Photochromic Polyamide 6 Based on Spiropyran Synthesized via Hydrolyzed Ring-Opening Polymerization

We report photochromic polyamide 6 (PA6) which was synthesized by hydrolyzed ring-opening polymerization of ε-caprolactam with spiropyran (SP) embedded in the polymer chains. It indicated that crystallinity degree of the resulting copolymers was decreased since only PA6 segments can crystallize with increasing content of SP modifier. Meanwhile, toughness of photochromic PA6 was decreased. The photochromic property analysis indicated that the sample with more flexibility and more content of SP was more sensitive to UV light at the beginning of irradiation than other samples and its color after being irradiated for 1 min tended to reddish. Investigation revealed that the UV-vis absorbance of SP-PA6-3 had negligible decay after 10 cycles, which indicated SP-modified PA6 possessed excellent photoresponse reversibility and fatigue resistance.

Dithienylethene metallodendrimers with high photochromic efficiency

It has been extremely challenging to achieve multi-photochromic systems with-out affecting the individual photoswitching properties of the constituent units. Herein, we present the design and synthesis of a new family of platinum-acetylide dendrimers containing up to twenty-one photochromic dithienylethene (DTE) units that exhibit both high photochromic efficiency and individual switch-ing properties. Upon irradiation with ultraviolet (UV) and visible (Vis) light, the resultant metallodendrimers display high conversion yield and excellent fatigue resistance. More interestingly, cyclization-cycloreversion kinetics revealed that the photochromic property of each DTE unit in these metallodendrimers is unaf-fected by its neighbor and the full ring-closure of up to twenty-one DTE units in one single dendrimer has been achieved.

Light-induced difference FTIR spectroscopy of primate blue-sensitive visual pigment at 163 K

ABSTRACTStructural studies of color visual pigments lag far behind those of rhodopsin for scotopic vision. Using difference FTIR spectroscopy at 77 K, we report the first structural data of three primate color visual pigments, monkey red (MR), green (MG), and blue (MB), where the batho-intermediate (Batho) exhibits photoequilibrium with the unphotolyzed state. This photochromic property is highly advantageous for limited samples since the signal-to-noise ratio is improved, but may not be applicable to late intermediates, because of large structural changes to proteins. Here we report the photochromic property of MB at 163 K, where the BL intermediate, formed by the relaxation of Batho, is in photoequilibrium with the initial MB state. A comparison of the difference FTIR spectra at 77 and 163 K provided information on what happens in the process of transition from Batho to BL in MB. The coupled C11=C12 HOOP vibration in the planer structure in MB is decoupled by distortion in Batho after retinal photoisomerization, but returns to the coupled C11=C12 HOOP vibration in the all-trans chromophore in BL. This suggests that BL harbors a planer all-trans configuration of retinal. The Batho formation accompanies helical structural perturbation, which is relaxed in BL. The H-D unexchangeable X-H stretch weakens the hydrogen bond in Batho, but strengthens it in BL. Protein-bound water molecules that form an extended water cluster near the retinal chromophore change hydrogen bonds differently for Batho and BL, being stronger in the latter than in the initial state. In addition to structural dynamics, the present FTIR spectra at 163 K show no signals of protonated carboxylic acids as well as 77 K, suggesting that E181 is deprotonated in MB, Batho and BL.

A zwitterionic ligand-based water-stable metal–organic framework showing photochromic and Cr(vi) removal properties

A water-stable In-MOF based on the zwitterionic viologen ligand was synthesized. It exhibits photochromic property and Cr(vi) removal performance.

Improvement in Photochromic Property of Nickel Oxide-Based Photochromic Composite Films by Cobalt Addition

Nickel oxide (NiO)-based composite films with various Cobalt/Nickel (Co/Ni) ratios were fabricated, and the photochromic properties of the resulting films were evaluated. The NiO particle sizes in the composite films with Co/Ni ratios of 0~0.02 were 40~70 nm. Increase in the Co addition ratio to the composite films caused a decrease in the initial transmittance of the films, and the films with Co/Ni ratio of 0.005 and 0.01 showed a larger transmittance modulation. Co addition caused an increase in the bleaching and coloring rates, which were the largest in the film with Co/Ni ratio of 0.005.