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A Fluorine-Substituted Hexakisdecyloxy- hexa- peri -hexabenzocoronene

A Fluorine-Substituted Hexakisdecyloxy- hexa- peri -hexabenzocoronene. Seth R. Marder et al., Org. Lett . 2005 , 7 , 5019-5022 Tobe Laboratory Mariko Ohno. Introduction. Hexa- peri -Hexabenzocoronene(HBC). Discotic columnar mesophase.

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A Fluorine-Substituted Hexakisdecyloxy- hexa- peri -hexabenzocoronene

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  1. A Fluorine-Substituted Hexakisdecyloxy-hexa-peri-hexabenzocoronene Seth R. Marder et al., Org. Lett. 2005, 7, 5019-5022 Tobe Laboratory Mariko Ohno

  2. Introduction Hexa-peri-Hexabenzocoronene(HBC) Discotic columnar mesophase ・strong p-p stacking interactions　・ high order parameter ・high thermal stability　　　　・ high charge carrier mobility

  3. Introduction Uniaxially ordered columnar stacks Substituted HBCs Amphiphilic HBC

  4. Introduction These HBCs usually have very high isotropic clearing points, in some cases higher than 420 °C. To lower the clearing point, HBCs with multiply branched substituents have been synthesized.

  5. Introduction 7 The undesirable oxidation reactions encountered in the synthesis of alkoxy HBCs could potentially be circumvented by using electron-withdrawing groups, to counteract the electron-donating effects.

  6. Previous Work R=C12H25

  7. Previous Work R=C12H25

  8. Synthesis of compound 7

  9. UV-vis spectrum of 7 in THF The absorption band of 7 red-shifted ~ 10 nm relative to n-alkyl-substituted HBCs withλmax ＝365, 408 nm .

  10. Cyclic voltammograms of 7 reversible reductions at E1/2＝-2.66 and -2.96V vs FeCp2+/0 (THF, 0.1 M nBu4NPF6) reversible oxidations at E1/2＝+0.53 and +0.96V vs FeCp2+/0 (CH2Cl2, 0.1 M nBu4NPF6) 7 shows two quasireversible reductions under the same conditions (E1/2＝-1.96 and -2.34V vs FeCp2+/0 at 250 mV s-1) The oxidation is irreversible (Eox ＝+1.59V vs FeCp2 +/0 at 250 mV s-1)

  11. DSC of 7 Using differential scanning calorimetry (DSC), the sample shows two endothermic peaks. ・The peak at 39 °C is assigned to a crystalline-to-mesophase transition. ・The transition at 310°C presumably represents the clearing point. This clearing point is lower than that for many alkyl- and phenyl-substituted HBC compounds (ca. 420°C for hexakis-n-alkyl derivatives ) Thermogravimetric analyzer(TGA) ･･･the onset of weight loss at 392 °C

  12. X-ray diffraction pattern of a thin film sample of 7 ahex＝26.8 Å (bulk LC) and ahex＝26.6Å (thin film) represent the intercolumn core-core distances. ※ahex＝ 28.6Å (the Colhd mesophase of dodecylsubstituted HBC ) These core-core distances are smaller than the diameter of 7 with fully extended alkyl chains (calculated by molecular modeling to be ca. 38Å), indicating some chain interdigitation or folding between columns.

  13. Pulse-radiolysis time-resolved microwave conductivity (PR-TRMC) • Samples (10 mg) of the materials were irradiated with 3 MeV electrons (10 ns pulses) from a Van de Graaff accelerator. • If the charge carriers formed are mobile, the conductivity of the sample will increase, which is monitored as a change in the microwave power. The charge-carrier mobility of 7･･･0.50 cm2 V-1 s-1 The charge-carrier mobility of hexakis-decyl-HBC ･･･0.55 cm2 V-1 s-1

  14. Electrochemical data The changes in energy levels revealed by the electrochemical data suggest that, at least relative to a hexakisalkyl HBC, electron injection might be facilitated in 7. 7 is more readily reduced than Alq3 (E1/2 = -2.30 V vs FeCp2 +/0). The fluorinated derivative that function as the electron- transport material.

  15. Summary • A fluorine-substituted hexakis-decyloxyhexa-peri-hexabenzocoronene has been synthesized and shown to form columnar assemblies in its LC phase and in thin films. • Its solubility in many common organic solvents suggests facile processibility. • The new fluorine-substituted HBC shows similar mobility characteristics to a nonfluorinated analogue, but electrochemical data suggests electron injection may be possible into this material.

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