Carbon Single Bond Research Articles

Formation of Carbon–Carbon Double Bond between Cp Ligand and Alkenyl Carbon of Titanacyclopentenes

AbstractReactions of bis(cyclopentadienyl)titanacyclopentenes with BiI3 gave coupling products of one Cp ligand and the alkenyl carbons in moderate yields. An NMR study of the tetracyanoethylene (TCNE) adduct of the product showed that the coupled Cp ring and the alkenyl carbons were connected by one carbon–carbon double bond. This is in sharp contrast to coupling reactions of one Cp ligand with the diene moiety in bis(cyclopentadienyl)titanacyclopentadienes, where two carbon–carbon single bonds were formed between those two components to give dihydroindenes or spiro compounds.

Multireference calculations on bond dissociation and biradical polycyclic aromatic hydrocarbons as guidance for fractional occupation number weighted density analysis in DFT calculations

This study explores open-shell biradical and polyradical molecular compounds based on extended multireference (MR) methods (MR-configuration interaction with singles and doubles (CISD) and MR-averaged quadratic coupled cluster (AQCC) approach) using the numbers of unpaired densities NU. These results were used to guide the analysis of the fractional occupation number weighted density (FOD) calculated within the finite temperature (FT) density functional theory (DFT) approach. As critical test examples, the dissociation of carbon–carbon (CC) single, double and triple bonds and a benchmark set of polycyclic aromatic hydrocarbons (PAHs) have been chosen. By examining single, double, and triple bond dissociations, we demonstrate the utility and accuracy but also limitations of the FOD analysis for describing these dissociation processes. In significant extension of previous work (Phys Chem Chem Phys 25: 27380–27393), the assessment of FOD applications for different classes of DFT functionals was performed examining the range-separated functionals ωB97XD, ωB97M-V, CAM-B3LYP, LC-ωPBE, and MN12-SX, the hybrid (M06-2X) functional and the double hybrid (B2P-LYP) functional. In all cases, strong correlations between NFOD and NU values are found. The major task was to develop a new linear regression formula for range-separated functionals allowing a convenient determination of the optimal electronic temperature Tel for the FT-DFT calculation. We also established an optimal temperature for the semiempirical extended tight-binding GFN2-xTB method. These findings significantly broaden the applicability of FOD analysis across various DFT functionals and semiempirical methods.

Enabling efficient and ultralong room-temperature phosphorescence from organic luminogens by locking the molecular conformation in polymer matrix

Tackling the challenge of developing ultralong organic phosphorescence (UOP) materials with a high phosphorescence quantum yield (Φphos.) and an ultralong phosphorescence lifetime (τphos.) under ambient conditions is urgently needed. Herein, typical organic luminogens with simple chemical structures, namely, triphenylamine (TPA), 9-phenylcarbazole (PCz), and indolo[3,2,1-jk]carbazole (ICz), are doped into a melamine–formaldehyde (MF) polymer matrix with a compact three-dimensional covalent network to prepare UOP materials, respectively. Both experiments and theoretical calculations suggest that restricting intramolecular motions to suppress the nonradiative decay of triplet excitons plays a critical role in achieving ultralong room-temperature phosphorescence from organic molecules in polymer matrices. The luminophore ICz with a planar and rigid chemical structure, constructed by locking the molecular conformation of TPA via carbon–carbon single bonds, exhibits a bright organic afterglow with a Φphos. up to 38.31 % and a τphos. up to 2.73 s in the MF polymer under ambient conditions, representing one of the most excellent polymer-based organic afterglow materials in comprehensive UOP performance. The gradual enhancement in UOP of the resulting luminescent materials has led to their successful use in multi-level anti-counterfeiting. This work provides an effective strategy for developing organic afterglow materials with both high Φphos. and τphos. values.

