scholarly journals Sulfur Versus Nitrogen Chelation in C-H Activation: Cobalt(III)-Catalyzed Unsymmetrical Double Annulation of Thioamides

2021 ◽  
Author(s):  
Majji Shankar ◽  
Arijit Saha ◽  
Somratan Sau ◽  
Arghadip Ghosh ◽  
Vincent Gandon ◽  
...  
Keyword(s):  
Density Functional ◽  
Chemical Space ◽  
Photophysical Properties ◽  
Structural Diversity ◽  
One Pot ◽  
Functional Theory ◽  
Biologically Relevant ◽  
Drug Candidates ◽  
Isoquinoline Derivatives ◽  
First Time

An unconventional cobalt(III)-catalyzed one-pot domino double annulation of aryl thioamides with unactivated alkynes is presented. Sulfur (S), nitrogen (N), and o,o'-C-H bonds of aryl thioamides are involved in this reaction, enabling access to rare 6,6-fused thiopyrano-isoquinoline derivatives. A reverse ‘S’ coordination over more conventional ‘N’ coordination of thioamides to Co-catalyst specifically regulates the formation of four [C-C and C-S at first and then C-N and C-C] bonds in a single operation, a concept which is uncovered for the first time. The power of the N-masked methyl phenyl sulfoximine (MPS) directing group in this annulation sequence is established. The transformation is successfully developed, building a novel chemical space of structural diversity (56 examples). In addition, late-stage annulation of biologically relevant motifs and drug candidates are disclosed (17 examples). Preliminary photophysical properties of thiopyrano-isoquinoline derivatives are discussed. Density functional theory (DFT) studies authenticate the participation of a unique 6p-electrocyclization of a 7-membered S-chelated cobaltacycle in the annulation process.<br>

scholarly journals Sulfur Versus Nitrogen Chelation in C-H Activation: Cobalt(III)-Catalyzed Unsymmetrical Double Annulation of Thioamides

2021 ◽  
Author(s):  
Majji Shankar ◽  
Arijit Saha ◽  
Somratan Sau ◽  
Arghadip Ghosh ◽  
Vincent Gandon ◽  
...  
Keyword(s):  
Density Functional ◽  
Chemical Space ◽  
Photophysical Properties ◽  
Structural Diversity ◽  
One Pot ◽  
Functional Theory ◽  
Biologically Relevant ◽  
Drug Candidates ◽  
Isoquinoline Derivatives ◽  
First Time

An unconventional cobalt(III)-catalyzed one-pot domino double annulation of aryl thioamides with unactivated alkynes is presented. Sulfur (S), nitrogen (N), and o,o'-C-H bonds of aryl thioamides are involved in this reaction, enabling access to rare 6,6-fused thiopyrano-isoquinoline derivatives. A reverse ‘S’ coordination over more conventional ‘N’ coordination of thioamides to Co-catalyst specifically regulates the formation of four [C-C and C-S at first and then C-N and C-C] bonds in a single operation, a concept which is uncovered for the first time. The power of the N-masked methyl phenyl sulfoximine (MPS) directing group in this annulation sequence is established. The transformation is successfully developed, building a novel chemical space of structural diversity (56 examples). In addition, late-stage annulation of biologically relevant motifs and drug candidates are disclosed (17 examples). Preliminary photophysical properties of thiopyrano-isoquinoline derivatives are discussed. Density functional theory (DFT) studies authenticate the participation of a unique 6p-electrocyclization of a 7-membered S-chelated cobaltacycle in the annulation process.<br>

scholarly journals Fluorescence and photophysical properties of xylene isomers in water: with experimental and theoretical approaches

