16858-01-8Relevant articles and documents
A series of organic-inorganic hybrid materials consisting of flexible organic amine modified polyoxomolybdates: synthesis, structures and properties
Gong, Chunhua,Zeng, Xianghua,Zhu, Chengfeng,Shu, Jiahui,Xiao, Pingxiu,Xu, Hao,Liu, Lichun,Zhang, Junyong,Zeng, Qingdao,Xie, Jingli
, p. 106248 - 106259 (2016)
A series of organic-inorganic hybrid complexes based on different types of polyoxomolybdates and transition metal complexes, namely, [Zn2(TPMA)2(H2P2Mo5O23)]·11H2O (1), [Zn2(TPMA)2(Mo8O26)] (2), [Co2(TPMA)2(Mo8O26)] (3), [Ni2(TPMA)2(Mo8O26)(H2O)2] (4), [Ni2(TPMA)2(2-PA)(H2O)](PMo12O40) (5) [Cu2(TPMA)2(Mo8O26)] (6), 2[Cu(TPMA)(CrMo6(OH)6O18)]·H[Cu2(TPMA)2(CrMo6(OH)6O18)]·4H2O (7) (TPMA = Tris[(2-pyridyl)methyl]amine, 2-PA = 2-picolinic acid), have been successfully synthesized under hydrothermal conditions. All complexes were characterized by single-crystal X-ray structural analysis, powder X-ray diffraction, IR spectroscopy and TG analysis. All the complexes showed polyoxomolybdate-based zero-dimensional (0D) structures, and could be further extended into three-dimensional (3D) supramolecular frameworks through hydrogen bonding interactions. In addition, the electrochemical properties of complexes 1-7 have been investigated. Interestingly, some complexes have efficient photocatalytic activities to degradate pararosaniline hydrochloride dye molecules.
Polypyridyl Co complex-based water reduction catalysts: why replace a pyridine group with isoquinoline rather than quinoline?
Guo, Xusheng,Li, Chao,Wang, Weibo,Hou, Yuanjun,Zhang, Baowen,Wang, Xuesong,Zhou, Qianxiong
, p. 2042 - 2049 (2021)
The electronic effect of the substituent has been fully leveraged to improve the activity of molecular water reduction catalysts (WRCs). However, the steric effect of the substituents has received less attention. In this work, a steric hindrance effect was observed in a quinoline-involved polypyridyl Co complex-based water reduction catalyst (WRC), which impedes the formation of Co(iii)-H from Co(i), two pivotal intermediates for H2evolution, leading to significantly impaired electrocatalytic and photocatalytic activity with respect to its parent complex, [Co(TPA)Cl]Cl (TPA = tris(2-pyridinylmethyl)-amine). In sharp contrast, two isoquinoline-involved polypyridyl Co complexes exhibited significantly improved H2evolution efficiencies compared to [Co(TPA)Cl]Cl, benefitting mainly from the more basic and conjugated features of isoquinoline over pyridine. The dramatically different influences caused by the replacement of a pyridine group in the TPA ligand by quinoline and isoquinoline fully demonstrates the important roles of both the electronic and steric effects of a substituent. Our results may provide novel insights for designing more efficient WRCs.
Tris(8-methoxy-2-quinolylmethyl)amine (8-MeOTQA) as a highly fluorescent Zn2+ probe prepared by convenient C3-symmetric tripodal amine synthesis
Mikata, Yuji,Nodomi, Yuki,Ohnishi, Risa,Kizu, Asako,Konno, Hideo
, p. 8021 - 8030 (2015)
A convenient synthesis of C3-symmetric tribenzylamine (TBA) derivatives has been investigated. The reaction of benzyl chlorides with acetaldehyde ammonia trimer (1) in the presence of base afforded tribenzylamines in high yields. This efficient method allows the diverse synthesis of TPA (tris(2-pyridylmethyl)amine) and TQA (tris(2-quinolylmethyl)amine) derivatives. Among the TQA compounds prepared, tris(8-methoxy-2-quinolylmethyl)amine (8-MeOTQA, 4) exhibited superior properties as a fluorescent zinc probe with high quantum yield (Zn = 0.51) and high sensitivity (limit of detection (LOD) = 3.4 nM). The X-ray crystallographic analysis of [Zn(8-MeOTQA)]2+ revealed that the steric and electronic effect of 8-methoxy substituents kicks out the solvent and counterion molecules from the metal coordination sphere, resulting in short Zn-Nquinoline coordination distances (2.04-2.07 ?). The pseudo hexacoordinate complex of 6-methoxy derivative, [Zn(6-MeOTQA)(DMF)(ClO4)]+, exhibited longer Zn-Nquinoline distances (2.07-2.19 ?) and much smaller fluorescence intensity (Zn = 0.027). The replacement of one of the three 8-methoxyquinolines with pyridine also afforded much less fluorescent zinc complex (Zn = 0.095) due to the solvent coordination (Zn-Nquinoline = 2.05-2.18 ? for [Zn(8-MeOBQPA)(CH3OH)]2+).
