Imidazoles hydrogen bonding distance

Figure 1. Solid state NMR chemical shifts of carboxylic acids and imidazoles are plotted against the hydrogen bonding distance a) data for carboxylic acids (data from reference (2021)), circles are compounds with COO—H COO motif, ApKa 0, and crosses are compounds with COO—H - COOH motif, Ap a > 15 b) data for imidazoles (data from Table I), circles present cationic imidazoles (Im+—H- COO , ApA a 3), and crosses are neutral imidazoles (Im COO , ApKa 10).

Table I. Solid State H NMR Chemical Shifts of Imidazoles and Hydrogen Bonding Distances in Crystals...

Another deviation (circle 10) is related to ET from that reduced primary quinone acceptor QA to the secondary quinone acceptor Qb- The process takes place at an edge-edge distance of about 14 A, but these centers are bridged with two hydrogen bonds and Fe atoms coordinated with two conducting imidazol groups (Rees et al 1989). The... 

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