Idaho Seminar
Transcript of Idaho Seminar
-
8/8/2019 Idaho Seminar
1/40
Intramolecular H-bonding Effects
on Ion Binding by AromaticAmides: An Ab Initio StudyRubn D. Parra, Ph.D
DePaul UniversityChicago, IL
-
8/8/2019 Idaho Seminar
2/40
I. IntroductionII. F- - amide InteractionsIII. Li+- amide Interactions
IV. Cooperativity in Ion-Pair BindingV. Summary and OutlookVI. ReferencesVII, QuestionsVIII. Acknowledgments
-
8/8/2019 Idaho Seminar
3/40
Introduction
The functional group of an amide is anacyl group (RCO-) bonded to a nitrogenatom.In particular, the amide RCO-NHRexhibits amphiphilic properties. T he C=O group is suitable to interact with
other groups, atoms, or ions deficient inelectrons. T he N-H group is suitable for interacting with
electron-rich units.
-
8/8/2019 Idaho Seminar
4/40
Introduction
Ion binding is the process by which amolecule, called the host, provides one or
more sites to bind an ion, called the guest,by means of non-covalent interactions. Multiple binding sites are usually neededbecause non-covalent interactions aregenerally weak.
-
8/8/2019 Idaho Seminar
5/40
IntroductionCh elate effect
Ni2+
+ 6 NH3 [Ni(NH3)6]2+
( G = -51.7 kj/mol
Ni2+ + 3 NH2CH
2CH
2NH
2[Ni(NH2CH2CH2NH2)3]2+( G = -101.1 kj/mol
-
8/8/2019 Idaho Seminar
6/40
Introduction
M acrocyclic EffectZn2+ + A [ZnA]2+ ( G = -64.2 kJ/mol
Zn2+ + B [ZnB]2+ ( G = -87.5 kJ/mol A B
-
8/8/2019 Idaho Seminar
7/40
Introduction
Amide-containing ligands have proven valuable in catioand anion binding.T he amide group exhibits amphiphilicproperties with the carbonyl group serving as a suitablebinding site for metal ions, and the N-H group serving a
a binding site for anions.Natural and syntethic amides are used for the transportof ions across bilayer membranes.
The great solubility in organic solvents usuallyaccompanied by a diminished solubility in aqueoussolution makes amides appealing for applications in thefield of ion-selective electrodes and liquid-liquidseparations Additionally, the hydrogen bonding capabilities of amidare known to be crucial in many relevant systemsincluding enzymes and proteins.
-
8/8/2019 Idaho Seminar
8/40
Introduction
P ositive C ooperativityHost compounds containing at least two spatiall
separated binding sites can show cooperativitydue to conformational coupling between sites.Comparatively few cases of amphi-receptorshave been reported which show binding
properties to both cations and anions.
-
8/8/2019 Idaho Seminar
9/40
Introduction
The conventional H bond is usually defined asX-H Y
X and Y are typically O, N, F, ClH-bonds are ubiquitous in nature.T hey areresponsible for the unusual properties of water,are mediators of chemical reactions, provide fordrug-molecule interactions in the body, and areimportant in the structure of DNA.
