Inverse electron demand Diels–Alder (iedDA) reactions between s ‐tetrazines and strained dienophiles have numerous applications in chemical biology and materials science. Tetrazines most often quench the emission of pendant fluorophores. This effect, however, is diminished upon iedDA, leading to the formation of emissive products with important applications in fluorescence labelling of biomolecules. Herein we investigate the effect of the dienophile on the fluorescence enhancement obtained upon...
Sat Aug 15, 2020 18:01
An efficient cascade reaction of tryptamine‐derived isocyanides with C,N‐cyclic azomethine imines is described. The polycyclic pyrrolo[2,3‐ c ]quinoline derivatives, which benefited from rearrangement process driven by hydrogen bonding, could be directly assembled in moderate to good yields (40‐87%) under metal‐free and mild conditions. This transformation involved four new heterocyclic rings formations and uniquely, ring opening of indole as well as ring expansion of C,N‐cyclic azomethine imine....
Sat Aug 15, 2020 10:41
We report the structural characterization of sublayer surfaces of MIL‐101 by low‐dose spherical aberration corrected high‐resolution transmission electron microscopy. The state‐of‐the‐art microscopy, directly imaging atomic/molecular configurations in thin crystals from charge density projections, uncovers the structures of sublayer surfaces and their evolution to stable surfaces regulated by inorganic Cr 3 (μ 3 ‐O) trimers. This study provides compelling evidence on the MOF crystal growth via...
Fri Aug 14, 2020 22:49
A significant amount of attention has been given to the design and synthesis of cocrystals by both industry and academia because of its potential to change a molecule’s physicochemical properties. Yet, difficulties arise when searching for adequate combinations of molecules (or coformers) to form cocrystals, hampering the efficient exploration of the target’s solid‐state landscape. This paper reports on the application of a data‐driven cocrystal prediction method, based on two types of artificial...
Fri Aug 14, 2020 22:00
The prototypical reactivity profiles of transition metal dihydrogen complexes (M‐H2) are well‐characterized with respect to oxidative addition (to afford dihydrides, M(H)2) and as acids, heterolytically delivering H+ to a base and H‐ to the metal. In the course of this study we explored plausible alternative pathways for H2 activation, namely direct activation through H‐atom or hydride transfer from the σ‐H2 adducts. To this end, we describe herein the reactivity of an isostructural pair of a neutral...
Fri Aug 14, 2020 20:55
Polarized‐light detection in solar‐blind ultraviolet region is indispensable for optoelectronic applications, whereas new 2D candidates targeted at solar‐blind UV range remain extremely scarce. 2D hybrid perovskite ferroelectrics that combine polarization and semiconducting properties have taken a booming position within this portfolio. Here, using the 3D‐to‐2D dimensional reduction of CH3NH3PbCl3, we successfully designed a multilayered hybrid perovskite ferroelectric, (CH3CH2NH3)2(CH3NH3)2Pb3Cl10...
Fri Aug 14, 2020 19:49
Protein allostery is a phenomenon involving the long range coupling between two distal sites in a protein. In order to elucidate allostery at atomic resoluion on the ligand‐binding WW domain of the enzyme Pin1 multistate structures were calculated from exact nuclear Overhauser effect (eNOE). In its free form the protein undergoes a micro‐second exchange between two states, one of which is predisposed to interact with its parent catalytic domain. In presence of the positive allosteric ligand, the...
Fri Aug 14, 2020 18:02
A ruthenium‐catalyzed formal anti‐Markovnikov hydroamination of allylic alcohols for the synthesis of chiral γ‐amino alcohols is presented. Proceeding via an asymmetric hydrogen‐borrowing process, the catalysis allows racemic secondary allylic alcohols to react with various amines, affording enantiomerically enriched chiral γ‐amino alcohols with broad substrate scope and excellent enantioselectivities (68 examples, up to >99% ee).
Fri Aug 14, 2020 18:00
Genetically encoded RNA devices have emerged for various cellular applications in imaging and bio‐sensing, but their functions as precise regulators in living systems are still limited. Inspired by protein photosensitizers, we propose here a G enetically encoded R NA A ptamer‐based P hotosensitizer (GRAP). Upon illumination, the RNA photosensitizer can controllably generate reactive oxygen species for targeted cell regulation. The GRAP system can be selectively activated by endogenous stimuli...
Fri Aug 14, 2020 16:29
Stimuli responsive photodynamic therapy (PDT) is a hot topic in precise medicine. However the low abundance of responsive trigger molecules in early‐stage diseases limits its application. Here we designed an amplifier with multiple upconversion luminances to achieve near‐infrared photo‐switched cascade reaction triggered by specific microRNA and precise PDT of early‐stage cancers. This amplifier was composed of photo‐caged DNA nanocombs and an upconversion nanoparticle (UCNP) sensitized with IRDye®...
Fri Aug 14, 2020 14:49
Metal–π‐complexation is shown, for the first time, to catalyze the disrotatory 6π electrocyclization of conjugated trienes. Unprecedented hexahapto metal coordination to the acyclic triene is implicated as the key mechanistic feature responsible for lowering the energetic barrier to disrotatory ring closure. Abstract Triene 6π electrocyclization, wherein a conjugated triene undergoes a concerted stereospecific cycloisomerization to a cyclohexadiene, is a reaction of great historical and...
Fri Aug 14, 2020 12:55
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