Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Shape-Shifting Molecules: Unveiling the Valence Tautomerism Phenomena in Bare Barbaralones.

ABSTRACT: We report a state-of-the-art spectroscopic study of an archetypical barbaralone, conclusively revealing the valence tautomerism phenomena for this bistable molecular system. The two distinct 1- and 5-substituted valence tautomers have been isolated in a supersonic expansion for the first time and successfully characterized by high-resolution rotational spectroscopy. This work provides irrefutable experimental evidence of the [3,3]-rearrangement in barbaralones and highlights the use of rotational spectroscopy to analyze shape-shifting mixtures. Moreover, this observation opens the window toward the characterization of new fluxional systems in the isolation conditions of the gas phase and should serve as a reference point in the general understanding of valence tautomerism.

SUBMITTER: Sanz-Novo M

PROVIDER: S-EPMC9311078 | biostudies-literature | 2022 Apr

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Shape-Shifting Molecules: Unveiling the Valence Tautomerism Phenomena in Bare Barbaralones.

Sanz-Novo Miguel M Mato Mauro M León Íker Í Echavarren Antonio M AM Alonso José L JL

Angewandte Chemie (International ed. in English) 20220324 18

We report a state-of-the-art spectroscopic study of an archetypical barbaralone, conclusively revealing the valence tautomerism phenomena for this bistable molecular system. The two distinct 1- and 5-substituted valence tautomers have been isolated in a supersonic expansion for the first time and successfully characterized by high-resolution rotational spectroscopy. This work provides irrefutable experimental evidence of the [3,3]-rearrangement in barbaralones and highlights the use of rotationa ...[more]

PMID: 35165988

Similar Datasets

Valence tautomerism in synthetic models of cytochrome P450.

Project description:CytP450s have a cysteine-bound heme cofactor that, in its as-isolated resting (oxidized) form, can be conclusively described as a ferric thiolate species. Unlike the native enzyme, most synthetic thiolate-bound ferric porphyrins are unstable in air unless the axial thiolate ligand is sterically protected. Spectroscopic investigations on a series of synthetic mimics of cytP450 indicate that a thiolate-bound ferric porphyrin coexists in organic solutions at room temperature (RT) with a thiyl-radical bound ferrous porphyrin, i.e., its valence tautomer. The ferric thiolate state is favored by greater enthalpy and is air stable. The ferrous thiyl state is favored by entropy, populates at RT, and degrades in air. These ground states can be reversibly interchanged at RT by the addition or removal of water to the apolar medium. It is concluded that hydrogen bonding and local electrostatics protect the resting oxidized cytP450 active site from degradation in air by stabilizing the ferric thiolate ground state in contrast to its synthetic analogs.

| S-EPMC4914151 | biostudies-literature

Valence tautomerism in a cobalt-verdazyl coordination compound.

Project description:Coordination of 1-isopropyl-3,5-dipyridyl-6-oxoverdazyl to cobalt results in a dication best described in the solid state as a high spin cobalt(ii) ion coordinated to two radical ligands with an S = 3/2 ground state. On dissolution in acetonitrile, the cobalt(ii) form equilibrates with a cobalt(iii) valence tautomer with an S = 1/2 ground state.

| S-EPMC7244305 | biostudies-literature

Putting the squeeze on valence tautomerism in cobalt-dioxolene complexes.

Project description:Molecules that can reversibly switch between electronic states under an external stimulus are of interest to numerous applications. Complexes of open shell metal ions with redox active ligands undergo valence tautomerism, resulting in magnetic, colour and structural switching, relevant to data storage and actuators. However, the precise structural changes occurring during valence tautomerism in the solid state are unclear due to the lack of atomic-resolution characterization. Here, variable temperature and high-pressure single crystal X-ray diffraction is used to characterize valence tautomerism in two isostructural cobalt complexes, [Co(bis(6-methyl-2-pyridylmethyl) amine)(3,5-di-tert-butyl-1,2-dioxolene)]+ and [Co(tris(6-methyl-2-pyridylmethyl)amine)(3,5-di-tert-butyl-1,2-dioxolene)]+ to atomic resolution. The less sterically hindered dimethylated complex exhibits two-step thermally-induced interconversion between the high-spin CoII-seminquinonate and low-spin CoIII-catecholate forms (valence tautomerism) at 155 and 95 K due to the presence of two symmetry-independent complexes. In contrast, the more sterically hindered trimethylated complex does not display thermal valence tautomerism. Both complexes exhibit unique behaviour under high pressure. The dimethylated species undergoes gradual, one-step valence tautomerism in both symmetry-independent complexes concurrently between 0.43 GPa and 1.30 GPa. In the trimethylated species, pressure is sufficient to overcome steric hindrance, leading to one-step valence tautomerism between 2.60 GPa and 3.10 GPa, demonstrating pressure-triggered valence tautomerism in a thermally inactive complex. This study is among the few investigations using in situ high-pressure single crystal X-ray diffraction to achieve atomic-level structural characterization of valence tautomerism, aiding the development of robust structure-property relationships in these types of complexes.

