The molecular conformations of threeN-alkyl-2-(methylsulfanyl)nicotinamide derivatives, namelyN-cyclohexyl-2-(methylsulfanyl)nicotinamide, C13H18N2OS, (I),N-isopropyl-2-(methylsulfanyl)nicotinamide, C10H14N2OS, (II), in which there are two molecules in the asymmetric unit which were chosen to form a hydrogen-bonded pair, andN-(2-hydroxyethyl)-2-(methylsulfanyl)nicotinamide dihydrate, C9H12N2O2S·2H2O, (III), are compared with those of four unsubstitutedN-alkylnicotinamide compounds. The substituted compounds show a higher degree of torsion of the pyridine ring with respect to the amide group than do the unsubstituted compounds, with dihedral angles in the range 40–60° for the former and 20–35° for the latter. In (I) and (II), the supramolecular structure is defined by amide-N to carbonyl-O chains. In (III), the nicotinamide molecules are linked by hydrogen bonds to two water molecules resulting in two linked chains of rings which form the three-dimensional network.
三种 N-烷基-2-(甲硫基)烟酰胺衍生物的分子构象,即 N-环己基-2-(甲硫基)烟酰胺,C13H18N2OS,(I);N-异丙基-2-(甲硫基)烟酰胺,C10H14N2OS,(II)、以及 N-(2-羟乙基)-2-(甲硫基)烟酰胺二水合物 C9H12N2O2S-2H2O(III)与四种未取代的 N-烷基烟酰胺化合物进行了比较。与未取代的化合物相比,取代的化合物显示出吡啶环相对于酰胺基的扭转程度更高,前者的二面角在 40-60° 之间,后者的二面角在 20-35° 之间。在(I)和(II)中,超分子结构由酰胺-N 至羰基-O 链确定。在(III)中,烟酰胺分子通过氢键与两个水分子相连,形成两个相连的环链,构成三维网络。