Self-assembly-sides 1_RFS
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Transcript of Self-assembly-sides 1_RFS
Kaushik Balakrishnan, PhD
Research Summary
Dimension and size control self-assembly of functional organic building blocks: New possibilities in organic
materials and device technologies
“0 D” “1 D” “2 D” “3 D”
FROM MOLECULES TO MATERIALS • Synthesis: π-rich molecules (PDI, and BTDs) and macrocycles • Self-assembly: Size and Dimension control • Applications: Sensing, Optical, Energy and Display
Kaushik Balakrishnan, PhD
Research Summary
Self-Assembly• Spontaneous organization of a component (building blocks) into
ordered structures using interactions (non-covalent, ionic, etc.) inherent of the component(s) in select environment (solvent, vapor, surface, etc.).
• The self-assembled structures possess unique properties (new function) specific to the nature of organization of the building blocks and are often distinctly different from those of the individual building blocks.
• The collective organization of the building blocks therefore allow for realizing structures larger than themselves - bottom-up construction tool.
• Ability to control dimension (0D, 1D, 2D, and 3D) and size of resulting structures.
Examples of self-assembly DNA structure, formation of crystals, etc.
100#nm#1#nm# 10#nm# 1#µm#1#Å#
Size of building blocks (e.g., molecules, polymers
To#exploit#this#concept#for#material#science,#it#is#important#to#understand#the#interac5ons#between#the#building#blocks.
Different#noncovalent# interac5ons#between#the#molecules#play# significant# roles#during# the# self@assembly#@#enabling#size#and#shape#control.#
Principles of Self-assembly• Like prefers like • Governed by energetically favorable interactions
Kaushik Balakrishnan, PhD
Research Summary
Self-Assembly of Functional Organic MoleculesImportance#of#Self@Assembled#Organic#Materials#• Broad'structural#diversity'in'terms'of'available'π@rich'molecules,'polymers,'oligomers'
• Ability'to'func9onalize'–'tailor#structural#and#electronic#characteris5cs'• Low'manufacturing'cost;'Suitable'for'large#area#applica9ons''• Fabrica9on'on'flexible#substrates'A'low'temperatures'of'deposi9on'A'solu5on#processing'• Device'performance'of'organic#devices#now#compe5ng'with'exis9ng'advance'materials'
• Good'Chromophores'A''High#absorp5vi5es'–'OptoAelectronic'applica9ons'• Fluorophores' with' high# quantum# yields' and' tunability# in# light# emission' depending' on'
func9onaliza9on'A' large'structural'diversity'to'allow' light'absorp9on'and'emission'over'broad#range#of#wavelengths#ranging#from'UV'to'Visible'to'InfraAred'
• Aggrega5on# Induced# Emission' (AIE)' in' designed' building' blocks' leads' to' new' opportuni9es' in'optoAelectronics,'photonics,'and'display'applica9ons'
• SelfAassembled' structures' with' varying' size’s' and' shapes' will' allow' both# fundamental#understanding' of' proper9es' associated'with' such' structures' and' enable'new#applica5ons' in'advance'op9cal,'and'photonics'devices
Optical
Electrical
Mechanical
Thermal
Novel&nano)scale&devices&
Dimension#and Size#Control
Tailor# Proper5es
Kaushik Balakrishnan, PhD
Research Summary
Self-Assembly of PTCDI*PTCDI’s#exhibit#unusual#proper5es#like#•#High'absorbi9viy'and'fluorescence'yields''•'Thermal,'chemical'and'photochemical'stability'
•'Solvatochromism'strongly'observed'in'these'dyes''
•'Strong'tendency'to'aggregate'via'πAstacking'between'the'perylene'units'•'nAtype'semiconductor'characteris9cs'as'compared'to'more'common'pAtype'
•'Synthe9c'advances'allow'func9onaliza9on'of'such'molecules'at'both'imide'nodes'(NAposi9ons)'and'
also'at'each'of'the'8Abay'func9onaliza9onA'leading'to'structural'diversity'A'structurally'these'dyes'
can'be'rigid#planar'to'unusually#twisted##•'Func9onaliza9on'also'influences'the'solubility
*PTCDI = 3,4,9,10-Perylene Tetracarboxylic Diimide
N N
O O
OO
R R
Chemical Structure of PTCDI
Hadicke,)Acta)Cryst.)1986,)C42,)189;)195)
Klebe,)Acta)Cryst.)1989,)B45,)69.)
