KR100873802B1 - Organic Rectifier with Fullerene Derivatives - Google Patents

Abstract

An organic rectifier having a fullerene derivative is disclosed. Unlike other fullerene derivatives having rectifying properties, the fullerene derivatives of the present application exhibit high molecular weight and homogeneous molecular orbital (HOMO) and low unoccupied molecular orbital (LUMO) levels in the fullerene structure. . In addition, the fullerene derivative has a functional group containing sulfur. Fullerenes combine five branches with a hydrophilic functional group containing sulfur. That is, the fullerene derivative of the pentapo structure which has a hydrophilic functional group comprises an amphiphilic fullerene derivative.

Description

Organic rectifiers having fullerene derivatives

1 shows the structure of a fullerene derivative prepared according to the present invention.

Figure 2 shows the ¹ H-NMR spectrum of the thiolate fullerene prepared in Scheme 3 in accordance with the present invention.

Figure 3 is an I-V curve of the device manufactured in Preparation Example 3 according to the present invention. Bias voltage: -1 V to +1 V.

Figure 4 is an I-V curve of the device manufactured in Preparation Example 4 according to the present invention. Bias voltage, (A) -2 V to +2 V, (B) -3 V to +3 V.

5 is a comparative graph of the I-V curve of the device manufactured in Preparation Examples 3 and 4 according to the present invention.

Figure 6 shows the results of (A) HOMO and (B) LUMO of (4-SH-C ₆ H ₄ ) ₅ HC ₆₀ through computer simulation of the fullerene derivative prepared according to the present invention.

The present invention relates to a fullerene derivative, and more particularly, to an amphiphilic fullerene derivative having a pentapo structure having various functional groups containing sulfur by introducing a method of thiolate and a parent having a molecular arrangement in a conductive substrate using the same. It relates to a rectifier using a solvent fullerene derivative.

Fullerene molecules have strong hydrophobic properties, so they are easily aggregated with each other, making it very difficult to uniformly arrange the substrate. However, many attempts have been reported in the literature to form self-assembled monolayers (SAM) of fullerenes to align well and densely align on a substrate.

For example, stable self-assembly has been reported by treating Au (111) substrate with (4-mercaptophenyl) anthrylacetylene (MPAA). As a result, in order to achieve a more improved molecular arrangement, the present invention synthesizes pentapod-type fullerenes in which five substituents immobilized on the Au (111) substrate are introduced into one fullerene, thereby providing a more stable nano-sized monolayer (mono). attempts to form a layer).

In a study involving organic rectifiers, a ^single electron donor (D) consists of a D-δ-A system connected via an isolated δ bridge to an electron acceptor (A). ^Two -molecule commutation characteristics were detected through the Langmuir-Blodgett (LB) monolayer of hexadecylquinolinium tricyanoquinodimethanide and confirmed after ³ , ^{4 and 5} . Fullerene derivatives LB single-membrane rectifiers were found when sandwiched between gold electrodes ⁶ . This first fullerene derivative, dimethylaminophenylazafullerene, has been reported to have a very pronounced rectification rate (up to 20,000). However, most of the forward current here seems to be due to the formation of stalagmite in gold. Other findings in the fullerene-bis- [4-diphenylamino- 4 '' - (N -ethyl- N -2 '''- ethyl) amino-1,4-diphenyl-1,3-butadiene] 7 of the malonate The Langmuir-Schaefer (LS) monolayer was shown to be commutated when sandwiched between two gold electrodes.

Fullerene molecules are strongly hydrophobic and easily aggregated. However, many attempts have been reported in the literature to form SAMs of fullerenes for good alignment and density alignment on substrates ⁸ . Stable self-assembly of (4-mercaptophenyl) anthrylacetylene (MPAA) on gold (111) substrates has been reported ⁹ . The molecule has a very good 2D alignment through strong pp intermolecular clusters and gold-thiol attraction. The superior physical and chemical properties of fullerenes combined with the benefits of controlling the nanosized alignment of SAMs based on MPAA.

Nakamura and his team added organic copper reagents to bind penta-addition materials to fullerenes. ¹⁰ This reaction is quantitative and can be tested in multi-gram units and is very common for various aryl and alkenyl groups as well as methyl groups. ¹¹ Synthesis of alkenyl products can be accomplished by using 1-alkenyl copper reagents produced using the corresponding lithium reagents instead of Grignard reagents through arylation and methylation synthesis. Do.

However, the above-mentioned conventional technology is not easy to adsorb the electrode and fullerene, and the organic rectifier and the fullerene derivative used therein are still easy to adsorb the gold electrode and the adsorption, and the alignment between the fullerene molecules is still developed. This will be requested.

