Conformational transmission in the glyceryl backbone of phospholipid model compounds, induced by a P(4-coordinated) into trigonal bipyramidal P(5-coord) transition

摘要: Triesterified phospholipid model compounds have been synthesized and extensively studied with 300-MHz 1H NMR in the monomer phase order to get additional support for effect of conformational transmission induced by a P(4-coord) into trigonal bipyramidal P(5-coord) transition, as was suggested Merkelbach Buck. To elucidate any preferences around C2-C3 bond, stereospecifically deuterated precursor 1,2-dihexanoyl-(3R)-sn-[3-2H]glycerol synthesized. The results reveal that coordinational change phosphorus from four five is transmitted significant increase population conformer, which vicinally substituted oxygens O-2 O-3 are trans located. impact this seems not be restricted changes adjacent but also present specific rotations C1-C2 thereby shifting equilibrium towards decreased contribution arrangement acyl chains. As consequence interchain distance will reduced thus van der Waals interactions maximized. interpreted terms increased electron density on when axially located compound, introducing enhanced electrostatic repulsions within oxygen pairs O-3, O-1. Relaxation energetically unfavourable geometry leads observed shifts. Absence transmission, found 2-ester group an alkyl moiety, can considered introduced concept. In part phospholipids, however, no were means 13C NMR. Extrapolating outcome more condensed phases, proposition could made about mechanism head-group and/or glyceryl backbone compensated.