CN110729915B - Preparation method of water supermolecule motor - Google Patents

Abstract

The invention discloses a preparation method of a water supermolecule motor, which comprises the following steps: s1, adhering the highly-oriented cracked graphite to a conductive metal plate by using low-temperature conductive silver adhesive, degassing, depositing water molecules on the surface of the highly-oriented cracked graphite in situ by using a microleakage valve under the condition that the temperature is 90-110K, and forming water clusters and water molecule chains by self-assembly; s2, moving the graphite sample adsorbed with water molecules into a scanning tunnel microscope under ultrahigh vacuum working environment at 77K, placing the needle tip of the scanning tunnel microscope above the water cluster, and applying a voltage pulse to inject tunneling electrons into the water cluster to form a negative electric water cluster; and S3, the negative electricity water cluster attracts a water molecular chain through electrostatic action, the water molecular chain rotates clockwise or anticlockwise around the negative electricity water cluster under the driving of tunneling electrons, and the water supermolecule motor with the negative electricity water cluster as a stator and the water molecular chain as a rotor is obtained. The method can realize the preparation of the water supermolecule motor on the solid surface.

Description

A kind of preparation method of water supramolecular motor

technical field

The invention relates to the preparation of a molecular motor, in particular to a preparation method of a water supramolecular motor.

Background technique

Molecular motors are nanomachines capable of converting external energy (thermal, chemical, light, or electrical) into directional motion or rotation. According to different working environments, molecular motors can be divided into molecular motors in solution and molecular motors on solid surfaces. In nature, most molecular motors work near the interface, so molecular motors mounted on solid surfaces have always been a research hotspot in nanoscience.

In the field of life science, all the activities of the living body are maintained by the push of protein macromolecules with motor functions, such as muscle contraction, material transportation, cell division, DNA replication, etc., and water is an indispensable part of the living body to maintain life activities. Therefore, the preparation of water supramolecular motors and the study of their internal mechanisms are of great significance for further understanding and understanding of the internal mechanisms of life activities.

So far, a variety of molecular motors have been fabricated on solid surfaces, including the rotation of thiophenol on the Cu(111) surface, the rotation of thioether molecules on the Cu(111) substrate, the rotation of n-butyl methyl sulfide ( The rotation of BuSMe) on the surface of Cu(111) and the rotation of zinc tetrabutylphthalocyanine molecules on the surface of Au(111) and so on. These single-molecule or motor arrays are often prepared by depositing molecules on a solid surface in a high vacuum environment. These molecular motors are covalent molecular motors, and their rotors and stators are connected by covalent bonds, which lead to high rotational barriers and low work efficiency. However, the stator and rotor of the water supramolecular motor are connected by electrostatic interaction, and the rotational potential barrier is small or negligible. Therefore, the above preparation method of the covalent bond molecular motor is not suitable for the preparation of the water supramolecular motor. Therefore, it is necessary to invent a method for preparing water supramolecular motors adsorbed on solid surfaces.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a preparation method of a water supramolecular motor, which can realize the preparation of a water supramolecular motor on a solid surface.

The preparation method of the water supramolecular motor of the present invention comprises the following steps:

S1, use low-temperature conductive silver glue to stick the highly oriented pyrolysis graphite to the conductive metal plate, degassing, and then use the micro-leak valve to deposit water molecules on the surface of the highly oriented pyrolysis graphite in situ at a temperature of 90~110K. Molecules self-assemble on the surface of highly oriented cracked graphite to form water clusters and water molecular chains;

S2, move the graphite sample with adsorbed water molecules into the scanning tunneling microscope, the working environment is ultra-high vacuum, the temperature is 77 K, the needle tip of the scanning tunneling microscope is placed above the water cluster, and a voltage pulse is applied to inject the tunneling electrons into the water clusters to form negatively charged water clusters;

S3, the negatively charged water cluster attracts a water molecular chain through electrostatic interaction, and the water molecular chain rotates clockwise or counterclockwise around the negatively charged water cluster driven by tunneling electrons, and the negatively charged water cluster is used as the stator and the water molecular chain. Water supramolecular motors as rotors.

Further, in S3, when the water molecular chain is chiral, a water supramolecular motor with negatively charged water clusters as the stator and the water molecular chain as the rotor is directly obtained; when the water molecular chain is achiral, a scanning tunneling microscope is used. The needle tip applies a tiny voltage to the water molecular chain to perturb the water molecular chain, so that the water molecular chain is converted into chirality, and a water supramolecular motor is obtained with the negatively charged water cluster as the stator and the water molecular chain as the rotor.

Further, the tiny voltage is 0.8~1V. If the voltage is too high, the structure of the water molecular chain will be destroyed, so that the water supramolecular motor cannot be formed. If the voltage is too low, the water molecular chain cannot be converted from achiral to Chirality.

