Back

CMTD

 

SOFTWARE FOR CALCULATION OF MOLECULAR TOPOLOGICAL DESCRIPTORS TAKING INTO ACCOUNT CHIRAL ATOMS AND ZE ISOMERISM

 

CMTD is software for calculation of chirality and ZE-isomerism molecular topological descriptors.

 

The theory of chirality descriptors is described in Golbraikh, A.; Bonchev, D.; Tropsha, A. Novel Chirality Descriptors Derived From Molecular Topology. J. Chem. Inf. Comput. Sci. 2001, 41, 147-158.

The theory of ZE-isomerism descriptors is described in Golbraikh, A.; Bonchev, D.; Tropsha, A. Novel ZE-Isomerism Descriptors Derived From Molecular Topology. J. Chem. Inf. Comput. Sci. 2002, 42, 769-787.

 

All indices are calculated using vertex degrees of hydrogen-suppressed molecular graph. For asymmetric atoms, a parameter named chirality correction is added to (for atoms in R configuration) or subtracted from (for atoms in S configuration) the corresponding vertex degrees. Similarly, a parameter named ZE-isomerism correction is introduced, which is added to or subtracted from, the vertex degrees of atoms in Z or E configurations, respectively. Modified vertex degrees were used in standard formulas defining overall Zagreb indices [1], molecular connectivity indices [2],[3],[4],[5], extended connectivity indices [6], and overall connectivity indices [7],[8]. Chirality and ZE-isomerism corrections can be real or an imaginary numbers. In the latter case, descriptors are complex numbers. Since QSAR software uses only real descriptors, three classes of real descriptors were defined using these complex numbers. In total, five classes of descriptors were defined.

 

1) Class S of descriptors: Standard (chirality and ZE-isomerism are not taken into account).

2) Class B of descriptors: Chirality and ZE-isomerism indices based on real chirality and ZE-isomerism corrections.

 

Let D be a complex descriptor.

 

3) Class C of descriptors is defined as Re(D) and Im(D).

4) Class U is defined as Re(D)+Im(D).

5) Class G is defined as arctan(Re(D),Im(D)). 

 

Class C is divided into two subclasses R and I for Real and Imaginary parts of descriptors.

 

If you are interested in obtaining CMTD, please send a message to Dr. Alexander Golbraikh.

 

 

Back to top

 

 

REFERENCES

 

1	Gutman I.; Ruscic, B.; Trinajstic, N.; Wilcox, C.F., Jr. Graph theory and molecular orbitals. XII. Acyclic polyenes. J. Chem. Phys., 1975, 62, 3399.
2	Molconn-Z.
3	Randic, M. On Characterization on Molecular Branching. J. Am. Chem. Soc., 1975,  97, 6609 - 6615.
4	Kier, L.B.; Hall, L.H. Molecular Connectivity in Chemistry and Drug Research. Academic Press, New York, 1976.
5	Kier, L.B.; Hall, L.H. Molecular Connectivity in Structure-Activity Analysis. Wiley, New York, 1986.
6	Rücker, G.; Rücker, C. Counts of All Walks as Atomic and Molecular Descriptors. J. Chem. Inf. Comput. Sci. 1993, 33, 683 – 695.
7	Bonchev, D. Overall Connectivity and Molecular Complexity. In: Topological Indices and Related Descriptors, Devillers J. and Balaban, A.T., Eds., Gordon and Breach, Reading, U.K., 1999, pp. 361 – 401.
8	Bonchev, D. Novel Indices for the Topological Complexity of Molecules, SAR QSAR Env. Res. 1997, 7, 23 –43.

 

            Back to top