Long carbon–carbon bonds and beyond

Advances in synthetic organic chemistry have facilitated the preparation and exploration of compounds exhibiting unusual bonding states. This review delves into carbon–carbon single bonds that are exceeding typical length of bonds, elucidating recent advances in understanding their bonding nature, properties, and chemical reactivity. Additionally, we examine factors contributing to the occurrence of such elongated bonds and their effects on other bonding parameters. Furthermore, we shift our focus toward the π-dimers of radical species, surpassing the limit of two-center two-electron (2c/2e) bonds, discussing their formation mechanisms, stability, and inherent properties. A key feature in the electronic structure of π-dimers is the bonding interaction of two unpaired electrons spanning multiple atoms, that is, multicenter two-electron (mc/2e) bonding. This review sheds light on the significant role played by extended carbon–carbon bonds (2c/2e bonds) and radical π-dimers (mc/2e bonding) in organic chemistry, providing valuable insight for future research on new functional materials.

High Mobility Emissive Excimer Organic Semiconductor Towards Color‐Tunable Light‐Emitting Transistors

AbstractOrganic light‐emitting transistors (OLETs) are highly integrated and minimized optoelectronic devices with significant potential superiority in smart displays and optical communications. To realize these various applications, it is urgently needed for color‐tunable emission in OLETs, but remains a great challenge as a result of the difficulty for designing organic semiconductors simultaneously integrating high carrier mobility, strong solid‐state emission, and the ability for potential tunable colors. Herein, a high mobility emissive excimer organic semiconductor, 2,7‐di(2‐anthryl)‐9H‐fluorene (2,7‐DAF) was reasonably designed by introducing a rotatable carbon–carbon single bond connecting two anthracene groups at the 2,7‐sites of fluorene, and the small torsion angles simultaneously guarantee effective conjugation and suppress fluorescence quenching. Indeed, the unique stable dimer arrangement and herringbone packing mode of 2,7‐DAF single crystal enables its superior integrated optoelectronic properties with high carrier mobility of 2.16 cm2 ⋅ V−1 ⋅ s−1, and strong excimer emission with absolute photoluminescence quantum yield (PLQY) of 47.4 %. Furthermore, the voltage‐dependent electrically induced color‐tunable emission from orange to blue was also demonstrated for an individual 2,7‐DAF single crystal based OLETs for the first time. This work opens the door for a new class of high mobility emissive excimer organic semiconductors, and provides a good platform for the study of color‐tunable OLETs.

Changes in the Composition of the Dried Asian Lacquer (Korean Lacquer) Film Irradiated with Ultraviolet Light

Asian lacquer is a material that has been used in Asia from ancient times to coat the surface of objects. It is a durable material, but is known to be weak to ultraviolet light (UV). Here, to understand the deterioration characteristics of Asian lacquer due to UV, the changes were analyzed using ultraviolet photometry, IR, and pyrolysis/GC/MS (pyrolysis/GC/MS), after exposing the lacquer coating film to UV (<i>λ</i>= 340 nm). In the ultraviolet photometry, the surface exposed to UV showed fluorescence. In IR analysis, the powder sample showed little change after exposure to UV, but on the surface, C = O groups increased, while C―H groups decreased significantly. Analysis with pyrolysis/GC/MS revealed that the composition of organic acid increased significantly. Carboxylic acids having 9 or less carbon atoms and dicarboxylic acids were significantly increased compared to carboxylic acid having 16 carbon atoms. In addition, urushiol with the oxidized side chain was also increased. This shows that the penetration depth of UV is the limiting factor for deterioration, and that the deterioration of lacquer due to UV proceeds with the destruction of carbon–carbon single and double bonds and the subsequent formation of carboxylic acid.

