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Quantitative Structure Activity Relationship (QSAR) and Quantitative Structure Property
Relationship (QSPR) study deals with the prediction of ground state molecular equilibration
(Thirunarayanan and Ananthakrishna, 2006a and 2006b; Thirunarayanan et al., 2007; and
Ranganathan et al., 2011) of organic substrates such as s-cis and s-trans isomers of alkenes,
alkynes, benzoylchlorides, styrenes and α, β-unsaturated ketones from spectral data. Their
use in structure parameter correlations has become popular for studying the biological
activities (Thirunarayanan, 2008a and 2008b; and Thirunarayanan et al., 2010), normal
coordinate analysis (Sharma et al., 2002) and transition states of reaction mechanisms
(Dass, 2001). The QSAR studies of natural and synthetic molecules were carried out by
Griffiths and Chalmers (2002) using Infrared (IR) spectroscopy. IR spectroscopy provides
information about the nature, concentration and structure of samples at the molecular
level in the area of material science (Pellerin and Pelletier, 2005). A theoretical study of
the substituent effects was conducted on long-range interactions in the β-sheet structure
of oligopeptides (Horváth et al., 2005) and enone-dienol tautomerism (Wang et al., 2005).
Spectral data was applied for QSAR study of substituted benzo[α] phenazine cancer
agents (Chen et al., 2005), Diels-Alder reactions (Dumont and Chaquin, 2006), density
functional theory (Senthilkumar et al., 2006), gas phase reactivity of alkyl allyl sulfides
(Izadyar and Gholami, 2006) and rotational barriers in selenomides (Kaur et al., 2006).
The quantitative structural relationships in α, β-unsaturated carbonyl compounds with their half wave reduction potential were studied by Santelli et al. (2006). The validity of
the additivity of substituent effect in aromatic shielding was first observed by Lauterber
(1961). The 1H Nuclear Magnetic Resonance (NMR) spectra of a large number of
acetophenones and styrenes were studied with a view to establishing the effects of
substituents (Dhami and Stothers, 1965). Good Hammett correlations were obtained for
the ethylenic protons with the NMR data of unsaturated ketones of the type RC6H4-
CH=CH-COMe3 by Savin et al. (1975). Solcaniova et al. (1980) studied the QSAR and
QSPR of 1H and 13C NMR spectra of substituted styrenes, styryl phenyls and obtained
good Hammett correlations for the olefinic protons and carbons. Nowadays scientists
(Sung and Anathakrishna, 2000; Thirunarayanan, 2008b; Ranganathan et al., 2011; and
Thirunarayanan et al., 2011) have shown more interest in correlating the group frequencies
of spectral data with Hammett substituent constants to explain the substituent effects of
organic compounds. Recently, Ranganathan et al. (2011) elaborately investigated the
single and multisubstituent effects on alpha and beta hydrogen and carbons of some
chloro substituted phenyl chalcones. Within the above view, there is no information
available for the study of IR and NMR study in literature in the past with substituted
styryl 3, 4-dichlorophenyl ketones. The authors have synthesized 3, 4-dichlorophenyl
chalcones by condensation of 3, 4-dichlorophenyl methyl ketones with various m- and
p-substituted benzaldehydes under solvent-free conditions (Thirunarayanan et al., 2010)
by stirring the reactants with sodium hydroxide at room temperature to yield the respective
E-2-propen-1-ones and study quantitative structure property relationship from the group
frequencies and study their antioxidant activities. The purities of these synthesized
chalcones were checked by their physical constants and spectral data. The methylene
units of chalcones derived from cyclic or acyclic ketones were found in many naturally
occurring compounds, and they are useful for the synthesis of pyrimidine derivatives
(Deli et al., 1984). The basic skeleton of chalcones is widely figured in natural products
and are known to have multipronged activity (Dasharathi et al., 2005). Many of the
chalcones are used as agrochemicals and drugs (Mirinda et al., 2000; Monostory et al.,
2003; and Nowakowska, 2007). 2, 2-Diphenyl-1-Picrylhydrazyl (DPPH)-radical
scavenging method was used for the study of antioxidant activities of these chalcones.
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