Spiropyran Photoswitches in the Context of DNA: Synthesis and Photochromic Properties

Abstract

A new design is presented for the incorporation of spiropyran photoswitches into nucleic acids by oligonucleotide solid phase synthesis. This design enables interaction of the 6-nitrospirobenzopyran (NitroBIPS) photoswitch with the adjacent nucleobases and leaves the photochemical properties of NitroBIPS intact. UV/Vis spectroscopy and HPLC revealed that NitroBIPS incorporated into DNA consists of up to 40 % merocyanine in its thermal equilibrium and undergoes reversible switching between the photoisomeric spiropyran (SP) and merocyanin (MC) state by alternating excitation using visible light or heat for at least fifteen switching cycles. Exchanging the chromene part of NitroBIPS on the DNA level gives access to differently substituted spiropyran derivatives allowing the screening for spiropyrans with suitable properties in a straightforward manner. Thus, by incorporating the highly hydrolysis-stable pyrido-spiropyran derivative PyBIPS pure light-triggered reversible switching of a spiropyran in DNA has been realized for the first time. Therefore, this design represents a new useful platform for investigating the photochromic behavior of different spiropyran photoswitches in a nucleic acid environment and for using spiropyrans to induce light- or heat-triggered changes in conformations or in fluorescence quenching properties of oligonucleotides.

Poly(2‐isopropyl‐2‐oxazoline) Bearing a Spiropyran Side‐Chain: Synthesis and Evaluation of Photo and Temperature‐Responsive Properties

“…Based on this result, we consider only two isomers, namely, the SP and MC forms for the introduced photofunctional groups in this study. The amount ratio of MC forms to the whole pendant groups was evaluated to be 7.8 mol% from the peak absorbance (0.875) in Figure and the introduction ratio of SPOx (3.8 mol%) using the reported molar extinction coefficient (36 850 L mol −1 cm −1 ) of an SP1 derivative . In Figure a, the absorption band around 523 nm almost disappears after the irradiation of the visible light, suggesting the conversion of most MC groups to the SP form.…”

Photochromic Materials in Biochemistry

“…In a report by Heckel, they describe the preparation of a series of spiropyranmodified oligonucleotides in which the spiropyran is directly positioned into the backbone of the nucleotide strand [99]. In this example, the spiropyran functions as a nucleobase analog, and the charged chromene unit of the planar merocyanine isomer is expected to intercalate into the base pairs and form favorable stacking interactions.…”

“…(b) The tethered glutamate-azobenzene derivative allows for photocontrol of glutamate binding and channel activation by isomerization of azobenzene from the trans-to the cis-isomer [89]. The planar charged merocyanine allows for more efficient intercalation into the base pairs than the bulkier spiropyran form [99].…”

Development of molecular photoswitch with very fast photoresponse based on asymmetrical bis-azospiropyran

“…A large variety of applications for photoresponsive molecules has been investigated in highlevel technologies such as controlling the conformation and activity of biomolecules [1][2][3], sensors [4][5][6][7][8][9][10], data recording, optical storage, optical switching [11][12][13][14], displays, non-linear optics [15][16][17][18], and other photochemical and photophysical reactions [19,20].…”