Theoretical studies on the photo protective mechanism of curcuminoids

In this work, the deactivation pathways of curcuminoids after photoexcitation was studied by employing density functional theory to explore their UVA radiation screening capacity. A comprehensive computational characterization of the excited-state processes of curcumin, demethoxycurcumin, and bis-demethoxycurcumin was done. The molecules exist in diketo and enol forms which are in equilibrium and interconvertible through keto-enol tautomerism. The enolic forms of each of the studied molecules have eight geometric cis–trans isomers as a result of torsion rotation about three different carbon–carbon double bonds across the aliphatic chain. For each geometric isomer, sixteen possible rotamers are found to exist due to rotation about five different carbon–carbon single bond rotations, also across the skeleton of the aliphatic chain. Upon photoexcitation, the studied molecules follow three main pathways of radiationless decay: (a) rotamerism and interconversion between rotamers of comparable energies which are in equilibrium, (b) interconversion between the cis–trans geometrical isomers where an efficient vibrational relaxation path is formed at ∼90° during torsion rotation about carbon–carbon double bond, and (c) excited state intramolecular proton transfer in a single O–H stretching vibration through a cyclic intramolecular hydrogen bonded ring formed at the centre of the molecule giving back the original structure. The absorption and emission spectra of the molecules were also simulated where the theoretically obtained absorption and emission maxima are close to the reported experimental values.

Multilevel Encoding Physically Unclonable Functions Based on The Multispecies Structure in Diamonds

AbstractThe multilevel encoding (MLE) scheme is an effective method for improving the anticounterfeiting encryption capabilities of physically unclonable functions (PUFs). However, owing to the correlation between encoding layers, the encoding capacity (EC) is difficult to improve by orders of magnitude. Herein, four noncorrelated structures in the diamond crystal structure (carbon–carbon single bond, defect luminescence structures, spin structures, and electron energy distribution structures) are considered for MLE. First, the microdiamonds containing nitrogen‐vacancy (NV) color centers are embedded into polydimethylsiloxane (PDMS) to fabricate PUFs. Using an optical imaging system, four codable images of four noncorrelated structures are read. The noncorrelation of the four‐level encoding structure is verified by calculating the Hamming distance (0.496 ± 0.02). The results show that EC exponentially improves to 24×10 000/(100 pixels)2. Furthermore, the encoding method based on the energy level does not depend on physical structure parameters, such as the size and position of the spin structure. Thus, it is protected from structural modeling attacks, resulting in high security. Moreover, PUF labels based on PDMS flexible substrates can be employed for various flexible applications. In the proposed scheme, the information is encrypted by a four‐level two‐dimensional (2D) barcode and decoded by self‐developed PUF authentication software. The proposed scheme presents a way for developing next‐generation PUFs with super‐high EC.

A coumarin hydrazone appended rotatable phenolic scaffold as fluorescent chemosensor for Ag+ ions and its bio imaging applications

A coumarin hydrazone-phenol conjugate, COH4 was designed, synthesized and utilized for the cation sensing studies by fluorimetry studies. The synthesized chemosensor was completely characterized by the usual spectroscopic and analytical studies. The COH4 receptor was examined for the detection of metal ions, in which it had a noticeable blue shifted fluorescence enhancement for Ag+ ions. Upon binding towards Ag+ ions, the photoinduced electron transfer (PET) process is inhibited via intramolecular charge transfer (ICT) process assisted by the arrest of the carbon–carbon single bond rotation. The binding stoichiometry of COH4 + Ag+ complexation ratio is noted to be 1:2, which was further confirmed by jobs plot method. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.41 µM and 0.13 µM respectively. Moreover, COH4 was successfully utilized for the practical applications of Ag+ ion detection in bacterial cell lines.

Direct Synthesis of Fluorinated Carbon Materials via a Solid‐State Mechanochemical Reaction Between Graphite and PTFE

AbstractFluorinated carbon materials (FCMs) have received significant attention, because of their exceptional stability, which is associated with the strong C‐F bonding, the strongest among carbon single bonds. However, the fluorination of carbon materials requires extremely toxic and moisture‐sensitive reagents, which makes it inapplicable for practical uses. Here, a straightforward and relatively safe method are reported for the scalable synthesis of FCMs, by mechanochemical depolymerization of polytetrafluoroethylene (PTFE) and fragmentation of graphite. The resultant FCMs are evaluated as anode materials for lithium‐ion batteries (LIBs). An optimized FCM delivered capacities as high as 951.6 and 329.3 mAh g −1 at 0.05 and 10 A g −1, respectively. It also demonstrated capacity retention as high as 76.6% even after 1000 cycles at 2.0 A g −1.

