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In the following study, a series of new lupeol-3-carbamate derivatives were synthesized, and the structures of all the newly derived compounds were characterized. The new compounds were screened to determine their anti-proliferative activity against human lung cancer cell line A549, human liver cancer cell line HepG2, and human breast cancer cell line MCF-7. Most of the compounds were found to show better anti-proliferative activity in vitro than lupeol. Among them, obvious anti-proliferation activity (IC50 = 5.39~9.43 μM) was exhibited by compound 3i against all three tumor cell lines. In addition, a salt reaction was performed on compound 3k (IC50 = 13.98 μM) and it was observed that the anti-proliferative activity and water solubility of compound 3k·CH3I (IC50 = 3.13 μM), were significantly enhanced subsequent to the salt formation process. The preliminary mechanistic studies demonstrated that apoptosis in HepG2 cells was induced by compound 3k·CH3I through the inhibition of the PI3K/AKT/mTOR pathway. In conclusion, a series of new lupeol-3-carbamate derivatives were synthesized via the structural modification of the C-3 site of lupeol, thus laying a theoretical foundation for the design of this new anticancer drug. [ABSTRACT FROM AUTHOR]

Molecular switches that reversibly change their structures and physical properties are important for applications such as sensing and information processing at molecular scales. In order to avoid the intermolecular aggregation that is often detrimental to the stimuli‐responses of molecular switches, previous studies of molecular switches have been often conducted in dilute solutions which are difficult for applications in solid‐state devices. Here we report molecular design and synthesis that integrates anthraquinodimethane as molecular switching units into polymers with amenable processibility in solid states. Optical and electron spin resonance characterizations indicate that the four‐arm polymers of poly(ϵ‐caprolactone) or poly(D,L‐lactide) tethered from anthraquinodimethane slow down the dynamics of the conformational switching between the folded and the twisted conformations, enhance the photoluminescence in solid states and impart materials with a small energy gap from singlet ground state to thermally accessible triplet state. [ABSTRACT FROM AUTHOR]

An intramolecular oxidative amidation of varied α‐[(β‐dimethylamino)propenoyl]‐alkylamides catalyzed by copper(II) bromide in the presence of PIFA and TFA has been described. This process features mild reaction conditions, simple execution, good yields, high regioselectivity, and thereby, provides not only a facile and efficient protocol for the construction of C−N bond, but also a straightforward synthetic route to densely substituted pyrrolidine‐2,4‐diones. [ABSTRACT FROM AUTHOR]

A facile and universal method is presented for the preparation of polymer brushes on amorphous TiO2 film. Homogeneous and stable poly(methyl methacrylate), polystyrene, poly(4-vinylpyridine), and poly( N-vinyl imidazole) (PNVI) brushes up to 550 nm are directly created onto TiO2 via UV-induced photopolymerization of corresponding monomers. Kinetic studies reveal a linear increase in thickness with the polymerization time. Characterization of the resulting polymer brushes by FTIR spectroscopy, X-ray photoelectron spectroscopy, contact angle, and atomic force microscopy (AFM) indicates an efficient UV-grafting reaction. Finally, we have demonstrated the possibility in converting the PNVI brushes to poly(vinyl imidazolium bromide), i.e., poly(ionic liquid) brushes by polymer-analogous reactions. [ABSTRACT FROM AUTHOR]

We present the first example of surface-initiated polymerization mediated by Lewis pairs for the synthesis of polymer brushes on planar substrates. The method enables the rapid grafting polymerization from the self-assembled monolayer or surface-attached macroinitiators, furnishing linear polymer brushes and bottle-brush brushes. Both homopolyester and block copolyester brushes can be synthesized via this versatile approach. This work not only opens up new opportunities for the application of Lewis pair-mediated polymerization but also enriches the surface-initiated polymerization on different surfaces.