarkson, Guy,Glover, Peter B.,Lawrence, Geoffrey A.,Moore, Peter,Napitupulu, Mery
, p. 518 - 527 (2005)
The potentially pentadentate ligand 2,6-bis[N-(2′-pyridylmethyl) carbamyl]pyridine (H2L1), readily prepared from reaction of a diester of pyridine-2,6-dicarboxylic acid (H2dipic) and 2-aminomethylpyridine (ampy), shows limited tendency to form 1: 1 M: L complexes with labile metal ions, although [CuL1] and [NIL1] were observed as minor species, the latter characterized by a crystal structure analysis. A mononuclear complex formed with inert Co(III) was characterized by a crystal structure as the neutral 1: 2 complex [Co(L1)(HL 1)] with two ligands acting as tridentate ligands, one coordinated by the central pyridine and its two flanking deprotonated amido groups, and the other by the central pyridine, one amido and one terminal pyridine group, with the remaining poorly coordinating protonated amide remaining unbound along with other terminal pyridine groups. Fe(III) is known to form a symmetrical 1: 2 complex, but that complex is anionic due to binding of all four deprotonated amido groups; the unsymmetrical neutral Co(III) complex converts into a symmetrical anionic species only on heating for hours in aqueous base in the presence of activated carbon. The most remarkable tendency of H 2L1, however, is towards the formation of robust double helical complexes: a dinuclear Cu(II) complex [Cu2L2 1] forms, as well as a trinuclear Ni(II) complex [Ni 3(L1)2(OAc)2(MeOH)2]. Moreover, in the presence of added H2dipic, the tetranuclear complex [Cu4(L1)2(dipic)2(OH 2)2] is obtained. All helical complexes have been characterized by X-ray crystal structure analyses, and all crystals feature a racemic mixture of left- and right-handed double helices stabilized by inter-ligand π-stacking (inter-ring distances of 3.2-3.8 A) of ligands which each span several metal ions. Using the chelating ligand pentane-2,4-dione (acac), each of the two pairs of adjacent monodentate ligands in [Ni 3(L1)2(OAc)2(OH2) 2] have been shown to be available for substitution without destroying the helical structure, to form [Ni3(L1) 2(acac)2], also characterized by a crystal structure.
Tubular porous coordination polymer for selective adsorption of CO2
Liu, Xing-Gui,Lu, Zhen-Zhong,Meng, Mei-Mei,Wang, Li-Fei,Xi, Ji-Ming,Xu, Yong-Kai,Zhang, Rui,Zhu, Rui
, (2021)
Multidentate chelating ligand is of an important influence on the structure and property of a coordination polymer. We designed a multidentate bridging ligands, 6,6′-(([1,1′-biphenyl]-4,4′-diylbis(azanediyl))bis(carbonyl))dipicolinic acid (bpdp), based on pyridine-2,6-dicarboxylate groups. A porous coordination polymer, [Mn(bpdp)]?2.8DMF (1, DMF = N,N,-dimethylacetamide), was obtained via solvothermal reaction. The bpdp ligand chelates to the Mn2+ atoms in a N,O,O’-tridentate mode, and link Mn2+ atoms into a helical chain. Three of these helical chains, which are related by translational symmetry, are intertwined together forming a tube structure. The tubes are arranged in parallel with strong hydrogen bonds and π???π interactions formed between tubes and forming a stable and highly porous structure, which showed high selectivity for adsorbing CO2 over N2.
Bis-(1,2,4-triazin-3-yl) ligand structure driven selectivity reversal between Am3+and Cm3+: solvent extraction and DFT studies
Ansari, S. A.,Bhattacharyya, Arunasis,Karthikeyan, N. S.,Mohapatra, P. K.,Rao, T. S.,Ravichandran, C.,Seshadri, H.,Venkatachalapathy, B.
supporting information, p. 7783 - 7790 (2021/06/16)
Selectivity between Am3+and Cm3+was investigated after their aqueous complexation with three structurally tailored hydrophilic bis-(1,2,4-triazin-3-yl) ligands followed by their extraction withN,N,N′N′-tetraoctyl diglycolamide (TODGA) dissolved in an ionic liquid (C4mim·Tf2N). The three hydrophilic ligands used were SO3PhBTP, SO3PhBTBP, and SO3PhBTPhen. It was evident from the solvent extraction studies that SO3PhBTP formed a stronger complex with Cm3+than with Am3+, but SO3PhBTPhen showed better complexation ability for Am3+than for Cm3+, and SO3PhBTBP showed no selectivity for the two actinide ions. DFT calculations indicated that the coordinating ‘N’atoms in BTP were more co-planar in the complex and this co-planarity was higher in the Cm3+complex as compared to that in Am3+. In the case of BTBP and BTPhen ligands, on the other hand, the co-planarity was more pronounced in the Am3+complexes. Mayer's bond order calculations of M-N bonds in the complexes also indicated a reversal of the complexation ability of the BTP and BTPhen ligands for Am3+and Cm3+. Calculations of the complexation energies further supported the higher selectivity of the BTP ligand for Am3+by ?52.0 kJ mol?1, and better selectivity of the BTPhen ligand for Cm3+by ?24.7 kJ mol?1
