Advancements in double decarboxylative coupling reactions of carboxylic acids.

The double decarboxylative coupling reaction between two (similar or different) molecules of carboxylic acids is an emerging area that has gained considerable attention as a new avenue for forging carbon-carbon bonds. Since this synthetic strategy only utilizes carboxylic acids as easily accessible, non-toxic and stable starting materials, and extrudes carbon dioxide (CO2) as the only waste by-product, it can be considered as an environmentally benign alternative to traditional coupling reactions which mainly rely on the use of toxic organic halides or organometallic reagents. The aim of this review is to highlight the recent advances and developments in this exciting new field that may serve as inspiration for future research to mature it.

Recent trends in incorporation of CO2 into organosulfur compounds via C-S bond cleavage.

Desulfurative functionalization of organosulfur compounds to form various carbon-carbon and carbon-heteroatom bonds has become established as a powerful tool in organic chemistry. In this context, desulfurative carboxylation of this class of compounds using carbon dioxide (CO2) as a sustainable and renewable source of carboxyl has recently been developed as an efficient option for the synthesis of carboxylic acid derivatives. The aim of this Focus Review is to summarize the major progress in this appealing research field with particular emphasis on the mechanistic features of the reactions. Literature has been surveyed until the end of February 2024, according to the data collected using SciFinder and Google Scholar engines.

Exploring porphyrins induced carbon nanocone TM-PICNC (TM = Sc2+, Ti2+, V2+, Cr2+, Fe2+, Co2+, Ni2+, Cu2+, and Zn2+) as a highly sensitive sensor for CO2 gas detection in presence O2 and H2O molecules: a computational study.

This study investigated the adsorption of CO2 molecules on transition metal ions (TM) porphyrins induced carbon nanocone (TM-PICNC) (TM = Sc2+, Ti2+, V2+, Cr2+, Fe2+, Co2+, Ni2+, Cu2+, and Zn2+) using density functional theory (DFT) to determine the stabilities, energetic, structural, and electronic properties. The results showed that the CO2 molecule is adsorbed on TM-PICNC with adsorption energies ranging from 0.03 to -12.12 kcal/mol. The weak interactions of CO2 gas with Cr, Ni, Cu, and Zn-PICNC were observed, while strong adsorption was found on Sc, Ti, and V-PICNC. The Ti, V, and Cr-PCNC structures were shown to have a suitable energy gap (Eg) for sensing ability because of the effective and physical interaction between these structures and CO2 gas, leading to a short recovery time. DFT calculations also revealed that V-PCNC had a high %ΔEg (about %56.79) and hence high sensitivity to CO2 gas, making it a promising candidate for having good sensing ability to CO2 gas in presence of O2 and H2O gas.

Metalloporphyrin reduced C70 fullerenes as adsorbents and detectors of ethenone; A DFT, NBO, and TD-DFT study.

In the present work, the structure and electronic properties of Ti-, Cr-, Fe-, Ni-, Zn-, and Cu-inserted in porphyrin-reduced C70 fullerenes (TM-PIC70Fs) and their interactions with the ethenone were studied using DFT, NBO, and TD-DFT at CAM-B3LYP/6-31G(d) level of theory. 2.89-3.83 and 4.02-4.56 eV were obtained for the HOMO-LUMO gap energies and work functions of TM-PIC70Fs, respectively, compared with 3.76 and 4.54 eV for PIC70F. Among considered TM-PIC70Fs, the adsorption of the ethenone on Ti-PIC70F appreciably changed the HOMO-LUMO energy gap and work function. Consequently, Ti-PIC70F may be used as the ethenone's electronic conductivity and work function types sensor. According to calculated UV-visible spectra, the ethenone adsorption may change the color of Fe- and Ti-PIC70Fs. Therefore, they can be used as color-changing sensors of ethenone. In addition, Ti-, Cr-, Fe-, and Zn-PIC70Fs can be employed as suitable adsorbents of ethenone. Among proper sensors and adsorbents of ethenone, Cr-, Fe-, and Zn-PIC70Fs may be recovered and reused.

Adsorption of O2 molecule on the transition metals (TM(II) = Sc2+, Ti2+, V2+, Cr2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+ and Zn2+) porphyrins induced carbon nanocone (TM(II)PCNC).

In this work, the adsorption of the O2 molecule on the transition metals (TM(II) = Sc2+, Ti2+, V2+, Cr2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+ and Zn2+) porphyrins induced carbon nanocone (TM(II)-PCNC) were investigated using density functional theory (DFT) in terms of stabilities, energetic, structural, and electronic properties. It has been found that the O2 molecule is adsorbed on the TM(II)-PCNC with adsorption energies in the range of 0.29 to -98.32 kcal/mol. The interaction between the O2 gas and the Sc-PCNC molecule from the outer site is the strongest. The interaction of the O2 gas over the Ni-PCNC molecule from both outer and inner sites is the weakest. It can be concluded that the suitable interaction energy (Eg) for sensing ability attributed to the Zn-PCNC because an effective and physical interaction between Zn-PCNC and the O2 gas leads to short recovery time. DFT calculations also clarified that the high %ΔEg of Zn-PCNC and hence the high sensitivity to the O2 gas confirm that the Zn-PCNC molecule is a promising candidate for having a good sensing ability to the O2 gas.

