Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Molecular building blocks:Molecular building blocks: MBBs are the link between classical MBBs are the link between classical

synthsis chemistry from in theory the synthsis chemistry from in theory the smallest possible unit, and large structures.smallest possible unit, and large structures.

MBBs are molecules that self assemble into MBBs are molecules that self assemble into larger units.larger units.

The limitations of this method are:The limitations of this method are: Availability of the units, connectivity, and Availability of the units, connectivity, and

suitable linkerssuitable linkers

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Bonding and connectivityBonding and connectivity– Covalent bondingCovalent bonding– Covalent bonds are formed by the sharing of pairs of Covalent bonds are formed by the sharing of pairs of

electrons between atoms.electrons between atoms.– Best example is the covalent bond between two C Best example is the covalent bond between two C

atoms.atoms.– Sigma bonding along the axis between the two atoms, Sigma bonding along the axis between the two atoms,

provides a means of low energy rotation in linear provides a means of low energy rotation in linear molecules and low energy angle twisting in cyclic molecules and low energy angle twisting in cyclic molecules.molecules.

– Sigma bonding defines the general connectivity and Sigma bonding defines the general connectivity and framework of the molecule framework of the molecule

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Covalent bonding has many advantages:Covalent bonding has many advantages:– Covalent bonds lead to extremely stable Covalent bonds lead to extremely stable

intermolecular connections, as compared to intermolecular connections, as compared to electrostatic interactions (temperature, ionic electrostatic interactions (temperature, ionic strength, pH)strength, pH)

– Covalnet bonds are dependable, they do not Covalnet bonds are dependable, they do not reorganise, like hydrogen bondsreorganise, like hydrogen bonds

– Protocols exist to form all kinds of covalent Protocols exist to form all kinds of covalent bonds for all kinds of building blocks, allowing bonds for all kinds of building blocks, allowing all possible connectivitiesall possible connectivities

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Coordination complexesCoordination complexes– In between the covalent bonds and the other In between the covalent bonds and the other

interamolecular interactions are the coordination interamolecular interactions are the coordination complexes between organic molecules and complexes between organic molecules and metal ions.metal ions.

– The initial description of these metal ligand The initial description of these metal ligand molecules stems from the ability of metal ions to molecules stems from the ability of metal ions to coordinate ligands electron donating molecules coordinate ligands electron donating molecules

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Dative bonds:Dative bonds:– Interaction of a lone pair with an atom centered Interaction of a lone pair with an atom centered

molecular orbital. Strength comparable to a molecular orbital. Strength comparable to a sigma bond.sigma bond.

– E.g. Bonding between B and N.E.g. Bonding between B and N.– Coupling of a molecule to B with a lone pair Coupling of a molecule to B with a lone pair

leads to change in boron from trigonal planar leads to change in boron from trigonal planar (sp2) to tetrahedral (sp3).(sp2) to tetrahedral (sp3).

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Boroadamantane is a special case, because B is already in sp3 hybridisation and has the final conformation already built in the molecule.

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

InteractionsInteractions– They play a role in base stacking in DNAThey play a role in base stacking in DNA– Molecular crystalsMolecular crystals– Polymer chemistryPolymer chemistry– Foramtion, shape and function of proteinsForamtion, shape and function of proteins

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Molecular building block approachesMolecular building block approaches– The ultimate goal is the assembly of nanostructures or The ultimate goal is the assembly of nanostructures or

nanoscale materials through the manipulation of a nanoscale materials through the manipulation of a subunit by chemical modificationsubunit by chemical modification

– The MBB is devisible into one or more The MBB is devisible into one or more chemically/electrostaically active regionchemically/electrostaically active region

Supramolecular ChemistrySupramolecular Chemistry Science of electrostatic interaction at the Science of electrostatic interaction at the

molecular levelmolecular level

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Hydrogen bondingHydrogen bonding It is used extensively in Supramolecular It is used extensively in Supramolecular

