keyword
https://read.qxmd.com/read/38488676/effect-of-benzo-annelation-on-triplet-state-energies-in-polycyclic-conjugated-hydrocarbons%C3%A2
#1
JOURNAL ARTICLE
Slavko Radenković, Slađana Đorđević, Marijana Nikolendžić
In a series of earlier studies, the effect of benzo-annelation was found to be a useful tool for tuning the aromaticity in polycyclic conjugated compounds to desired level. In this work we studied the (anti)aromaticity of benzo-annelated derivatives of three conjugated hydrocarbons (anthracene, fluoranthene and biphenylene) in their lowest lying singlet (S0) and triplet (T1) states by means of the energy effect (ef), harmonic oscillator model of aromaticity (HOMA), multicentre delocalization indices (MCI), magnetically induced current densities (MICDs) and nucleus independent chemical shifts (NICS)...
March 15, 2024: Chemistry: a European Journal
https://read.qxmd.com/read/38482736/catalytic-ring-expanding-difluorination-an-enantioselective-platform-to-access-%C3%AE-%C3%AE-difluorinated-carbocycles
#2
JOURNAL ARTICLE
Louise Ruyet, Christoph Roblick, Joel Häfliger, Zi-Xuan Wang, Tobias Jürgen Stoffels, Constantin Daniliuc, Ryan Gilmour
Cyclic β,β-difluoro-carbonyl compounds have a venerable history as drug discovery leads, but limitations in the synthesis arsenal continue to impede chemical space exploration. This challenge is particularly acute in the arena of fluorinated medium rings where installing the difluoromethylene unit subtly alters the ring conformation by expanding the internal angle (∠C-CF2-C > ∠C-CH2-C): this provides a handle to modulate physicochemistry (e.g. pKa). To reconcile this disparity, a highly modular ring expansion has been devised that leverages simple α,β-unsaturated esters and amides, and processes them to one-carbon homologated rings with concomitant geminal difluorination (6 to 10 membered rings, up to 95% yield)...
March 14, 2024: Angewandte Chemie
https://read.qxmd.com/read/38444397/palladium-catalyzed-cascade-heck-coupling-and-allylboration-of-iododiboron-compounds-via-diboryl-radicals
#3
JOURNAL ARTICLE
Yi Wei, Xiao-Yu Xie, Jiabin Liu, Xiaoxiao Liu, Bo Zhang, Xin-Yi Chen, Shi-Jun Li, Yu Lan, Kai Hong
Geminal bis(boronates) are versatile synthetic building blocks in organic chemistry. The fact that they predominantly serve as nucleophiles in the previous reports, however, has restrained their synthetic potential. Herein we disclose the ambiphilic reactivity of α-halogenated geminal bis(boronates), of which the first catalytic utilization was accomplished by merging a formal Heck cross-coupling with a highly diastereoselective allylboration of aldehydes or imines, providing a new avenue for rapid assembly of polyfunctionalized boron-containing compounds...
March 6, 2024: Angewandte Chemie
https://read.qxmd.com/read/38441063/conformational-analysis-explores-the-role-of-electrostatic-nonclassical-cf%C3%A2-%C3%A2-%C3%A2-hc-hydrogen-bonding-interactions-in-selectively-halogenated-cyclohexanes
#4
JOURNAL ARTICLE
Mengfan He, Bruno A Piscelli, Rodrigo A Cormanich, David O'Hagan
The conformational equilibria of selectively halogenated cyclohexanes are explored both experimentally (VT-NMR) for 1,1,4,-trifluorocyclohexane 7 and by computational analysis (M06-2X/aug-cc-pVTZ level), with the latter approach extending to a wider range of more highly fluorinated cyclohexanes. Perhaps unexpectedly, 7 ax is preferred over the 7 eq conformation by Δ G = 1.06 kcal mol-1 , contradicting the accepted norm for substituents on cyclohexanes. The axial preference is stronger again in 1,1,3,3,4,5,5,-heptafluorocyclohexane 9 (Δ G = 2...
March 5, 2024: Journal of Organic Chemistry
https://read.qxmd.com/read/38432357/identification-of-atalkbh1a-and-atalkbh1d-as-dna-n-6-adenine-demethylases-in-arabidopsis-thaliana
#5
JOURNAL ARTICLE
Donghao Li, Juan Du, Min Gao, Chongsheng He
DNA N6 -methyladenine (6mA) has recently been discovered as a novel DNA modification in animals and plants. In mammals, AlkB homolog 1 (ALKBH1) has been identified as a DNA 6mA demethylase. ALKBH1 tightly controls the DNA 6mA methylation level of mammalian genomes and plays important role in regulating gene expression. DNA 6mA methylation has also been reported to exist in plant genomes, however, the plant DNA 6mA demethylases and their function remain largely unknown. Here we identify homologs of ALKBH1 as DNA 6mA demethylases in Arabidopsis...