Butadiyne-linked porphyrin nanoring as a highly selective O2 gas sensor: A fast response hybrid sensor.

The butadiyne-linked six-metalloporphyrin nanoring (Mg6-P6) and it's complex with a hexapyridyl template, Mg6-P6·T6 have a great potential for employment in future nanoelectronic applications such as a nanosensor for small gas molecules. The goal of this study is to scrutinize and improvement of the CO, N2, and O2 gas sensing capacity of Mg6-P6 and Mg6-P6·T6 using DFT calculations at CAM-B3LYP/6-31G (d,p) level of theory. The geometrical structures, binding energies, band gaps, the density of states (DOS), adsorption energies, HOMO and LUMO energies, Fermi level energies (EFL), NBO, FMO and TD-DFT spectrum were calculated to predict gas adsorption properties of Mg6-P6 and Mg6-P6·T6 systems. Based on the calculated adsorption energies and remarkable decrease in the Eg, it is expected that the Mg6-P6 and Mg6-P6·T6 are sensitive to O2 molecule. Surprisingly, the Mg6-P6-O2 and specially the Mg6-P6.T6-O2 record promising values of recovery times for different attempt frequencies. Therefore, the results open a way for the development of a new and selective O2 nanosensor in the presence of CO and N2 gas molecules.

Strategies for the direct oxidative esterification of thiols with alcohols.

This review paper provides an overview of the main strategies for the oxidative esterification of thiols with alcohols. The review is divided into two major parts according to final products. The first includes the methods for the synthesis of sulfinic esters, while the second contains the procedures for the fabrication of sulfonic ester derivatives.

Selective adsorption and dissociation of NO, NO2, and N2O molecules on Si-doped haeckelite boron nitride nanotube: an investigation for sensitive molecular sensors and catalysts.

The current study describes the investigation of the adsorption NO, N2O, and NO2 on haeckelite boron nitride nanotube doped with Si (Si-doped haeck-BNNT) by means of density functional theory calculation (DFT). The obtained results confirmed the energetic stability of the optimized geometries and revealed that the adsorption of the gas molecules with the nanotube sidewall is a spontaneous process. The calculated work function of Si-doped haeck-BNNT in the presence of gas molecules is greater than that of a bare Si-doped haeck-BNNT sheet. The energy gap of the Si-doped haeck-BNNT is sensitive to the adsorption of the gas molecules, which implies possible future applications in gas sensors. For most of the adsorption configurations studied, the adsorption energies for the SiB-doped haeck-BNNT are higher than those for SiN-doped haeck-BNNTones. The N2O gas molecule is totally dissociated into N2 and O species through the adsorption process, while the other gas molecules retain their molecular forms. Thus, the SiN-doped haeck-BNNT is a likely catalyst for dissociation of the N2O gas molecule. Our findings divulge promising potential of the doped haeck-BNNT as a highly sensitive molecular sensor for NO and NO2 detection and a catalyst for N2O dissociation.

Cross-Dehydrogenative Coupling Reactions Between C(sp)-H and X-H (X = N, P, S, Si, Sn) Bonds: An Environmentally Benign Access to Heteroatom-Substituted Alkynes.

Form a green and sustainable chemistry point of view, cross-dehydrogenative coupling (or oxidative cross-coupling) reactions have been recognized as environmentally sustainable and atom economical synthetic routes for the construction of new carbon-carbon and carbon-heteroatom bonds, since no pre-functionalization of starting materials is required. In the past few years, the direct coupling of sp-hybridized C-H bonds with heteroatom-H bonds has received much attention because of the importance of heteroatom-substituted alkynes in organic and medicinal chemistry. This review examines the recent developments in cross-dehydrogenative coupling reactions between C(sp)-H and X-H (X = N, P, S, Si, Sn) bonds, with a particular focus on the mechanistic aspects of the reactions.

Recent developments in decarboxylative cross-coupling reactions between carboxylic acids and N-H compounds.

Carboxylic acids and their derivatives are ubiquitous compounds in organic chemistry, and are widely commercially available in a large structural variety. Recently, carboxylic acids have been frequently used as non-toxic and environmentally benign alternatives to traditional organohalide coupling partners in various carbon-carbon and carbon-heteroatom cross-coupling reactions. Along this line, several methods have been reported for the synthesis of nitrogen-containing organic compounds through decarboxylative cross-coupling reactions between carboxylic acids and N-H compounds. This review focuses on recent advances and discoveries on these reactions with special attention on the mechanistic aspects of the reactions.

Solvent-free incorporation of CO2 into 2-oxazolidinones: a review.

This review is an attempt to give an overview on the recent advances and developments in the synthesis of 2-oxazolidinone frameworks through carbon dioxide (CO2) fixation reactions under solvent-free conditions. The cycloaddition of CO2 to aziridine derivatives is discussed first. This is followed by carboxylative cyclization of N-propargylamines with CO2 and three-component coupling of epoxides, amines, and CO2. Finally, cycloaddition of CO2 to propargylic alcohols and amines will be covered at the end of the review. The literature has been surveyed up until the end of 2018.

