The pseudotetrasaccharide acarbose has high affinity for the active site = 1 b ~) and low a secondary (& 2.3 mM) in barley a-amylase 1, distinguished by inhibition kinetics spectral perturbation.Mutants of putative catalytic residues, DlSON, E205Q, D291N, are inactive display acarbose-Sepharose, H93N H290N mutants, at invariant have kc,JKm p-nitrophenylmaltoheptaoside 0.3 1.2% wildtype.A corresponding 370and 85-fold increased Ki,,,, lack shifts pH activity profiles indicate that these...

An economical and effective protocol for large scale synthesis of the 2-phenyl-1,8adihydroazulene-1,1-dicarbonitrile (DHA) photoswitch has been developed.This compound is ring-opened by light to a vinylheptafulvene (VHF), which thermally closed back DHA.This serves as an important starting material dihydroazulene photoswitches incorporating substituent in seven-membered ring reference comparison properties.A detailed NMR spectroscopic characterization allowed assignment all proton carbon...

Abstract Photochemical conversion of molecules into high‐energy isomers that, after a stimulus, return to the original isomer presents closed‐cycle light‐harvesting, energy storage, and release. One challenge is achieve sufficiently high storage capacity. Here, we present efforts tune dihydroazulene/vinylheptafulvene (DHA/VHF) couple through loss/gain aromaticity. Two derivatives were prepared, one with aromatic stabilization DHA second VHF. The consequences for switching properties...

A selection of dihydroazulene (DHA) photoswitches incorporating an arylethynyl-substituent in the seven-membered ring was prepared by palladium-catalyzed Sonogashira cross-coupling reactions employing a suitable bromo-functionalized DHA. Shielding alkyne bridge and separating aryl DHA units, sterically demanding groups, required to obtain stable compounds. The DHAs underwent light-induced ring-opening vinylheptafulvenes (VHFs) which were thermally converted mixture two regioisomers, one...

The structure of a recombinant peroxidase from the ink cap, Coprinus cinereus , CiP, is reported to 2.6 Å resolution and refined R ‐value 18.1%. was solved by molecular replacement using coordinates newly published ligninase structure, LiP. CiP crystallizes in space group P2 1 2 ) with two independent molecules asymmetric unit related vector 0.29b + 0.5C. are structurally identical; each contains Ca 2+ ions positions equivalent those found LiP structure. Two N ‐acetylglucosamines one mannose...

[reaction: see text] Novel oligo(phenyleneethynylene) (OPE)-tetrathiafulvalene (TTF) cruciform molecules containing thiol end-groups have been prepared and characterized. These redox-active are interesting for future applications as molecular wires/transistors electronics.

Abstract We present the synthesis and switching studies of systems with two photochromic dihydroazulene (DHA) units connected by a phenylene bridge at either para or meta positions, which correspond to linear cross‐conjugated pathway between photochromes. According UV/Vis absorption NMR spectroscopic measurements, ‐phenylene‐bridged DHA–DHA exhibited sequential light‐induced ring openings DHA their corresponding vinylheptafulvenes (VHFs). Initially, VHF–DHA species was generated, and,...

The conversion and efficient storage of solar energy is recognized to hold significant potential with regard future solutions. Molecular thermal batteries based on photochromic systems exemplify one possible technology able harness apply this potential. Herein described the synthesis a macrocycle dimer dihydroazulene/vinylheptafulvene (DHA/VHF) photo/thermal couple. By taking advantage conformational strain, DHA-DHA presents an improved ability absorb store incident light in chemical bonds...

Molecular solar thermal energy storage (MOST) systems based on photochromic molecules that undergo photoisomerization to high‐energy isomers are attractive for of in a closed‐energy cycle. One challenge is control the discharge time isomer. Here we show incorporation strong acceptor substituent seven‐membered ring dihydroazulene/vinylheptafulvene (DHA/VHF) couple increases half‐life energy‐releasing VHF‐to‐DHA back‐reaction from hours more than day polar solvent. For some derivatives,...

Abstract Graphyne allotropes of carbon are fascinating materials, and their electronic properties predicted to rival those the “wonder material” graphene. One allotrope graphyne, having rectangular symmetry rather than hexagonal, stands out as particularly attractive, namely 6,6,12-graphyne. It is currently an insurmountable challenge, however, design execute a synthesis this material. Herein, we present molecules that serve model compounds. These oligomers, so-called radiaannulenes,...