2018 ◽  
Vol 5 (2) ◽  
pp. 171719 ◽  
Author(s):  
Muhammad Farooq Saleem Khan ◽  
Jing Wu ◽  
Bo Liu ◽  
Cheng Cheng ◽  
Mona Akbar ◽  
...  
Keyword(s):  
Density Functional ◽  
Photophysical Properties ◽  
Emission Spectra ◽  
Energy Difference ◽  
Fast Method ◽  
Functional Theory ◽  
Vertical Excitation ◽  
Theoretical Approaches ◽  
Xylene Isomers ◽  
First Time

A thorough analysis of the photophysical properties involved in electronic transitions in excitation–emission spectra of xylene isomers has been carried out using the time-dependent density functional theory (PBEPBE/6-31 + G(d,p)) method. For the first time a structural and spectroscopic investigation to distinguish isomers of xylene, a widespread priority pollutant, was conducted experimentally and theoretically. The fluorescence properties of xylene isomers (sole and mixture (binary and ternary)) in water were studied. The fluorescence peak intensities of xylenes were linearly correlated to concentration, in the order of p -xylene >  o -xylene >  m -xylene at an excitation/emission wavelength (ex/em) of 260 nm/285 nm for o -, m -xylene and ex/em 265 nm/290 nm for p -xylene at the same concentration. The theoretical excitation/emission wavelengths were at ex/em 247 nm/267 nm, 248 nm/269 nm and 251 nm/307 nm for o -, m - and p -xylene, respectively. The vertical excitation and emission state energies of p -xylene (ex/em 4.94 eV/4.03 eV) were lower and the internal conversion energy difference (0.90 eV) was higher than those of m -xylene (ex/em 5.00 eV/4.60 eV) (0.4 eV) and o -xylene (ex/em 5.02 eV/4.64 eV) (0.377 eV). The order of theoretical emission and oscillator strength (0.0187 > 0.0175 > 0.0339) for p -xylene >  o -xylene >  m -xylene was observed to be in agreement with the experimental fluorescence intensities. These findings provide a novel fast method to distinguish isomers based on their photophysical properties.

scholarly journals 2,4-Bis(arylethynyl)-9-chloro-5,6,7,8-tetrahydroacridines: synthesis and photophysical properties

2021 ◽  
Vol 17 ◽  
pp. 1629-1640
Author(s):  
Najeh Tka ◽  
Mohamed Adnene Hadj Ayed ◽  
Mourad Ben Braiek ◽  
Mahjoub Jabli ◽  
Noureddine Chaaben ◽  
...  
Keyword(s):  
Density Functional ◽  
Photophysical Properties ◽  
Chemical Properties ◽  
Efficient Synthesis ◽  
One Pot ◽  
Visible Absorption ◽  
Functional Theory ◽  
Uv Visible ◽  
Physical And Chemical ◽  
And Chemical Properties

Acridine derivatives have attracted considerable interest in numerous areas owing to their attractive physical and chemical properties. Herein, starting from readily available anthranilic acid, an efficient synthesis of 2,4-bis(arylethynyl)-9-chloro-5,6,7,8-tetrahydroacridine derivatives was accomplished via a one-pot double Sonogashira cross-coupling method. The UV-visible absorption and emission properties of the synthesized molecules have been examined. Additionally, theoretical studies based on density functional theory (DFT/B3LYP/6-31G(d)) were carried out.

scholarly journals Rapid Sequentially Palladium Catalyzed Four-Component Synthesis of Novel Fluorescent Biaryl-Substituted Isoxazoles

Catalysts ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1412
Author(s):  
Tobias Deden ◽  
Lars May ◽  
Guido J. Reiss ◽  
Thomas J. J. Müller
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Photophysical Properties ◽  
Quantum Yields ◽  
Catalyst Loading ◽  
One Pot ◽  
Functional Theory ◽  
Fluorescence Quantum Yields ◽  
Palladium Catalyzed ◽  
High Fluorescence

A series of novel 3- and 5-biaryl-substituted isoxazoles was prepared by a rapid microwave-assisted four-component three-step synthesis: concatenating Sonogashira coupling, cyclocondensation, and Suzuki coupling in a one-pot fashion. The Pd-catalyst was successfully employed in the sense of a sequentially catalyzed process, i.e., without the addition of further catalyst loading. Biaryl-substituted isoxazoles with donor–acceptor decoration possess remarkable photophysical properties, such as high fluorescence quantum yields in solution up to ΦF = 0.86 and large Stokes shifts up to 10,000 cm−1. The experimental absorption and emission characteristics can be reproduced and rationalized by computations on the DFT (density functional theory) and TDDFT (time-dependent density functional theory) level of theory.