Wurthner,)Chem.)Eur.)J.)2007,)13,)450)–)465
π@stacking#distance#(d)#0.335#(graphite)#–#0.43#(distorted)#nm#Generally,#most#π@interac5ons#result
in#d@spacing#around#0.38#nm#
Highly efficient molecular stacking Such ideal stacking is difficult to achieve because of side-chains association and energy balance by optimizing the lateral, and transverse offset
1D- assembly Pathway for rapid change movement
Kaushik Balakrishnan, PhD
Research Summary
Self-Assembly of PTCDI
Propoxyethyl-PTCDI (PE-PTCDI)
Time dependence (methanol)
Balakrishnan)et)al.,)JACS,)2005,)pp10496
A
Molecular behavior- well defined absorption - - Fluorescence
Aggregation behavior - Formation of crystals phase - Quenching of free molecule emission
High solubility in chloroform with short side-chains for PE-PTCDI
Kaushik Balakrishnan, PhD
Research Summary
Self-Assembly of PTCDI
Balakrishnan,+et+al.+JACS,+2006,+pp7390+25 µM Ethanolic solution
Side%chain*effect*
Kaushik Balakrishnan, PhD
Research Summary
Self-assembly: Toolkits for solution processing
A- Dispersion - Rapid approach injection of components into ‘poor’ solvents B- Phase-transfer: Slow diffusion of molecules from ‘good’ to ‘poor’ solvents C - Phase transfer at high temperature: Controlling the rate of diffusion by improving solubilityD- Gelation: Coercing components to maximize molecular interactions (useful in non-planar systems) E - Vapor phase treatment: Another slow diffusion process to control size, and shape of assemblies
Kaushik Balakrishnan, PhD
Research Summary
Some more examples for Self-Assembly of PTCDI
Sayyad,)Balakrishnan)et)al.)manuscript)under)preparaJon
2D-assemblies
Controlling nature, and size of functionalization (i.e., side-chain) enables influencing solubilities and using the solution processing toolkit allows for controlling size, and shape of resulting assemblies. In turn this allows for fine tuning optical and electrical characteristics.
Ultralong fluorescent wires
Balakrishnan)et)al.)manuscript)under)preparaJon
Tuning light emission
Under UV-light excitation length of wires ~5 mm
Under ambient conditions
Balakrishnan,)et)al.)JACS,)2006,)pp7390
Kaushik Balakrishnan, PhD
Research Summary
Self-Assembly of Macromolecular Building Blocks
Arylene#Ethynylene#Macrocycles#(AEMs)#•'Shape'persistent'πAsurface;'πArich'nonAcollapsible'core'(rigid);'Planar'(near'planar);'''•'Large'area;''Pores'filled'with'ac9ve'func9onal'material.'(Hybrid'systems:'Applica9ons)
Highly'organized'1D'assembly'
Hoger,)Chem.)Eur.)J.)2004,)10,)1320
For 1D nanostructure – Control lateral association
J.S.Moore,Acc.Chem.Res,1997,402O413.
Nanofibers from a tetracyclic non-planar
building block
Balakrishnan)et)al.,)J.)Am.)Chem.)Soc.;'2006;'pp6576'
Nanofibers from a tetracyclic planar
building block
Such structures open new possibilities in sensing applications (see slides on Applications of self-
assembles structures )
Kaushik Balakrishnan, PhD
Research Summary
Self-Assembly of Benzothiadiazole (BTD) Building Blocks
Balakrishnan)et)al.)Chem.)Commun.)2012,)pp11668
Ultra-long fluorescent micro-tube assembly
Planar yet flexible - how does this influence morphology?
Kaushik Balakrishnan, PhD
Research Summary
Applications: π-rich self-assembled structures
J.Am.Chem.Soc. 2007, pp7234
Influence of molecular ordering: Enhanced Electrical Properties3-5x current flow upon doping
Doping of molecular wires
Influence of molecular ordering: Enhanced Sensing of Explosives
J.Am.Chem.Soc. 2007, pp6978
11
Kaushik Balakrishnan, PhD
Research Summary
Applications of π-rich self-assembled structures
Optical Waveguides Tunable Light Emission
TgHCC-60TgHCC-60
UV-Photodetection System
Org
anic
Sol
ar C
ells Polarized Light Emission
Chem. Commun., 2012, pp11668
Chem. Commun., 2014, pp5600Chem. Commun., 2012, pp11668
J. Phys. Chem. B,, 2006, pp12327Chem. Mater., 2009, pp2930
12
Kaushik Balakrishnan, PhD
Research Summary
Self-assembly: Dimension and size control from π-rich moleculesSolution Processing Toolkits
2D 3D micro-G
F
H I
Functional structures:
J.Am.Chem.Soc., 2005, pp10496 J.Am.Chem.Soc. 2006, pp7390 J.Am.Chem.Soc. 2006, pp6576 J.Am.Chem.Soc. 2007, pp6978 J.Am.Chem.Soc. 2007, pp7234 J. Phys. Chem. B,, 2006, pp12327 Nanoscale, 2011, pp3605 Chem. Commun., 2012, pp11668 Chem. Commun., 2014, pp5600 Chem. Commun., 2012, pp8904 Chem. Commun., 2013, pp684 Chem. Mater., 2009, pp2930 Unpublished results
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✓Applica5ons#✓'Op9cal'Sensing'✓'Electrical'Response'✓'OptoAelectronic'response'✓'Tuning'absorp9on'✓'Tuning'light'emission'and'bandAgap'
✓'Polarized'light'absorp9on' and'emission'
✓'Molecular'materials'for'Display''
✓'Exploring'new'chemical'pathways'
from'selfAassembled'structures
Conclusions• Morphology control via self-assembly can be an effective
approach to achieve new functional properties • The advances in toolkits and synthetic advances to tailor make
desired structures are furthering the scope of applications • Recent advances with co-assembled structures and post
chemical control over self-assembled structures are paving new frontiers in materials science
• The chemical, physical, and structural diversity enable addressing new challenges (see applications)