Photocatalytic hydrogen evolution by Cu(II) complexes
Wang, Junfei,Li, Chao,Zhou, Qianxiong,Wang, Weibo,Hou, Yuanjun,Zhang, Baowen,Wang, Xuesong
, p. 5439 - 5443 (2016)
[Cu(TMPA)Cl]Cl (1) and [Cu(Cl-TMPA)Cl2] (2) exhibited efficient photocatalytic H2 evolution with a TON of 6108 and 10014 (6 h), respectively, in CH3CN/H2O solution (9:1, v/v) containing an Ir complex as the photosensitizer and triethylamine as the sacrificial reductant, representing the first example of photocatalytic Cu complex-based water reduction catalysts.
Fast Oxygen Reduction Catalyzed by a Copper(II) Tris(2-pyridylmethyl)amine Complex through a Stepwise Mechanism
Langerman, Michiel,Hetterscheid, Dennis G. H.
, p. 12974 - 12978 (2019)
Catalytic pathways for the reduction of dioxygen can either lead to the formation of water or peroxide as the reaction product. We demonstrate that the electrocatalytic reduction of O2 by the pyridylalkylamine copper complex [Cu(tmpa)(L)]2+ in a neutral aqueous solution follows a stepwise 4 e?/4 H+ pathway, in which H2O2 is formed as a detectable intermediate and subsequently reduced to H2O in two separate catalytic reactions. These homogeneous catalytic reactions are shown to be first order in catalyst. Coordination of O2 to CuI was found to be the rate-determining step in the formation of the peroxide intermediate. Furthermore, electrochemical studies of the reaction kinetics revealed a high turnover frequency of 1.5×105 s?1, the highest reported for any molecular copper catalyst.
Characterization of cobalt(III) hydroxamic acid complexes based on a tris(2-pyridylmethyl)amine scaffold: Reactivity toward cysteine methyl ester
Alimi, Mickael,Allam, Anas,Galardon, Erwan,Artaud, Isabelle,Selkti, Mohamed,Tomas, Alain,Roussel, Pascal
, p. 9350 - 9356,7 (2012)
Six Co(III) complexes based on unsubstituted or substituted TPA ligands (where TPA is tris(2-pyridylmethyl)amine) and acetohydroxamic acid (A), N-methyl-acetohydroxamic acid (B), or N-hydroxy-pyridinone (C) were prepared and characterized by mass spectrometry, elemental analysis, and electrochemistry: [Co(III)(TPA)(A-2H)](Cl) (1a), [Co(III)((4-Cl2)TPA)(A-2H)](Cl) (2a), [Co(III)((6-Piva)TPA)(A-2H)](Cl) (3a), [Co(III)((4-Piva)TPA)(A-2H)](Cl) (4a) and [Co(III)(TPA)(B-H)](Cl)2 (1b), and [Co(III)(TPA)(C-H)](Cl) 2 (1c). Complexes 1a-c and 3a were analyzed by 1H NMR, using 2D (1H, 1H) COSY and 2D (1H, 13C) HMBC and HSQC, and shown to exist as a mixture of two geometric isomers based on whether the hydroxamic oxygen was trans to a pyridine nitrogen or to the tertiary amine nitrogen. Complex 3a exists as a single isomer that was crystallized. Its crystal structure revealed the presence of an H-bond between the pivaloylamide and the hydroximate oxygen. Complexes 1a, 2a, and 4a are irreversibly reduced beyond -900 mV versus SCE, while complexes 1b and 1c are reduced at less negative values of -330 and -190 mV, respectively. The H-bond in 3a increased the redox potential up to -720 mV. Reaction of complex 1a with l-cysteine methyl ester CysOMe was monitored by 1H NMR and UV-vis at 2 mM and 0.2 mM in an aqueous buffered solution at pH 7.5. Complex 1a was successively converted into an intermediate [Co(III)(TPA)(CysOMe-H)] 2+, 1d, by exchange of the hydroximate with the cysteinate ligand, and further into Co(III)(CysOMe-H)3, 5. An authentic sample of 1d was prepared and thoroughly characterized. A detailed 1H NMR analysis showed there was only one isomer, in which the thiolate was trans to the tertiary amine nitrogen.