Metal-, and Organocatalyst-Free One-Pot Assembly of Chiral Aza-Tricyclic Molecules: Creating Six Contiguous Stereocenters from 2-D-Structures and an Amino Acid

2020 ◽  
Author(s):  
Dung Do
Keyword(s):  
Amino Acid ◽  
Chemical Space ◽  
Structural Diversity ◽  
Therapeutic Agents ◽  
Chiral Molecules ◽  
One Pot ◽  
Complex Molecules ◽  
Chiral Catalyst ◽  
Chiral Complex ◽  
Free Process

<p>Chiral molecules with their defined 3-D structures are of paramount importance for the study of chemical biology and drug discovery. Having rich structural diversity and unique stereoisomerism, chiral molecules offer a large chemical space that can be explored for the design of new therapeutic agents.<sup>1</sup> Practically, chiral architectures are usually prepared from organometallic and organocatalytic processes where a transition metal or an organocatalyst is tailor-made for desired reactions. As a result, developing a method that enables rapid assembly of chiral complex molecules under metal- and organocatalyst-free condition represents a daunting challenge. Here we developed a straightforward route to create a chiral 3-D structure from 2-D structures and an amino acid without any chiral catalyst. The center of this research is the design of a <a>special chiral spiroimidazolidinone cyclohexadienone intermediate</a>, a merger of a chiral reactive substrate with multiple nucleophillic/electrophillic sites and a transient organocatalyst. <a>This unique substrate-catalyst (“subcatalyst”) dual role of the intermediate enhances </a><a>the coordinational proximity of the chiral substrate and catalyst</a> in the key Aza-Michael/Michael cascade resulting in a substantial steric discrimination and an excellent overall diastereoselectivity. Whereas the “subcatalyst” (hidden catalyst) is not present in the reaction’s initial components, which renders a chiral catalyst-free process, it is strategically produced to promote sequential self-catalyzed reactions. The success of this methodology will pave the way for many efficient preparations of chiral complex molecules and aid for the quest to create next generation of therapeutic agents.</p>

scholarly journals Single-crystalline epitaxial TiO film: A metal and superconductor, similar to Ti metal

2021 ◽  
Vol 7 (2) ◽  
pp. eabd4248
Author(s):  
Fengmiao Li ◽  
Yuting Zou ◽  
Myung-Geun Han ◽  
Kateryna Foyevtsova ◽  
Hyungki Shin ◽  
...  
Keyword(s):  
Transition Metal ◽  
Density Functional ◽  
Tight Binding ◽  
Crystal Form ◽  
Titanium Monoxide ◽  
Binding Model ◽  
Functional Theory ◽  
Single Crystalline ◽  
First Time ◽  
Lattice Matched

Titanium monoxide (TiO), an important member of the rock salt 3d transition-metal monoxides, has not been studied in the stoichiometric single-crystal form. It has been challenging to prepare stoichiometric TiO due to the highly reactive Ti2+. We adapt a closely lattice-matched MgO(001) substrate and report the successful growth of single-crystalline TiO(001) film using molecular beam epitaxy. This enables a first-time study of stoichiometric TiO thin films, showing that TiO is metal but in proximity to Mott insulating state. We observe a transition to the superconducting phase below 0.5 K close to that of Ti metal. Density functional theory (DFT) and a DFT-based tight-binding model demonstrate the extreme importance of direct Ti–Ti bonding in TiO, suggesting that similar superconductivity exists in TiO and Ti metal. Our work introduces the new concept that TiO behaves more similar to its metal counterpart, distinguishing it from other 3d transition-metal monoxides.