March 1, 2024: Plant Science: An International Journal of Experimental Plant Biology
https://read.qxmd.com/read/38421064/correlated-pair-ansatz-with-a-binary-tree-structure
#6
JOURNAL ARTICLE
Rishab Dutta, Fei Gao, Armin Khamoshi, Thomas M Henderson, Gustavo E Scuseria
We develop an efficient algorithm to implement the recently introduced binary tree state (BTS) ansatz on a classical computer. BTS allows a simple approximation to permanents arising from the computationally intractable antisymmetric product of interacting geminals and respects size-consistency. We show how to compute BTS overlap and reduced density matrices efficiently. We also explore two routes for developing correlated BTS approaches: Jastrow coupled cluster on BTS and linear combinations of BT states. The resulting methods show great promise in benchmark applications to the reduced Bardeen-Cooper-Schrieffer Hamiltonian and the one-dimensional XXZ Heisenberg Hamiltonian...
February 28, 2024: Journal of Chemical Physics
https://read.qxmd.com/read/38418405/redesigned-nylon-6-variants-with-enhanced-recyclability-ductility-and-transparency
#7
JOURNAL ARTICLE
Jun-Jie Tian, Xiaoyang Liu, Liwei Ye, Zhen Zhang, Ethan C Quinn, Changxia Shi, Linda J Broadbelt, Tobin J Marks, Eugene Y-X Chen
Geminal (gem-) disubstitution in heterocyclic monomers is an effective strategy to enhance polymer chemical recyclability by lowering their ceiling temperatures. However, the effects of specific substitution patterns on the monomer's reactivity and the resulting polymer's properties are largely unexplored. Here we show that, by systematically installing gem-dimethyl groups onto ɛ-caprolactam (monomer of nylon 6) from the α to ε positions, both the redesigned lactam monomer's reactivity and the resulting gem-nylon 6's properties are highly sensitive to the substitution position, with the monomers ranging from non-polymerizable to polymerizable and the gem-nylon properties ranging from inferior to far superior to the parent nylon 6...
February 28, 2024: Angewandte Chemie
https://read.qxmd.com/read/38405523/geminal-dicationic-ionic-liquids-gdils-and-their-adsorption-on-graphene-nanoflakes
#8
JOURNAL ARTICLE
Mehdi Shakourian-Fard, Hamid Reza Ghenaatian, Ganesh Kamath
In this work, the configuration and stability of 15 geminal dicationic ionic liquids (GDILs) and their adsorption mechanism on the graphene nanoflake (GNF) are investigated using the density functional theory (DFT) method. We find that the interactions of dications ([DAm]+ , [DIm]+ , [DImDm]+ , [DPy]+ , and [DPyrr]+ )) are stabilized near the anions ([BF4 ]- , [PF6 ]- , and [Tf2 N]- ) in the most stable configurations of GDILs through electrostatic interactions, van der Waals (vdW) interactions, and hydrogen bonding (H-bonding)...
February 20, 2024: ACS Omega
https://read.qxmd.com/read/38367253/direct-synthesis-of-tertiary-phosphines-via-alkoxide-mediated-deborylative-phosphination-of-organoboronates
#9
JOURNAL ARTICLE
Huaxing Sun, Jing Wang, Zihang Du, Kun Zhang, Jiefeng Hu, Su Jing
The direct transformation of alkylboron has emerged as a versatile and powerful methodology for creating carbon-carbon and carbon-heteroatom bonds. However, its potential application in the formation of carbon and phosphorus remains unexplored. In this study, we present an alkoxide base-promoted reaction system that enables deborylative phosphination of benzylic organoboronates and geminal bis(boronates) via selective C-B bond cleavage. This approach allows for the synthesis of valuable tertiary phosphines in good yields under mild conditions...
