Synthesis and characterization of a new photoinduced switchable β-cyclodextrin dimer

Abstract

SummaryThis paper reports an efficient preparation of bridged bis-β-CD AZO-CDim 1 bearing azobenzene as a linker and exhibiting high solubility in water. The photoisomerization properties were studied by UV–vis and HPLC and supported by ab initio calculations. The cis/trans ratio of AZO-CDim 1 is 7:93 without irradiation and 37:63 after 120 min of irradiation at 365 nm; the reaction is reversible after irradiation at 254 nm. The photoinduced, switchable binding behavior of AZO-CDim 1 was evaluated by ITC, NMR and molecular modeling in the presence of a ditopic adamantyl guest. The results indicate that AZO-CDim 1 can form two different inclusion complexes with an adamantyl dimer depending on its photoinduced isomers. Both cavities of cis-AZO-CDim 1 are complexed simultaneously by two adamantyl units of the guest forming a 1:1 complex while trans-AZO-CDim 1 seems to lead to the formation of supramolecular polymers with an n:n stoichiometry.

Sequence-Specific DNA Binding by Noncovalent Peptide–Azocyclodextrin Dimer Complex as a Suitable Model for Conformational Fuzziness

“…In our system, the effector was the azoCyDdimer, which triggered host–guest interaction of β-CyD of the dimer and two GCN4 peptides containing each an adamantane moiety. The different geometry the azoCyDdimer was previously calculated as 9.1 Å and 6.6 Å for E and Z isomers, respectively [16]. As confirmed here, the azoCyDdimer exists under two photo-states: the first thermodynamically stable with an E:Z isomer ratio of 95:5 and the second obtained after irradiating with ultraviolet light, E:Z 60:40 ratio.…”

“…Herein, we simplified the synthesis of the β-CyD double host, azoCyDdimer [16] (Figure 2A) by direct coupling of 4,4′-bis (carboxy) azobenzene acid and mono-6-amino-6-deoxy-β-cyclodextrin (β-CyDNH 2 ) in DMF using HATU, as a coupling agent and DIPEA. The reaction was monitored by TLC until the disappearance of β-CyDNH 2, and purified by preparative HPLC obtaining 20% yield.…”

“…Previously, it was reported that azoCyDdimer forms supramolecular aggregates in water above the concentration 1 mM, while below this concentration it reaches the photostationary state of E:Z 60:40 as determined by UV–Vis spectroscopy [16]. Here, we analyzed the dependence of the concentration and isomerization by the integration of the peaks using 1 H-NMR in DMSO.…”

Azo group(s) in selected macrocyclic compounds

“…Photochemical properties of bis- β -cyclodextrin bearing azobenzene unit 184 was reported by Djedaini-Pilard and co-workers [ 247 ]. It was found that 184 can form two different inclusion complexes with adamantyl derivative 185 depending on 184 photoinduced isomers (Fig.…”

Photoswitchable Carbohydrate‐Based Macrocyclic Azobenzene: Synthesis, Chiroptical Switching, and Multistimuli‐Responsive Self‐Assembly

“…Of particular interest for supramolecular constructs are “smart gels”, that is, gels whose properties can be controlled reversibly or irreversibly by external stimuli like chemical, photon, electron, temperature, or mechanical stress . Design and synthesis of photoswitchable carbohydrate‐based macrocycles should be very interesting for spatiotemporally controlling various chemical, structural, and biological properties of sugar‐based macrocyclic compounds by light . After preliminary design and molecular mechanics (MM2) calculations, we envisioned the synthesis of carbohydrate‐based macrocyclic azobenzene 1 bearing one 2,2′‐carboxymethoxyazobenzene moiety on the 4,6‐position of phenyl thio‐α‐ d ‐mannopyranoside (Scheme ).…”