dusan veljkovic skd2011 presentation
DESCRIPTION
Dusan Veljkovic presentation, Serbian Crystallographic Society conference, Fruska Gora, 2011 Predavanje Dusana Veljkovica na Konferenciji Srpskog kristalografskog drustva, Fruska Gora, 2011. godinaTRANSCRIPT
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Are C-H∙∙∙O interactions linear? Are C-H∙∙∙O interactions linear? The case of aromatic CH donors The case of aromatic CH donors
DuDuššanan Ž. Ž. VeljkoviVeljkoviććaa,, Goran Goran V. JanjiV. Janjiććbb, , SneSnežžanaana DD. . ZariZariććaa
aaDepartment of Chemistry, University of Belgrade, Studentski trg Department of Chemistry, University of Belgrade, Studentski trg 16, 11000 Belgrade, Serbia16, 11000 Belgrade, Serbia
e-mail: [email protected]: [email protected], Njegoševa 12, 11 000 Belgarde, SerbiaICTM, Njegoševa 12, 11 000 Belgarde, Serbia
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Non-covalent C-H∙∙∙O interactions are Non-covalent C-H∙∙∙O interactions are of great importance in chemistry, of great importance in chemistry, biology and biochemistrybiology and biochemistry
They play prominent role in crystal They play prominent role in crystal packing, conformational control, packing, conformational control, stabilizing protein structures and stabilizing protein structures and DNA base pairsDNA base pairs
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WWater/aromatic ater/aromatic interactions interactions
OH/π interaction C-H…O interaction
Parallel alignment interactions
Aromatic molecules can form few types of weak hydrogen bonds:Aromatic molecules can form few types of weak hydrogen bonds:
B. D. Ostojić, G. V. Janjić, S. D. Zarić, Chemical Communications (48), 6546-6548, (2008). G. V. Janjić, D. Veljković, S. D. Zarić, Crystal Growth & Design (2011), in press
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Directionality of C-H∙∙∙O Directionality of C-H∙∙∙O interactionsinteractions
One of the most important One of the most important characteristics of hydrogen bondscharacteristics of hydrogen bonds
Based on directionality it was shown Based on directionality it was shown that the C–H···O interactions, that the C–H···O interactions, although can be weak, are hydrogen although can be weak, are hydrogen bonds and not the van der Waals bonds and not the van der Waals interactionsinteractions
T. Steiner and G. R. Desiraju, Chem. Commun., (1998), 891-892.
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However…However…
Are C-H∙∙∙O interactions REALLY Are C-H∙∙∙O interactions REALLY
linear?linear?
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Geometry of C–H•••O interactions of aromatic Geometry of C–H•••O interactions of aromatic C–H donors was studied using crystal C–H donors was studied using crystal structures from the Cambridge Structural structures from the Cambridge Structural Databank (CSD)Databank (CSD)
Crystal structures involving CCrystal structures involving C66-H aromatic -H aromatic groups and oxygen atoms were screened for groups and oxygen atoms were screened for intermolecular contactsintermolecular contacts
Following systems with oxygen atom were Following systems with oxygen atom were taken: HOH (non-coordinated), HOZ, Ztaken: HOH (non-coordinated), HOZ, Z11OZOZ22, , O=CZ and O=YZ (Z, ZO=CZ and O=YZ (Z, Z11, and Z, and Z22 are not are not hydrogen atoms, Y is not carbon atom) hydrogen atoms, Y is not carbon atom)
Data screeningData screening
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The preference for linear geometries The preference for linear geometries in in
C–H∙∙∙O interactions of aromatic C-C–H∙∙∙O interactions of aromatic C-H groups was observed by the H groups was observed by the distributions of angle α distributions of angle α
To obtain more reliable data cone To obtain more reliable data cone correction was used correction was used
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Cone correctionCone correction
The angle covered by an angular The angle covered by an angular interval interval ΔαΔα is smaller for nearly is smaller for nearly linear angles linear angles αα then for bent ones then for bent ones
Angular distribution must be Angular distribution must be weighted by a correction factor weighted by a correction factor 1/sin1/sinαα to properly reflect angular to properly reflect angular preferencespreferences
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For the purpose of this analysis, we used For the purpose of this analysis, we used parameters which were directly retrieved parameters which were directly retrieved from CSD (H…O distance d, angle from CSD (H…O distance d, angle αα), as well ), as well as parameters which were derived (distances as parameters which were derived (distances R, r and angle R, r and angle φφ).).