February 17, 2024: Organic Letters
https://read.qxmd.com/read/38364001/charge-photogeneration-dynamics-in-non-fullerene-polymer-solar-cells-with-fluorinated-and-non-fluorinated-acceptors
#10
JOURNAL ARTICLE
Zekai Cai, Rong Hu, Zijie Xiao, Junyi Feng, Xianshao Zou, Guanzhao Wen, Geng Dong, Wei Zhang
In this work, charge photogeneration and recombination processes of PM6:IDIC-4F and PM6:IDIC blend films were investigated by the steady-state and time-resolved spectroscopies, as well as the time-dependent density functional theory calculations. The peaks in absorption and photoluminescence (PL) spectra of IDIC and IDIC-4F solutions were assigned by combining the experiment and the simulation of UV-vis absorption and PL spectra. For neat acceptor films, the exciton diffusion length of neat IDIC and IDIC-4F films was estimated as ∼28...
February 21, 2024: Journal of Chemical Physics
https://read.qxmd.com/read/38362166/validating-a-molecular-clock-for-nudibranchs-no-fossils-to-the-rescue
#11
JOURNAL ARTICLE
Kara K S Layton, Nerida G Wilson
Time calibrated phylogenies are typically reconstructed with fossil information but for soft-bodied marine invertebrates that lack hard parts, a fossil record is lacking. In these cases, biogeographic calibrations or the rates of divergence for related taxa are often used. Although nudibranch phylogenies have advanced with the input of molecular data, no study has derived a divergence rate for this diverse group of invertebrates. Here, we use an updated closure date for the Isthmus of Panama (2.8 Ma) to derive the first divergence rates for chromodorid nudibranchs using multigene data from a geminate pair with broad phylogeographic sampling...
February 2024: Ecology and Evolution
https://read.qxmd.com/read/38335449/synthesis-quality-control-and-bench-to-bed-translation-of-a-new-68-ga-ga-labeled-nota-conjugated-bisphosphonate-for-imaging-skeletal-metastases-by-positron-emission-tomography
#12
JOURNAL ARTICLE
Sudipta Chakraborty, Sucheta Chatterjee, Rubel Chakravarty, Haldhar D Sarma, Raviteja Nanabala, Dibakar Goswami, Ajith Joy, Maroor Raghavan Ambikalamajan Pillai
Background : Early detection of skeletal metastasis is of great interest to determine the prognosis of cancer. Positron emission tomography-computed tomography (PET-CT) imaging provides a better temporal and spectral resolution than single photon emission computed tomography-computed tomography (SPECT-CT) imaging, and hence is more suitable to detect small metastatic lesions. Although [18 F]NaF has been approved by U.S. FDA for a similar purpose, requirement of a medical cyclotron for its regular formulation restricts its extensive utilization...
February 9, 2024: Cancer Biotherapy & Radiopharmaceuticals
https://read.qxmd.com/read/38330247/divergent-geminal-alkynylation-allylation-and-acylation-allylation-of-carbenes-evolution-and-roles-of-two-transition-metal-catalysts
#13
JOURNAL ARTICLE
Hongda Chen, Wenhan Yang, Jinyu Zhang, Bin Lu, Xiaoming Wang
Cooperative bimetallic catalysis to access novel reactivities is a powerful strategy for reaction development in transition-metal-catalyzed chemistry. Particularly, elucidation of the evolution of two transition-metal catalysts and understanding their roles in dual catalysis are among the most fundamental goals for bimetallic catalysis. Herein, a novel three-component reaction of a terminal alkyne, a diazo ester, and an allylic carbonate was successfully developed via cooperative Cu/Rh catalysis with Xantphos as the ligand, providing a highly efficient strategy to access 1,5-enynes with an all-carbon quaternary center that can be used as immediate synthetic precursors for complex cyclic molecules...
February 8, 2024: Journal of the American Chemical Society
https://read.qxmd.com/read/38323917/descriptor-based-volcano-relations-predict-single-atoms-for-hydroxylamine-electrosynthesis
#14
JOURNAL ARTICLE
Rong Yang, Yuting Wang, Hongjiao Li, Jin Zhou, Zeyuan Gao, Cuibo Liu, Bin Zhang
Hydroxylamine (NH2OH) is an important feedstock in fuels, pharmaceuticals, and agrochemicals. Nanostructured electrocatalysts drive green electrosynthesis of hydroxylamine from nitrogen oxide species in water. However, current electrocatalysts still suffer from low selectivity and manpower-consuming trial-and-error modes, leaving unclear selectivity/activity origins and a lack of catalyst design principles. Herein, we theoretically analyze key determinants of selectivity/activity and propose the adsorption energy of NHO (Gad(*NHO)) as a performance descriptor...