Further, the degassing in the S1 is degassing for 5 to 7 hours under the conditions of a vacuum of 10 ^-8 to 10 ^-7 mbar and a temperature of 80 to 100°C. In order to obtain a clean and highly directional cracked graphite surface, it lays a good foundation for the subsequent deposition of water molecules.

Further, the ultra-high vacuum in the S2 is 1.0×10 ⁻¹⁰ to 1.2×10 ⁻¹⁰ mbar.

Further, the conductive metal plate in the S1 is a copper plate, and copper still has good electrical conductivity under low temperature conditions, which provides a basis for the preparation of the water supramolecular motor.

In the invention, the low-temperature deposition technology is used to prepare water clusters and water molecular chains from the highly directional cracked graphite surface in a high vacuum environment, and then the water clusters are charged by the needle tip of a scanning tunnel microscope to form negatively charged water clusters, and the negatively charged water clusters pass through Electrostatic interaction attracts water molecular chains with permanent dipole moments, negatively charged water clusters act as stators, and water molecular chains act as rotating bodies of supramolecular motors, which are driven by tunneling electrons flowing out of the tip of a scanning tunneling microscope to surround the negatively charged water clusters Cluster rotation enables the fabrication of water supramolecular motors on solid surfaces.

The temperature for in-situ deposition of water molecules in the present invention is 90-110K. When the temperature is too high, the water molecules are in a disordered state, and water clusters and water molecular chains cannot be formed. difficulty.

Description of drawings

Fig. 1 is a schematic diagram of a device for preparing water clusters and water molecular chains on the surface of highly oriented pyrolysis graphite;

Figure 2 is a schematic diagram of the morphology of water clusters and water molecular chains on the surface of highly oriented cracked graphite;

Fig. 3 is the preparation schematic diagram of the water supramolecular motor of the present invention;

Figure 4 is a schematic diagram showing the comparison of the morphology of the water clusters before and after the pulse voltage is applied to the tip of the scanning tunnel microscope, wherein a is the morphology of the water clusters before applying the pulse voltage, and b is the morphology of the water clusters after the pulse voltage is applied;

Figure 5 is a schematic diagram of the height comparison of water clusters before and after applying pulse voltage through the tip of a scanning tunneling microscope;

Figure 6 is a schematic diagram of the structure of the water supramolecular motor.

In the figure, 1—magnetic handle, 2—magnetic sample transfer rod, 3—molecular pump, 4—micro-leak valve, 5—sample holder, 6—sample, 7—vacuum chamber.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings.

A preparation method of a water supramolecular motor, comprising the following steps:

S1, referring to Figure 1, the device for preparing water clusters and water molecular chains on the surface of highly oriented pyrolysis graphite includes a magnetic handle 1, a magnetic sample transfer rod 2, a molecular pump 3, a micro-leakage valve 4, a sample holder 5, and a sample 6 and vacuum chamber 7, the magnetic handle 1 is arranged outside the vacuum chamber and is connected with one end of the magnetic sample transfer rod 2, and the other end of the magnetic sample transfer rod 2 is connected with the sample holder 5, and the sample holder 5 is used for fixing The conductive metal plate is controlled to enter or exit the vacuum chamber 7 by the magnetic sample transmission rod 2; the micro-leak valve 4 is arranged on the right side of the vacuum chamber 7 to supply water molecules, and the molecular pump 3 is arranged on the left side of the vacuum chamber 7 The side part is used to control the vacuum degree of the vacuum chamber 7 .

In the specific work, the highly oriented pyrolysis graphite is glued to the conductive metal plate with low-temperature conductive silver to obtain sample 6. First, the sample 6 is degassed in a high vacuum environment. The specific process parameters are: 10 ^-8 ~10 ^-7 mbar In a vacuum environment of 90 °C, degassing was performed for 6 h at a temperature of 90 °C to obtain a clean and highly directional cracked graphite surface, which laid a good foundation for the subsequent deposition of water molecules. Then fix the sample 6 on the bottom surface of the sample holder 5, and use the magnetic handle 1 to drive the magnetic sample transfer rod 2 to send the sample 6 into the vacuum chamber 7. The sample 6 is located directly above the micro-leakage valve 4, and then the temperature is 90~110K. The micro-leakage valve 4 is used to deposit water molecules on the surface of the highly oriented pyrolysis graphite in situ. Referring to Figure 2, using scanning tunneling microscopy in situ detection, water molecules self-assemble on the surface of highly oriented cracked graphite to form water clusters and water molecular chains.

