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991.
Xiao Xiao Ivan Kurganskii Partha Maity Jianzhang Zhao Xiao Jiang Omar F. Mohammed Matvey Fedin 《Chemical science》2022,13(45):13426
Spiro rhodamine (Rho)-naphthalenediimide (NDI) electron donor–acceptor orthogonal dyads were prepared to generate a long-lived charge separation (CS) state based on the electron spin control approach, i.e. to form the 3CS state, not the 1CS state, to prolong the CS state lifetime by the electron spin forbidden feature of the charge recombination process of 3CS → S0. The electron donor Rho (lactam form) is attached via three σ bonds, including two C–C and one N–N bonds (Rho-NDI), or an intervening phenylene, to the electron acceptor NDI (Rho-Ph-NDI and Rho-PhMe-NDI). Transient absorption (TA) spectra show that fast intersystem crossing (ISC) (<120 fs) occurred to generate an upper triplet state localized on the NDI moiety (3NDI*), and then to form the CS state. For Rho-NDI in both non-polar and polar solvents, a long-lived 3CS state (lifetime τ = 0.13 μs) and charge separation quantum yield (ΦCS) up to 25% were observed, whereas for Rho-Ph-NDI (τT = 1.1 μs) and Rho-PhMe-NDI (τT = 2.0 μs), a low-lying 3NDI* state was formed by charge recombination (CR) in n-hexane (HEX). In toluene (TOL), however, CS states were observed for Rho-Ph-NDI (0.37 μs) and Rho-PhMe-NDI (0.63 μs). With electron paramagnetic resonance (EPR) spectra, weak electronic coupling between the Rho and NDI moieties for Rho-NDI was proved. Time-resolved EPR (TREPR) spectra detected two transient species including NDI-localized triplets (formed via SOC-ISC) and a 3CS state. The CS state of Rho-NDI features the largest dipolar interaction (|D| = 184 MHz) compared to Rho-Ph-NDI (|D| = 39 MHz) and Rho-PhMe-NDI (|D| = 41 MHz) due to the smallest distance between Rho and NDI moieties. For Rho-NDI, the time-dependent e,a → a,e phase change of the CS state TREPR spectrum indicates that the long-lived CS state is based on the electron spin control effect.Spiro compact rhodamine-naphthalenediimide electron donor–acceptor dyads show a long-lived charge separated state (lifetime: 0.72 μs) based on the electron spin control effect were reported. 相似文献
992.
Carlos Velzquez-Carriles María Esther Macías-Rodríguez Omar Ramírez-Alvarado Rosa Isela Corona-Gonzlez Adriana Macías-Lamas Ismael García-Vera Adriana Cavazos-Garduo Zuamí Villagrn Jorge Manuel Silva-Jara 《Molecules (Basel, Switzerland)》2022,27(19)
Due to the current concerns against opportunistic pathogens and the challenge of antimicrobial resistance worldwide, alternatives to control pathogen growth are required. In this sense, this work offers a new nanohybrid composed of zinc-layered hydroxide salt (Simonkolleite) and thymol for preventing bacterial growth. Materials were characterized with XRD diffraction, FTIR and UV–Vis spectra, SEM microscopy, and dynamic light scattering. It was confirmed that the Simonkolleite structure was obtained, and thymol was adsorbed on the hydroxide in a web-like manner, with a concentration of 0.863 mg thymol/mg of ZnLHS. Absorption kinetics was described with non-linear models, and a pseudo-second-order equation was the best fit. The antibacterial test was conducted against Escherichia coli O157:H7 and Staphylococcus aureus strains, producing inhibition halos of 21 and 24 mm, respectively, with a 10 mg/mL solution of thymol–ZnLHS. Moreover, biofilm formation of Pseudomonas aeruginosa inhibition was tested, with over 90% inhibition. Nanohybrids exhibited antioxidant activity with ABTS and DPPH evaluations, confirming the presence of the biomolecule in the inorganic matrix. These results can be used to develop a thymol protection vehicle for applications in food, pharmaceutics, odontology, or biomedical industries. 相似文献
993.
