1665-79-8Relevant academic research and scientific papers
Supramolecular Chemistry of Some Metal Acetylacetonates with Auxiliary Pyridyl Sites
Gunawardana, Chamara A.,Sinha, Abhijeet S.,Desper, John,Lakovi?, Marijana,Aaker?y, Christer B.
, p. 6936 - 6945 (2018/10/20)
Hetero-bifunctional ligands can pave the way for elaborate metallo-supramolecular systems and are also useful for combining metal-ligand bonding with other types of noncovalent interactions. We synthesized two new pyridyl-acetylacetonate ligands, 3-(4-(pyridin-4-yl)phenyl)pentane-2,4-dione (L1) and 3-(4-(pyridin-4-ylethynyl)phenyl)pentane-2,4-dione (L2), and explored their metal binding ability with selected di- and trivalent transition metal ions. As expected, the acetylacetonate ligation with metal dications remains consistent among four structures, [Cu(L1)2(MeOH)2]n, [Co(L2)2]n, [Cu(L2)2(MeOH)2], and [Zn(L2)2(MeOH)2]; the metal is four-coordinate and resides in a square planar environment. Differences in the overall architectures arise basically from the role played by the terminal heterocycle (i.e., the pyridyl group). In [Cu(L1)2(MeOH)2]n and [Co(L2)2]n, the heterocyclic end directly binds to the metal (through vacant axial positions), thereby producing coordination networks. In [Cu(L2)2(MeOH)2] and [Zn(L2)2(MeOH)2], metal-methanol coordination and intermolecular O-H(methanol)···N(pyridine) hydrogen-bond interactions work in concert to weave those bis-acetylacetonate complexes into ribbon-like supramolecular polymeric arrays. Somewhat surprisingly, the only tris-chelated acetylacetonate complex characterized in this study, [Fe(L2)3], essentially exists as discrete dimeric aggregates.
New constituents related to 3-methyl-2,4-nonanedione identified in green tea
Naef, Regula,Jaquier, Alaini,Velluz, Alain,Maurer, Bruno
, p. 9201 - 9205 (2008/02/03)
The volatile constituents of two exquisite green tea varieties, Kiyosawa tea from Japan and Long Jing tea from China, were investigated in order to identify new compounds responsible for the characteristic flavor of a green tea brew. The extracts were prepared by solid-phase extraction using Oasis-HLB-cartridges. Besides the common compounds of green tea chemistry, the already described compounds 3-methyl-2,4-nonanedione (1) and 3-hydroxy-3-methyl-2,4-nonanedione (2), products of degradation of furan fatty acids, as well as three new compounds related to compound 1 were identified. These were 1-methyl-2-oxopropyl hexanoate (3), 1-methyl-2-oxoheptyl acetate (4) and 2-butyl-4,5-dimethyl-3(2H)-furanone (5). Their syntheses and spectroscopic data are reported. Compound 2 increases the sweet, creamy aroma and the characteristic mouthfeel of a green tea flavor, compounds 3 and 4 contribute to its floral, juicy notes and compound 5 exhibits an interesting sweet, buttery flavor.
Diisocyanates containing hydantoin groups and polyurethanes in which they are present
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, (2008/06/13)
Diisocyanates of the formula (I) where R1is a C1-C10-hydrocarbon radical and R3is a C1-Cl2-hydrocarbon group and n is an integer from 1 to 10, are described.
Dynamic Equilibria between Pentavalent Protonated Oxyphosphoranes and Their Isomeric Tetravalent Enol Phosphonium Ions via Inter- and Intramolecular Proton Transfer
Castelijns, Marianne M. C. F.,Schipper, Pieter,Aken, Dirk van,Buck, Henk M.
, p. 47 - 53 (2007/10/02)
Low-temperature NMR (1H, 13C, 31P) measurements of the reaction of several pentavalent oxyphosphoranes with FSO3H in CH2Cl2 are described.Rapid equilibria between the neutral oxyphosphoranes and the enol phosphonium ions involving an intermolecular proton transfer can be obtained by implying certain structural constraints on the system, which means that less entropy has to be expended in order to obtain the rigid closed form of the protonated oxyphosphorane.Moreover, in one case evidence is presented for an intramolecular proton-exchange process which is also controlled by an intermediary pentavalent protonated oxyphosphorane.These reactions may be regarded as a model for intramolecular (biological) phosphorylation processes.
