Self-Assembly The spontaneous and reversible association of molecular - - PowerPoint PPT Presentation

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Self-Assembly The spontaneous and reversible association of molecular - - PowerPoint PPT Presentation

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Self-Assembly The spontaneous and reversible association of molecular species to form larger, more complex supramolecular entities according to the intrinsic information contained in the components. Metal-Ligand Interaction Metal as connector : -

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Self-Assembly

The spontaneous and reversible association of molecular species to form larger, more complex supramolecular entities according to the intrinsic information contained in the components.

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Metal-Ligand Interaction

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Metal as connector :

  • labile M-L interaction (kinetic)
  • stable compound (thermodynamic)
  • highly directional with many geometries available

Metal as functional group :

  • redox active (electron transfer)
  • UV-vis active (color)
  • photo active (phosphorescence)
  • magnetic properties
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mer- fac- cis cis trans Classical metals used: Pd(II), Pt(II), Cu(I), Cu(II), Re(I), Co(II), Fe(II), Ag(I), Zn(II), Ru(II)…

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Directonal Bonding Approach

M = bb acido, L = bb basico, definiti secondo il numero e geometria relativa dei siti acidi e basici

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Specie poligonali 2D

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Triangoli Molecolari

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Square = Triangle endothermic H < 0 S < S < 0 Solvent Concentration Temperature

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Directonal Bonding Approach

M = bb acido, L = bb basico, definiti secondo il numero e geometria relativa dei siti acidi e basici

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Gabbie Molecolari

M6L4 d ca. 11 Å Portali 8 Å

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Molecular Paneling

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carborano 1-adamantanolo

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difenilmetano

cis-azobenzene cis-stilbene 4,4’-dimetossi-dibenzoile

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tetrabenzilsilano tri-tert-butilbenzene

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1:1 1:2 1:4 1:8 M6L4/adamantancarbossilato4

Effetto allosterico!

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dibenzoile

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6:2:3

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Stabilizzazione di intermedi reattivi: alcossi-silani ciclici Ship in a Bottle

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Stabilizzazione di intermedi reattivi: Oligomerizzazione di tri alcossi-silani

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acenaftileni naftochinoni Fotodimerizzazioni 2+2

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controllo stereochimica, [ ] 2mM resa > 98% benzene: [ ] 150mM, 3h, resa 40%, no stereoselettività

acenaftilene

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Controllo regiochimica, [ ] 2mM resa > 98%

1-metil-acenaftilene

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controllo stereochimica, [ ] 2mM resa > 98% benzene: [ ] > >, t > >, resa 25%, 21% anti

naftochinone

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M4L6, (Ga3+, Fe3+; biscatecol-amidi) 12-, , , 300-350 Å Stabilizzazione di cationi organici

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Supramolecular Catalysis of a Unimolecular Transformation: Aza‐Cope Rearrangement within a Self‐Assembled Host

Supramolecular Catalysis of a Unimolecular Transformation: Aza‐Cope Rearrangement within a Self‐Assembled Host, Volume: 43, Issue: 48, Pages: 6748-6751, First published: 08 December 2004, DOI: (10.1002/anie.200461776)

Left: A schematic view of the [G⊂M4L6] (G=guest) supramolecular tetrahedral assembly, looking down the C3‐axis. For clarity only one ligand is drawn, the other ligands are represented as sticks. Middle: CAChe model of [NPr4⊂Fe4L6]11−, the guest molecule is shown in a space‐filling view, the hydrogen atoms are omitted for clarity. Right: The same CAChe model as in the middle, now with host and guest in space filling view. This representation shows that the guest molecule is not exposed to the assembly exterior, but rather is tightly surrounded by the host.

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Top: A general reaction scheme of the 3‐aza‐Cope rearrangement. Starting from the enammonium cation A, [3,3] sigmatropic rearrangement leads to iminium cation B, which then hydrolyzes to the aldehyde, C. Bottom: 1H NMR spectrum of [1⊂Ga4L6]11− (1: R1, R2, R3=H). The observed upfield shift of guest resonance signals illustrates the close contact between host and guest.

Supramolecular Catalysis of a Unimolecular Transformation: Aza‐Cope Rearrangement within a Self‐Assembled Host

Supramolecular Catalysis of a Unimolecular Transformation: Aza‐Cope Rearrangement within a Self‐Assembled Host, Volume: 43, Issue: 48, Pages: 6748-6751, First published: 08 December 2004, DOI: (10.1002/anie.200461776)

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Substrate R1 R2 R3 kfree [×10−5 s−1] kencaps [×10−5 s−1] Accelerat ion 1 H H H 3.49 16.3 5 2 Me H H 7.61 198 26 3 H Et H 3.17 446 141 4 H H Et 1.50 135 90 5 H nPr H 4.04 604 150 6 H H nPr 1.69 74.2 44 7 H iPr H 0.37 316 854

Table 1. Rate constants for free (kfree) and encapsulated (kencaps) rearrangements (measured at 50 °C) and their acceleration factors.

Supramolecular Catalysis of a Unimolecular Transformation: Aza‐Cope Rearrangement within a Self‐Assembled Host

Supramolecular Catalysis of a Unimolecular Transformation: Aza‐Cope Rearrangement within a Self‐Assembled Host, Volume: 43, Issue: 48, Pages: 6748-6751, First published: 08 December 2004, DOI: (10.1002/anie.200461776)

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The 2D NOESY spectrum of [3⊂Ga4L6]11− in a D2O/MeOD mixture (70:30) recorded at −10 °C, mixing time 100 ms. Indicated in red are selected NOEs. The correlation between Me and Me at the two distal ends of the molecule demonstrates the cavity's enforcement of a compressed and folded guest conformation. Hn=naphthyl protons, Hc=catechol protons.

Supramolecular Catalysis of a Unimolecular Transformation: Aza‐Cope Rearrangement within a Self‐Assembled Host

Supramolecular Catalysis of a Unimolecular Transformation: Aza‐Cope Rearrangement within a Self‐Assembled Host, Volume: 43, Issue: 48, Pages: 6748-6751, First published: 08 December 2004, DOI: (10.1002/anie.200461776)

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Proposed catalytic cycle for the cationic 3‐aza‐Cope rearrangement, see text for details.

Supramolecular Catalysis of a Unimolecular Transformation: Aza‐Cope Rearrangement within a Self‐Assembled Host

Supramolecular Catalysis of a Unimolecular Transformation: Aza‐Cope Rearrangement within a Self‐Assembled Host, Volume: 43, Issue: 48, Pages: 6748-6751, First published: 08 December 2004, DOI: (10.1002/anie.200461776)

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  • Fig. 1 Synthesis of tetrahedral cage 1 and subsequent incorporation of P4.
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  • Fig. 2 Crystal structure of P4⊂1.
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  • Fig. 3 Extraction of P4 from 1 by n-heptane is not possible, whereas replacing P4 with another

suitable guest (benzene or cyclohexane) results in the facile removal of P4 into the organic solvent.

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