Cross-dehydrogenative coupling reactions between arenes (C-H) and carboxylic acids (O-H): a straightforward and environmentally benign access to O-aryl esters.

Transition-metal catalyzed cross-dehydrogenative-coupling reactions encompass highly versatile and atom economical methods for the construction of various carbon-carbon and carbon-heteroatom bonds by combining two C(X)-H (X = heteroatom) bonds. Along this line, direct acyloxylation of C-H bonds with carboxylic acids has emerged as a powerful and green approach for the synthesis of structurally diverse esters. In this focus-review we will describe recent progress in direct esterification of aromatic C-H bonds with special emphasis on the mechanistic features of the reactions. Literature has been surveyed until the end of February 2019.

A novel aluminum-sensitive fluorescent chemosensor based on 4-aminoantipyrine: An experimental and theoretical study.

A practical and an efficient Schiff base fluorescent chemosensor, salicylidene-4-aminoantipyrinyl-4-aminophenol (A2) has been synthesized through the condensation procedure of 1-phenyl-2,3-dimethyl-4-(N-2-hydroxybenzylidene)-3-pyrazoline-5-one and 4-aminophenol. Compound A2 has displayed a considerable fluorescence enhancement with high selectivity and sensitivity toward Al3+ ion and exhibited an emission band at 484 nm, which contained a low detection limit (LOD) of 1.06 × 10-7 M. In accordance to the experimental study, DFT, TDDFT calculations, and the enhancement of fluorescence intensity might be attributed to the inhibition of Photoinduced Electron Transfer (PET) along with the Excited-State Intramolecular Proton Transfer (ESIPT). As it has been specified by Job's plot and DFT calculations, the binding stoichiometries of A2 with Al3+ are 1:1, while the association constant (Ka) of Al3+ has been calculated and observed to be 2.67 ×â€¯× 105 M-1. Furthermore, the binding behavior and sensing mechanism of A2 with Al3+ have been confirmed through the experiments of 1H NMR titration.

Chemical constituents of Swertia longifolia Boiss. with α-amylase inhibitory activity.

α-Amylase inhibitors play a critical role in the control of diabetes and many of medicinal plants have been found to act as α-amylase inhibitors. Swertia genus, belonging to the family Gentianaceae, comprises different species most of which have been used in traditional medicine of several cultures as antidiabetic, anti-pyretic, analgesic, liver and gastrointestinal tonic. Swertia longifolia Boiss. is the only species of Swertia growing in Iran. In the present investigation, phytochemical study of S. longifolia was performed and α-amylase inhibitory effects of the plant fractions and purified compounds were determined. Aerial parts of the plant were extracted with hexane, chloroform, methanol and water, respectively. The components of the hexane and chloroform fractions were isolated by different chromatographic methods and their structures were determined by (1)H NMR and (13)C NMR data. α-Amylase inhibitory activity was determined by a colorimetric assay using 3,5-dinitro salysilic acid. During phytochemical examination, α-amyrin, ß-amyrin and ß-sitosterol were purified from the hexane fraction, while ursolic acid, daucosterol and swertiamarin were isolated from chloroform fraction. The results of the biochemical assay revealed α-amylase inhibitory activity of hexane, chloroform, methanol and water fractions, of which the chloroform and methanol fractions were more potent (IC50 16.8 and 18.1 mg/ml, respectively). Among examined compounds, daucosterol was found to be the most potent α-amylase inhibitor (57.5% in concentration 10 mg/ml). With regard to α-amylase inhibitory effects of the plant extracts, purified constituents, and antidiabetic application of the species of Swertia genus in traditional medicine of different countries, S. longifolia seems more appropriate species for further mechanistic antidiabetic evaluations.

Theoretical investigation of tautomerism in N-hydroxy amidines.

A DFT study with QST3 approach method is used to calculate kinetic, thermodynamic, spectral and structural data of tautomers and transition state structures of some N-hydroxy amidines. All tautomers and transition states are optimized at the B3LYP/6-311++g** and B3LYP/aug-cc-pvtz level, with good agreement in energetic result with energies obtained from CBS-QB3, a complete basis set composite energy method. The result shows that the tautomer a (amide oxime) is more stable than the tautomer b (imino hydroxylamine) as is reported in the literature. In addition, our finding shows that, the energy difference between two tautomers is only in about 4-10 kcal/mol but the barrier energy found in traversing each tautomer to another one is in the range of 33-71 kcal/mol. Therefore, it is impossible to convert these two tautomers to each other at room temperature. Additionally, transition state theory is applied to estimate the barrier energy and reaction rate constants of the hydrogen exchange between tautomers in presence of 1-3 molecules of water. The computed activation barrier shows us that the barrier energy of solvent assisted tautomerism is about 9-20 kcal/mol and lower than simple tautomerism and this water-assisted tautomerism is much faster than simple tautomerism, especially with the assisting two molecules of water.