Aquathermolysis of heavy oil using a mixed nickel-oxide/iron-oxide catalyst: Effects induced by crystal phase of iron oxide

Nickel and iron compounds have garnered attention as catalysts for upgrading heavy oil via aquathermolysis. However, research on the performance of bimetallic oxide catalysts in aquathermolysis remains limited. To that end, NiO–Fe2O3 catalysts were prepared in this study using a simple physical mixing method and employed in heavy-oil aquathermolysis to investigate the synergistic relationship between NiO and Fe2O3. The product distributions and quality were systematically analyzed, and an asphaltene upgrading index was introduced to evaluate the coke-inhibiting ability of the catalysts. Interestingly, the crystal structure of Fe2O3 in the NiO–Fe2O3 catalysts remarkably influenced the catalytic performance. Particularly, the NiO/α-Fe2O3 catalyst with highly crystalline α-Fe2O3 considerably prolonged the coke induction period up to ∼30% of residue conversion and induced a high deasphalted oil yield from asphaltenes. Moreover, NiO/α-Fe2O3 improved the product quality by removing impurities (S, N, and O) and increasing the H/C ratio. However, the liquid product distribution remained dependent on the thermal cracking effect, as the NiO–Fe2O3 catalysts did not participate in C–C cleavage. Deuterium tracing was performed to elucidate the hydrogen-transfer mechanism in catalytic aquathermolysis. The formation of deuterium–carbon single bonds from catalytic aquathermolysis was three times higher than that in the absence of the catalyst, confirming that NiO/α-Fe2O3 facilitated hydrogen transfer from water molecules to hydrocarbons during aquathermolysis.

Synthesis, Characterization, Antioxidant and Biological Activities of Polyglucose Based Hydrazides and their Metal Nano Composites

The interaction of carbon (C) and nitrogen (N) single, double, and triple bonds with an aliphatic and aromatic carbon skeleton is widely used for medications and polymer synthesis. Many scientists have employed these compounds as target structures to determine their diverse chemical synthesis and use in various fields. The synthesis of polyglucose-hydrazide metal nanocomposites is a novel area of chemistry research. Polyglucose metal nanocomposites are widely used for drug delivery to target cancer and other lethal diseases. The major interests of this research were to synthesize, characterize, and find out the antibacterial properties of hydroxyl groups present in polyglucose-hydrazide metal nanocomposites. These nanocomposites were synthesized by acidification, esterification, and hydrazination of glucose and mixing of metal nanoparticles with polyglucose, respectively. The characterization of proposed nanocomposites was done by using scanning electron microscopy (SEM) and, energy dispersive X-Ray (EDX) spectroscopy. The biological activities of polyglucose-hydrazides cobalt, silver, and iron nano-composites were tested against Xanthomonas campestris malvacearum (a bacterial strain) by agar disc diffusion method. Amongst all, polyglucose-hydrazides cobalt nanocomposite yielded the highest antibacterial activity. Silver and iron nanocomposites also showed good activity. These results indicate that the antibacterial activities of metal nanoparticles are remarkably enhanced by combining with polyglucose hydrazide. These polyglucose-hydrazide metal nanocomposites have great potential as biocompatible antibacterial agents.