Abdelsattar M. Omar Anfal S. Aljahdali Martin K. Safo Gamal A. Mohamed Sabrin R. M. Ibrahim 《Molecules (Basel, Switzerland)》2023,28(1)
Cannabinoid receptor ligands are renowned as being therapeutically crucial for treating diverse health disorders. Phenylspirodrimanes are meroterpenoids with unique and varied structural scaffolds, which are mainly reported from the Stachybotrys genus and display an array of bioactivities. In this work, 114 phenylspirodrimanes reported from Stachybotrys chartarum were screened for their CB2 agonistic potential using docking and molecular dynamic simulation studies. Compound 56 revealed the highest docking score (−11.222 kcal/mol) compared to E3R_6KPF (native agonist, gscore value −12.12 kcal/mol). The molecular docking and molecular simulation results suggest that compound 56 binds to the putative binding site in the CB2 receptor with good affinity involving key interacting amino acid residues similar to that of the native ligands, E3R. The molecular interactions displayed π–π stacking with Phe183 and hydrogen bond interactions with Thr114, Leu182, and Ser285. These findings identified the structural features of these metabolites that might lead to the design of selective novel ligands for CB2 receptors. Additionally, phenylspirodrimanes should be further investigated for their potential as a CB2 ligand. 相似文献
994.
The objective of this paper is to study oscillation of fourth-order neutral differential equation. By using Riccati substitution and comparison technique, new oscillation conditions are obtained which insure that all solutions of the studied equation are oscillatory. Our results complement some known results for neutral differential equations. An illustrative example is included. 相似文献
995.
Mengni Zhou Omar R. Yehia Christopher B. Reuter Christopher M. Burger Yuki Murakami Hao Zhao Yiguang Ju 《Proceedings of the Combustion Institute》2021,38(2):2351-2360
The kinetic effects of NO addition on the flame dynamics and burning limits of n-dodecane cool and warm diffusion flames are investigated experimentally and computationally using a counterflow system. The results show that NO plays different roles in cool and warm flames due to their different reaction pathway sensitivities to the flame temperature and interactions with NO. We observe that NO addition decreases the cool flame extinction limit, delays the extinction transition from warm flame to cool flame, and promotes the ignition transition from warm flame to hot flame. In addition, jet-stirred reactor (JSR) experiments of n-dodecane oxidation with and without NO addition are also performed to develop and validate a n-dodecane/NOx kinetic model. Reaction pathway and sensitivity analyses reveal that, for cool flames, NO addition inhibits the low-temperature oxidation of n-dodecane and reduces the flame temperature due to the consumption of RO2 via NO+RO2?NO2+RO, which competes with the isomerization reaction that continues the peroxy radical branching sequence. The model prediction captures well the experimental trend of the inhibiting effect of NO on the cool flame extinction limit. For warm flames, two different kinds of warm flame transitions, the warm flame extinction transition to cool flame and the warm flame reignition transition to hot flame, were observed. The results suggest that warm extinction transition to cool flame is suppressed by NO addition while the warm flame reignition transition to hot flame is promoted. The kinetic model developed captures well the experimentally observed warm flame transitions to cool flame but fails to predict the warm flame reignition to hot flame at similar experimental conditions. 相似文献
996.
Wubulikasimu A. Omar A. Gao Y. Mukhamedov N. Arken A. Wali A. Mirzaakhmedov Sh. Ya. Yili A. 《Chemistry of Natural Compounds》2021,57(2):346-349
Chemistry of Natural Compounds - Sericin was obtained from Bombyx mori cocoons in 28% yield with 92.06% purity. Its hydrolysate was produced by an enzymatic method. A fraction with molecular mass... 相似文献
997.