[(1) Metzger, RM Chem . Rev. 2003 , 103 , 3803. (2) Aviram, A; Ratner, MA Chem . Phys . Lett. 1974 , 29 , 277. (3) Martin, AS; Sambles, JR; Ashwell, GJ Phys . Rev. Lett . 1993 , 70 , 218. (4) Metzger, RM; Chen, B .; Ho¨pfner, U .; Lakshmikantham, MV; Vuillaume, D .; Kawai, T .; Wu, X .; Tachibana, H .; Hughes, TV; Sakurai, H .; Baldwin, JW; Hosch, C .; Cava, MP; Brehmer, L .; Ashwell, GJ J. Am . Chem . Soc . 1997 , 119 , 10455. (5) Metzger, RM; Xu, T .; Peterson, IR J. Phys . Chem . B 2001 , 105 , 7280. (6) Metzger, RM; Baldwin, JW; Shumate, WJ; Peterson, IR; Mani, P .; Mankey, GJ; Morris, T .; Szulczewski, G .; Bosi, S .; Prato, M .; Comito, A .; Rubin, Y. J. Phys . Chem . B 2003 , 107 , 1021. (7) Honciuc, A .; Jaiswal, A .; Gong, A .; Ashworth, K .; Spangler, CW; Peterson, IR; Dalton, LR; Metzger, RM J. Phys . Chem . B 2005, 109, 857. (8) (a) Shi, X .; Caldwell, WB; Chen, K .; Mirkin, CA J. Am . Chem . Soc . 1994 , 116 , 11598. (b) Arias, F .; God Kenz, LA; Wilson, SR; Kaifer, AE; Echegoyen, L. J. Am . Chem . Soc . 1996 , 118 , 6086. (9) Zareie, MH; Ma, H .; Reed, BW; Jen, AK-Y .; Sarikaya, M. Nano Lett . 2003 , 3 , 139. (10) Nakamura, E; Isobe, H. Acc . Chem . Res . 2003 , 36 , 807. (11) (a) Sawamura, M .; Iikura, H .; Nakamura, E. J. Am . Chem . Soc . 1996 , 118 , 12850. (b) Sawamura, M .; Iikura, H .; Ohama, T .; Hackler, UE; Nakamura, E. J. Organo - metal . Chem . 2000 , 599 , 32 . (c) Sawamura, M .; Toganoh, M .; Kuninobu, Y .; Kato, S .; Nakamura, E. Chem . Lett . 2000 , 262. (d) Sawamura, M .; Nagahama, N .; Toganoh, M .; Nakamura, E. J. Organometal. Chem . 2002 , 652 , 31 .

The first object of the present invention for solving the above problems is to introduce a method of thiolate to provide an amphiphilic fullerene derivative of pentapod structure having various functional groups including sulfur.

Further, a second object of the present invention is to provide an organic rectifier using a fullerene derivative obtained by achieving the first object.

The present invention for achieving the first object provides a fullerene derivative having the amphiphilic properties of the pentapod structure, and having the formula (RX) ₅ HCn.
In the formula, the functional group RX is a functional group having sulfur, and n is 60 or more.

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The present invention for achieving the second object, a conductive substrate; And fullerene derivatives formed on the conductive substrate as a langet voltet monolayer or self-assembled monolayer, wherein the fullerene derivative is a system having an electron donor-insulated δ bridge-electron receiving portion in one molecular structure. An organic rectifier is provided.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First Example

1 shows the structure of a fullerene derivative according to a preferred embodiment of the present invention.

Referring to FIG. 1, a fullerene derivative having an amphiphilic property of a pentapod structure and having a chemical formula of (RX) ₅ HCn is disclosed. In the above formula, RX is a functional group having sulfur. Specifically, R is a straight or branched saturated or unsaturated alkyl or aryl group, and X includes a structure of -SH or -SS- as a functional group moiety that can be adsorbed with the substrate surface. Specific examples of RX are as shown in FIG. 1.
The synthesis of the fullerene pentapod was carried out using a penta-addition method, which is very easy and yields over 90% yield. As an example of a fullerene derivative having the formula (RX) ₅ HCn, a fullerene derivative having a pentapod structure containing a thiol and a thiol derivative as a functional group, that is, (4-SX'-C ₆ H ₄ ) ₅ HCn The synthesis was successful, where X 'may be a protecting group such as pyran. In the formulas of the fullerene derivative, n is preferably 60 or more.

That is, the fullerene molecule is provided with five thiolated (-SX ') functional groups. The structure of the functional group bound to the fullerene molecule is shown in detail in FIG. 1 above.

