CN-117720436-B - Organic crystal with thermal phase transition induced mechanical behavior and fluorescence enhancement and preparation method and application thereof

Abstract

The invention discloses an organic crystal with thermal phase change induced mechanical behavior and fluorescence enhancement, and a preparation method and application thereof. The molecular formula of the organic crystal is C 18 H 15 N 3 , the organic crystal belongs to a monoclinic system, the space group is P2 1 /C, and the unit cell parameters are as follows: α=90°,β=105.357~105.957°,γ=90°, Z=8. The crystal material has obvious mechanical behavior generated by thermally induced phase transition, and has a thermally induced fluorescence enhancement phenomenon, the crystal rotates for 20-25 degrees in 25-30 min at an angular speed of 0.01-0.015 degrees/s, the mechanical behavior is similar to circular motion, the emission wavelength of the organic crystal is 720-740 nm, the fluorescence thermal quenching effect is shown at 300-370K, and the thermally induced fluorescence enhancement effect is shown at 370-440K. The mechanical behavior induced by thermal phase change of the crystal material can be used as an actuator, a crystal robot material and the like, and the phenomenon of fluorescence enhancement in the high-temperature phase change process can be used as a high-temperature fluorescent probe, a thermally induced fluorescence enhanced light emitting diode material and the like.

Inventors

• HU FEILONG
• YANG QINGXU
• MI YAN
• NONG QIAN
• Huang Qianlun
• FENG HAICHAO
• LI YALI
• ZHAO SHUANG

Assignees

• 广西民族大学

Dates

Publication Date

20260505

Application Date

20231130

Claims (1)

1. 1. Use of an organic crystal as an actuator material, a crystalline robot material, a high temperature fluorescent probe material, a thermally induced fluorescence enhanced light emitting diode material; The structural formula of the organic crystal is as follows: The molecular formula of the organic crystal is C 18 H 15 N 3 , the organic crystal belongs to a monoclinic system, and the space group is P2 1 /C; At 298K, the organic crystal has unit cell parameters of a= 16.0745 a, b= 7.53573 a, c= 25.6902 a, α=90°, β= 105.357 °, γ=90°, v= 3000.81 a 3 , z=8; The unit cell parameters of the organic crystal at 400K are a= 16.228A, b= 7.6192A, c= 25.840A, alpha=90°, beta= 105.957 °, gamma=90°, V= 3071.7A 3 and Z=8; the organic crystal rotates for 20-25 degrees in 25-30 min at an angular speed of 0.01-0.015 degrees/s in the thermal phase transition process, and is similar to the mechanical behavior of circular motion, the emission wavelength of the organic crystal is 720-740 nm, the fluorescence thermal quenching effect is shown at 300-370K, and the thermally induced fluorescence enhancement effect is shown at 370-440K.

Description

Organic crystal with thermal phase transition induced mechanical behavior and fluorescence enhancement and preparation method and application thereof Technical Field The invention belongs to the technical field of functional organic fluorescent materials, and particularly relates to an organic crystal with thermal phase change induced mechanical behavior and fluorescence enhancement, and a preparation method and application thereof. Background Materials that are capable of reacting to external stimuli such as light, heat, electricity, humidity, pH and concentration gradients are of great interest in the fields of chemistry, materials and engineering. Many polymers and gel materials exhibit mechanical movement in response to external stimuli, exhibiting a characteristic of movement. However, the movement of the material is limited. It has been reported that molecular crystals exhibit slow mechanical behavior such as creeping due to repeated crystallization and melting of the molecular crystals under irradiation of light, and that the molecular crystals still play an important role as a mechanical motion material, particularly in the field of robots, although there are limitations in the mechanical behavior pattern at present. The crystal shows mechanical behaviors such as bending, twisting, rolling, crawling, jumping and the like in the heating process, but the movement of the crystal is disordered after the internal molecules of the crystal are heated, cannot be predicted, and is mostly difficult to control in the movement direction, so that the movement of the crystal is limited. But the phase change of the crystal is continuously stretched and bent under the heating/cooling condition, and the movement track of the crystal under different width gradients can be controlled, so that a new idea is provided for the directional movement of the crystal. Meanwhile, the crystal phase change generates a phenomenon of fluorescence enhancement in the mechanical movement process, and most of semiconductor and fluorescent molecular materials show fluorescence Thermal Quenching (TQ) with different degrees, namely the photoluminescence intensity (PL) in solid is reduced along with the temperature rise. Because the non-radiative relaxation of excited electrons to the ground state increases rapidly with increasing temperature, the energy loss is large and the emission intensity decreases. This TQ effect severely affects the efficiency and reduces the performance of the light emitting diode. While in some semiconductor nanostructures PL intensity increases with increasing temperature, this is known as thermal fluorescence enhancement of PL, and this anomaly typically occurs at very low temperatures of conventional semiconductors. Publication number CN 115246848A discloses a zero/negative thermal quenching near infrared photoluminescent material, a preparation method thereof, and application of the material (λ ex =400 nm) in 295K-385K to exhibit fluorescence thermal quenching effect, 385K-475K to exhibit fluorescence negative thermal quenching effect, and fluorescence intensity is very stable in a high temperature region, and the material can be used as an OLED photoluminescent material, but cannot be used as a mechanical response crystal, thereby limiting application range thereof. Thus, a difficulty in achieving thermal fluorescence enhancement in molecular materials is the necessary rearrangement of molecular or electronic structures within the crystal matrix under external thermal stimulus to effectively convert from thermal fluorescence quenching to thermal fluorescence enhancement. Disclosure of Invention Aiming at the problems, the invention provides the organic crystal with both thermal phase change induced mechanical behavior and fluorescence enhancement, the preparation method and the application thereof, and the organic crystal has obvious thermal phase change induced behavior and visual fluorescence change, thereby providing a new material for the organic crystal with mechanical response to thermal stimulation and providing a new choice for the application of the thermally induced fluorescence enhanced light emitting diode. The invention is realized by the following technical scheme: An organic crystal with thermal phase transition induced mechanical behavior and fluorescence enhancement, wherein the molecular formula of the organic crystal is C 18H15N3, the organic crystal belongs to a monoclinic system, and when a space group is P2 1/C, and 298-400K, unit cell parameters are as follows: α=90°,β=105.357~105.957°,γ=90°,Z=8。 further, the organic crystal rotates for 20-25 degrees in 25-30 min at an angular speed of 0.01-0.015 degrees/s, which is similar to the mechanical behavior of circular motion, the emission wavelength of the organic crystal is 720-740 nm, the fluorescence thermal quenching effect is shown at 300-370K, and the thermally induced fluorescence enhancement effect is shown at 370-440K. A method for