Chemical diversity is a strong driver in drug discovery, and chemical reactions that produce multi-substituted heterocycles can result in significant chemical diversity. Here, we report a reaction that leads to highly substituted piperazinone derivatives in a single step. This was discovered accidently while reacting phenylglyoxal and anilines under Povarov conditions. We elucidated the structure of the compound formed when 2-(4-trifluoromethyphenyl)-2-oxoacetaldehyde was reacted with 4-methoxyaniline as (1,4-bis(4-hydroxyphenyl)-5-[(4-hydroxyphenyl)imino]-3,6-diphenylpiperazin-2-one) ( 5e ). The structure was confirmed after extensive spectral analyses, including correlation spectroscopy, nuclear Overhauser effect spectroscopy, heteronuclear single quantum correlation spectroscopy, and heteronuclear multiple-bond correlation nuclear magnetic resonance spectroscopy, in addition to high-resolution mass spectrometry. This reaction is unprecedented and can potentially be exploited as a short route to highly diversified heterocycles. 相似文献
998.
Dr. Mostafa Zeama Prof. Mohamed A. Morsy Dr. Mahmoud Abdelnaby Dr. Luis Gutiérrez-Arzaluz Prof. Omar F. Mohammed Prof. Zain H. Yamani 《化学:亚洲杂志》2021,16(17):2520-2528
This study aims to investigate the effect of replacing Ti with Zr in the SBU of MIL-125-NH2. We were able to replace Ti with Zr in the mixed metal synthesis of MIL-125-NH2, for the first time. After experimentally confirming the consistency in their framework structure and comparing their morphology, we related the femtosecond light dynamics with photocatalytic CO2 visible light conversion yield of the different variants in order to establish the composition-function relation in MIL-125 vis a vis CO2 reduction. Introducing Zr to the system was found to cause structure defects due to missing linkers. The lifetime of the charge carriers for the mixed metal samples were shorter than that of the MIL-125-NH2. The study of CO2 photocatalytic reduction under visible light indicated that the NH2 group enhances the photocatalytic activity while the Zr incorporation inside the MIL framework introduces no significant improvements. In addition, the material systems were modelled and simulated through DFT calculations which concluded that the decrease of the photocatalytic activity is not related to the system electronic structure, insinuating that defects are the culprit. 相似文献
999.
Abu-Dief Ahmed M. El-Metwaly Nashwa M. Alzahrani Seraj Omar Alkhatib Fatmah Abumelha Hana M. El-Dabea Tarek Ali El‐Remaily Mahmoud Abd El Aleem Ali 《Research on Chemical Intermediates》2021,47(5):1979-2002
Research on Chemical Intermediates - A series of new complexes derived from Pd(II), Cu(II) and Fe(III) ions reacted with thiazole derivative (HL, CPTP) was prepared. Structures of all new compounds... 相似文献
1000.
Penghao Li Peng Li Matthew R. Ryder Zhichang Liu Charlotte L. Stern Omar K. Farha J. Fraser Stoddart 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(6):1678-1683
We describe an example of “interpenetration isomerism” in three‐dimensional hydrogen‐bonded organic frameworks. By exploiting the crystallization conditions for a peripherally extended triptycene H6PET, we can modulate the interpenetration of the assembled frameworks, yielding a two‐fold interpenetrated structure PETHOF‐ 1 and a five‐fold interpenetrated structure PETHOF‐ 2 as interpenetration isomers. In PETHOF‐ 1 , two individual nets are related by inversion symmetry and form an interwoven topology with a large guest‐accessible volume of about 80 %. In PETHOF‐ 2 , five individual nets are related by translational symmetry and are stacked in an alternating fashion. The activated materials show permanent porosity with Brunauer‐Emmett‐Teller surface areas exceeding 1100 m2 g?1. Synthetic control over the framework interpenetration could serve as a new strategy to construct complex supramolecular architectures from simple organic building blocks. 相似文献