الفهرس 
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 |  | from | 178 |  |  |
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Abstract
The present thesis include the investigation of the CT
complexes which are formed between schiff bases of pyridine,
Quinolin and Indolyl derivatives as donors and p-Benzoquinone
derivatives as acceptors; it contains five chapters:-
* The first chapter includes the introduction which deals with
the chemistry of the molecular compound, classification of electron
donors, acceptor s and complexes f ormed from them. This
chapter also includes a literature survey of the subjects
earned out by previous authors on charge-transfer complexes of
p-benzoquinone derivatives.
* In chapter II, the experimental details for the preparation
of the schiff bases derived from aromatic aldehydes and amino
pyridine amino quinaldine as well as sane aramatic amines and
indolyl aldehyde are given. Also the preparation of some halogenated
p-Benzoquinones derivatives and their charge-transfer
complexes. are inclUded. The working procedures for spectral
measurements are as well described, the spectral methods comprise
Infrared, ultra violet-visible and proton magnetic resonance.
The conductometric titration and elemental analysis are
also in eluded.
* The third chapter is devoted to the results and discussion of
the work carried on the CT complexes in solution. This chapter
is subdivided in to parts, the first post deals with the spectral behaviour of the CT complexes in different organic solvents;
the change in the position of the CT band for different organic
solvents are interpreted according to tehe macroscopic
Polarity parameters viz dielectric and refractive index the
values of ” of CT band in different solvents are plotted
max
against the dielectric constant and the refractive index, the
plots indicate that such parameters affecting on the shift of
the band. The secand part includes the determination of the
stiochiometry of the charge-transfer comp Lexes so formed by.
molar ratio (spectrophotometrically) and conductometric titration,
the results indicate the formation of 1:1 and 1:2 types
of complexes. Confirmation of such conclusion was based on the
performance of elemental analysis
complexes.
(C,H,N and X % ) for these
The equilibrium studies are discussed in the theired part
the equilibrium constant, molar extinction coefficient, osc~
illator strength of CT band, transition dipole moment and free
energy changes are calculated and depicted in Table ( ) .
Chapter IV compases the studies of the, solid CT complexes
using measurements.
The IR results show that the 1CH bands of the benzal
ring display a shift to lower wave numbers whereas thase of
the hetero ring display an appasit shift this indicates an
intermolecular electron transfer from the hetero to the benzal ring. The presence of substituents on the benzal ring show
an interesting effect on the position of the C-H out of plan
and deformation ((f CH) of the azomethine -CH=N-; electron
with drowing substituents shifts the bands position to lower
wavemumbers, while electron donating substituents cause an
opposite shift. The acceptors are classified inte acidic and
nonacidic ones which has a pronounced on the nature of the
CT complex formed. from the results obtained, it was noticed
that the acceptor bands disploy a shift to lower wavenumbers
where as thase of the donors display a counter shift. Such a
behaviour is a cr iter ion for J( - j(” * electron transfer of
the type (DHOMO--*~ ALUMO). The acidic acceptors exhibit
proton transfer interactions, whereby a proton from the acidic
centre of the acceptor is located on the basic centre of the
donor with the sUbsequent formation of the +N-H group. Such
interaction leads to the appearance of a group of bands within
-1 the wave number rang 2900 - 2400 cm in the IR spectra of the
complexes. A substantial support for the results obtained from
the ir spectra is gained by considering the changes of the
1H NMR spectra of some molecular complexes under investigation
in comparison to thase of their: constituents.
As a matter of fact the signal due to the aromatic protons
of the donor sarts are shifted down fields while thase of the acceptor parts exhibit a reverse displacement. Such shifts
indicate the decreased shielding effect on the proton of the
donor ring and its increase on those of the acceptor which
.••..*.
resul ts .from the intermolecular JT - J’ inter action.
The uv-vis absorption spectra of the prepared complexes
were obtained using the Nujol mull technique, the spectra
reveal the presence of a new band at the longer wavelength
region which was not observed in the spectra of either the
free donor or free acceptor molecules. Such band is assigned
to the (DROMO
--~7 A *
LUMO
) -;r - J( CT interaction. The other
band is very brood and of composite nature, this is taken as
. * an indication for the occurance of n- ~ interaction in the
complexes. The energies of these CT bands are calculated and
their values compared with those obtained experimently, the
two sites of values were concordance witheachother to a satesfactary
extent .
The ionization potentials of the donors and the electron
affinity of acceptor (IDL) are colculated using the Breigleb
equation:-
ECT = Ip - (EA + C).
Chapter V comprises the general discussion, summary and References.