We search for structures in which the distance We search for structures in which the distance between the O atom of the water molecule between the O atom of the water molecule and the H atom of the Cand the H atom of the C66 - aromatic ring is - aromatic ring is less than 2.8 Å, and the angle α greater than less than 2.8 Å, and the angle α greater than 110°110°
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Non-corrected and corrected distributions of Non-corrected and corrected distributions of angle α for C–H∙∙∙O interactions of C-H angle α for C–H∙∙∙O interactions of C-H aromatic donors with different types of aromatic donors with different types of acceptorsacceptors
0.0
5.0
10.0
15.0
20.0
25.0
110-120
120-130
130-140
140-150
150-160
160-170
170-180
α(˚)
%
H2O
HOZ
Z1OZ2
O=CZ
O=YZ
0.0
5.0
10.0
15.0
20.0
25.0
110-120
120-130
130-140
140-150
150-160
160-170
170-180
α(˚)
%
H2O
HOZ
Z1OZ2
O=CZ
O=YZ
Non-corrected Non-corrected Corrected Corrected
1111
Distributions of angle φ for C–H∙∙∙O Distributions of angle φ for C–H∙∙∙O interactions of CH aromatic donors with interactions of CH aromatic donors with different types of acceptorsdifferent types of acceptors
-5.0
0.0
5.0
10.0
15.0
20.0
25.0
30.0
0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40
φ(˚)
%
H2OHOZ1Z2OZ1O=CO=Z
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Type of the atom in the o-position influence linearityType of the atom in the o-position influence linearity
Influence of substituents in o-position on linearity of C–H∙∙∙O interactions
0.0
5.0
10.0
15.0
20.0
25.0
30.0
110- 120
120- 130
130- 140
140- 150
150- 160
160- 170
170- 180
α (°)
%
H2O
HOZ
Z2OZ1
O=CZ
O=YZ
0.0
5.0
10.0
15.0
20.0
25.0
30.0
110- 120
120- 130
130- 140
140- 150
150- 160
160- 170
170- 180
α (°)
%
H2OHOZZ2OZ1O=CZO=YZ
0
5
10
15
20
25
30
35
110- 120
120- 130
130- 140
140- 150
150- 160
160- 170
170- 180
α (°)
%
HOZ
Z2OZ1
O=CZ
O=YZ
0
5
10
15
20
25
30
35
110- 120 120- 130 130- 140 140- 150 150- 160 160- 170 170- 180
α (°) coor
%
HOZ
Z2OZ1
O=CZ
O=YZ
H atom in H atom in o-positiono-position
Cl atom in Cl atom in o-positiono-position
Non-corrected CorrectedNon-corrected Corrected
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Diagrams showing the distribution of Diagrams showing the distribution of angle φ for C–H∙∙∙O interactions of C-angle φ for C–H∙∙∙O interactions of C-H aromatic donors with different types H aromatic donors with different types of acceptors. of acceptors.
-5
0
5
10
15
20
25
30
35
0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40
φ (°)
%
H2O
HOZ
Z1OZ2
O=CZ
O=YZ
-5
0
5
10
15
20
25
30
35
40
45
0-5 5-10 10-15 15-20 20-25 25-30 30-35 35-40
φ (°)
%
HOZ
Z2OZ1
O=CZ
O=YZ
X=H X=H X=ClX=Cl
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Ab initio calculationsAb initio calculations
Ab initio calculations were performed Ab initio calculations were performed on three model systems: benzene-on three model systems: benzene-water, benzene-methanolwater, benzene-methanol and and benzene-acetonebenzene-acetone
Four different orientations of Four different orientations of acceptor molecules were consideredacceptor molecules were considered
Linear Linear BifurcatedBifurcated
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Ab initio calculationsAb initio calculations
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CONCLUSIONSCONCLUSIONS
Preference for the linear contact depends on the Preference for the linear contact depends on the type of the atom in the o-position to the interacting type of the atom in the o-position to the interacting C-H groupC-H group
The C–H•••O interactions of the aromatic The C–H•••O interactions of the aromatic molecules with two hydrogen atoms in the o-molecules with two hydrogen atoms in the o-position do not show preference for the linear position do not show preference for the linear contacts contacts
Nonlinear interactions are not energetically Nonlinear interactions are not energetically disfavored because of simultaneous interactionsdisfavored because of simultaneous interactions
This result is very important because it can help in This result is very important because it can help in the recognizing important C–H···O interactions in the recognizing important C–H···O interactions in biomolecules containing aromatic groups (proteins)biomolecules containing aromatic groups (proteins)D. Veljković, G. V. Janjić, S. D. Zarić, CrysEngComm (2011), accepted
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AcknowledgementAcknowledgement
Prof. SneProf. Snežana Zarićžana Zarić Goran JanjićGoran Janjić Vesna MedakovićVesna Medaković Dragan NinkovićDragan Ninković Dubravka VojislavljevićDubravka Vojislavljević Jelena AndrićJelena Andrić
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THANK YOUTHANK YOU