Abstract A novel and efficient three‐step protocol for synthesizing functionalized dibenzothiophenes (DBTs) from common starting materials by using palladium‐catalyzed carbon–carbon carbon–sulfur bond formations is presented. The reaction conditions offer significantly improved functional‐group tolerance regioselectivity as compared to previously reported methods.

Abstract A protocol for functionalizing the seven‐membered ring of DHA/VHF photochromic system via a Suzuki cross‐coupling was developed. Kinetic studies reveal that direct attachment an aromatic moiety on strongly affects thermal back reaction. By introduction anilino group, pH control both and thermochromic properties obtained. Furthermore, it possible to switch between three different states: two one thermochromic.

Abstract The ability of molecules to change colour on account changes in solvent polarity is known as solvatochromism and used spectroscopically characterize charge-transfer transitions donor–acceptor molecules. Here we report that donor–acceptor-substituted molecular wires also exhibit distinct properties single-molecule electronics under the influence a bias voltage, but absence solvent. Two oligo(phenyleneethynylene) with substitution central ring (cruciform-like) remarkably broad...

A series of boron subphthalocyanine-tetracyanobutadiene-ferrocene (SubPc-TCBD-Fc) triads was synthesized by subjecting SubPcs with a ferrocenylethynyl substituent at either the axial or peripheral position to [2 + 2] cycloaddition reaction tetracyanoethylene followed retroelectrocyclization. The unit introduced (at atom) simple aluminum chloride-mediated alkynylation reaction, while functionalization SubPc periphery accomplished Sonogashira coupling reaction. conversion one alkyne into TCBD...

We report a Michael-type cyanation reaction of coumarins by using CO2 as catalyst. The delivery the nucleophilic cyanide was realized catalytic amounts CO2, which forms cyanoformate and bicarbonate in presence water. Under ambient conditions, CO2-catalyzed reactions afforded high chemo- diastereoselectivity β-nitrile carbonyls, whereas only low reactivities were observed under argon or N2. Computational experimental data suggest role functions Lewis acid, protecting group to mask reactivity...

Native carboxypeptidase A has been crystallized in a new crystal form, and the structure refined with X-ray data to 2.0 Å resolution. In contrast previously published [Rees, D. C., Lewis, M., Lipscomb, W. N. (1983) J. Mol. Biol. 168, 367−387], no active-site amino acids are involved packing. The important Tyr248 is stabilized inside active site by hydrogen bond interactions Ile247. proposed role of induced fit mechanism therefore not supported findings this native A. partly populated...

Abstract The first synthetic protocol for functionalizing the dihydroazulene (DHA) photoswitch in its seven‐membered ring has been developed. This is based on regioselective bromination, followed by elimination of HBr, and finally a palladium‐catalyzed cross‐coupling reaction with terminal alkyne. position functionalization (C‐7) was confirmed X‐ray crystal structure analysis. Light‐induced opening this compound to vinylheptafulvene (VHF) isomer thermal closure provides mixture two DHA...

Tweezer-like molecules comprised of two boron subphthalocyanine (SubPc) units were prepared by Sonogashira couplings and investigated using NMR spectroscopy for their ability to bind fullerenes (C60 C70). The preorganization the tweezers provided association constants ca. 103 M–1 in toluene-d8, while a SubPc monomer did not show any association. Nevertheless, crystallized with as 2:1 complexes, supporting favorable tweezer-like design complexation, which was further corroborated computations.

Abstract Polycyclic aromatic hydrocarbons (PAHs) have found strong interest for their electronic properties and as model systems graphene. While PAHs been studied intensively single units, here were constructed in ladder‐type arrangements using cross‐conjugated fulvalene dithiafulvalene motifs connecting units moving forward a convenient synthetic approach dimerizing (thio)ketones into olefins by the action of Lawesson's reagent. Some can also be regarded “super‐extended” tetrathiafulvalenes...

Abstract Three new chromophores containing an electron‐donating dithiafulvene (DTF) unit attached to derivatives of retinal, diethynylethene (DEE), and dihydroazulene (DHA), respectively, are synthesized characterized by using X‐ray crystallography as well absorption fluorescence spectroscopy. In general, the DTF induces a significant red‐shift in lowest‐energy all investigated chromophores. The influence on light‐induced cis–trans isomerization retro‐electrocyclization is investigated....