Fast magic-angle spinning (MAS), frequency selective (FS) heteronuclear multiple quantum coherence (HMQC) experiments which function in an analogous manner to solution SOFAST HMQC NMR experiments, are demonstrated. MAS enables efficient FS excitation of 1 H solid-state signals. Selective and observation preserves magnetization, leading a significant shortening the optimal inter-scan delay. Dipolar scalar H{14 N} routinely provide 4- 9-fold reductions experiment times as compared conventional...

The aromatic character of an arene is proposed to switch from in the ground state (S0) antiaromatic S1 and T1 excited states. This behavior known as Baird's rule has been invoked explain excited-state properties, primarily triplet state, whereas rationalization antiaromaticity singlet less developed. work demonstrates first application rationalize previously unexplained experimental process intramolecular proton transfer (ESIPT). Further, by analyzing variations isotropic magnetic shielding...

The ubiquity of oxygen in organic, inorganic, and biological systems has stimulated the application development 17O solid-state NMR spectroscopy as a probe molecular structure dynamics. Unfortunately, experiments are often hindered by combination broad signals low sensitivity. Here, it is demonstrated that fast MAS proton detection with D-RINEPT pulse sequence can be generally applied to enhance sensitivity resolution experiments. Complete 2D → 1H correlation spectra were typically obtained...

Abstract For many years, Clar's aromatic sextet theory has served as a qualitative method for assessing the character of polycyclic hydrocarbons. A new approach, based on calculation isotropic magnetic shielding (IMS) contour plots, is shown to provide feature‐rich picture aromaticity that both quantitative yet still easily interpreted. Chemists are visual creatures who adept at discerning reactivity and chemical behavior from molecular structures. To quote Roald Hoffmann, “People like...

Thioamide substitution of backbone peptide bonds can probe interactions along the main chain proteins. Despite theoretical predictions enhanced hydrogen bonding propensities thioamides, previous studies often do not consider geometric constraints imposed by folded secondary structure. This work addresses drawbacks in that ignored geometry dependence and local dielectric properties thioamide identifies cases where thioamides may be either stronger or weaker hydrogen-bonding partners than amides.

Thioamides are useful biophysical probes for the study of peptide structure and folding. The α-C stereochemistry thioamide amino acids, however, is easily epimerized during solid-phase synthesis (SPPS), which limits sequence space that available to incorporation. This work demonstrates thioamides can be reversibly protected in a manner compatible with standard methodology SPPS enable facile implementation probes.

A new class of push–pull dyes based on the reactive isobenzofuran core have been synthesized. The a smaller HOMO–LUMO gap than related benzofurazan and allow for isolation structural factors that contribute to environmental sensitivity. Experimental theoretical evidence implicate different photophysical processes are responsible reversal emissive behavior is observed between analogues.

Peptides constrained by intramolecular cross-links, especially stapled α-helices, have emerged as versatile scaffolds for drug development. However, there are fewer examples of similarly other secondary structures. Here, we used a novel computational strategy to identify an optimal staple antiparallel β-strands, and then incorporated that within β-hairpin peptide. The hairpin uses 4-mercaptoproline component, which contributes unique, kinked structure. hairpins show high degree structure in...

Fluorogenic dyes enable wash-free turn-on fluorescent readouts. Here, we report novel fluorogenic HaloTag benzothiadiazole for cellular imaging by optimizing both dye brightness and low background in cells.

The delocalization of electron density upon tautomerization a proton across conjugated bridge can alter the strength hydrogen bonds. This effect has been dubbed resonance-assisted bonding (RAHB) and plays major role in energetics tautomeric equilibrium. goal this work was to investigate that π-delocalization stability RAHBs by engaging other isomerization processes. Similarly, acid–base chemistry received little experimental attention studies RAHB, we address effects play We find disruption...

