Conventional Fabrication Method for TCNQ Radical Anion Salts Molecular Wires

1. Conventional Fabrication Method for TCNQ Radical Anion Salts Molecular Wires Kazumasa Uedaa, b, Tomoki Suzuki b, Ryusuke Kita b, c a Division of Applied Science and Basic Technology, Faculty of Engineering b Innovative Joint Research Center c Department of Electrical and Electronics Engineering, Faculty of Engineering, Shizuoka University, Johoku, Hamamatsu, Shizuoka 432-8561, Japan

2. Nano-Cooking = Recipe No.2 Nano-noodle = Kazumasa Uedaa, b, Tomoki Suzuki b, Ryusuke Kita b, c a Division of Applied Science and Basic Technology, Faculty of Engineering b Innovative Joint Research Center c Department of Electrical and Electronics Engineering, Faculty of Engineering, Shizuoka University, Johoku, Hamamatsu, Shizuoka 432-8561, Japan

3. Nano-Cooking = Recipe No.2 Nano-noodle = = Recipe No.2 Nano-doughnut = 

4. NMP(TCNQ) Quinolinium (TCNQ)2 NEt4 (TCNQ) Acridinium (TCNQ)2 Obtained TCNQ radical anion salts molecular wires

5. Today’s talk • Our goal and motivation • Fabrication of wires • Relationship between size and experimental condition • Physical properties of the wire • Summary

6. So far known technique • Preparation of surface • TTF TCNQ nanowire on stainless steel conversion coating substrates by dipping process. (D. de Caro et al., C. R. Acad. Sci. Paris, Serie IIc, Chimie : Chemistry, 3, 675 (2000).) • Micro/nano wire of AgTCNQ on Ag coated substrate via the reaction between Ag film and TCNQ dissolved in acetonitrile. (G. Cao et al., Mat. Sci. Eng. B, 119, 41 (2005).) • Modification of molecules for introducing self-assembling • Nanowires of (amphiphilic bis(TTF) annelated macrocycle)(TCNQF4)2 on a mica (T. Nakamura, et al., Bull. Chem. Soc. Jpn,78, 247 (2005).)

7. Aim of this research • Use of commercially available substrates • No preparation of substrate surface!! • Fabrication of so far known materials • No chemical modification of materials!! • Construction of molecular wires without any structural change during fabrication.  • Easy estimation of the wires properties referring huge physical properties libraries so far known in the molecular materials.

8. Crystal structure single crystal NMP(TCNQ) • High conductivity of order of 100 S cm-1 • Cell parameters: a = 3.8682 Å, b = 7.7807 Å, c = 15.745 Å, a = 91.67°, b = 95.38°

9. Recrystallization of NMP(TCNQ) • Cooling down the saturated solution slowly • Preparing saturated acetonitrile solution of NMP(TCNQ) under refluxing condition • Cooling down slowly • Evaporating solvent from the saturated solution slowly • Preparing saturated solution at room temperature • Evaporating solvent slowly

10. Our motivation Change of crystal habit crystal face which grows slower • Low concentration  small crystal • Rapid crystallization  highly anisotropic crystals  wire? crystal face which grows faster

11. Fabrication of wires • NMP TCNQ acetone solution was introduced into a weighting bottle. • A glass substrate was dipped in the bottle. • Solvent was evaporated. • Deposits grew on the substrate.

12. width /mm concentration / mmol l-1 Relationship between width and concentration evaporating ratio: 5 ml/48 h wire platelet

13. 40 nm width / mm time / h Relationship between width and solvent evaporating time

14. CN stretching mode • No electronic structural change during fabrication

15. XRD patterns of the wire and the single crystal a = 3.87 Å, b = 7.78 Å, c = 15.75 Å, a = 91.67°, b = =92.67° g= 95.38° a = 3.87 Å, b = 7.78 Å, c = 15.78 Å, a = 91.67°, b =92.67° g= 95.38° • Molecular arrangement of the wires is as same as that of single crystals. Single crystals Wires

16. Summary • The shorter the evaporating time, the narrower the width of the wire. • The wire has same electronic structure and crysatllinity as the single crystal. • The preferentially grown direction was parallel to the stacking direction of TCNQ molecules

17. Acknowledgement Financial support • Grant-in-Aid for Scientific Research (No. 16750114) from JSPS • Inoue Foundation for Science • Foundation for Engineering Promotion from Faculty of Engineering, Shizuoka University • Post-doctoral Fellowship form Innovative Joint Research Center, Shizuoka University

