Supramolecular Chemistry

Transcription

1 Supramolecular Chemistry 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

2 Supramolecular Chemistry Steed, J. W.; Atwood, J. L. Supramolecular Chemistry, Wiley 2000 $ 40,- Balzani, V.; Venturi, M.; Credi, A. Molecular Devices and Machines Wiley VCH 2003 Schneider, H.-J.; Yatsimirski, A. Principles and Methods in Supramolecular Chemistry Wiley ,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. Steed Dekker, ,500 pages $489.00

3 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 their properties

4 What is Supramolecular Chemistry? The ultimate supramolecular material? Held together by many specific hydrogen bonds, π-π stacking, etc. Encodes gigabytes of data Can Self-Replicate Built-in Error Correction Information Storage Is the basis of life

5 What is Supramolecular Chemistry? Tobacco Mosaic Virus (TMV)

6 What is Supramolecular Chemistry? Actin-Myosin Complex

7 What is Supramolecular Chemistry? Kinesin Crawling Along a Microtubule

8 What is Supramolecular Chemistry? MOLECULAR CHEMISTRY covalent bonds formation SUPRAMOLECULAR CHEMISTRY non-covalent bond formation

9 What is Supramolecular Chemistry? J. M. Lehn: Supramolecular chemistry is the chemistry of the intermolecular bond, covering the structures and functions of the entities formed by the association of two or more chemical species F. Vögtle: In contrast to molecular chemistry, which is predominantly based upon the covalent bonding of atoms, supramolecular chemistry is based upon intermolecular interactions, i.e. on the association of two or more building blocks, which are held together by intermolecular bond

10 What is Supramolecular Chemistry?

11 What is Supramolecular Chemistry? But also: Molecular Devices Supramolecular Photochemistry Electronic Switches Dendrimers

12 What is Supramolecular Chemistry? 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)

13 What is Supramolecular Chemistry? Supramolecular Aggregates 1-50 nm nm Nanoelectronics nanobiology

14 Development - History

15 Development - History

16

17 Classification of Host-Guest Compounds

18 Classification of Host-Guest Compounds Spherand

19 Classification of Host-Guest Compounds

20 Corpora non agunt nisi fixata

21 Receptors and the Lock and Key Analogy

22 The Chelate and Macrocyclic Effects

23 The Chelate and Macrocyclic Effects

24 The Chelate and Macrocyclic Effects Less entropically favorable Stabilization offered by the chelate effect

25 Preorganization and Complementarity

26 Preorganization and Complementarity

27 Nature of Supramolecular Interactions Covalent bond energies: C-O bond 340kJ / mol 1.43Å C-C bond 360kJ / mol 1.53Å C-H bond 430kJ / mol 1.11Å C=C bond 600kJ / mol 1.33Å C=O bond 690kJ / mol 1.21Å Compared to most non-covalent interactions these are: Very high energies Very short distances Highly dependant on orientation

28 Nature of Supramolecular Interactions Driving Forces for the Formation of Supramolecular Structures hydrophobic interaction electrostatic interaction hydrogen bond interaction van der Waals interaction cation π interaction π π stacking <40 kj/mol ~20 kj/mol kj/mol kj/mol 5-80 kj/mol 0-50 kj/mol The total inter-molecular force acting between two molecules is the sum of all the forces they exert on each other.

29 Nature of Supramolecular Interactions

30 Nature of Supramolecular Interactions Ion - Ion Interactions Can be a very strong bond - even stronger then covalent bonds in some cases. Can be an attractive or a repulsive force. Non-directional force Long range (1/r) Highly dependant on the dielectric constant of the medium

31 Nature of Supramolecular Interactions Ion Ion Interactions Energy = (k * z 1 * z 2 * e 2 ) / (ε r 12 ) k = 1 / 4πε o = Coulomb constant = 9*10 9 Nm 2 /C 2 e = elementary charge = 1.6*10-19 C ε = dielectric constant r 12 = meters between the objects The energy of an ion-ion interaction only falls of at a rate proportional to 1 / r. Therefore these are very long range forces.