First theoretical engineering of robust C-C single bond-based acceptor materials for efficient organic photovoltaics

Organic photovoltaics with prolonged photo stability need further attention from researchers around the world. In this report, a new series of photostable acceptor molecules for possible applications in organic photovoltaics have been presented. In these molecules, a robust carbon–carbon single bond initiates a unique N---S covalent interaction that enhances the photo and thermal stability of the studied designed systems. In this regard, density functional theory (DFT) and time-dependent density functional theory (TD-DFT) have been employed at different appropriate levels. The position of frontier molecular orbitals (FMOs) reduces the band gap with maximum charge transportation. Further, the modeled systems have also shown light absorption in the near infra-red (IR) region with easy excitation of the exciton. High electron and hole mobilities towards the respective electrodes are also noted for the studied systems (SSFL-1 to SSFL-4). Finally, enhanced fill factor (FF%) along with high power conversion efficiency (PCE) of 21.36 % is noted in the designed systems.

One‐Pot Construction of Sulfonyl Benzonorcaradienes

One-pot stereoselective synthesis of strained sulfonyl benzonorcaradienes proceeds through base-mediated tandem annulation of o-bis-sulfonylmethyl arenes with diversified chalcones (α,β-unsaturated carbonyls) via intermolecular desulfonylative cyclopropanation, followed by intramolecular condensation. A plausible mechanism is proposed and discussed. The proposed synthetic route forms two carbon–carbon single (C–C) bonds and one carbon–carbon double (C=C) bond.

Rotational Isomerization of Carbon-Carbon Single Bonds in Ethyl Radical Derivatives in a Room-Temperature Solution.

The rotational isomerization of 1,2-disubstituted ethyl radical derivatives, reaction intermediates often found in the reaction of 1,2-disubstituted ethane derivatives, has never been measured because of their short lifetime and ultrafast rotation. However, the rotational time constant is critical for understanding the detailed reaction mechanism involving these radicals, which determine the stereoisomers of compounds produced via the intermediates. Using time-resolved infrared spectroscopy, we found that the CF2BrCF2 radical in a CCl4 solution rotationally isomerizes with a time constant of 47 ± 5 ps at 280 ± 2 K. From this value and the rotational barrier heights of related compounds, CH3CH2 and CH3CH2CHCH3 radicals in CCl4 were estimated to rotationally isomerize within 1 ps at 298 K, considerably faster than ethane and n-butane, which rotationally isomerize with time constants of 1.8 and 81 ps, respectively. The time constant for the rotational isomerization was similar to that calculated using transition state theory with a transmission coefficient of 0.75.

Effect of pH and Ozone Dosage on Characteristic of Ozonated Rice Bran Oil


 
 
 The influence of pH and ozone dose, as well as ascorbic acid addition during the ozonation process, on the properties of Rice Bran Oil (RBO), was examined. The spectroscopic characteristic of RBO before and after ozonation was analysis directly, while the physicochemical property was assessed by density, viscosity, pH, iodine number, peroxide number, and acid number. With an increase in ozone dose, the carbon double bond in the RBO reduced. The primary product of the ozonation process is ozonide, and one of its by-products is 1,2,4-trioxolane, which contains a carbon single bond as a result of the ozonation reaction. According to this study, the pH 4 and ozone dose of 440 mg O3/L are the optimum parameters utilized in the RBO ozonation process. RBO's density and viscosity were 0.918 g/mL and 0.042 cP, respectively, at these conditions. Its iodine number, acid number, and peroxide number were also 3.173 g/g RBO, 2.3 mg NaOH/g RBO, and 55 mgeq/kg, respectively. Analyses of gas chromatography and nuclear magnetic resonance spectroscopy revealed the presence of 1,2,4-trioxolane. Ozone dosage is critical because greater ozone concentrations place RBO in a saturated state, making the 1,2,4-trioxolane unstable and readily destroyed, whereas lower temperatures can avoid this.
 
