Supra Molecular Chemistry 1 - Concepts

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Supramolecular Chemistry

http://homepage.univie.ac.at/jeanluc.mieusset/teaching.html

Supramolecular Chemistry 1 - Concepts.pdf

Supramolecular Chemistry 2 - Cation binding.pdf

Supramolecular Chemistry 3 - Binding of anions.pdf

Supramolecular Chemistry 4 - Neutral molecules.pdf

Supramolecular Chemistry 5 - Methods.pdf

Supramolecular Chemistry 6 - Self-Assembly.pdf

Supramolecular Chemistry 7 - Artificial enzyms.pdf

Supramolecular Chemistry 8 - Molecular Devices.pdf

Supramolecular Chemistry 9 - Molecular Machines.pdf

Supramolecular Chemistry 10 - New.pdf


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Supramolecular Chemistry

Steed, J. W.; Atwood, J. L.Supramolecular Chemistry,

Wiley 2000 $ 40,- Balzani, V.; Venturi, M.; Credi, A.

Molecular Devices and MachinesWiley VCH 2003

Schneider, H.-J.; Yatsimirski, A.Principles and Methods in Supramolecular ChemistryWiley 2000 39,95

Comprehensive Supramolecular Chemistry, Vol. 1-10;Lehn, J.-M., Series editor,

Pergamon/Elsevier Oxford etc, 1996 $ 425 per volume Encyclopedia of Supramolecular Chemistry

edited by Jerry L. Atwood and Jonathan W. SteedDekker, 2004 1,500 pages $489.00


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What is Supramolecular Chemistry?

MULTIDISCIPLINARY FIELD

NATURE (biological systems) - inspiration

ORGANIC and INORGANIC CHEMISTRY building blocks(supramolecular synthons)

PHYSICAL CHEMISTRY methods to study and understand theirproperties


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The ultimate supramolecular material?

Held together by many specifichydrogen bonds, - stacking, etc.

Encodes gigabytes of data Can Self-Replicate

Built-in Error Correction Information Storage Is the basis of life


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Tobacco Mosaic Virus (TMV)


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Actin-Myosin Complex


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Kinesin Crawling Along a Microtubule


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MOLECULAR CHEMISTRY covalent bonds formation

SUPRAMOLECULAR CHEMISTRY non-covalent bond formation


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J. M. Lehn:

Supramolecular chemistry is the chemistry of the intermolecular

bond, covering the structures and functions of the entities formed bythe association of two or more chemical species

F. Vgtle:In contrast to molecular chemistry, which is predominantly basedupon the covalent bonding of atoms, supramolecular chemistry is

based upon intermolecular interactions, i.e. on the association of twoor more building blocks, which are held together by intermolecularbond


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But also:

Molecular Devices

Supramolecular Photochemistry

Electronic Switches

Dendrimers


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Top-Down (current technology).

Continued reduction in size of bulk semiconductor devices

optical, ultra-violet, ion-beam, electron-beam lithography

Bottom-Up (molecular scale electronics).

Design of molecules with specific electronic function

Design of molecules for self-assembly into supramolecular structures

Connecting molecules to the macroscopic world

Man-made synthesis (e.g. carbon nanotubes)


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1-50 nm 1-500 nm

Supramolecular

Aggregates

Nanoelectronics

nanobiology


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Development - History


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Development - History


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Classification of Host-Guest Compounds


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Spherand


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Corpora non agunt nisi fixata


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Receptors and the Lock and Key Analogy


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The Chelate and Macrocyclic Effects


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Less entropically favorable

Stabilization offered by the chelate effect


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Preorganization and Complementarity


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Preorganization and Complementarity


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Nature of Supramolecular Interactions

Covalent bond energies:

C-O bond 340kJ / mol 1.43C-C bond 360kJ / mol 1.53C-H bond 430kJ / mol 1.11C=C bond 600kJ / mol 1.33

C=O bond 690kJ / mol 1.21

Compared to most non-covalent interactions these are:

Very high energies Very short distances Highly dependant on orientation


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Driving Forces for the Formation of Supramolecular Structures

hydrophobic interaction


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Ion - Ion Interactions

Can be a very strong bond - even stronger then covalent bonds in somecases.

Can be an attractive or a repulsive force.

