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Internet Electronic Journal of Molecular Design - IEJMD, ISSN 1538-6414, CODEN IEJMAT
| ABSTRACT - Internet Electron. J. Mol. Des. September 2003, Volume 2, Number 9, 621-641 |
Eigenvalues of the Bond Adjacency Matrix Extended to Application in
Physicochemical Properties of Alkanes
Chenzhong Cao, Lihui Jiang, and Hua Yuan
Internet Electron. J. Mol. Des. 2003, 2, 621-641
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Abstract:
Eigenvalue of bonding orbital-connection matrix is a good
descriptor for expressing the relative bond energies of C-C
and C-H bonds in alkane. Its application can be extended to
the physicochemical properties of alkanes. Based on
polarizability effect index (PEI), the bond adjacency matrix
BCH for each C-H bond and orbital
overlapping matrix BCC
for whole carbon skeleton in alkane molecule, respectively,
were built. The eigenvalues X1CH, X2CH
for every BCH and
X1CC, ..., X(n-1)CC,
XnCC, ..., X2(n-1)CC for BCC were obtained.
Then the parameters SX1CH and SX2CH were calculated by
summing eigenvalues X1CH and X2CH
of all BCH, and SX1CC
and SX2CC were computed by summing eigenvalues from
X1CC to X(n-1)CC and from
XnCC to X2(n-1)CC, respectively. In
addition, another parameter Vij was developed for C-C bond
and summed to get parameter SVij. This set of descriptors
combined with odd-even index (OEI) and N2/3 (N is the
number of carbon atoms) can express most of the important
molecular structural information of alkanes. The correlations
between 10 physicochemical properties (including boiling
point Bp, critical temperature Tc, critical volume Vc, critical
pressure Pc, density D, refraction index nD, vapor pressure
log Pv, heat capacities Cp, heats of vaporization Hv and
chromatographic retention index Ipt) and the five parameters
SX1CH, SX1CC, SVij,
OEI, and N2/3 were carried out, and good
results were obtained with Bp (r = 0.9987, s = 3.06 °C), Tc
(r = 0.9991, s = 4.03 °C), Vc (r = 0.9995,
s = 7.66 cm3·mol-1),
Pc (r = 0.9941, s = 0.0771 Mpa), D (r = 0.9906, s = 0.0048
g·cm-3), nD (r = 0.9499, s = 0.0055),
log Pv (r = 0.9974, s =
0.0959), Cp (r = 0.9997, s = 2.02 J·mol-1·K-1),
Hv (r = 0.9994,
s = 0.66 kJ·mol-1) and Ipt (r = 0.9986,
s = 8.09) respectively.
The model equations developed by present paper can be used
for estimating and predicting the 10 physicochemical
properties of alkanes. This method may be extended to QSPR
of other compounds.
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