Bond counts, molecular descriptor

Molecular descriptors related to the dimensions of the molecule and often calculated from the - molecular geometry. Combined with molecular shape information, they are closely related to - steric descriptors. The simplest size descriptors are atom count, -> bond count, -> molecular weight, and some among the -> volume descriptors such as van der Waals volume. Other size descriptors are - Sterimol parameters and - WHIM size descriptors. 

We can also look at other literature datasets to gain an idea of how similar our compounds are to compounds for which QMPRPlus gives very good predictions. We have looked at four simple descriptors molecular weight, topological polar surface area [40], chemical complexity [41], and rotatable bond count, using John Bradshaw s... 

The L index was proposed as the molecular descriptor defined as the simple linear combination of molecular path counts of order one P (the number of bonds), order two (the -> connection number Na), and order three P ... 

These are simple molecular descriptors based on counting the defined elements of a compound. The most common chemical count descriptors are atom number A, bond number B, cyclomatic number C, -> hydrogen-bond acceptor number and -> hydrogen-bond donor number, -> distance-counting descriptors, -> path counts, walk counts. 

The intrinsic state of an atom can be simply thought of as the ratio of it and lone-pair electrons over the count of the g bonds in the molecular graph for the atom considered. Therefore, the intrinsic state reflects the possible partitioning of non-0 electron s influence along the paths starting from the considered atom the less partitioning of the electron influence, the more available are the valence electrons for intermolecular interactions. The sum of the intrinsic states of all of the atoms is a molecular descriptor called intrinsic state sum moreover, from the intrinsic state sum the —> Q polarity index was derived. 

The matrix of molecular descriptors frequently contains columns of values that are correlated with each other. This might arise from a poorly designed set in which there is a correlation between the MR and n of a substituent, or from descriptors that are intrinsically correlated, such as TPSA and the counts of nitrogen and oxygen atoms and the protons bonded to them. Principal component analysis considers the matrix of properties and extracts orthogonal components that contain a contribution (loading) from one or more of the... 

For each molecule in these struetures, 131 molecular descriptors were calculated. These included simple atom, bond and group eounts, hydrogen bond donor and acceptor counts, topological indices, a variety of partitioned and charge weighted surface areas and deseriptors of molecular size, shape, polarity... 

Topological Representation and Topology), geometrical, electronic, and physicochemical. Topological de.scriptors are derived directly from the connection table repre.sentation of the structure and include atom and bond counts,. substructure counts, molecular connectivity indices (see Topological Indices), kappa indices, substructure environments, path descriptors, distance-sum connectivity, and molecular symmetry. Substructure-ba.sed descriptors are topological de.scriptors which allow the tailoring of the descriptor set to. specific user-defined substructures contained in the molecules of the data set. 

One of the simplest and most common ways to evaluate a molecule for ADME properties is a qualitative examination of its basic descriptor values such as molecular weight (MW), ClogP for lipophilicity, polar surface area (PSA), counts of hydrogen bond donors and acceptors (HBD, HBA), and count of rotatable bonds (RB). This type of approach popularized by Lipinski s famous Rule of 5 was published a decade ago [6]. Lipinski et al. established cutoffs for MW (500), ClogP (5), HBA (10), and HBD (5). These cutoffs were based on the 90th percentile of distributions of molecules in the World Drug Index having USAN or INN names. The Rule of 5 considers a violation of any two of these cutoffs to be an alert for poor absorption or permeability. 

ADMET Predictor Constitutional, functional group counts, topological, E-state, Moriguchi descriptors, Meylan flags, molecular patterns, electronic properties, 3D descriptors, hydrogen bonding, acid-base ionization, empirical estimates of quantum descriptors 297... 

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