Compact molecular codes

Randić, Milan

doi:10.1021/ci00051a010

Cited by 30 publications

(14 citation statements)

References 9 publications

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“…This is not surprising since, as has been discussed elsewhere [49], the second entry in the profile (derived from the quadratic contributions of the interatomic separations) is proportional to the moment of inertia. For planar molecules it is not uncommon to find distinct structures having the same '0 component which corresponds to the moment of inertia about the axis perpendicular to the plane of the molecule [49]. However, in the case of cuboctahedron and twist cuboctahedron not only are the moments of inertia around the preferred axis the same but all the three moments of inertia are equal, leading thus to the same '0 component for the two polyhedra.…”

Section: Twist Cuboctahedronsupporting

confidence: 58%

“…In Figure 1 we illustrate the "shrinking" of the molecular profiles from that of the "elongated" pentacene to that of the "circular" triphenylene as the shapes of other smaller benzenoids vary in between. Molecular profiles for a number of smaller planar and nonplanar molecules have been reported [39][40][41][42][43][44]. The molecules considered include benzenoids having seven and less fused benzene rings, fused cyclohexane rings, different conformers of n-alkane (superimposed on the diamond grid), different conformations of puckered rings, and several highly symmetrical polyhedra.…”

Section: Molecular Profilesmentioning

confidence: 99%

“…For example, the boiling points of benzenoids (and alkanes) can be partitioned into bond contributions, but molecular profiles are not bond additive quantities. In another study it was shown that the prevailing view that the chromatographic retention indices in benzenoids are shape-dependent is somewhat misleading [49]. They are not when benzenoids are characterized by molecular profiles and the shape profiles, which are obtained by considering only the contributions from carbon atoms at the molecular periphery.…”

Section: Molecular Profilesmentioning

confidence: 99%

“…Neither the J index nor ID number'were designed to serve as structure discriminator; they were introduced to serve as molecular descriptors for structureproperty studies and have been used in such studies (applications of J index [21-241 and applications of ID index . On the other hand the prime number ID was designed to increase the already high differentiation power of ID numbers [28]. h o p and collaborators [291 found that the prime number ID discriminates all alkanes with less than n = 20 carbon atoms, in all 251,731 structures, that is, almost by a factor of 100 better than the ID number or a factor of 1000 better than the J index.…”

Section: Introductionmentioning

confidence: 99%

“…First, several studies dealing with molecular profiles were confined to planar molecules (polycyclic aromatic hydrocarbons [39][40][41][42][43]), which may give an erroneous impression that application of the approach to three-dimensional structures needs further attention. This is not the case, as illustrated in the recent study of eight-and nine-member puckered rings [44,451. By considering polyhedral structures, this will only strengthen the message that indeed the molecular profile approach is quite general.…”

Section: Introductionmentioning

confidence: 99%

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Bond profiles for cuboctahedron and twist cuboctahedron

Randić

Krilov

1996

Int. J. Quantum Chem.

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rnUsing the information on the interatomic separations in a molecule, one can construct structural invariants that are the components of a molecular profile. The entries in the profile are derived by averaging different powers of the interatomic separations, suitably normalized so that the increasing powers do not dominate the sequence. Although only a few hundreds of structures have been so analyzed, no two different chemical structures were found to be characterized by the same sequences. A critical test for the conjecture that molecular profiles are unique is to consider structurally closely related systems that are very similar and have several similar properties. In this contribution we investigated the cuboctahedron and the accompanying polyhedron obtained by rotating half of the cuboctahedron against the other half, resulting in the so-called twist cutoctahedron. We show that even this pair of closely related structures has different profiles. We have also examined the generalized molecular profiles obtained by inserting n additional points along each edge of the polyhedra. The convergence of the profiles as n increases is discussed. It appears thus that these generalized molecular profiles, called line profiles or bond profiles, are likely to lead to a unique characterization of structures in which not only the geometry of atoms is recorded but also the geometry of the connectivity of the structure. 0 1996 John Wiley 19 Sons, Inc. ent constitution. Such characterization would allow one to compare different conformations of a molecule and determine which conformation is more similar to a desired standard. In contrast to a representation of molecules by codes that require canonical rules for labeling of atoms, a list of invariants is independent of atomic labels. Hence characterization of a molecule by invariants is independent of ordering of atoms and of rigid-body

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Section: Twist Cuboctahedronsupporting

confidence: 58%