Non-directional force

Long range (1/r)

Highly dependant on the dielectric constant of the medium


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IonIonIonIonInteractionsInteractions

Energy = (k * z1 * z2 * e2) / ( r12)

k = 1 / 4o= Coulomb constant = 9*109Nm2/C2

e = elementary charge = 1.6*10-19C

= dielectric constant

r12 = meters between the objects

The energy of an ion-ion interaction only falls of at a rateproportional to 1 / r. Therefore these are very long range

forces.


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IonIonIonIonInteractionsInteractions

1 nm in water?

1 nm in Chloroform?

Energy = (k * z1 * z2 * e2) / ( r12)

= 9*109 * 1 * -1 * (1.6*10-19)2/ 78.5 * 1 * 10-9

= -2.3 * 10 -28/ 0.8 * 10 -7

= -29.4 * 10-22 J= -1.77 kJ / mole (-0.42 kcal / mole)

= 9*109 * 1 * -1 * (1.6*10-19)2/ 4.8 * 1 * 10-9

= -2.3 * 10 -28/ 4.8 * 10-9

= -4.79 * 10-20 J= -28.8 kJ / mole (-6.89 kcal / mole) -> 8% of a C-C bond


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Energy = -(k * Q * u * cos/ e * r2)If = zero= -k * Q * u / e * r2

= -9*109 * 1.6*10-19 * 2.9 * 3.336 *10-30/ e * r2= -1.39 * 10-38 / 4.8 * (10-9)2

= -2.9 * 10-21 J= -1.75kJ / mole

Example: Acetone pointing directly at Na ion ( = zero) ata distance of 1nm (in chloroform)

IonIon--Dipole InteractionDipole Interaction

u = q * l (dipole moment)l = length of the dipoleq = partial charge on dipoler = distance from charge tocenter of dipoleQ = charge on ion


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IonIon--Dipole InteractionDipole Interaction

Directional forces

Can be attractive or repulsive

Medium range (1/r2)

Significantly weaker then ion-ioninteractions


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Nature of Supramolecular Interactions :

Hydrogen Bonding


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Hydrogen Bonding


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Hydrogen Bonding


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Hydrogen Bonding

Van der Waals radius of H: 1.1, O1.5. Therefore closest approachshould be 2.6.

Actual separation is about 1 less!Distance of 1.76.

Intermediate between vdw distance andtypical O-H covalent bond of 0.96.

O H O

R

RH

O

H O R

RH


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Hydrogen Bonding


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Hydrogen Bonding


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Hydrogen Bonding


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Halogen Bonding

Halogen atoms iodine, bromine, chlorine and even fluorine can

function as Lewis acids and engage in electron donor-acceptor

interactions with atoms with lone pairs such as nitrogen, oxygen,phosphorus and sulfur.

BIX-

Halogen bonding may involve dihalogenes X2 and X-Y as well as

organic halides

The strength of the donor-acceptor interaction depends on thepolarizability of the halogen atom, decreases in the order:

I > Br > Cl (> F)


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Halogen Bonding

DMSO to haloarene halogen bondinggeometry:

head on to C-X, ~ 158(13)(Cl),162(12)(Br), and ~165(8)(I);

side on to S=O,

: 125-135.

Increase of polarity of the both C-Xand S=O bond increases the strengthof interaction:


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The Cation Interaction


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Stacking


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Stacking

N f S l l I i


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Stacking

N t f S l l I t ti


50/56


Interactions

Chem. Rev. 2000,100, 4145-4185.

N t f S l l I t ti


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Charge-Transfer Complex



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Van der Waals Forces

Strength of interaction is essentially a function of the surface area ofcontact. The larger the surface area the stronger the interaction will be.

Regardless of other interactions found within a complex there will almost

always be a contribution from vdw.

This is what drives molecules to eliminate spaces or vacuums and makes itdifficult to engineer porous or hollow structures and gives rise to the phrase

Nature abhors a vacuum.



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Van der Waals Forces



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CLOSE PACKING IN THE SOLID STATE

Conformers allowing maximum intermolecular

interactions, even very weak (which do not play a rolein solution)

Empty space: crystal pores and channels -> inclusioncrystals

TETRIS analogy



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Hydrophobic Effects



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Hydrophobic Effects

Supra Molecular Chemistry 1 - Concepts

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