February 7, 2024: Angewandte Chemie
https://read.qxmd.com/read/38321703/nickel-catalyzed-selective-arylation-of-geminal-dinitriles-direct-access-to-%C3%AE-cyano-carbonyl-compounds
#15
JOURNAL ARTICLE
Anwesha Bhattacharya, Subhashini V Subramaniam, Nagesh Kumar Kandukuri, Saravanan Peruncheralathan
The catalytic intermolecular arylation of disubstituted geminal dinitriles with in situ generated arylnickel complexes is disclosed. This method efficiently provides various all-carbon substituted α-cyanocarbonyl compounds without additives and an inert atmosphere. It also demonstrates the arylation of R -BINOL and S -BINOL derived geminal dinitriles, preserving optical purity. Mechanistic studies proved that the in situ generated organonickel complex is involved in arylation.
February 6, 2024: Journal of Organic Chemistry
https://read.qxmd.com/read/38308376/%C3%AE-boryl-carbanions-the-influence-of-geminal-heteroatoms-in-c-c-bond-formation
#16
REVIEW
Elena Fernández
The wide applications of alpha-boryl carbanions in selective coupling with organohalides, imines/carbonyls and conjugated unsaturated substrates has become an interesting tool for organic synthesis. Strategically, the inclusion of heteroatoms, such as Si, S, N, F, Cl, Br and I in the alpha position opens a new venue towards multifunctionalities in molecular design. Here, a conceptual and practical view on powerful carbanions, containing α-silicoboron, α-thioboron, α-haloboron and α-aminoboron is given, as well as a prespective on their efficient application for selective electrophilic trapping...
February 2, 2024: Chemical Record: An Official Publication of the Chemical Society of Japan ... [et Al.]
https://read.qxmd.com/read/38295270/structural-biochemical-and-bioinformatic-basis-for-identifying-radical-sam-cyclopropyl-synthases
#17
JOURNAL ARTICLE
Yi Lien, Jake C Lachowicz, Aigera Mendauletova, Cynthia Zizola, Thacien Ngendahimana, Anastasiia Kostenko, Sandra S Eaton, John A Latham, Tyler L Grove
The importance of radical S-adenosyl-l-methionine (RS) enzymes in the maturation of ribosomally synthesized and post-translationally modified peptides (RiPPs) continues to expand, specifically for the RS-SPASM subfamily. We recently discovered an RS-SPASM enzyme that installs a carbon-carbon bond between the geminal methyls of valine residues, resulting in the formation of cyclopropylglycine (CPG). Here, we sought to define the family of cyclopropyl (CP) synthases because of the importance of cyclopropane scaffolds in pharmaceutical development...
January 31, 2024: ACS Chemical Biology
https://read.qxmd.com/read/38284335/geminal-bimetallic-coordination-of-a-carbone-to-main-group-and-transition-metals
#18
JOURNAL ARTICLE
Akachukwu D Obi, Chun-Lin Deng, Andrew J Alexis, Diane A Dickie, Robert J Gilliard
The non-bonding carbone lone pair in geometrically-constrained antimony and bismuth carbodiphosphorane complexes readily complexed AuCl to afford rare examples of geminal bimetallic carbone coordination featuring a main-group metal.
January 29, 2024: Chemical Communications: Chem Comm
https://read.qxmd.com/read/38268636/fluke-of-fusion-and-concrescence-in-maxillary-deciduous-incisors-a-case-report
#19
Vipin Ahuja, Arunima Pathak
AIM: The aim of this paper is to report a rare case in a 6-year-old girl where two dental anomalies, fusion and concrescence, coexisted in primary dentition. This highlights the significance of the accurate early diagnosis of these dental anomalies. BACKGROUND: Odontogenic anomalies are frequently encountered in dental practice. These anomalies can occur due to abnormalities during the differentiation stage and may lead to aberrations in hard tissue formation. Some of the uncommon and unusual dental anomalies of number and form include fusion, gemination, and concrescence...
November 2023: International Journal of Clinical Pediatric Dentistry
https://read.qxmd.com/read/38206657/the-association-between-linguistic-characteristics-of-physicians-communication-and-their-economic-returns-mixed-method-study
#20
JOURNAL ARTICLE
Shuang Geng, Yuqin He, Liezhen Duan, Chen Yang, Xusheng Wu, Gemin Liang, Ben Niu
BACKGROUND: Web-based health care has the potential to improve health care access and convenience for patients with limited mobility, but its success depends on active physician participation. The economic returns of internet-based health care initiatives are an important factor that can motivate physicians to continue their participation. Although several studies have examined the communication patterns and influences of web-based health consultations, the correlation between physicians' communication characteristics and their economic returns remains unexplored...
January 11, 2024: Journal of Medical Internet Research
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