Bioinspired manganese complex for room-temperature oxidation of primary amines to imines by t-butyl hydroperoxide
Lei, Lin,Chen, Yaju,Feng, Zhenfeng,Deng, Chunyan,Xiao, Yepeng
, (2021/02/21)
A sustainable method is developed for the selective and additive-free synthesis of imines from primary amines with TBHP catalyzed by bioinspired manganese complex (MnCl2(TPA)) at room temperature. Use of 0.2 mol % MnCl2(TPA) was efficient enough for this transformation by offering excellent conversions up to 98.2% along with 93.4% product yield within 1 h. The influence of reaction parameters (catalyst dosage, solvent, reaction temperature, time, etc.) on the catalytic performance was also investigated in detail. Building on these results, the selected MnCl2(TPA) was further employed to transform various primary amines into corresponding imines and exhibited good compatibility even for the challenging aliphatic amine. The high efficiency, combining with a large substrate scope and ambient reaction conditions, makes the developed bioinspired Mn complex/TBHP system a promising pathway to produce imines. This work also paves a way to the expansion of non-heme metal catalysts as efficient platforms for various oxidation reactions.
Understanding the Origin of One- or Two-Step Valence Tautomeric Transitions in Bis(dioxolene)-Bridged Dinuclear Cobalt Complexes
Boskovic, Colette,Gable, Robert W.,Gransbury, Gemma K.,Hay, Moya A.,Janetzki, Jett T.,Livesay, Brooke N.,Shores, Matthew P.,Starikova, Alyona
supporting information, p. 10692 - 10704 (2020/07/04)
Valence tautomerism (VT) involves a reversible stimulated intramolecular electron transfer between a redox-active ligand and redox-active metal. Bis(dioxolene)-bridged dinuclear cobalt compounds provide an avenue toward controlled two-step VT interconversions of the form {CoIII-cat-cat-CoIII} ? {CoIII-cat-SQ-CoII}?{CoII-SQ-SQ-CoII} (cat2- = catecholate, SQ·- = semiquinonate). Design flexibility for dinuclear VT complexes confers an advantage over two-step spin crossover complexes for future applications in devices or materials. The four dinuclear cobalt complexes in this study are bridged by deprotonated 3,3,3′,3′-tetramethyl-1,1′-spirobi(indan)-5,5′,6,6′-tetraol (spiroH4) or 3,3,3′,3′-tetramethyl-1,1′-spirobi(indan)-4,4′,7,7′-tetrabromo-5,5′,6,6′-tetraol (Br4spiroH4) with Mentpa ancillary ligands (tpa = tris(2-pyridylmethyl)amine, n = 0-3 corresponds to methylation of the 6-position of the pyridine rings). Complementary structural, magnetic, spectroscopic, and density functional theory (DFT) computational studies reveal different electronic structures and VT behavior for the four cobalt complexes; one-step one-electron partial VT, two-step VT, incomplete VT, and temperature-invariant {CoIII-cat-cat-CoIII} states are observed. Electrochemistry, DFT calculations, and the study of a mixed-valence {ZnII-cat-SQ-ZnII} analog have allowed elucidation of thermodynamic parameters governing the one- and two-step VT behavior. The VT transition profile is rationalized by (1) the degree of electronic communication within the bis(dioxolene) ligand and (2) the matching of cobalt and dioxolene redox potentials. This work establishes a clear path to the next generation of two-step VT complexes through incorporation of mixed-valence class II and class II-III bis(dioxolene) bridging ligands with sufficiently weak intramolecular coupling.