-
8/8/2019 Idaho Seminar
10/40
F- - Amide InteractionsR1 = H or NHC=OR2 = H or NHC=O
N N
O O
H H
R2R1
X-
-
8/8/2019 Idaho Seminar
11/40
F--Binding Amides
DA tA T A
-
8/8/2019 Idaho Seminar
12/40
Li+-Binding Amides
DA tA T A
-
8/8/2019 Idaho Seminar
13/40
DA
-
8/8/2019 Idaho Seminar
14/40
DA
-
8/8/2019 Idaho Seminar
15/40
DA_F
-
8/8/2019 Idaho Seminar
16/40
DA_F
-
8/8/2019 Idaho Seminar
17/40
tA_F
-
8/8/2019 Idaho Seminar
18/40
T A_F
-
8/8/2019 Idaho Seminar
19/40
DA
-
8/8/2019 Idaho Seminar
20/40
DA
-
8/8/2019 Idaho Seminar
21/40
DA_Li
-
8/8/2019 Idaho Seminar
22/40
tA_Li
-
8/8/2019 Idaho Seminar
23/40
T A
-
8/8/2019 Idaho Seminar
24/40
T A_Li
-
8/8/2019 Idaho Seminar
25/40
T A_Li
-
8/8/2019 Idaho Seminar
26/40
T A_LiF
-
8/8/2019 Idaho Seminar
27/40
Binding Energies (kcal/mol)
Li+
BindingDi-amide -109 Tri-amide -107 Tetra-amide -107
F-BindingDi-amide -114
Tri-amide -120 Tetra-amide -127
LiF Binding Tetra-amide -294
C
C
H
-
8/8/2019 Idaho Seminar
28/40
H22O 11
Li+
Binding Tri-amide1.779 (1.789 )
Tetra-amide1.751 (1.773 )
F- Binding Tri-amide
1.721 (1.773 ) Tetra-amide
1.717 (1.773 )LiF Binding
Tetra-amide1.696 (1.773 )
C
O
H H
C
O11
HH
H
H22
OH
H
O
H
-
8/8/2019 Idaho Seminar
29/40
N BO analysis
lpO11W
*H22NLi+ Binding Tri-amide
30 (30 kcal/mol) Tetra-amide
34 (29 kcal/mol)F- Binding Tri-amide
42 (27 kcal/mol) Tetra-amide
42 (29 kcal/mol)LiF Binding Tetra-amide
48 (29 kcal/mol)
C
N
H H
C
N
HH
H
NH22
H
NH
H
-
8/8/2019 Idaho Seminar
30/40
N BO Ch argesLi+ Binding
Tri-amideqO11 = -0.69 (-0.70)qH22= +0.50 (+0.47)
Tetra-amideqO11 = -0.69 (-0.69)
qH22= +0.50 (+0.47)F- Binding Tri-amide
qO11 = -0.76 (-0.69)qH22= +0.48 (+0.47)
Tetra-amide
qO11 = -0.76 (-0.69)qH22= +0.47 (+0.47)LiF Binding
qO11 = -0.75 (-0.69)qH22= +0.50 (+0.47)
C
O
N
H H
C
O11
N
HH
H
NH
22
C
OH
NH
C
OH
-
8/8/2019 Idaho Seminar
31/40
D ipole M oments ( D ebye)Li+ BindingDi-amide 0.9
Tri-amide 6.2 Tetra-amide 3.6
F- BindingDi-amide 2.9
Tri-amide 4.3 Tetra-amide 1.1
LiF Binding Tetra-amide 11.3
C
O
N
H H
C
O
N
HH
H
N
C
OH
NH
C
OH
H
-
8/8/2019 Idaho Seminar
32/40
N -H Stretc h ing FrequenciesLi+ Binding
Di-amideRN-H22 = 3769 (3800 cm-1)
Tri-amideRN-H22 = 3517 (3608 cm-1)
Tetra-amideRN-H22 = 3487 (3608 cm-1)
F-Binding Tri-amide
RN-H22 = 3457 (3617 cm-1) Tetra-amide
RN-H22 = 3295 (3608 cm-1)LiF Binding
RN-H22 = 3287 (3608 cm-1)
C
O
N
H H
C
O 11
N
HH
H
NH22
C
OH
NH
C
OH
-
8/8/2019 Idaho Seminar
33/40
F- BindingHF Di-amide 1.649
Tri-amide 1.561 ; 1.679 Tetra-amide 1.585
Li+ BindingOLiDi-amide 1.771
Tri-amide 1.762 ; 1.780 Tetra-amide 1.775
LiF BindingHF 1.588 OLi 1.770
C
O
N
H H
C
O
N
HH
H
N
C
OH
NH
C
OH
H
-
8/8/2019 Idaho Seminar
34/40
F- BindingNCCC (degs.)
