Biodiesel is a well-established biofuel that contains unsaturated and saturated fatty esters, and their contents influence oxidation stability and solidification properties, respectively. Also, these properties can be aggravated during use after long-term storage. In this research, a new class of antioxidant/antifreeze bifunctional additives was developed by copolymerization of monomers containing an active site for addition reactions. Hydroquinone was added to these active sites after polymerization, and this chemical modification improved the performance of the additive as an antioxidant and pour point depressant of soybean oil biodiesel. This unique class of bifunctional additives was more soluble in biodiesel than hydroquinone and polymethacrylates at the same molar concentrations. The best performance was obtained by poly(oleyl acrylate-co-stearyl acrylate hydroquinone), which improved the pour point of neat biodiesel (B100) by 10 °C using a charge of just 1000 mg/kg. Also, hydroquinone performed as good as dodecyl acrylate as the pendent group, hindering crystal growth while improving B100 oxidation stability.
Herein we report on the synthesis, single crystal X-ray structure and spectroscopic properties of [{Cu 2 (tidf)(l-ppz)}(ClO 4 ) 2 ] n (tidf = a Robson-type macrocyclic ligand obtained by condensation of 2,6-diformyl-4-methylphenol and 1,3-diaminopropane). The two copper(II) centers in the dicopper(II,II) chromophore share identical coordination environment. The geometry around the copper(II) is square pyramidal and has [Cu 2 (tidf)] 2? units bridged by piperazine and forming a 1D-coordination polymer. The structure is also supported by non-classic hydrogen bonding such as C-HÁÁÁO perchlorate . Electronic spectroscopy agrees with the C 4v micro-symmetry around the metal center as ligand-field transitions are splitted when compared to the spectrum of the parent complex [Cu 2 (tidf)(ClO 4 ) 2 (H 2 O) 2 ].
The molecule of the title compound C7H8N4O·0.5H2O, alternatively called (E)-1-(pyridin-4-ylmethylene)semicarbazide hemihydrate, is in the E conformation and is almost planar; the r.m.s. deviation of the positions of the atoms of the pyridine ring from the best-fit plane is 0.0039 Å. The C, N and O atoms of the rest of the molecule sits close on this plane with a largest deviation of 0.115 (4) Å for the O atom of the semicarbazone moiety. There is an intramolecular N—H⋯N hydrogen bond. In the crystal, molecules are linked into an infinite three-dimensional network by classical N—H⋯Os (s = semicarbazone) and Ow—H⋯N (w = water) hydrogen bonds.
In order to study the key atoms and their spatial disposition necessary for high aldose reductase inhibitory activity, the space group for the title compound (I) (P1, Z=2) is determined.
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