SELF ASSEMBLY OF COORDINATION CAGES ON SI(100) SURFACES

1. SELF ASSEMBLY OF COORDINATION CAGES ON SI(100) SURFACES G. G. Condorelli1, M. Busi2, E. Dalcanale2, M. Favazza1, I. L. Fragalà1, M. Laurenti2, M. Montalti3, A. Motta1, L. Prodi3 Dip. di Scienze Chimiche, Università di Catania and INSTM UdR di Catania Dip. di Chimica Organica e Industriale, Università di Parma,and INSTM UdR di Parma Dip. di Chimica "G. Ciamician", Universitàdi Bologna

2. Cavitands for Self-assembly Nanotechnologies: Precise control over the formation of nanoscale molecular architectures Self-assembly is a key technology for the formation of two- and three-dimensional structures. Appealing points: Thermodynamic control Reversibility Metal-directed self-assembly of coordinantion cages 4 MLX2 NEt3 M=Pt, Pd L=1,3-bis(diphenylphosphino)propane (dppp) X= CF3SO3- (OTf-) Internal volume 18003Å

3. From solution to technological surface (Si(100)) Nanostructured hybrid material covalent bonded to Si: Stable for long time storage Possible integration in real device Reversible inclusion of single molecules with functional properties A possible route towards nanoreplication 4 MLX2

4. 254nm Si Si Si Si Si Cavitand grafting on Si(100) SiOx Oxidated Si: layer not densely packed pure cavitad decorated freshly HF etched Si 2p XPS spectra: give information on the quality of the monolayer SiOx

5. Not oxidated Si: layer densely packed mixed cavitad decorated freshly HF etched Cavitand grafting on Si(100) Si 2p XPS spectra: give information on the quality of the monolayer

6. 8 + O 8 O T f - O O O O O O O N O M L O N N M L N N L M N N O L M O N O O O O O O o O ii ) Si Si Si Si Si Si Si Si Si Si M= Pt L= dppp Self-assembly of coordination cages Self –assembly treatment on cavitand functionalised silicon Control experiment: Self –assembly treatment on octene functionalised silicon

7. Chatacterization techniques • X-ray Photoelectron Spectroscopy (XPS) • Atomic Force Microscopy (AFM) • Fluorescence Spectroscopy

8. XPS analysis Pt 4f

9. 3 nm Line B 1.8nm A 6,6 nm/div 500 nm/div Height Profile 500 nm/div 2,1 nm 1,9 nm A B 37,0 nm 43,2 nm AFM analysis AFM on the 20% cavitand decorated substrate Molecular modeling

10. 3,9 nm/div 3,8 nm Line A B 500 nm/div 500 nm/div C 3,5 nm 1.8 nm Height Profile 4,0 nm 3,9 nm 3,5 nm C A B 58,9 nm 58,8 nm 53,0 nm AFM analysis AFM of the Self-assembled cages on Si Molecular modeling

11. AFM of the 1-octene decorated substrate after the same treatment of the self-assembled cages substrate 4,5 nm/div 3,9 nm/div Line A B 500 nm/div 500 nm/div C 500 nm/div 500 nm/div Line A No Cages! Height Profile Height Profile 4,0 nm 3,9 nm 3,5 nm C A B A 0,8 nm 58,9 nm 58,8 nm 53,0 nm AFM analysis AFM of the Self-assembled cages on Si Cages!

12. Fluorescence analysis • Excitation by dedicated UV laser at 355nm on severalareas (1mm2) give: • No fluorescence emission for all investigated areas on the 20% decorated cavitand substrate. • Fluorescence emission in different area for the 20% decorated cavitand substrate after the self-assembly treatment. • No fluorescence emission for all the investigated areas for the 1-ottene decorated substrate after the self-assembly treatment. UV fluorescence in reflection on surfaces Excimer band Emission of self-assembled cages on Si. Reference of phyisisorbed cages deposited on Si Emission of the 1-ottene decorated substrate after the self-assembly treatment.

13. Conclusion • A new route for Si-integrattion of 3D nanosize coordination cages through the self-assembly • The approach associated to the possibility of introducing specific probes offers the advantages of an easy, error-free characterization of complex 3D structures. • Observation for the first time of fluorescence of a dye covalently linked on a Si(100) surface.

14. Thank you for your attention

15. XPS analysis Calculated cage formation 4%