conformation

conformation
/kon'fawr may"sheuhn/, n.
1. manner of formation; structure; form, as of a physical entity.
2. symmetrical disposition or arrangement of parts.
3. the act or process of conforming; adaptation; adjustment.
4. the state of being conformed.
5. Chem. an atomic spatial arrangement that results from rotation of carbon atoms about single bonds within an organic molecule. (contrasted with configuration).
[1505-15; < L conformation- (s. of conformatio), equiv. to conformat(us) ptp. of conformare to shape (con- CON- + form(a) FORM + -at(us) -ATE1) + -ion- -ION]
Syn. 1. configuration, shape.

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▪ molecular structure
      any one of the infinite number of possible spatial arrangements of atoms in a molecule that result from rotation of its constituent groups of atoms about single bonds.

      Different conformations are possible for any molecule in which a single covalent bond connects two polyatomic groups, in each of which at least one atom does not lie along the axis of the single bond in question. The simplest such molecule is that of hydrogen peroxide, in which the two hydroxyl groups can rotate with respect to one another about the axis of the oxygen-oxygen bond. The presence of more than one such single bond in a molecule—as in that of propane (CH3−CH2−CH3), for example—merely adds to the complexity of the situation without changing its nature. In molecules such as those of cyanogen (N≡C−C≡N) or butadiyne (H−C≡C−C≡C−H), all the atoms lie along the axis of the central single bond, so that no distinguishable conformations exist.

      In general, every distinguishable conformation of a molecule represents a state of different potential energy because of the operation of attractive or repulsive forces that vary with the distances between different parts of the structure. If these forces were absent, all conformations would have the same energy, and rotation about the single bond would be completely free or unrestricted. If the forces are strong, different conformations differ greatly in energy or stability: the molecule will ordinarily occupy a stable state (one of low energy) and undergo a transition to another stable state only upon absorbing enough energy to reach and pass through the unstable intervening conformation.

      The intramolecular forces in ethane, for example, are so weak that their existence can be inferred only from subtle effects on thermodynamic properties such as enthalpy and entropy. (Even if internal rotation in ethane were severely restricted, its three most stable conformations are indistinguishable.) The molecular structures of certain more complex compounds, however, impose such strong barriers to rotation that stereoisomeric forms—differing only in conformation—are stable enough to be isolated.

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Universalium. 2010.

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  • conformation — [ kɔ̃fɔrmasjɔ̃ ] n. f. • 1560; bas lat. conformatio ♦ Disposition naturelle des différentes parties d un corps organisé. ⇒ configuration, constitution, forme, organisation, structure. Conformation anatomique. Conformation du squelette. Mauvaise… …   Encyclopédie Universelle

  • Conformation — generally means structural arrangement and may refer to: Carbohydrate conformation, the three dimensional shape of a carbohydrate Chemical structure, also called the chemical conformation, the spatial arrangement of atoms and chemical bonds in a… …   Wikipedia

  • Conformation — Con for*ma tion, n. [L. conformatio: cf. F. conformation.] 1. The act of conforming; the act of producing conformity. [1913 Webster] The conformation of our hearts and lives to the duties of true religion and morality. I. Watts. [1913 Webster] 2 …   The Collaborative International Dictionary of English

  • conformation — CONFORMATION. s. f. Manière dont un corps organisé est conformé. La conformation des parties d un corps. La conformation des organes. Cette maladie vient d un vice de conformation. [b]f♛/b] On appelle Vice de conformation dans un animal, Ce qu il …   Dictionnaire de l'Académie Française 1798

  • conformation — Conformation. s. f. Maniere dont une chose est formée. La conformation des parties d un corps. la conformation des traits. Il ne se dit guere que dans ces phrases …   Dictionnaire de l'Académie française

  • conformation — index adjustment, arrangement (ordering), building (business of assembling), composition (makeup), configuration (form) …   Law dictionary

  • conformation — 1510s, from L. conformationem (nom. conformatio) a symmetrical forming, noun of action from pp. stem of conformare (see CONFORM (Cf. conform)) …   Etymology dictionary

  • conformation — configuration, *form, shape, figure Analogous words: *structure, anatomy, framework, skeleton …   New Dictionary of Synonyms

  • conformation — [n] shape anatomy, arrangement, build, cast, configuration, figure, form, formation, frame, framework, outline, structure, symmetry, type; concepts 754,757 …   New thesaurus

  • conformation — [kän΄fôr mā′shən, kän΄fərmā′shən] n. [L conformatio < pp. of conformare] 1. Rare a conforming or being conformed; adaptation 2. a) a completed or symmetrical formation and arrangement of the parts of a thing b) the structure or form of a thing …   English World dictionary

  • CONFORMATION — s. f. Manière dont une chose est conformée. Il se dit plus particulièrement Des corps organisés. La conformation des parties d un corps. La conformation des organes. Une bonne conformation. Conformation vicieuse.   Vice de conformation dans une… …   Dictionnaire de l'Academie Francaise, 7eme edition (1835)

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