32 Nature of Supramolecular Interactions 1 nm in water? Ion Ion Interactions Energy = (k * z 1 * z 2 * e 2 ) / (ε r 12 ) = 9*10 9 * 1 * -1 * (1.6*10-19 ) 2 / 78.5 * 1 * 10-9 = -2.3 * / 0.8 * 10-7 = * J = kj / mole (-0.42 kcal / mole) 1 nm in Chloroform? = 9*10 9 * 1 * -1 * (1.6*10-19 ) 2 / 4.8 * 1 * 10-9 = -2.3 * / 4.8 * 10-9 = * J = kj / mole (-6.89 kcal / mole) -> 8% of a C-C bond

33 Nature of Supramolecular Interactions

34 Nature of Supramolecular Interactions Ion-Dipole Interaction Example: Acetone pointing directly at Na ion (θ = zero) at a distance of 1nm (in chloroform) Energy = -(k * Q * u * cosθ / e * r 2 ) If θ = zero = -k * Q * u / e * r 2 = -9*10 9 * 1.6*10-19 * 2.9 * *10-30 / e * r 2 = * / 4.8 * (10-9 ) 2 = -2.9 * J = -1.75kJ / mole u = q * l (dipole moment) l = length of the dipole q = partial charge on dipole r = distance from charge to center of dipole Q = charge on ion

35 Nature of Supramolecular Interactions Ion-Dipole Interaction Directional forces Can be attractive or repulsive Medium range (1/r 2 ) Significantly weaker then ion-ion interactions

36 Nature of Supramolecular Interactions

37 Nature of Supramolecular Interactions : Hydrogen Bonding

38 Nature of Supramolecular Interactions : Hydrogen Bonding

39 Nature of Supramolecular Interactions : Hydrogen Bonding

40 Nature of Supramolecular Interactions : Hydrogen Bonding R H O H O R Van der Waals radius of H: 1.1Å, O 1.5Å. Therefore closest approach should be 2.6Å. R H Actual separation is about 1Å less! Distance of 1.76Å. O H O R Intermediate between vdw distance and typical O-H covalent bond of 0.96Å.

41 Nature of Supramolecular Interactions : Hydrogen Bonding

42 Nature of Supramolecular Interactions : Hydrogen Bonding

43 Nature of Supramolecular Interactions : Hydrogen Bonding

44 Nature of Supramolecular Interactions : 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. BI X- Halogen bonding may involve dihalogenes X2 and X-Y as well as organic halides The strength of the donor-acceptor interaction depends on the polarizability of the halogen atom, decreases in the order: I > Br > Cl (> F)

45 Nature of Supramolecular Interactions : Halogen Bonding DMSO to haloarene halogen bonding geometry: head on to C-X, Γ~ 158(13) (Cl), 162(12) (Br), and ~165(8) (I); side on to S=O, Ω: Increase of polarity of the both C-X and S=O bond increases the strength of interaction:

46 Nature of Supramolecular Interactions : The Cation π Interaction

47 Nature of Supramolecular Interactions : π π Stacking

48 Nature of Supramolecular Interactions : π π Stacking

49 Nature of Supramolecular Interactions : π π Stacking

50 Nature of Supramolecular Interactions : π π Interactions Chem. Rev. 2000,100,

51 Nature of Supramolecular Interactions : Charge-Transfer Complex

52 Nature of Supramolecular Interactions : Van der Waals Forces Strength of interaction is essentially a function of the surface area of contact. 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 it difficult to engineer porous or hollow structures and gives rise to the phrase Nature abhors a vacuum.

53 Nature of Supramolecular Interactions : Van der Waals Forces

54 Nature of Supramolecular Interactions : CLOSE PACKING IN THE SOLID STATE Conformers allowing maximum intermolecular interactions, even very weak (which do not play a role in solution) Empty space: crystal pores and channels -> inclusion crystals TETRIS analogy

55 Nature of Supramolecular Interactions : Hydrophobic Effects

56 Nature of Supramolecular Interactions : Hydrophobic Effects