4th EucheMs chemistry congress

wednesday, 29-Aug 2012
s610
chem. Listy 106, s587–s1425 (2012)
Analytical chemistry Electrochemistry, Analysis, sample manipulation
Biosensor strategies
o - 2 6 3
the intrinSiC non-CovALent interACtionS
within CoMPLexeS of A-CyCLodextrin And
BenzoAte derivAtiveS
z. Li 1 , x. zhAnG 1
1 ETH Zurich, Laboratory of Organic chemistry, Zürich,
Switzerland
Dissociation energies and structural assignments of
α-cyclodextrin (α-CD) complexes with three benzoate derivatives
3-methylbenzoic acid (3-MeBA), benzoic acid (BA) and
3-hydroxylbenzoic acid (3-OHBA) were for the first time studied
by the combination of experiments and theoretical calculations.
Qualitative experiments were performed for these α-cyclodextrin
complexes to obtain the relative stability order that [a-CD·3-
-MeBA] - (1) < [a-CD·BA] - (2) < [a-CD·3-OHBA] - (3). [1]
Threshold collision-induced dissociation experiments were
performed on a customized 24-pole Finnigan TSQ–700 tandem
mass spectrometer to get absolute dissociation energies. [2] The
obtained experimental quantitative non-covalent interactions for
complexes 1, 2 and 3 are 40.8, 41.1 and 41.8 kcal mol –1
respectively.
DFT calculations were carried out to further interpret
non-covalent interactions within host-guest complexes. The bond
dissociation energies for complexes 1, 2 and 3 are 40.6, 40.7 and
44.0 kcal mol –1 respectively according to DFT calculations.
Furthermore, hydrogen bonding interactions, such as O–H···O,
C–H···O and C–H···π interactions contribute mainly for the
stability of gaseous complexes. Inclusion geometries are still
favored according to the experimental and computational results.
The experimental stability order and absolute dissociation
energies are in excellent agreement with DFT calculation results.
references:
1. Li, Z.; Couzijn, P. A.; Zhang, X. J. Phys. Chem. B. 2012,
116, 943.
2. Narancic, S.; Bach, A.; Chen, P. J. Phys. Chem. A. 2007,
111, 7006.
Keywords: non-covalent interactions; a-cyclodextrin;
dissociation energies; DFT calculations; mass spectrometer;
New analytical methodologies
4 th EucheMs chemistry congress
o - 2 6 4
the inveStiGAtion of enerGetiC
BenzALdoxiMeS with therMoAnALytiCAL And
CoMPutAtionAL MethodS.
A. AtAKoL 1 , M. KundurACi 2 , e. ÖzKArAMete 2 ,
n. yiLMAz 2 , o. AtAKoL 2 , M. A. AKAy 2
1 METU, Chemistry, Ankara, Turkey
2 Ankara University, Chemistry, Ankara, Turkey
3,5-dinitro-2-hydroxybenzaldehyde and 3,5-dinitro-4-
-hydroxybenzaldehyde were synthesized by nitration of
salicylaldehyde and 4-hydroxybenzaldehyde, respectively. [1]
These nitroaldehydes were converted into oximes with
hydroxylamine [2] and were investigated by thermoanalytical (TG,
DSC) and computational methods (G09W). It was observed from
IR and MS spectra that 3,5-dinitro-2-hydroxybenzaldehyde yields
4,6-dinitrobenzoxazine by elimination of water via Beckmann
rearrangment at 210–215 °C. On the other hand, 3,5-dinitro-4-
-hydroxybenzaldoxime was converged into benzonitrile by
elimination of water at 160-190°C. The released heat for each
exothermic reaction was measured analytically by DSC.
All theoretical calculations were carried out using the
Gaussian G09W (revision B.01) program package. [3] DFT-based
structure optimizations and frequency analyses were performed
at the B3LYP/cc-pVDZ level of theory. The enthalpies of
formation of both reactants and products were calculated using
complete basis set (CBS-4M) method of Petersson and coworkers
in order to obtain accurate energies. From the calculated heat of
formations, the enthalpies of decomposition were calculated
according to Hess’s Law and were compared with the
experimental values which were available from DSC analysis.
The good agreement between the experimentally observed
enthalpies of decomposition and the CBS-4M calculated values
gives credence to the accuracy of the applied CBS-4M method.
references:
1. P. Ionita, S. Af. J. Chem, 61, 123-126, 2008
2. J. Hull, S.T. Hilton, R. H. Crabtree, Inorg. Chim. Acta,
363, 1243-1245, 2010
3. a) Gaussian 09 Software, Revision B01.2009
b) A. D. Becke, J. Chem. Phys., 88, 1053-1062, 1988
c) Jr. A. J. Montgomery, M. J. Frisch, J. W. Ochterski,
G. A. Petersson, J. Chem. Phys. 112, 6532-6553, 2000
Keywords: Oxygen heterocycles; Computational Chemistry;
Elimination; Nitrides; Rearrangement;
AUGUst 26–30, 2012, PrAGUE, cZEcH rEPUbLIc