Molecular mechanics (MM2) studies have also predicted that the functional groups of the thiols and thiol derivatives that form the bridge of fullerenes will act as donors and the fullerene moieties will act as acceptors. It was confirmed by computer simulation that both HOMO (Highest Occupied Molecular Orbital) and LUMO (Lowest Unoccupied Molecular Orbital) exist in the fullerene cage as shown in FIG. 6.

This is in contrast to previous fullerene rectifiers, in which five thiolated (-SX ') functional groups help to connect to the substrate as well as provide a fixed support for the fullerene molecules. Thus, the amphipathic fullerene pentapod itself, in which the HOMO and LUMO are placed in the fullerene cage, can be called a single molecule rectifier.

Production Example  One : Bromophenylsulfanyl - Tetrahydro Piran ( Bromo - phenylsulfanyl -Preparation of tetrahydro-pyran) Grignard  reaction

Preparation of Bromophenylsulfanyl-tetrahydro-pyran

A small amount of camphor sulfonic acid was added as a catalyst to the solution of bromobenzenethiol dissolved in dichloromethane (MC) together with 3,4-dihydro-2H-pyran and then reacted at 40 ° C for 3 hours.

As the reaction solvent, not only dichloromethane but also chloroform and tetrachlorocarbon may be used, and the reaction solvent may be used 10 to 20 times with respect to the weight of bromo benzenethiol. At this time, the above-mentioned protection (protection) is carried out in the range of 20 ℃ to 60 ℃, if the reaction temperature is less than 20 ℃ yield is low and there is a problem that the addition reaction occurs when it exceeds 60 ℃.

Grignard reaction with bromophenylsulfanyl-tetrahydro-pyran

Referring to Scheme 2, the Grignard reaction is very sensitive to moisture, so the reaction vessel is completely dried and refluxed with nitrogen or argon. The dried magnesium metal (Mg) is added while fully refluxed, and anhydrous tetrahydrofuran (THF) is added with a trace amount to the height of the magnesium metal and stirred. Slowly add 1,2-dibromoethane (1,2-dibromoethane) to activate magnesium under stirring and reflux, and slowly inject THF under ice bath to prevent overheating reaction. After confirming that the color of the reaction solution turned dark brown, bromophenylsulfanyl-tetrahydro-pyran is slowly injected. Reflux at 80 ° C. for 2 hours and terminate the reaction. Through this bromomagnesium-phenylsulfanyl-tetrahydro-pyran (Bromomagnesium-Phenylsulfanyl-Tetrahydro-pyran; BMPST) can be obtained.

Preparation Example 2 Preparation of Thiolate Fullerene Pentapod (4-SH-C ₆ H ₄ ) ₅ HC ₆₀

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Thiolated fullerene pentapod (4-SH-C ₆ H ₄ ) ₅ HC ₆₀ Preparation is as described in Scheme 3 above. Specifically, after dissolving in a fullerene (C ₆₀ ) and a copper catalyst and toluene / tetrahydrofuran mixed solvent, BMPST prepared in Scheme 2 is slowly added at -78 ° C and reacted for 2 hours. After the temperature was raised to room temperature, the reaction was terminated by adding ammonium chloride solution.

By using such a protective reaction, the addition reaction in which the thiol group (-SH) reacts with each other is prevented, thereby obtaining (4- (SC ₅ H ₅ O) -C ₆ H ₄ ) ₅ HC ₆₀ . In this case, when the use of the thiol group (-SH) is required in the step of adsorption with Au (111), the para-protected thiol functional group is converted to a thiol (-SH) functional group in-situ for use. Toluic sulferic acid or tetra-n-butylammonium fluoride is injected under the addition of a solution of trifluoroacetic acid in methanol. From Scheme 3, the final product (4-SH-C ₆ H ₄ ) ₅ HC ₆₀ was prepared in 95% yield.

The _{(4- (SC 5 H 5 O} ) -C 6 H 4) were attached in Figure 2 to ¹ H-NMR the structure of the HC ₅ to ₆₀ verification data.

2nd Example

In the conventional organic rectifier, a fullerene is disposed between the upper electrode and the lower electrode. Therefore, when the electrical characteristics of the organic rectifier are to be measured, a method of applying power to the upper electrode and the lower electrode is used.

However, the fullerene derivative prepared by the present invention adsorbs the fullerene derivative only on the lower substrate. The thioleate fullerene pentapod structure produced by the first embodiment has an electron donor-δ bridge-electron acceptor system configured in a mono layer.

