Design, Synthesis, and Performance of Photo-Responsive Liquid Crystal Polymers with Stepwise Deformation Capability.

Photo-responsive liquid crystal polymers (LCPs) have potential application value in flexible robots, artificial muscles, and microfluidic control. In recent years, significant progress has been made in the development of LCPs. However, the preparation of LCPs with continuous and controllable stepwise deformation capabilities remains a challenge. In this study, visible photo-responsive cyanostilbene monomer, UV photo-responsive azobenzene monomer, and multiple hydrogen bond crosslinker are used to prepare photo-responsive LCPs capable of achieving continuously and controllable stepwise deformation. The comprehensive investigation of the multiple light response ability and photo-induced deformation properties of these copolymers is conducted. The results reveal that in the first stage of photo-induced deformation under 470 nm blue light irradiation, the deformation angle decreases with a reduction in cyanostilbene content in the copolymer component, ranging from 40° in AZ0-CS4 to 0° in AZ4-CS0. In the second stage of photo-induced deformation under 365 nm UV irradiation, the deformation angle increases with the increase of azobenzene content, ranging from 0° of AZ0-CS4 to 89.4° of AZ4-CS0. Importantly, the deformation between these two stages occurs as a continuous process, allowing for a direct transition from the first-stage to the second-stage deformation by switching the light source from 470 to 365 nm.

Manipulated and Improved Photoinduced Deformation Property of Photoresponsive Liquid Crystal Elastomers by Copolymerization.

Photoresponsive liquid crystal elastomers (LCEs) have aroused much attention due to their unique structures, properties, and potential applications. However, many reported photoresponsive LCEs show small photoinduced deformation with a slow deformation speed, which limits their application to a certain extent. In this article, multiple hydrogen bond component and biphenyl component was introduced into photoresponsive LCEs bearing cyanostilbene by copolymerization, and prepared a series of LCEs CSm-BPn (CS and BP means cyanostilbene and biphenyl component, respectively; m, n means the content ratio of CS and BP). All uniaxially oriented CSm-BPn fibers show photoinduced deformation behavior under 365 nm UV light except for CS0-BP5. The introduction of hydrogen bond and the decrease of glass transition temperature realize large deformation and fast deformation speed. Besides, the properties of LCEs are successfully regulated by changing the content ratio of each component. What's more interesting is that the addition of appropriate amount of biphenyl can significantly improve and manipulate the deformation property of the CSm-BPn fibers. The maximum bending angle can reach 175° , and the whole photoinduced deformation process only takes 11 s. The photoresponsive LCEs with such large bending angle and fast deformation rate are rarely reported.

Synthesis, crystal structure and nuclease activity of a Schiff base copper(II) complex.

A new Schiff base copper(II) complex, Cu(o-VANAHE)(2) (o-VANAHE = 2-(o-vanillinamino)-1-hydroxyethane), has been synthesized and characterized. Single crystal X-ray diffraction results suggest that this complex structure belongs to triclinic crystal system, space group P1 with the following crystallographic parameters: a = 8.819(4) angstroms, b = 10.794(5) angstroms, c = 11.350(5) angstroms, alpha = 70.262(6) degrees, beta = 70.816(6) degrees, gamma = 78.360(6) degrees, V = 955.4(7) angstroms3, Z = 2, D(c) = 1.571 Mg x m(-3), and the final R1 = 0.0393, wR2 = 0.0994 for the observed reflections 2620(I > 2sigma(I)). The molecular geometry is almost coplanar. Viscosity, fluorescence spectroscopy and cyclic voltammetry have been conducted to assess their interaction between this complex and DNA. Results showed that the copper(II) complex can increase DNA's relative viscosity and quench the fluorescence intensity of EB bound to DNA. The adding of DNA to the solution of Cu(o-VANAHE)2 causes a slight decrease in the voltammetric current, as well as a slight shift in the E(1/2) to less negative potential. The interaction between the complex and DNA has also been investigated by submarine gel electrophoresis, interestingly, we found that the copper(II) complex can cleave circular plasmid pBR322 DNA to nicked and linear forms.