| S-EPMC11484925 | biostudies-literature

Disentangling chemical pressure and superexchange effects in lanthanide-organic valence tautomerism.

Project description:Valence tautomerism in molecule-based f-block materials remains virtually elusive. As a result, the effects driving and controlling the valence conversion phenomenon are poorly understood. Herein, we unravel these fundamental factors by systematic chemical modification of a bona fide lanthanide coordination solid, SmI2(pyrazine)2(tetrahydrofuran), in which a complete, temperature-driven conversion between Sm(ii) and Sm(iii) occurs abruptly around 200 K. Solid solutions incorporating either divalent, diamagnetic metal ions or Sm(iii) ions feature disparate behavior. Substitution with redox-inactive, divalent metal ions invariably leads to lower conversion temperatures and reduced cooperativity. In contrast, incorporation of redox-inactive Sm(iii) ions leads to trapped pyrazine anion radicals in the ligand scaffold, shifting the valence tautomeric conversion phenomenon towards higher temperature with virtually no loss of cooperativity. These materials are rare examples of lanthanide-organic materials hosting mixed valency in both the lanthanide and organic scaffold, affording switchable conductivity associated with the valence tautomeric conversion.

| S-EPMC11921795 | biostudies-literature

Racemization as a stereochemical measure of dynamics and robustness in shape-shifting organic molecules.

Project description:Bullvalene is a structurally unique dynamic molecule thought to interconvert among 1.2 million degenerate isomers. The incorporation of different chemical substituents onto the bullvalene core should lead to a "shape-shifting" molecule that can interconvert among thousands of discrete structural isomers. Previous NMR spectroscopy and HPLC studies on substituted bullvalenes ascertained the fact that these compounds are dynamic, but they could not attest to whether the molecules are only interconverting among only a few isomers or if a multitude of structures are being accessed. Here we confirm the remarkable shape-shifting property of a tetrasubstituted bullvalene by means of a racemization experiment. We show that a single, though fleeting, chiral, enantioenriched tetrasubstituted bullvalene isomer can spontaneously equilibrate to a racemic population of dynamic compounds. Despite the fact that conversion from one enantiomer of a bullvalene isomer to the other may require dozens or even hundreds of rearrangements and involve many potential pathways, CD spectroscopy and HPLC analysis of different bullvalene populations showed that multiple pathways exist and result in the complete racemization of an initial enantioenriched chiral bullvalene. These oligosubstituted bullvalenes represent a very rare example of an entity that can spontaneously transform itself into different discrete structures using ambient thermal energy. The confirmation that these shape-shifting organic molecules are chemically robust yet structurally dynamic is an important step toward their further use as materials, sensors, and biologically active compounds.

| S-EPMC3169120 | biostudies-literature

Programmable shape-shifting micelles.

Project description: Not available

| S-EPMC4671773 | biostudies-literature

Geometry-dependent valence tautomerism, magnetism, and electrical conductivity in 1D iron-tetraoxolene chains.