Di-amide 7 Tri-amide 5 Tetra-amide 4
Li+
BindingCNCC (degs.)Di-amide 47
Tri-amide 31, 34 Tetra-amide 22
LiF BindingNCCC 9CNCC 24
C
O
N
H H
C
O
N
HH
H
N
C
OH
NH
C
OH
H
-
8/8/2019 Idaho Seminar
35/40
NBO analysis: E2 (kcal/mol)Lp F- W* N-H,W* C-H
Di-amide 197 Tri-amide 187 Tetra-amide 193
Li+ BindingLp O Li+
Di-amide 45 Tri-amide 43 Tetra-amide 41
LiF BindingLp F- W* N-H,W* C-H 204Lp O Li+ 48
C
O
N
H H
C
O
N
HH
H
N
C
OH
NH
C
OH
H
-
8/8/2019 Idaho Seminar
36/40
Symmetric Stretching frequenciesF- Binding
RN-H +RC-HDi-amide 3304 cm-1
Tri-amide 3327 cm-1 Tetra-amide 3205 cm-1
Li+ BindingRC=O
Di-amide 1813 cm-1 Tri-amide 1814 cm-1 Tetra-amide 1801 cm-1
LiF BindingRN-H +RC-H 3216 cm-1RC=O 1784 cm-1
C
O
N
H H
C
O
N
HH
H
N
C
OH
NH
C
OH
H
-
8/8/2019 Idaho Seminar
37/40
Summary
Anion (F-) and cation (Li+) binding througharomatic amides has been presented.Ion binding results in substantial changes in the
equilibrium conformation of the amide modelsystems.Binding affinity of the anion is greater than thatof the cation.
Intramolecular H-bonding enhances F-binding,but has negligible effect on the binding energy o
Li+.
-
8/8/2019 Idaho Seminar
38/40
Summary The presence of either ion induces significant
polarization on the ligand.T here is charge transfer fromthe anion to the ligand, and from the ligand to the metalion.
Charge separation is notorious in the ion-pair bindingwhich presents the largest dipole moment.Evidence of positive cooperativity is presented, wherebinding of an ion at one site enhances significantly theaffinity of the ligand for the other ion at thecorresponding binding site.Binding of one ion induces conformational changesalong with polarization of the ligand, which is transmittto the second binding site.
-
8/8/2019 Idaho Seminar
39/40
References
R. D. Parra, B. Yoo,M . Wemhoff,J. Phys. Chem. A. 110, 4487 (2006).Bianchi, A.; Bowman-James, K.;Garcia-Espana, E., Eds.
Supramolecular Chemistry of Anions; Wiley-VCH: New York, 1997.Saenger, JeffreyG. A.Hydrogen Bonding in Biological Structures;Springer-Verlag: Berlin, 1991.Kavallieratos, K.; Bertao, C.M .; Crabtree, R. H.J. Org. Chem ., 1999, 64,1675.Constable, E. C.M etals and Ligand Reactivity (VCH Publishers, NewYork, 1996).Desiraju,G. R.; Steiner,T ., The Weak Hydrogen Bond In Structural Chemistry and Biology ; Oxford University Press, 1999.Wheeler, O. H.; Rosado, O. inThe Chemistry of Amides , IntersciencePublishers, 1970, p. 352.Schneider, H-J; Yatsimirsky, A.Principles and Methods inSupramolecular Chemistry ; Wiley, Chichester, 2000.Steed, J. W.; Atwood, H. L.;Supramolecular Chemistry ; Wiley,Chichester, 2000.
-
8/8/2019 Idaho Seminar
40/40
Acknowledgments
Megan Ghorbanpour Michael P. Wemhoff Paul D. KofoedLucia Petkovic and Idaho National Laboratoryfor the invitation