ChemistryChemistry Easy means to self assemble large units Easy means to self assemble large units

from smaller subunits, can rearrangefrom smaller subunits, can rearrange Stability increases with the total amount of Stability increases with the total amount of

Hydrogen bondsHydrogen bonds

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Crystal EngineeringCrystal Engineering– Hydrogen Bonding has been extensively used Hydrogen Bonding has been extensively used

in the stabilisation of crystal lattices.in the stabilisation of crystal lattices.– Hydrogen bonding is one of the main bonding in Hydrogen bonding is one of the main bonding in

biological moleculesbiological molecules– Stabilisation of structures and backbonesStabilisation of structures and backbones– Secondary structure stabilisationSecondary structure stabilisation

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Supramolecular structuresSupramolecular structures Whole families of Supramolecular structures Whole families of Supramolecular structures

are known that have been built up only by are known that have been built up only by Hydrogen bondingHydrogen bonding

Mixing the units in te correct ratios will lead Mixing the units in te correct ratios will lead to the self assembly of the desired to the self assembly of the desired structuresstructures

Cavities, sheets, triangular structures,…..Cavities, sheets, triangular structures,…..

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

CatenanesCatenanes– Catenanes are a very special class of Catenanes are a very special class of

supramolecular moleculessupramolecular molecules– They come into existence when two They come into existence when two

macrocycles interpenetrate each other.macrocycles interpenetrate each other.– The first catenane has been synthesised in very The first catenane has been synthesised in very

poor yieldspoor yields

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Molecular ZippersMolecular Zippers– Molecular zippers are formed by amide oliomersMolecular zippers are formed by amide oliomers– They maximise the amount of Hydrogen They maximise the amount of Hydrogen

bonding and bonding and -stacking-stacking– Stabiloity increases with oligomer lengthStabiloity increases with oligomer length– Decrease in stability in polar solvents Decrease in stability in polar solvents

(methanol)(methanol)

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Covalent ArchitecturesCovalent Architectures

The Tinkertoy chemistThe Tinkertoy chemist Idea behind the concept to build all possible Idea behind the concept to build all possible

structures and shapes from a limited set of structures and shapes from a limited set of molecules where all possible connectivities molecules where all possible connectivities of each single are known of each single are known

LEGO block system for organic chemistryLEGO block system for organic chemistry

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Stability:Stability:– Stability and reactivity are the most important Stability and reactivity are the most important

factorsfactors– The MBBS should only react during the The MBBS should only react during the

formation of the structure and result in an inert formation of the structure and result in an inert structure at the end of the reactionstructure at the end of the reaction

SizeSize– Control over the size is better the smaller the Control over the size is better the smaller the

single building blocks are.single building blocks are.

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Chemical reactivityChemical reactivity– From the box of the 24 molecules the reactivity From the box of the 24 molecules the reactivity

and reaction chemistry is known and described.and reaction chemistry is known and described.– Protocols for all possible linking reactions are Protocols for all possible linking reactions are

knownknown– Engineering all possible shapes is possibleEngineering all possible shapes is possible

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Honeycomb lattices

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Symmetry interaction modelSymmetry interaction model– Symmetry interaction model builds on the Symmetry interaction model builds on the

understanding that many highly symmetric understanding that many highly symmetric naturally occuring structures are formed as a naturally occuring structures are formed as a consequence of lock and key interactions consequence of lock and key interactions between the subunits.between the subunits.

– Metal complex chemistry uses these principles Metal complex chemistry uses these principles to generate new metal-ligand assembliesto generate new metal-ligand assemblies

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

2 Dimensional structures2 Dimensional structures Virtually no limit in structural combinationsVirtually no limit in structural combinations

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

3D structures3D structures Spotaneous self assembly from non Spotaneous self assembly from non

covalent self assembly is a known principle covalent self assembly is a known principle in biological structuresin biological structures

ProteinsProteins LaddersLadders RodsRods

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks

Nanostructural Architectures from Nanostructural Architectures from Molecular Building BlocksMolecular Building Blocks