Information Technology Reference
In-Depth Information
the electrophilicity index have direct link to the process of polarization
and transfer of charge from a substrate and, hence, control the energetic ef-
fect—the protonation energy. Considering all the above-mentioned funda-
mental nature of the physicochemical process of protonation and its prob-
able relationship with the quantum mechanical descriptors, we suggest an
ansatz for the computation of the PA in terms of these theoretical descrip-
tors. The physicochemical process and the energetic effect must entail the
above-stated four parameters. To derive an explicit relation to compute the
PA in terms of the above-stated descriptors, we suggest explicit interrela-
tionships between the protonation energy and the descriptors relying upon
their response toward the protonation.
PA
∞(-I)
(10)
PA
∞ S
(11)
PA ∞ 1
/
χ
(12)
PA ∞ 1
/
ω
(13)
Combining the above four relations, we obtain
PA=C+C
1
(-I) +C
2
S + C
3
(1/χ)+C
4
(1/ω)
(14)
where PA is the proton affi nity; C, C
1
, C
2
, C
3
, and C
4
are the
regression
coeffi cient
; I is ionization energy; S is global softness; χ is the electronega-
tivity; and ω is the global electrophilicity index of the molecule.
In our model, we have invoked multilinear regression (MLR) to evalu-
ate these
regression coeffi cient
(C, C
1
, C
2
, C
3
, and C
4
) and then we have
combined these calculated
regression coeffi cient
(C, C
1
, C
2
, C
3
, and C
4
)
with the aforesaid akin quantum chemical descriptors, the ionization en-
ergy (I), the global softness (S), the electronegativity (χ), and the global
electrophilicity index (ω) according to the Eq. (14) to evaluate the PA of
the individual molecule.
Search WWH ::
Custom Search