Conformation symbols

The conformational symbols for enantiomers are different. It is therefore important to state in the context whether the d or the L form is under consideration. Enantiomers have the same reference plane (see 2-Caib-7.3), and it should be noted that the mirror image of a-D-glucose-4Ci is a-L-glucose-C4. 

Fig. 9. Energetically favourable cyclodecane conformations with calculated angles (deg inner values) and torsion angles (53) (force field of Ermer and Lifson (19)). The conformations are further characterised by (from top) conformational symbol (11), symmetry, calculated relative potential energy (AV) and relative enthalpy (AH kcal mole-1 T = 298 K reference BCB AH = AV + AHvibr, see Section 3.3.). For BCB experimental angles and torsion angles (46) are also given (in parentheses)...

Any deviations result from a deliberate choice, either to conform to current usage in the profession, or to avoid ambiguity in the interpretation of symbols. 

Figure 8 A joint principal coordinate projection of the occupied regions in the conformational spaces of linear (Ala) (triangles) and its conformational constraint counterpart, cyclic-CAla) (squares), onto the optimal 3D principal axes. The symbols indicate the projected conformations, and the ellipsoids engulf the volume occupied by the projected points. This projection shows that the conformational volume accessible to the cyclic analog is only a small subset of the conformational volume accessible to the linear peptide, (Adapted from Ref. 41.)...

Figure 2.32 Conformability matrix symbols and their quantification...

For each q and q risk value and the Severity Rating (S), a level of design acceptability is determined from where these values intersect on the Conformability Map. The symbols, relating to the levels of design acceptability, are then placed in the nodes of the Conformability Matrix for each variability risk which the failure mode is directly dependent on for the failure to occur. Once the level of design acceptability has been determined, it can then be written on the Conformability Matrix in the Comments section. Cpi values predicted or comments for suppliers can be added too, although predicted Cp values can also be written in the variability risks results table. 

The definitions of the torsional angles are illustrated in Figure 2.7. To emphasize the symmetry (Cs) of the above conformation, the Z-matrix may also be given in terms of symbolic variables, where variables which aie equivalent by symmetry have identical names. 

Note. The Fischer projection is not intended to be a true representation of conformation. 2-Carb-4. Configurational symbols and prefixes 2-Carb-4.1. Use of d and l... 

IUPAC-IUB Joint Commission on Biochemical Nomenclature (JCBN), Symbols for specifying the conformation of polysaccharide chains (Recommendations 1981), Eur. J. Biochem, 131, 5-7, (1983) Pure Appl. Chem., 55,1269-1272 (1983) ref. 2, pp. 177-179. 

Fig. 7.1 Symbolic drawings of cyclohexane chair and boat conformations in two dimensions using different line thickness and wedge symbols.

Drawings should conform to accepted drawing conventions, preferably those laid down by the national standards. The symbols used for flow-sheets and piping and instrument diagrams are discussed in Chapter 4. Drawings and sketches are normally made on detail paper (semi-transparent) in pencil, so modifications can be easily made, and prints taken. 

Fig. 2.5. Possible applications of a coupling parameter, A, in free energy calculations, (a) and (b) correspond, respectively, to simple and coupled modifications of torsional degrees of freedom, involved in the study of conformational equilibria (c) represents an intramolecular, end-to-end reaction coordinate that may be used, for instance, to model the folding of a short peptide (d) symbolizes the alteration of selected nonbonded interactions to estimate relative free energies, in the spirit of site-directed mutagenesis experiments (e) is a simple distance separating chemical species that can be employed in potential of mean force (PMF) calculations and (f) corresponds to the annihilation of selected nonbonded interactions for the estimation of e.g., free energies of solvation. In the examples (a), (b), and (e), the coupling parameter, A, is not independent of the Cartesian coordinates, x. Appropriate metric tensor correction should be considered through a relevant transformation into generalized coordinates...

Fig. 17. Calculated conformations (top and side views, drawn to scale) of cyclohexane (force field of ref. (79) outer values bond lengths in A and angles in degrees, inner values torsion angles). The quantities below the symmetry symbols are calculated A V- and AH-values (kcal mole-1 T = 298 K reference chair conformation)...

Table B.l. The currently known chemical elements, showing atomic number (Z), chemical symbol, name, relative atomic mass, ground-state electron configuration, and APH indices (t = turn number l-n = angular number) asterisks (, ) symbolize anomalous (APH non-conforming) ground-state electronic configurations, which are indicative of configurational near-degeneracy...

Although the definitions of isotactic, syndiotactic, and atactic polymers according to International Union of Pure and Applied Chemistry (IUPAC) rules are well established in terms of succession of mesa (m) or racemic (r) dyads,12 the symbolism of (+) and (—) bonds allows the easy treatments of possible configurations in cases of any complexity.1 Moreover, the (+) or (—) character of the bonds in a polymer chain is strictly related to the accessibility of gauche+ or gauche conformations of the bonds and, therefore, to the formation of right-handed or left-handed helical conformations.1... 

---