3073-57-2Relevant academic research and scientific papers
Network-forming liquids from metal-bis(acetamide) frameworks with low melting temperatures
Liu, Mengtan,McGillicuddy, Ryan D.,Vuong, Hung,Tao, Songsheng,Slavney, Adam H.,Gonzalez, Miguel I.,Billinge, Simon J.L.,Mason, Jarad A.
, p. 2801 - 2811 (2021)
Molten phases of metal-organic networks offer exciting opportunities for using coordination chemistry principles to access liquids and glasses with unique and tunable structures and properties. Here, we discuss general thermodynamic strategies to provide an increased enthalpic and entropic driving force for reversible, low-temperature melting transitions in extended coordination solids and illustrate this approach through a systematic study of a series of bis(acetamide)-based networks with record-low melting temperatures. The low melting temperatures of these compounds are the result of weak coordination bonds, conformationally flexible bridging ligands, and weak electrostatic interactions between spatially separated cations and anions, which collectively reduce the enthalpy and increase the entropy of fusion. Through a combination of crystallography, spectroscopy, and calorimetry, enthalpic trends are found to be dictated by the strength of coordination bonds and hydrogen bonds within each compound, while entropic trends are strongly influenced by the degree to which residual motion and positional disorder are restricted in the crystalline state. Extended X-ray absorption fine structure (EXAFS) and pair distribution function (PDF) analysis of Co(bba)3[CoCl4] [bba = N,N′-1,4-butylenebis(acetamide)], which features a record-low melting temperature for a three-dimensional metal-organic network of 124 °C, provide direct evidence of metal-ligand coordination in the liquid phase, as well as intermediate- and extended-range order that support its network-forming nature. In addition, rheological measurements are used to rationalize differences in glass-forming ability and relaxation dynamics. These results provide new insights into the structural and chemical factors that influence the thermodynamics of melting transitions of extended coordination solids, as well as the structure and properties of coordination network-forming liquids.
Unexpected Acetylation of Endogenous Aliphatic Amines by Arylamine N-Acetyltransferase NAT2
Bergdahl, Ingvar A.,Conway, Louis P.,Correia, Mário S. P.,Globisch, Daniel,Rendo, Veronica,Sj?blom, Tobias
supporting information, p. 14342 - 14346 (2020/07/13)
N-Acetyltransferases play critical roles in the deactivation and clearance of xenobiotics, including clinical drugs. NAT2 has been classified as an arylamine N-acetyltransferase that mainly converts aromatic amines, hydroxylamines, and hydrazines. Herein, we demonstrate that the human arylamine N-acetyltransferase NAT2 also acetylates aliphatic endogenous amines. Metabolomic analysis and chemical synthesis revealed increased intracellular concentrations of mono- and diacetylated spermidine in human cell lines expressing the rapid compared to the slow acetylator NAT2 phenotype. The regioselective N8-acetylation of monoacetylated spermidine by NAT2 answers the long-standing question of the source of diacetylspermidine. We also identified selective acetylation of structurally diverse alkylamine-containing drugs by NAT2, which may contribute to variations in patient responses. The results demonstrate a previously unknown functionality and potential regulatory role for NAT2, and we suggest that this enzyme should be considered for re-classification.
Anodic oxidation of bisamides from diaminoalkanes by constant current electrolysis
Golub, Tatiana,Becker, James Y.
, p. 861 - 868 (2018/04/30)
In general, bisamides derived from diamines and involving 3 and 4 methylene groups as spacers between the two amide functionalities behave similar to monoamides upon anodic oxidation in methanol/LiClO4 because both types undergo majorly mono- and dimethoxylations at the α-position to the N atom. However, in cases where the spacer contains two methylene groups only the anodic process leads mostly to CH2-CH2 bond cleavage to afford products of type RCONHCH2OCH3. Moreover, upon replacing LiClO4 with Et4NBF4 an additional fragmentation type of product was generated from the latter amides, namely RCONHCHO. Also, the anodic process was found to be more efficient with C felt as the anode, and in a mixture of 1:1 methanol/acetonitrile co-solvents.
Amide exchange reaction: A simple and efficient CuO catalyst for diacetamide synthesis
Li, Qinghe,Wang, Peixue,Deng, Youquan
, p. 40890 - 40894 (2016/05/19)
A highly copper-catalysed amide exchange reaction of hexamethylenediamine (HDA) with CH3CN and H2O for the synthesis of hexamethylenebisacetamide (HMBA) without an organic solvent or gas protection was developed. 100% HDA conversion and >99% HMBA selectivity was obtained. X-ray diffraction, scanning emission microscopy, and temperature-programmed reduction of hydrogen were used to characterize the structural properties of the catalyst. The reaction mechanism was also investigated.
Substrate specificity of the bovine serum amine oxidase and in situ characterisation of aminoaldehydes by NMR spectroscopy
Houen, Gunnar,Struve, Casper,Sondergaard, Roar,Friis, Tina,Anthoni, Uffe,Nielsen, Per H.,Christophersen, Carsten,Petersen, Bent O.,Duus, Jens .
, p. 3783 - 3796 (2007/10/03)
The oxidation of spermidine or homospermidine with bovine serum amine oxidase (BSAO) was monitored in situ, using proton nuclear magnetic resonance spectroscopy in water with 10% D2O. NMR assignments were performed by spin decoupling and COSY spectra or by comparison with data from synthetic aminoaldehydes. The results represent the first in situ characterisation of the highly reactive aminoaldehydes and showed oxidation at the N1 amino group of spermidine and homospermidine. Comparison of homospermidine with a variety of substrates revealed that among straight chain di- and polyamines both an aminopropyl group and two primary amino groups separated by seven (norspermidine) or eight (spermidine) carbon atoms were required for optimal substrate ability. However, highest activity was seen with the substrate N-(4-aminobutyl)hexahydropyrimidine, showing that the substrate channel of BSAO has a dual substrate preference, with moderately bulky substituents at the distal end of a diamine contributing equally well as an alkyl amino group. Cytotoxic investigations of a variety of substrates for BSAO, confirmed previous results, that cytotoxicity is primarily linked to polyamines encompassing the aminopropyl moiety. No acrolein was observed at any time during the oxidation showing that it reacts very fast with available amino groups forming a variety of derivatives.
AMINOSILANES IN ORGANIC SYNTHESIS: PREPARATION OF N,N'-DISUBSTITUTED PUTRESCEINE DERIVATIVES
Taddei, Maurizio,Tempesti, Federica
, p. 1019 - 1024 (2007/10/02)
Polyfunctional disubstituted putresceines are prepared from the corresponding aminosilane and electrophiles, without or in presence of Lewis acids.
The +-Peak in the Mass Spectra of Diamines
Kuehne, Hardy,Hesse, Manfred
, p. 1470 - 1481 (2007/10/02)
The mass spectra of di- and polyamines containing a 1,2-ethandiamine or a 1,3-propandiamine unit are quite often characterized by +-peaks.It is demonstrated that these peaks correspond to a fragment-ion formed by loss of H. from a formaldehyde-condensation product (e. g. 15) or by loss of CH3. from a acetalaldehyde-condensation product (e. g. 16) with the diamine.The aldehydes are usually impurities in solvents (especially methanol) used by chromatography, synthesis etc. of the diamines.