S2, see Fig. 3, the conductive metal plate is moved into the scanning tunneling microscope, the tip of the scanning tunneling microscope is located above the water cluster, and a voltage pulse is applied under the condition of 1.2 × ^10-10 mbar ultra-high vacuum environment at a temperature of 77K to Tunneling electrons are injected into the water clusters on the surface of highly oriented cracked graphite, and the water clusters form negatively charged water clusters after accepting one tunneling electron. Negatively charged water clusters play the role of stators in water supramolecular motors, which can trap water molecular chains with permanent dipole moments through electrostatic interactions. Referring to Figure 4, the morphology of the water clusters before and after the pulse voltage was applied to the scanning tunneling microscope tip were observed. Figure 4a shows the three water dimers adsorbed on the graphite surface before the pulse voltage was applied. Using the scanning tunneling microscope tip After injecting tunneling electrons into the lowermost water dimer, see Fig. 4b, the negatively charged water dimer is significantly brighter than the upper two neutral water dimers. After measuring and comparing the height of water dimer before and after charging, the results are shown in Figure 5. The height of water dimer after applying pulse voltage is much higher than that before applying pulse voltage, indicating that the water dimer after applying pulse voltage is negatively charged water dimer.

S3, see Fig. 3, the negatively charged water cluster attracts a water molecular chain with a permanent dipole moment through electrostatic interaction, and the water molecular chain rotates clockwise or counterclockwise around the negatively charged water cluster driven by tunneling electrons, resulting in a A water supramolecular motor with negatively charged water clusters as the stator and water molecular chains as the rotor.

It should be noted that when the water molecular chain is chiral, a water supramolecular motor with negatively charged water clusters as the stator and water molecular chains as the rotor is directly obtained. When the water molecular chain is achiral, as shown in Figure 6c, the water molecular chain will randomly rotate clockwise or counterclockwise under the drive of tunneling electrons to form a supramolecular rotor. At this time, a scanning tunneling microscope tip is required A small voltage is applied to the water molecular chain for perturbation, and the small voltage is 0.8-1V, so that the achiral water molecular chain is converted into a chiral molecular chain with left-handedness or right-handedness. At this time, referring to Fig. 6d, when the left-handed water molecular chain rotates around the negatively charged water cluster, its rotational barrier in the clockwise direction will increase, and finally a water supramolecular motor with anti-clockwise chirality is formed. Referring to Figure 6e, when the right-handed water molecular chain rotates around the negatively charged water cluster, its rotational barrier in the counterclockwise direction increases, finally forming a water supramolecular motor with clockwise chirality.

The above descriptions are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included in the protection of the present invention. within the range.

Claims (6)

1. a preparation method of a water supramolecular motor, is characterized in that, comprises the steps: S1, use low-temperature conductive silver glue to stick the highly oriented pyrolysis graphite to the conductive metal plate, degassing, and then use the micro-leak valve to deposit water molecules on the surface of the highly oriented pyrolysis graphite in situ at a temperature of 90~110K. Molecules self-assemble on the surface of highly oriented cracked graphite to form water clusters and water molecular chains; S2, move the graphite sample with adsorbed water molecules into the scanning tunneling microscope, the working environment is ultra-high vacuum, the temperature is 77 K, the needle tip of the scanning tunneling microscope is placed above the water cluster, and a voltage pulse is applied to inject the tunneling electrons into the water clusters to form negatively charged water clusters; S3, the negatively charged water cluster attracts a water molecular chain through electrostatic interaction, and the water molecular chain rotates clockwise or counterclockwise around the negatively charged water cluster driven by tunneling electrons, and the negatively charged water cluster is used as the stator and the water molecular chain. Water supramolecular motors as rotors. 2. the preparation method of water supramolecular motor according to claim 1, is characterized in that: when water molecular chain is chirality in described S3, directly obtains the water with negative electric water cluster as stator, water molecular chain as rotor Supramolecular motor; When the water molecular chain is achiral, a tiny voltage is applied to the water molecular chain with the tip of a scanning tunneling microscope to perturb the water molecular chain, so that the water molecular chain is converted into chirality, and the negatively charged water cluster is used as the stator and the water molecular chain as the rotor. water supramolecular motors. 3 . The preparation method of a water supramolecular motor according to claim 2 , wherein the tiny voltage is 0.8-1V. 4 . 4. the preparation method of the water supramolecular motor according to claim 1 and 2, is characterized in that, in described S1, degassing is the condition that vacuum is ^10-8 ～ ^10-7 mbar, temperature is 80～100 ℃ Lower degassing for 5~7h. 5. The method for preparing a water supramolecular motor according to claim 1 or 2, wherein the ultra-high vacuum in the S2 is 1.0×10 ⁻¹⁰ to 1.2×10 ⁻¹⁰ mbar. 6. The method for preparing a water supramolecular motor according to claim 1 or 2, wherein the conductive metal plate in the S1 is a copper plate.

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