Therefore, the measurement of rectification characteristics of the conventional organic rectifier is performed after arranging organic materials between the upper and lower electrodes, but in the present invention, a new measuring method is used in the lower portion of the conductive electrode such as gold, silver or platinum, specifically Au (111) is used to arrange the fullerene derivative on the conductive electrode. In addition, a tip of a conductive AFM (CAFM) measuring instrument was used as an electrode on the fullerene derivative. In addition, the conductive electrode is conductive and is made of gold, silver or platinum.

The rectification characteristic measurement using the above-described measuring device can measure the rectification characteristic of the organic material by preventing the rectification characteristic by tunneling between electrodes generated in the conventional method, and measure the accurate rectification characteristic of the monolayer. The method is presented. Hereinafter, the method for measuring the rectification characteristics of the fullerene derivative is described using CAFM.

Preparation Example 3 Preparation of Organic Rectifier Using Conductive AFM (Atomic Force Microscopy)
[Formula 1]

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Pentapods perthiolated with in-situ using tetra- n- butylammonium fluoride (TBAF) dissolved in tetrahydrofuran (THF) SX'-C ₆ H ₄ ) ₅ HC ₆₀ was deprotected.

In the molecular formula of the perthiolated pentapod, X 'is a protecting group such as a pyran moiety.

First, a solution prepared by dissolving (4-SX'-C ₆ H ₄ ) ₅ HC ₆₀ (1.5 mmol) in tetrahydrofuran (10 mL) was immersed in an Au (111) substrate and in tetrahydrofuran (15 mL) in the air. A solution of -n-butylammonium fluoride (8mmol) was added to adsorb the fullerene derivative and the substrate for 12 hours, repeatedly washed with tetrahydrofuran, and dried with nitrogen gas (N ₂ ). It was then dried for 24 hours in a vacuum desiccator under nitrogen dried at room temperature. IV characteristics of the fabricated device were analyzed in the air using a conductive AFM.

The I-V characteristics of the device manufactured above are attached to FIGS. 3 and 5.

Production Example  4: conductive AFM ( Atomic Force Microscopy Organic Rectifier Using 2)

[Formula 2]

perthiolate pentapod (4-SH-C ₆ H ₄ ) ₅ HC ₆₀ prepared by in-situ deprotection was converted to mercaptooctanoic acid (MOA), mercaptododecanoic acid Mercaptocarboxylic acids such as mercaptohexadecanoic acid (MHA), mercaptosuccinic acid (MSA) or thioctic acid (TOA); And hydrogen bond to form.

To this end, first, a self-assembly monolayer (SAM) of mercapdocaropsilic acid was made on a substrate. For example, a solution of MHA was made by dissolving MHA (1.5 mmol) in THF (25 mL). In addition, a clean Au (111) substrate was immersed in this solution at room temperature for 24 hours, washed several times with THF and dried with nitrogen gas. It was then dried in a vacuum desiccator for 24 hours. Perthiolate pentapod (4-SH-C ₆ H ₄ ) ₅ HC ₆₀ was adsorbed on the SAM-converted substrate by in-situ deprotection. Its IV characteristics were measured using conductive AFM in the atmosphere.

The I-V characteristics of the device manufactured above are attached to FIGS. 4 and 5.

According to the present invention as described above, the fullerene derivative of pentapod structure containing a thiol or thiol derivative functional group is monolayer monolayer (mono layer is possible because of the strong adsorption capacity of the thiol functional group to Au (111) ) It is easy to adjust and shows rectification at forward low voltage. As a result, these molecular rectifier materials can be used for a variety of nanoscale device applications such as memory materials.

Although described above with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below I can understand that you can.

Claims (9)

delete delete delete Conductive substrates; And Fullerene derivatives formed in a single film on the conductive substrate, The fullerene derivative is represented by the following formula (1), characterized in that the organic rectifier system characterized in that the HOMO and LUMO levels are provided at the same time in one molecular structure. [Formula 1]

In Formula 1, the functional group RX is at least one selected from the group consisting of the following formulas.

The organic rectifier of claim 4, wherein the conductive substrate is gold, silver, or platinum. delete 5. The organic rectifier of claim 4, wherein the fullerene derivative is adsorbed onto the conductive substrate by multi-hydrogen bond with mercaptocarboxylic acid. The method according to claim 7, wherein the mercaptocarboxylic acid (MOA) is 8-mercaptooctanoic acid (MOA), 12-mercaptododecanoic acid (12-mercaptododecanoic acid) acid (MDA)), 16-mercaptohexadecanoic acid (MHA), mercaptosuccinic acid (MSA) or thioctic acid (TOA) Characterized by organic rectifier. 8. The organic rectifier of claim 7, wherein the mercaptocarboxylic acid is formed into a self-assembled monolayer.

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