Confining molecules to volumes only slightly larger than the molecules themselves can profoundly alter their properties. Molecular switches—entities that can be toggled between two or more forms upon exposure to an external stimulus—often require conformational freedom to isomerize. Therefore, placing these switches in confined spaces can render them non-operational. To preserve the switchability of these species under confinement, we work with a water-soluble coordination cage that is flexible enough to adapt its shape to the conformation of the encapsulated guest. We show that owing to its flexibility, the cage is not only capable of accommodating—and solubilizing in water—several light-responsive spiropyran-based molecular switches, but, more importantly, it also provides an environment suitable for the efficient, reversible photoisomerization of the bound guests. Our findings pave the way towards studying various molecular switching processes in confined environments.

In situTEM imaging reveals the dynamics of micelle formation and nanoparticle encapsulation.

General Considerations. All commercially available chemicals were used as received unless otherwise stated. All polymerizations were prepared in the glovebox under nitrogen atmosphere unless otherwise stated. CH3CN used for oxidations of 1-3 was purified via a solvent purification system and kept in the glovebox. All monomers were degassed and stored with 4Å molecular sieves. 4-Vinylanisole (97%), 4-methylstyrene (96%), styrene (≥99%), 4-fluorostyrene (99%), 4tert-butylstyrene (93%), 4-chlorostyrene (97%), 3-chlorostyrene (98%), and 2,6-difluorostyrene (99%) were purchased from Sigma-Aldrich. Acetonitrile (≥99.9%), dichloromethane (≥99.5%), ethyl acetate (≥99.5%), hexanes (≥98.5%), methanol (≥99.8%), N,N-diisopropylethylamine (≥99%), and tetrabutylammonium hexafluorophosphate (≥99.0%, electrochemical grade) were purchased from Sigma-Aldrich. Tetrabutylammonium hexafluorophosphate was further purified by recrystallization from ethanol and drying under vacuum at 90 °C and benzyl bromide (99%) was purchased from Alfa Aesar. Perfluorotoluene (TCI) was dried 72h over 3Å molecular sieves and degassed prior to use. [NBu4]2B12(OH)12 was synthesized according to reported procedures. 1 NMR spectra were recorded using spectrometers at 400 or 500 MHz (1 H), 125 MHz (13 C), 80 MHz (11 B), and 282 MHz (19 F) reported in δ (parts per million) relative to tetramethylsilane (1 H, 13 C), BF3•Et2O (11 B), and C6H5F (19 F), respectively, and referenced to residual 1 H/ 13 C signals of the deuterated solvent (1 H (δ) CDCl3 7.26; 13 C (δ) CDCl3 77.16; 11 B (δ) BF3•Et2O 0.00 ppm; 19 F (δ) C6H5F-113.15 ppm). Deuterated solvents (Cambridge Isotope Laboratories) for NMR spectroscopic analyses were stored over 4Å molecular sieves. 1 H NMR spectra were acquired with a relaxation of 2 s for small molecules and 30 s for polymers. Gel permeation chromatography (GPC) for all polymers was conducted on a Shimadzu HPLC Prominence-i system equipped with a UV detector, Wyatt DAWN Heleos-II Light Scattering detector, Wyatt Optilab T-rEX RI detector, one MZ-Gel SDplus guard column, and two MZ-Gel SDplus 100 Å 5µm 300x8.0 mm columns. Eluent was CHCl3 or THF at 40 °C (flow rate: 0.70 mL/min), a dn/dc value of 0.160 was used for chloroform and 0.1828 was used for samples in THF. GPC chromatograms were analyzed using Astra 6.0 software. All GPC samples were dissolved in HPLC grade solvent at a concentration of 4-5 mg/mL and filtered through a 0.2 µm TFE filter. All reported molecular weight and dispersity data determined by GPC are the average of two runs unless otherwise noted. Mass spectrometry data was acquired using a Thermo ScientificTM Q-ExactiveTM Plus instrument with a quadrupole mass filter and Orbitrap mass analyzer. UV-Vis spectra were recorded on a Hewlett-Packard 8453 diode array spectrometer. Extinction coefficients were determined through a series of 5 dilutions with a maximum absorption between 0.1 and 0.7 absorbance units. Microwave reactions were performed using a CEM Discover SP microwave synthesis reactor at 140 °C with the pressure re...

Self-adjusting omniphilic nanocarriers (OPNs) with a multisolvent aptitude were prepared via a Schiff base reaction between chitosan, a natural polysaccharide, and bioactive aldehydes. Experimental studies supported by atomistic molecular dynamics simulations revealed these OPNs can encapsulate insoluble molecular cargo, transport them in aqueous or lipid environments, and deliver them through cross-phase barriers. N-imine dynamic covalent bonds have been incorporated to endow the OPNs with pH responsiveness, also allowing the amplification of their bioactivity, as demonstrated in vitro with the ability to delay fungal proliferation in wheat grains. The reported OPNs hold remarkable potential as biocompatible nanocarriers for the effective delivery of active agents in agriculture, medicine, and cosmetics.