Quantum mechanical investigation of the tautomerism in the azo dye Sudan III

Santos, Hélio F. Dos; Oliveira, Luiz Fernando Cappa de; Dantas, Simone; Santos, Paulo S.; Almeida, Wagner B. De

doi:10.1002/1097-461x(2000)80:4/5<1076::aid-qua57>3.0.co;2-r

Cited by 24 publications

(4 citation statements)

References 63 publications

(76 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is opportune to mention that a somehow similar situation concerning imidazolidine compounds was reported some years ago where two methyl groups in axial and equatorial positions become indistinguishable at 300 K, producing a single NMR signal, implying a rapid axial–equatorial inversion of the Me groups, and a relatively low energy barrier. This experimental finding in DMSO- d 6 solution is closely related to the results describe here in chloroform solution for compound 9 . In addition, the same averaging procedure was used for the DFT optimized M1 and M2 solvated structures originated from MD simulations containing 4, 10, and 20 CHCl 3 solvent molecules.…”

Section: Resultssupporting

confidence: 89%

“…This intramolecular hydrogen bond is assisted by resonance and is expected to be short with the corresponding H signal appearing in the low-field region in 1 H NMR. 56 This might be due the DFT approach, which overestimated hydrogen bond strength. It is noted in Figure 9 that the OH signal shifts to high field with inclusion of explicit solvent molecules.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Conversely, the OH-5···O4 hydrogen bond seems too short (1.70 Å), which explains the low-field shift of the H5 hydrogen peak. This intramolecular hydrogen bond is assisted by resonance and is expected to be short with the corresponding H signal appearing in the low-field region in 1 H NMR . This might be due the DFT approach, which overestimated hydrogen bond strength.…”

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Conformational Analysis of 5,4′-Dihydroxy-7,5′,3′-trimethoxyisoflavone in Solution Using ¹H NMR: A Density Functional Theory Approach

et al. 2020

Self Cite

View full text Add to dashboard Cite

Among 20 compounds isolated from the extracts of Ouratea ferruginea the 5,4′-dihydroxy-7,5′,3′-trimethoxyisoflavone (9) showed the best inhibitory effect on glutathione S-transferase (GST) and so deserves our attention. In this work we investigated the preferred molecular structure of 9 in chloroform solution using the density functional theory (DFT) and molecular dynamics simulation. Comparison between experimental 1H NMR data in CDCl3 solution and calculated chemical shifts enabled us to precisely determine the conformation adopted by 9 in solution, which can be used in further theoretical studies involving interaction with biological targets. Moreover, the experimental NMR data were used as reference to assess the ability of DFT based methods to predict 1H NMR spectrum in solution for organic compounds. Among various DFT functionals the hybrid B3LYP was the most adequate for the calculation of chemical shifts in what CH n protons are concerned. Regarding the OH hydrogen, inclusion of explicit CHCl3 solvent molecules adequately placed around the solute led to good agreement with the experimental chemical shifts (in CDCl3). It is a well-known fact that theoretical prediction of chemical shifts for OH hydrogens poses as a challenge and also revealed that the way the solvent effects are included in the DFT calculations is crucial for the right prediction of the whole 1H NMR spectrum. It was found in this work that a supermolecule solute–solvent calculation with a minimum of four CHCl3 molecules is enough to correctly reproduce the 1H NMR experimental profile observed in solution, revealing that the calculated solvated structure used to reproduce the NMR chemical shifts is not unique.

show abstract

Section: Resultssupporting

confidence: 89%

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Conformational Analysis of 5,4′-Dihydroxy-7,5′,3′-trimethoxyisoflavone in Solution Using ¹H NMR: A Density Functional Theory Approach

et al. 2020

Self Cite

View full text Add to dashboard Cite

show abstract

“…It is worth mentioning that, although the Sudan series are formally neutral, their behavior in solution is complicated due to the equilibrium of the different protonation states of the dyes in the MOF/DMF solution (Figure S24). 51 The adsorption of a small amount of SD1 in both ANT-1(Fe) and ANT-1(Zn@ Fe) might be due to the adsorption of the zwitterionic form, which is in equilibrium with the neutral form in the DMF solution.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Symmetry-Mismatched SBU Transformation in MOFs: Postsynthetic Metal Exchange from Zn to Fe and Its Effects on Gas Adsorption and Dye Selectivity