Photophysical Properties of N-Methyl and N-Acetyl Substituted Alloxazine: A Theoretical Investigation

2021 ◽  
Author(s):  
Huimin Guo ◽  
Xiaolin Ma ◽  
Zhiwen Lei ◽  
Yang Qiu ◽  
Bernhard Dick ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Theoretical Investigation ◽  
Density Functional ◽  
Photophysical Properties ◽  
Time Dependent ◽  
Functional Theory ◽  
Td Dft ◽  
Dependent Density

The electronic structure and photophysical properties of a series of N-Methyl and N-Acetyl substituted alloxazine (AZs) were investigated with extensive density functional theory (DFT) and time-dependent density functional theory (TD-DFT)...

Experimental and computational investigations of TiIrB: a new ternary boride with Ti1+x Rh2−x+y Ir3−y B3-type structure

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jan P. Scheifers ◽  
Kate A. Gibson ◽  
Boniface P. T. Fokwa
Keyword(s):  
Density Functional ◽  
Ternary Phase ◽  
Structure Type ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
Arc Melting ◽  
Ternary Boride ◽  
Charge Analysis ◽  
First Time ◽  
Bader Charge Analysis

Abstract A new ternary phase, TiIrB, was synthesized by arc-melting of the elements and characterized by powder X-ray diffraction. The compound crystallizes in the orthorhombic Ti1+x Rh2−x+y Ir3−y B3 structure type, space group Pbam (no. 55) with the lattice parameters a = 8.655(2), b = 15.020(2), and c = 3.2271(4) Å. Density Functional Theory (DFT) calculations were carried out to understand the electronic structure, including a Bader charge analysis. The charge distribution of TiIrB in the Ti1+x Rh2−x+y Ir3−y B3-type phase has been evaluated for the first time, and the results indicate that more electron density is transferred to the boron atoms in the zigzag B4 units than to isolated boron atoms.

Anthracene Based AIE Active Probe for Colorimetric and Fluorimetric Detection of Cu2+ Ions

2019 ◽  
Vol 233 (7) ◽  
pp. 895-911 ◽  
Author(s):  
Abdullah G. Al-Sehemi ◽  
Ahmad Irfan ◽  
Mehboobali Pannipara ◽  
Mohammed A. Assiri ◽  
Abul Kalam
Keyword(s):  
Charge Transfer ◽  
Density Functional ◽  
Photophysical Properties ◽  
Functional Theory ◽  
Water Fraction ◽  
Cu Complex ◽  
Active Probe ◽  
And Function ◽  
Intra Molecular Charge Transfer ◽  
Metal Charge Transfer

Abstract A novel aggregation induced emission (AIE) active anthracene based dihydroquinazolinone derivative (probe 1) has been synthesized and characterized by means of spectroscopic methods. The photophysical properties of this probe have been investigated in solvents of different polarity display that fluorescence states are of intramolecular charge transfer (ICT) character. Probe 1 show clear AIE behavior in water/THF mixture on reaching water fraction 95%. The AIE behavior of probe 1 have been exploited for the detection of metal ions in aqueous solution which reveals high selectivity and sensitivity towards Cu2+ ions by colorimetrically and function as a chemosensor in a remarkable turn-off fluorescence manner. Further, the experimental results were investigated by computational means by optimizing the ground state geometries of probe 1 and probe 1-Cu complex using density functional theory (DFT) at B3LYP/6-31G∗∗ and B3LYP/6-31G∗∗(LANL2DZ) levels of theory. Intra-molecular charge transfer was observed in probe 1 while ligand to metal charge transfer (LMCT) for probe 1-Cu complex.

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