Project description:Redox-active tetraoxolene ligands such as 1,4-dihydroxybenzoquinone provide access to a diversity of metal-organic architectures, many of which display interesting magnetic behavior and high electrical conductivity. Here, we take a closer look at how structure dictates physical properties in a series of 1D iron-tetraoxolene chains. Using a diphenyl-derivatized tetraoxolene ligand (H2Ph2dhbq), we show that the steric profile of the coordinating solvent controls whether linear or helical chains are exclusively formed. Despite similar ligand environments, only the helical chain displays temperature-dependent valence tautomerism, switching from (FeII)(Ph2dhbq2-) to (FeIII)(Ph2dhbq3˙-) at temperatures below 203 K. The stabilization of ligand radicals leads to exceptionally strong magnetic exchange coupling (J = -230 ± 4 cm-1). Meanwhile, the linear chains are more amenable to oxidative doping, leading to Robin-Day class II/III mixed-valency and an increase in electrical conductivity by nearly three orders of magnitude. While previous studies have focused on the effects of changing metal and ligand identity, this work highlights how altering the metal-ligand connectivity can be a similarly powerful tool for tuning materials properties.

| S-EPMC10094740 | biostudies-literature

Bidirectional photoswitching of magnetic properties at room temperature: ligand-driven light-induced valence tautomerism.

Project description:Valence tautomeric (VT) metal complexes are highly promising bistable molecular compounds for applications as molecular switches in molecular electronics and spintronics. Although VT species can be switched with light, the photoswitching in all reported systems requires very low temperatures (usually below 20 K) because photoinduced states are highly unstable at room temperature. The thermal instability hinders any practical application of these complexes in genuine devices. In this report, for the first time we demonstrate photoswitching of VT species and associated magnetic properties at room temperature. The bidirectional photoswitching in solution is due to cis-trans photoisomerizable 4-styrylpyridine ligands deliberately integrated into cobalt dioxolene molecular complexes. The novel type of photoswitching has been coined Ligand-Driven Light-Induced Valence Tautomerism (LD-LIVT). The photoconversion of VT states of 28% has been achieved in solution at room temperature. The photoinduced states show extraordinary thermal stability for hours at room temperature, as compared to common nanoseconds reported previously. The switching proceeds at molecular level with the effective photoswitching rate of 3 × 1013 molecules per s under our conditions. Consequently, this work may open new horizons in applications of molecular switches based on VT metal complexes in molecular devices functioning at room temperature.

| S-EPMC5851081 | biostudies-literature

Do nonlinear vocal phenomena signal negative valence or high emotion intensity?

Project description:Nonlinear vocal phenomena (NLPs) are commonly reported in animal calls and, increasingly, in human vocalizations. These perceptually harsh and chaotic voice features function to attract attention and convey urgency, but they may also signal aversive states. To test whether NLPs enhance the perception of negative affect or only signal high arousal, we added subharmonics, sidebands or deterministic chaos to 48 synthetic human nonverbal vocalizations of ambiguous valence: gasps of fright/surprise, moans of pain/pleasure, roars of frustration/achievement and screams of fear/delight. In playback experiments (N = 900 listeners), we compared their perceived valence and emotion intensity in positive or negative contexts or in the absence of any contextual cues. Primarily, NLPs increased the perceived aversiveness of vocalizations regardless of context. To a smaller extent, they also increased the perceived emotion intensity, particularly when the context was negative or absent. However, NLPs also enhanced the perceived intensity of roars of achievement, indicating that their effects can generalize to positive emotions. In sum, a harsh voice with NLPs strongly tips the balance towards negative emotions when a vocalization is ambiguous, but with sufficiently informative contextual cues, NLPs may be re-evaluated as expressions of intense positive affect, underlining the importance of context in nonverbal communication.

| S-EPMC7813245 | biostudies-literature

Local Phenomena Shape Backyard Soil Metabolite Composition.

Project description:Soil covers most of Earth's continental surface and is fundamental to life-sustaining processes such as agriculture. Given its rich biodiversity, soil is also a major source for natural product drug discovery from soil microorganisms. However, the study of the soil small molecule profile has been challenging due to the complexity and heterogeneity of this matrix. In this study, we implemented high-resolution liquid chromatography-tandem mass spectrometry and large-scale data analysis tools such as molecular networking to characterize the relative contributions of city, state and regional processes on backyard soil metabolite composition, in 188 soil samples collected from 14 USA States, representing five USA climate regions. We observed that region, state and city of collection all influence the overall soil metabolite profile. However, many metabolites were only detected in unique sites, indicating that uniquely local phenomena also influence the backyard soil environment, with both human-derived and naturally-produced (plant-derived, microbially-derived) metabolites identified. Overall, these findings are helping to define the processes that shape the backyard soil metabolite composition, while also highlighting the need for expanded metabolomic studies of this complex environment.

| S-EPMC7143036 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data