Nickel(II)–NΛNΛO Pincer Type Complex-Catalyzed N-alkylation of Amines with Alcohols via the Hydrogen Autotransfer Reaction

2020 ◽  
Vol 85 (11) ◽  
pp. 7125-7135 ◽  
Author(s):  
Gunasekaran Balamurugan ◽  
Rengan Ramesh ◽  
Jan Grzegorz Malecki
Keyword(s):  
Type Complex ◽  
Hydrogen Autotransfer

Ruthenium(II) Complexes with N-Heterocyclic Carbene-Phosphine Ligands for the N-Alkylation of Amines with Alcohols

2021 ◽  
Author(s):  
Ming Huang ◽  
Yinwu Li ◽  
Xiao-Bing Lan ◽  
Jiahao Liu ◽  
Cunyuan Zhao ◽  
...  
Keyword(s):  
Metal Hydride ◽  
Phosphine Ligands ◽  
Hydride Complexes ◽  
Borrowing Hydrogen ◽  
Hydrogen Autotransfer

Metal hydride complexes are key intermediates for N-alkylation of amines with alcohols by borrowing hydrogen/hydrogen autotransfer (BH/HA) strategy. Reactivity tuning of metal hydride complexes could adjust the dehydrogenation of alcohols...

scholarly journals Deciphering the Role of Residues Involved in Disorder-To-Order Transition Regions in Archaeal tRNA Methyltransferase 5

Genes ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 399
Author(s):  
Ambuj Srivastava ◽  
Dhanusha Yesudhas ◽  
Shandar Ahmad ◽  
M. Michael Gromiha
Keyword(s):  
Three Dimensional ◽  
Md Simulations ◽  
Order Transition ◽  
Free Form ◽  
Wild Type ◽  
Intrinsically Disordered ◽  
Intrinsically Disordered Regions ◽  
Type Complex ◽  
In The Wild ◽  
Trna Methyltransferase

tRNA methyltransferase 5 (Trm5) enzyme is an S-adenosyl methionine (AdoMet)-dependent methyltransferase which methylates the G37 nucleotide at the N1 atom of the tRNA. The free form of Trm5 enzyme has three intrinsically disordered regions, which are highly flexible and lack stable three-dimensional structures. These regions gain ordered structures upon the complex formation with tRNA, also called disorder-to-order transition (DOT) regions. In this study, we performed molecular dynamics (MD) simulations of archaeal Trm5 in free and complex forms and observed that the DOT residues are highly flexible in free proteins and become stable in complex structures. The energetic contributions show that DOT residues are important for stabilising the complex. The DOT1 and DOT2 are mainly observed to be important for stabilising the complex, while DOT3 is present near the active site to coordinate the interactions between methyl-donating ligands and G37 nucleotides. In addition, mutational studies on the Trm5 complex showed that the wild type is more stable than the G37A tRNA mutant complex. The loss of productive interactions upon G37A mutation drives the AdoMet ligand away from the 37th nucleotide, and Arg145 in DOT3 plays a crucial role in stabilising the ligand, as well as the G37 nucleotide, in the wild-type complex. Further, the overall energetic contribution calculated using MMPBSA corroborates that the wild-type complex has a better affinity between Trm5 and tRNA. Overall, our study reveals that targeting DOT regions for binding could improve the inhibition of Trm5.

A 4-acyl-5-pyrazolone ligand (HQ) in N-unidentate coordination mode in a Rh(CO)2Cl(HQ)-type complex

2004 ◽  
Vol 7 (2) ◽  
pp. 235-237 ◽  
Author(s):  
Augusto Cingolani ◽  
Fabio Marchetti ◽  
Claudio Pettinari ◽  
Riccardo Pettinari ◽  
Brian W. Skelton ◽  
...  
Keyword(s):  
Coordination Mode ◽  
Type Complex

The Synthesis and Biological Function of a Novel Sandwich‐Type Complex Based on {SbW 9 } and Flexible bpp Ligand

2019 ◽  
Vol 8 (18) ◽  
pp. 1900471 ◽  
Author(s):  
Lu Wang ◽  
Shubin Li ◽  
Yu Kai ◽  
Jiang Zhu ◽  
Huijie Shi ◽  
...  
Keyword(s):  
Biological Function ◽  
Type Complex ◽  
Sandwich Type

Fine structure of the heterochromatin of the kangaroo rat Dipidomys ordii, and examination of the possible role of actin and myosin in heterochromatin condensation

1976 ◽  
Vol 21 (3) ◽  
pp. 465-477
Author(s):  
D.E. Comings ◽  
T.A. Okada
Keyword(s):  
Constitutive Heterochromatin ◽  
Divalent Cations ◽  
Random Coils ◽  
Type Complex ◽  
Kangaroo Rat ◽  
Thin Section Electron Microscopy ◽  
Section Electron ◽  
Liver Nuclei ◽  
The Brain

