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Supramolecular Chemistry of Nanomaterials
Department of ChemistryImperial College of Science,Technology and Medicine
r.vilar@ic.ac.ukj.steinke@ic.ac.uk
Joachim SteinkeRamon Vilar
Lecture 7 –Increased Complexity and Size
Lecture Content
• Polyrotaxanes• Nanotubes• Nanowires• Supramolecular Dendrimers
Polyrotaxanes – Molecular Necklace
• Polyrotaxane containing alpha-cyclodextrins.
POLY
MER
S FO
R A
DV
AN
CED
TEC
HN
OLO
GIE
S, 8
, 241
(199
7)
Polyrotaxanes –Molecular Necklace
POLY
MER
S FO
R A
DV
AN
CED
TEC
HN
OLO
GIE
S, 8
, 241
(199
7)
Polyrotaxane Drugs
• Design of a drug–polyrotaxane conjugate.
J. Contr. Release 58, 1999, 251
Polyrotaxane Drugs
• Final image of drug release from drug–polyrotaxaneconjugates via enzymatic degradations.
J. Contr. Release 58, 1999, 251
Polyrotaxane Drugs
J. Contr. Release 58, 1999, 251
Polyrotaxane Drugs
Release profile of theophylline-immobilized HP-α-CDs (Theo-HP-α-CDs) from Theo-HP-/E4-PHE: (circle ): Theo-HP- /E4-PHE 1 with 20 unit/ml of papain, ( triangle): Theo-HP-/E4-PHE 2 with 20 unit/ml of papain, ( filled triangles): Theo-HP- /E4-PHE 2 withoutpapain.
J. Contr. Release 58, 1999, 251
Insulated Molecular Wires
Hydrophobic binding directs the synthesis of an insulated molecular wireAng
ew. C
hem
. Int
. Ed.
39,
200
0, 3
456
Insulated Molecular Wires
Angew. Chem. Int. Ed. 39, 2000, 3456 300 nm 700 nm
Supramolecular Sensors
Band diagram illustrating the mechanism by which the molecular wire receptor assembly can produce an enhancement in a fluorescence chemosensory response. The horizontal dimension represents the position along the conjugated polymer shown schematically at the top. Excitonsare created by absorption of a photon (hυ) and then migrate along the polymer backbone. Analyte binding produces a trapping site whereby the excitation is effectively deactivated by electron-transfer quenching.
Nanotubes
(center) Appropriately designed cyclic d,l-α-peptides and β-peptides can adopt a low-energy flat ring-shaped conformation in which the amide backbone moieties lie nearly perpendicular to the plane of the ring structure with side chains radiating around a central pore, the size of which is determined by the number of amino acids employed (for illustrative purposes only an eight-residue cyclic d,l-α-peptide is depicted). Depending on the peptide sequence and conditions employed, peptide subunits can be assembled into:
a) transmembrane ion channels and pore structures, b) soluble cylindrical ensembles, c) solid-state tubular arrays, and d) surface-supported composites.
Chem. Eur. J. 1998, 4, 1368
Metal Nanowires - Junction
• Synthetic scheme for the fabrication of bimetallic nanowires with in-wiremonolayer junctions.
J. Am. Chem. Soc., 124 (15), 4020 -4026, 2002
Metal Nanowires - Junction
TEM images of (a) a nanowire with a 16-
mercaptohexadecanoicacid SAM between two Au segments (the bottom half of the wire was electroplated and the top half was grownelectrolessly),
(b) a 16-mercaptohexadecanoicSAM junction between two electroplated segments of ananowire; and
(c) a nanowire with a 16-mercaptohexadecanoicSAM junction after 5 min in the electron beam.
J. Am. Chem. Soc., 124 (15), 4020 -4026, 2002
Metal Nanowires - Junction
FESEM images of an Au-SAM-Aunanowire spanning the gap between Au contact electrodes (a) at high magnification and (b) at lower magnification showing the region making contact with the probe pads.
J. Am. Chem. Soc., 124 (15), 4020 -4026, 2002
Supramolecular Wires
Natural and syntheticsupramolecularsystems with cylindrical and spherical shapes: a, tobacco mosaic virus; b, ico.
Membrane
Schematic representation of the bilayer fluid mosaic model of the cell membrane. Integral proteins are embedded in the bilayer composed ofphospholipids.
Tetrahedron, 58, 4031, 2002.
Membrane
Self-assembly and self-organization followed by polymerization or polymerization followed by self-assembly and self-organization of tapered monodendrons containing a polymerizablegroup at the apex (a) or on the periphery of the taper (b). The R group in (b) represents the ionic, electronic or protonic active element.
Tetra
hedr
on, 5
8, 4
031,
200
2.
