Figure 2: (a) Schematic representation of more stable pyrrol-2-yl carbonyl conformers syn and anti where R= H, OH, OCH3, NH2, NHCH3, N(CH3)2, CH2Cl, CHCl2, CCl3; (b) conformation of different types of 2-acylpyrrole dimers, where R= OH, NH2, NHCH3. The dimer represents combination of a 2-acylpyrrole pair which was found in many aggregates presented in Table 2; small circles correspond to ring critical points (RCP).