Biochemical studies have suggested that some actin and myosin may be present in the nucleus. This raises the possibility that heterochromatin condensation might be the result of an actin-myosin rigour type complex. Since ATP dissociates actin and myosin, this possibility could be examined by determining the effect of ATP on heterochromatin condensation. Thin-section electron microscopy showed large amounts of condensed constitutive heterochromatin in the kidney nuclei and somewhat less in the liver nuclei of the kangaroo rat, Dipidomys ordii. Surprisingly, there were some nuclei in the brain which contained no condensed heterochromatin despite the fact that this genome is composed of 50% satellite DNA. Although washing kidney nuclei with solutions of 10 mM Tris-ATP caused marked decondensation of the heterochromatin, when they were washed with Mg-ATP the heterochromatin was more condensed than in the controls. This suggests the decondensation by Tris-ATP is due to its ability to chelate divalent cations and provides no support for condensation of heterochromatin being the result of myosin-actin interaction. Despite being decondensed, the chromatin fibres of heterochromatin were distinct from those of euchromatin. The heterochromatin formed rod-like 19-5 nm fibres, the euchromatin formed random coils of 11-0-nm fibres.

A Novel Synthetic Approach to Asymmetric Salen, Dihydrosalen, and Tetrahydrosalen Ligands: Structures and O2-Activating Properties of their Nickel(II) and Cobalt(II) Complexes

1994 ◽  
Vol 49 (8) ◽  
pp. 1089-1100 ◽  
Author(s):  
Arnd Böttcher ◽  
Horst Elias ◽  
Brigitte Eisenmann ◽  
Elke Hilms ◽  
Andreas Huber ◽  
...  
Keyword(s):  
Equilibrium Constants ◽  
Spectrophotometric Titration ◽  
Acetone Solution ◽  
Synthetic Approach ◽  
Coordination Core ◽  
Type Complex ◽  
Square Planar ◽  
Synthetic Procedure ◽  
Derivatives Of ◽  
Methyl Phenyl

A synthetic procedure is described for the preparation of the tetradentate N2O2 ligands H2[H4]L1=6-(2-hydroxyphenyl)-2,5-diaza-3,3-dimethyl-1-(2-hydroxy-3-t-butyl-5-methyl- phenyl)heptane, H2[H2]L1 = 6-(2-hydroxyphenyl)-2,5-diaza-3,3-dimethyl-1-(2-hydroxy-3-t-butyl-5-methylphenyl)-1-heptene, and H2L1 = 6-(2-hydroxyphenyl)-2,5-diaza-3,3-dimethyl-1-(2- hydroxy-3-t-butyl-5-methylphenyl)-1,5-heptadiene, which are asymmetric derivatives of the ligands tetrahydrosalen, dihydrosalen, and salen. Complexes Ni[H4]L1, Ni[H2]L1, NiL1, CoL1, Ni[H4]L2 (([H4]L2)2- = anion of H2[H4]L2 = N,N'-bis(2-hydroxy-3-t-butyl-5-methylbenzyl)- trans-(S,S)-1,2-diaminocyclohexane), and NiL2 were prepared, characterized (VIS and IR ab­sorption, magnetic moment) and subjected to spectrophotometric titration with pyridine, to determine the equilibrium constants for adduct formation. Single crystal X-ray structure analy­ses were carried out for Ni[H2]L1 (monoclinic, P21/n; a = 8.926(4), b = 29.324(7), c = 8.411(4) Å; β = 95.3(1)°; Z = 4), CoL1 (monoclinic, C2/c; a = 25.389(2), b = 18.139(2), c = 10.179(1) Å; β = 112.227(6); Z = 8), and Ni[H4]L2·acetone (tetragonal, P41212; a = 13.928(3), c = 33.698(5) Å; Z = 8). In all of the three complexes, the N2O2-metal coordination core is square-planar. The skeleton of the tetradentate ligand is more or less twisted. The planar cobalt(II) complex CoL1 is a low spin d7 system with μexp = 2.02 BM at 298 K, whereas the planar complexes NiL1, Ni[H2]L1 and Ni[H4]L2 are diamagnetic (μexp = 0.28-0.64 BM). The blue solvate Ni[H4]L1- 3EtOH · H2O is paramagnetic (μexp = 3.04 BM), which points to octahedral coordination. In aerated acetone solution, the tetrahydrosalen-type complex Ni[H4]L1 activates dioxygen and one C-N bond is oxidatively dehydrogenated. The VIS spectrum of the dihydrosalen-type complex formed is virtually identical with that of the aldimine complex Ni[H2]L1. In the pres­ence of dioxygen, Co[H4]L1 and Co[H2]L1 are readily oxidized to CoL1 in acetone solution.

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