 

One‐pot Construction of Dibenzooxabicyclo[5.5.0]dodecanes

AbstractUnder the open‐vessel atmosphere conditions, the one‐pot synthesis of bis‐sulfonyl dibenzooxabicyclo[5.5.0]dodecanes was developed by double substitution of 1,3‐dichloroacetone with arenesulfinic acid sodium salts, and C‐ and O‐alkylation of the resulting 1,3‐bis‐sulfonylacetones with 2 equivalents of o‐bis(bromomethyl)arenes. A plausible mechanism is proposed and discussed. This high‐yielding protocol provides an intermolecular substitution and an intramolecular ring‐closure via the formations of three carbon−carbon single (C−C) bonds, two carbon−sulfur single (C−S) bonds, and one carbon−oxygen single (C−O) bond.magnified image

Ultralong C(sp3)–C(sp3) Single Bonds Shortened and Stabilized by London Dispersion

AbstractA carbon–carbon (C–C) single bond longer than 1.7 Å shows unique bond flexibility, even though a C–C single bond is typically rigid and robust. We report here that the bond length of flexible C–C single bonds surrounded by bulky alkyl groups in novel hexaphenylethane-type hydrocarbons might be affected by weak noncovalent interactions, such as London dispersion. Thanks to London dispersion, an ultralong and flexible C–C single bond exhibits an obvious bond contraction. X-ray analyses and Raman spectroscopy provided direct information regarding the bond length and strength, whereas density functional theory calculations explained the bond contraction driven by London dispersion. The change in bond length of an extremely elongated flexible C–C bond would be a good probe for quantifying weak interactions that are usually difficult to detect.

Genome-Wide Characterization and Expression Analysis of Fatty acid Desaturase Gene Family in Poplar.

Fatty acid desaturases (FADs) modulate carbon–carbon single bonds to form carbon–carbon double bonds in acyl chains, leading to unsaturated fatty acids (UFAs) that have vital roles in plant growth and development and their response to environmental stresses. In this study, a total of 23 Populus trichocarpa FAD (PtFAD) candidates were identified from the poplar genome and clustered into seven clades, including FAB2, FAD2, FAD3/7/8, FAD5, FAD6, DSD, and SLD. The exon–intron compositions and conserved motifs of the PtFADs, clustered into the same clade, were considerably conserved. It was found that segmental duplication events are predominantly attributable to the PtFAD gene family expansion. Several hormone- and stress-responsive elements in the PtFAD promoters implied that the expression of the PtFAD members was complicatedly regulated. A gene expression pattern analysis revealed that some PtFAD mRNA levels were significantly induced by abiotic stress. An interaction proteins and gene ontology (GO) analysis indicated that the PtFADs are closely associated with the UFAs biosynthesis. In addition, the UFA contents in poplars were significantly changed under drought and salt stresses, especially the ratio of linoleic and linolenic acids. The integration of the PtFAD expression patterns and UFA contents showed that the abiotic stress-induced PtFAD3/7/8 members mediating the conversion of linoleic and linolenic acids play vital roles in response to osmotic stress. This study highlights the profiles and functions of the PtFADs and identifies some valuable genes for forest improvements.

Study of the Electronic and Spectrum Properties for a Medication Hydroxychloroquine

Calculated the electronics and vibrational properties of the medicine hydroxy-chloroquine nanoparticles based on the fitting of their UV–vis spectra, transmittable, IR, Raman spectrum, Electronic circular dichroism (ECD) and HOMO and LUMO, These properties were theoretically studied using Gaussian 09 program. The result shows the stability of hydroxy-chloroquine. The longer wavelength that (500 nm) means high absorbance and less energy. Transmittable, the highest transmittable value in the region is (0 - 3000cm-1) and (2600-1250 cm-1) is offset by the lowest absorption here, the sample has good transparency characteristics at this region. Infrared spectrum, the area (2900 cm-1) it is for the carbon and hydrogen Single bond C-H, and hybridization type sp3. Raman scattering, electronic effect on bond C-H in the area (2800 cm-1) is very large and this bond type stretch. Electronic circular dichroism (ECD), when finding the sign of one or more bands can be an AC limitation. A positive skew angle is foretelling to become connected CD of the low-lying p−p* move at about 600 nm; certainly, for a negative CD, can find a negative angle is expected.