Understanding X-ray-induced isomerisation in photoswitchable surfactant assemblies

• Beatrice E. Jones,
• Camille Blayo,
• Jake L. Greenfield,
• Matthew J. Fuchter,
• Nathan Cowieson and
• Rachel C. Evans

Beilstein J. Org. Chem. 2024, 20, 2005–2015, doi:10.3762/bjoc.20.176

• guidelines for future X-ray experiments using photoswitchable molecules, which can aid more accurate understanding of these materials for application in solar energy storage, catalysis or controlled drug delivery. Keywords: arylazopyrazole; azobenzene; micelle; photoswitch; X-ray; Introduction The design

• ubiquitous cetyltrimethylammonium bromide (CTAB), which contain either an Azo (i.e., AzoTAB, Figure 1a) or arylazopyrazole (i.e., AAPTAB, Figure 1b) photoswitch. AzoTAB and AAPTAB were chosen as they display distinct changes in micelle morphology on irradiation with UV light to form the Z-rich PSS [4][19

Photoswitchable glycoligands targeting Pseudomonas aeruginosa LecA

• Yu Fan,
• Ahmed El Rhaz,
• Stéphane Maisonneuve,
• Emilie Gillon,
• Maha Fatthalla,
• Franck Le Bideau,
• Guillaume Laurent,
• Samir Messaoudi,
• Anne Imberty and
• Juan Xie

Beilstein J. Org. Chem. 2024, 20, 1486–1496, doi:10.3762/bjoc.20.132

• factor up to 1.6 has been observed for the divalent ligand [23]; while almost no difference of inhibition was observed for LecA and LecB upon irradiation, probably due to the low photoisomerization of glycodendrimers [24]. Very recently, the group of Wittmann reported an arylazopyrazole-linked divalent N

A combinatorial approach to improving the performance of azoarene photoswitches

• Joaquin Calbo,
• Aditya R. Thawani,
• Rosina S. L. Gibson,
• Andrew J. P. White and
• Matthew J. Fuchter

Beilstein J. Org. Chem. 2019, 15, 2753–2764, doi:10.3762/bjoc.15.266

• azoarenes have been ortho-substitution of the benzene ring(s) or replacement of one of the benzenes for a pyrazole (to give arylazopyrazole switches). Here we study the combination of such high-performance features within a single switch architecture. Through computational analysis and experimental

• ring, so-called arylazopyrazoles, which have excellent potential against the current state of the art (Figure 1b) [17][18]. Specifically, arylazopyrazole 4pzMe can be near quantitatively (>98%) photoswitched in both directions, and 4pzH demonstrated an exceptionally long thermal Z-isomer half-life

• 4pzH, with t1/2 = 2000 and 15000 days for 4pzH-OMe1 and 4pzH-OMe2, respectively, and 34000 days for 4pzH-Pyr1 (Table 1). Unexpectedly, the inclusion of two bulky pyrrolidine groups in ortho (4pzH-Pyr2) leads to a decrease in t1/2 (76 days). For the arylazopyrazole scaffold 4pzMe, in line with the trend

Reversible switching of arylazopyrazole within a metal–organic cage

• Anton I. Hanopolskyi,
• Soumen De,
• Michał J. Białek,
• Yael Diskin-Posner,
• Liat Avram,
• Moran Feller and
• Rafal Klajn

Beilstein J. Org. Chem. 2019, 15, 2398–2407, doi:10.3762/bjoc.15.232

• Arylazopyrazoles represent a new family of molecular photoswitches characterized by a near-quantitative conversion between two states and long thermal half-lives of the metastable state. Here, we investigated the behavior of a model arylazopyrazole in the presence of a self-assembled cage based on Pd–imidazole

• coordination. Owing to its high water solubility, the cage can solubilize the E isomer of arylazopyrazole, which, by itself, is not soluble in water. NMR spectroscopy and X-ray crystallography have independently demonstrated that each cage can encapsulate two molecules of E-arylazopyrazole. UV-induced

• switching to the Z isomer was accompanied by the release of one of the two guests from the cage and the formation of a 1:1 cage/Z-arylazopyrazole inclusion complex. DFT calculations suggest that this process involves a dramatic change in the conformation of the cage. Back-isomerization was induced with

Reversible end-to-end assembly of selectively functionalized gold nanorods by light-responsive arylazopyrazole–cyclodextrin interaction

• Maximilian Niehues,
• Patricia Tegeder and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2019, 15, 1407–1415, doi:10.3762/bjoc.15.140

• assembly and disassembly of the AuNR could be induced by host–guest interaction of CD on the nanorods and a photoswitchable arylazopyrazole cross-linker in aqueous solution. The end-to-end assembly of AuNR could be effectively controlled by irradiation with UV and visible light, respectively, over four