Membrane
The corresponding polymers (14–16) self-assemble and subsequently self-organize intosupramolecular networks, which form a 2-D hexagonal columnar lattice via thefluorophobic effect. These networks consist of a continuous phase, which is based on the semifluorinated,paraffinic barrier layer and which is perforated in a hexagonal array by ion-selective or ion-active channels constructed from the benzocrown-ether and tetraethyleneglycol respectively.
Tetrahedron, 58, 4031, 2002.
Supramolecular Electronics
Shown are the self-assembly, co-assembly and self-organization of dendrons containing donor (D) and acceptor (A) groups with each other and with disordered amorphous polymers containing D and A side groups. The different systems form hexagonal columnar ( h), centred rectangular columnar ( r-c) and simple rectangular columnar ( r-s) liquid crystals. a and b are lattice dimensions; space groups are shown.
Nat
ure
419,
384
-38
7 (2
002)
S
Supramolecular Electronics
•Charge carrier mobility of supramolecular columns and related systems.
Nat
ure
419,
384
-38
7 (2
002)
Supramolecular Polymers
• X-ray
Nature 419, 384 - 387 (2002)
Dendrimer Synthesis
Divergent Synthesis
H2N NH2
CO2Me
CO2Me
MeO2C
MeO2C
Divergent Synthesis
N N
CO2Me
CO2Me
MeO2C
MeO2C
H2N
NH2 H2N
NH2
H2N
NH2H2N
NH2
Divergent Synthesis
N N
H2N
NH HN
NH2
HN
NH2H2N
NH
O
O O
O
CO2Me
MeO2CCO2Me
MeO2C
MeO2C
CO2Me MeO2C
CO2Me
NH2
H2N
NH2H2N
H2N
NH2
H2N NH2
NH2
H2N
NH2H2N
H2N
NH2
H2N NH2
Divergent Synthesis
N N
N
NH HN
N
HN
NN
NH
O
O O
O
NH2
NH
NH2HN
H2N
HN
H2N NH
NH2
HN
NH2HN
H2N
NH
H2N NH
O O
O O
O O
O O
Divergent Synthesis
N N
NNH HN
N
HNNN
NH
O
O O
O
N
NH
HN
N
HN
NH
N
HN
HN
N
NH
NH
O O
O O
O O
O O
NH2
HNH2N
N H
OO
H2N
NHNH2
N H
OO
NH2
HNH2N
H N O
O
H2N
NHNH2
H N
OO
NH2HN
NH2
NH
O
O
NH2
NH
NH2HN
O
O
H2N NH
H2N
HN
O
O
H2N
HN
H2N NH
O
O
N N
NNH HN
N
HNNN
NHO
O O
O
N
NH
HN
N
HN
NH
N
HN
HN
N
NH
NH
O O
O O
O O
O O
NH2
HNH2N
N H
OO
H2N
NHNH2
N H
OO
NH2
HNH2N
H N O
O
H2N
NHNH2
H NO
O
NH2HN
NH2
NH
O
O
N
NH2
NH
NH2HN
O
ON
H2N NH
H2N
HN
O
O
N
H2N
HN
H2N NH
O
ON
Core
2nd Generation
1st Generation
3rd Generation
Dendrimers - Architecture
Dendrimers - Architecture
Dendrimers
Sketch of the fourth generationdendrimer G4-SH with 96 SH functions.
Nan
o Le
tters
,2(1
1), 1
239
-124
2, 2
002
Dendrimers –Self-assembly
Proc. Natl. Acad. Sci. U. S. A. 99: 5099-5104, 2002
Dendrimers –Self-assembly• Scheme showing
different conformations of spacer unit of 7 and its affect on the assembly process.
Proc. Natl. Acad. Sci. U. S. A. 99: 5099-5104, 2002
Dendrimers – Self-assembly
• Structural integrity - GPC
Proc. Natl. Acad. Sci. U. S. A. 99: 5099-5104, 2002
Dendrimers – Molecular Imprinting
Polymer Network
Functional Monomer
+
Template Molecule
Step 1 Step 2
Crosslinker
Step 3
Dendrimers – Molecular ImprintingN
atur
e41
8, 3
99 -
403
(200
2)
Dendrimers –Molecular ImprintingPorphyrins used to study binding properties of imprinteddendrimer 6.
Nature 418, 399 - 403 (2002)
Dendrimers – Molecular Imprinting
Calculated structure of imprinted dendrimer 6 built by iterative attachment of dendrons to the core porphyrin, minimization and cross-linking of neighbouring double bonds. a, van der Waals surface of a representative dendrimer structure produced by a 60 ps annealed dynamics simulation. b, Calculated binding pocket inside 6; yellow clouds represent positions of carboxyl groups when 6 is minimized without the host porphyrin 8, cyan clouds represent positions of carboxyl groups when 6 is minimized in the presence of the hostporphyrin 8, red arrows show the movement of carboxylic groups.
Nature 418, 399 - 403 (2002)
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