19. Below 0.8 mmol/l

21. Recrystallization of NMP(TCNQ) • Preparing saturated acetonitrile solution of NMP(TCNQ) under refluxing condition or at room temperature • Cooling down slowly • Precipitation of Crystals

23. Humidified Fabrication Method for Dithiolene Oxovanadium Complexes Molecular Rings Kazumasa Uedaa, b, Tomoki Suzuki b, Ryusuke Kita b, c a Division of Applied Science and Basic Technology, Faculty of Engineering b Innovative Joint Research Center c Department of Electrical and Electronics Engineering, Faculty of Engineering, Shizuoka University, Johoku, Hamamatsu, Shizuoka 432-8561, Japan

24. Introduction Dithiolene transition metal complexes Fabrication on several substrate Thin films of magnetic, highly conductive or semiconducting material • Fundamental scientific interests • Potential application for devices

25. This Work • Preparation of thin films of dithiolene metal complexes (n-Bu4N)2 [(dmit)2Zn] and (n-Bu4N)2 [(dcbdt)2VO] • Investigation of morphologies on glass, magnesium oxide and silicon substrates under ambient and highly humidified conditions

26. Materials • (n-Bu4N)2[(dmit)2Zn] was used as purchased from Tokyo-Kasei Ltd. • (n-Bu4N)2[(dcbdt)2VO] was obtained from the reaction of Na2dcbdt and VCl3 (K. Ueda et al., Polyhedron)

27. Dipping process • 2.5 ml acetone solution containing 1.0  10-2 mol of dithiolene metal complex was introduced into a weighting bottle. • Substrates were dipped under ambient condition . • Slow solvent evaporation. • Deposit grew on substrates.

28. (n-Bu4N)2[(dcbdt)2VO] deposits on a glass substrate • A lot of micro-scale porous structures on the surface • The diameter of these pores lies from 2 to 80 mm

29. (n-Bu4N)2[(dcbdt)2VO] depositson a magnesium oxide substrate • Bead structures with a diameter around 5mm

30. (n-Bu4N)2[(dcbdt)2VO] deposits on a non-polished surface of silicon substrate • Two dimensional network

31. (n-Bu4N)2[(dcbdt)2VO] deposits on a polished surface of silicon substrate • Needle like microcrystals • Thickness: 5 to 8 mm • Length: 20 to 150 mm

32. Shape and size of (n-Bu4N)2[(dcbdt)2VO]molecular rings AFM 5.6 µm SEM 18.4 µm thickness0.6 µm 1～10 µm ～1 µm 10～20 µm

33. Speculative explanation for formation of micro-scale rings Water droplet Droplet of acetone solution 1. Micrometer sized droplets of acetone disperse on the polished surface of the silicon wafer randomly. 2. Water vapor condenses on the surface of the acetone solution droplets. 3. Micro-sized water droplets grow in the middle of the solution droplets by further evaporation of acetone. 4. This water droplet acts as the template to form the hole of the micro-scale rings.

34. Size dependence of (n-Bu4N)2[(dcbdt)2VO] ringsunder ambient and highly humidified conditions Highly humidified condition (internal diameter: ~ 2 mm, outer diameter: ~ 4 mm) Ambient condition (internal diameter: 1 – 10 mm, outer diameter: 10 – 20 mm)

35. Morphology of (n-Bu4N)2[(dmit)2Zn]under ambient and humidified conditions Microcrystalline (ambient condition) Ring structure (highly humidified condition)

36. XRD patterns of (n-Bu4N)2[(dmit)2Zn] • the crystallinity is maintained during the fabrication (a) the rings and (b) the corresponding single crystals

37. Summary • We have successfully fabricated molecular rings of (n-Bu4N)2[(dcbdt)2VO] and (n-Bu4N)2[(dmit)2Zn] on several substrates using a simple and easy deposition method under ambient and highly humidified conditions. • The XRD diffraction patterns of the complex reveals that the molecular rings have same crystallinity as the corresponding single crystals. • Our result suggests that our fabrication technique is one of the strong tool for device application of molecular materials maintaining the crystalline physical properties of them.

38. Acknowledgement Financial support • Grant-in-Aid for Scientific Research (No. 16750114) from JSPS • Inoue Foundation for Science • Foundation for Promotion of Engineering from Faculty of Engineering, Shizuoka University • Post-doctoral Fellowship form Innovative Joint Research Center, Shizuoka University