Excited-state intramolecular proton transfer involves a photochemical isomerization and creates the opportunity for emission of two distinct wavelengths light from single fluorophore. The selectivity between these is dependent on environment around fluorophore suggests possibility ratiometric monitoring protein microenvironments. Unfortunately, nonspecific binding ESIPT fluorophores does not often lead to dramatic changes in ratio emission. A pocket was designed selectively discriminate...

BenzoTag, a self-labeling protein developed using molecular evolution, enables wash-free labeling in live cells seconds low nanomolar dye concentrations.

An unexpected nucleophilic aromatic substitution lead to a novel benzothiadiazole scaffold that bore the functional group pattern associated with benzyl-type photocleavable protecting groups. The new molecules display efficient photochemical release of leaving groups blue light. performance both ortho- and meta-substituted derivatives was probed through structural manipulation computational metrics improve performance.

A strategy to control the oxidation potential of catechol using borinic acids is presented. Borinic reversibly bind form boron “ate” complexes (BACs) that alter electron density on oxygen atoms and, in turn, propensity toward electrochemical oxidation. The effect different substituents acid are investigated determine their efficacy tuning within BAC and resulting potential.

Abstract For many years, Clar's aromatic sextet theory has served as a qualitative method for assessing the character of polycyclic hydrocarbons. A new approach, based on calculation isotropic magnetic shielding (IMS) contour plots, is shown to provide feature‐rich picture aromaticity that both quantitative yet still easily interpreted. Chemists are visual creatures who adept at discerning reactivity and chemical behavior from molecular structures. To quote Roald Hoffmann, “People like...

Abstract Self-labeling proteins are powerful tools in chemical biology as they enable the precise cellular localization of a synthetic molecule, often fluorescent dye, with genetic specificity protein fusion. HaloTag7 is most popular self-labeling due to its fast labeling kinetics and simplicity chloroalkane ligand. Reaction rates different chloroalkane-containing substrates highly variable only very for rhodamine-based dyes. This major limitation HaloTag system because critical live-cell...

We describe a method to protect the sensitive stereochemistry of thioamide—in analogy protection functional groups amino acid side chains—in order preserve thioamide moiety during peptide elongation.

<p>A strategy to control the efficiency of a photocleavage reaction based on changing nature excited state is presented. A novel class photoactive compounds has been synthesized by combining classical o-nitrobenzyl scaffold with an environmentally sensitive dye, 4-amino-nitrobenzothiazole. Irradiation in polar solvent lead that inoperative for photochemistry whereas excitation nonpolar photochemically active. photochemical degradation appears be preferred process contrast intended...

ESIPT involves a photochemical isomerization and creates the opportunity for emission of two distinct wavelengths light from single fluorophore. The selectivity between these is dependent on environment around fluorophore suggests possibility ratiometric monitoring protein microenvironments. Unfortunately, nonspecific binding fluorophores does not often lead to dramatic changes in ratio emission. A pocket was designed selectively discriminate channels available an More broadly, this work...

<p>ESIPT involves a photochemical isomerization and creates the opportunity for emission of two distinct wavelengths light from single fluorophore. The selectivity between these is dependent on environment around fluorophore suggests possibility ratiometric monitoring protein microenvironments. Unfortunately, nonspecific binding ESIPT fluorophores does not often lead to dramatic changes in ratio emission. A pocket was designed selectively discriminate channels available an More...

A strategy to control the efficiency of a photocleavage reaction based on changing nature excited state is presented. novel class photoactive compounds has been synthesized by combining classical o-nitrobenzyl scaffold with an environmentally sensitive dye, 4-amino-nitrobenzothiazole. Irradiation in polar solvent lead that inoperative for photochemistry whereas excitation nonpolar photochemically active. photochemical degradation appears be preferred process contrast intended process.

We describe a method to protect the sensitive stereochemistry of thioamide—in analogy protection functional groups amino acid side chains—in order preserve thioamide moiety during peptide elongation.<br>