Han,

Kim,

Lee

et al. 2023

ACS Appl. Mater. Interfaces

View full text Add to dashboard Cite

This research explores the alteration of metal–organic frameworks (MOFs) using a method called postsynthetic metal exchange. We focus on the shift from a Zn-based MOF containing a [Zn4O(COO)6] secondary building unit (SBU) of octahedral site symmetry (ANT-1(Zn)) to a Fe-based one with a [Fe3 IIIO(COO)6]+ SBU of trigonal prismatic site symmetry (ANT-1(Fe)). The symmetry-mismatched SBU transformation cleverly maintains the MOF’s overall structure by adjusting the conformation of the flexible 1,3,5-benzenetribenzoate linker to alleviate the framework strain. The process triggers a decrease in the framework volume and pore size alongside a change in the framework’s charge. These alterations influence the MOF’s ability to adsorb gas and dye. During the transformation, core–shell MOFs (ANT-1(Zn@Fe)) are formed as intermediate products, demonstrating unique gas sorption traits and adjusted dye adsorption preferences due to the structural modifications at the core–shell interface. Heteronuclear clusters, located at the framework interfaces, enhance the heat of CO2 adsorption. Furthermore, they also influence the selectivity of the dye size. This research provides valuable insights into fabricating novel MOFs with unique properties by modifying the SBU of a MOF with flexible organic linkers from one site symmetry to another.

show abstract

Controlled Synthesis of α‐Allenic Ester and Spiro Ketone Derivatives from Tailored α‐Substituted Cycloalkanones Through Cascade Reactions: Exploring the Possible Reaction Pathways by Means of Semiempirical MO Calculations

et al. 2005

View full text Add to dashboard Cite

Functionalized bicyclic electrophilic allenes and (or) spiro ketones have been obtained through a cascade reaction when acetylenic ω-keto esters were treated with tetra-n-butylammonium fluoride (TBAF). The isolated products can be modulated by using different starting materials (i.e. varying ring size, spacer length) and reaction times. The results indicate that these reactions take place under kinetic control. In line with this, a semiempirical study was carried out in order

show abstract

Quantum mechanical investigation of the tautomerism in the azo dye Sudan III

Cited by 24 publications

References 63 publications

Conformational Analysis of 5,4′-Dihydroxy-7,5′,3′-trimethoxyisoflavone in Solution Using ¹H NMR: A Density Functional Theory Approach

Conformational Analysis of 5,4′-Dihydroxy-7,5′,3′-trimethoxyisoflavone in Solution Using ¹H NMR: A Density Functional Theory Approach

Symmetry-Mismatched SBU Transformation in MOFs: Postsynthetic Metal Exchange from Zn to Fe and Its Effects on Gas Adsorption and Dye Selectivity

Controlled Synthesis of α‐Allenic Ester and Spiro Ketone Derivatives from Tailored α‐Substituted Cycloalkanones Through Cascade Reactions: Exploring the Possible Reaction Pathways by Means of Semiempirical MO Calculations

Contact Info

Product

Resources

About

Quantum mechanical investigation of the tautomerism in the azo dye Sudan III

Cited by 24 publications

References 63 publications

Conformational Analysis of 5,4′-Dihydroxy-7,5′,3′-trimethoxyisoflavone in Solution Using 1H NMR: A Density Functional Theory Approach

Conformational Analysis of 5,4′-Dihydroxy-7,5′,3′-trimethoxyisoflavone in Solution Using 1H NMR: A Density Functional Theory Approach

Symmetry-Mismatched SBU Transformation in MOFs: Postsynthetic Metal Exchange from Zn to Fe and Its Effects on Gas Adsorption and Dye Selectivity

Controlled Synthesis of α‐Allenic Ester and Spiro Ketone Derivatives from Tailored α‐Substituted Cycloalkanones Through Cascade Reactions: Exploring the Possible Reaction Pathways by Means of Semiempirical MO Calculations

Contact Info

Product

Resources

About

Conformational Analysis of 5,4′-Dihydroxy-7,5′,3′-trimethoxyisoflavone in Solution Using ¹H NMR: A Density Functional Theory Approach

Conformational Analysis of 5,4′-Dihydroxy-7,5′,3′-trimethoxyisoflavone in Solution Using ¹H NMR: A Density Functional Theory Approach