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991.
992.
New complex [Mn (SB)2(DMF)2] [W (CN)8] hereafter referred to as complex 1 , which was prepared by self–assembly of [Mn (SB)2(DMF)2]3+ and [W (CN)8]3− and structurally characterized by elemental analysis, infrared (IR) and single crystal X–ray techniques (H2SB is Schiff base derived from the condensation of salicylaldehyde and N,N–diethylethylenediamine and DMF is dimethylformamide). The structure consists of 1–D supramolecular chains and further stacks to give a 3–D supramolecular architecture whose molecular fragments are linked by hydrogen bond as well as C − H···π interactions between [Mn (SB)2(DMF)2]3+ and [W (CN)8]3−. An underlying net for the representation consists of two types of fragments with 1,4 M5–1 and 1,8 M9–1 topologies and further illustration of the molecular network in terms of a graph−theory approach using simplification procedure resulted in the underlying net of 2C1topological type in the complex 1 . Magnetic susceptibility measurements of complex 1 was carried out in the temperature range 2–300 K, indicates the presence of either magnetic anisotropy zero field splitting, the effect of intramolecular interactions, or both. Complex 1 follows the Curie–Weiss law with Curie constant value of 3.43 cm3mol−1K, and the slight negative Weiss constant (−0.60 K) value indicates the predominant antiferromagnetic magnetic exchange interactions. The magnetic properties of Title complex was investigated thoroughly and showed that ferromagnetic interaction between W(V) and Mn (III) operate via the intramolecular H–bonding interaction between cyanide nitrogens and a hydrogen atom. 相似文献
993.
The potential to bias chemical reaction pathways is a significant goal for physicists and material researchers to design revolutionary materials. Recently, two‐dimensional materials have appeared as a promising candidate for exploring novel catalyst activity in organic reaction. In this context, herein we report an easy and efficient synthesis of substituted benzodiazepines in high yields through the graphene‐based mesoporous TiO2 nanocomposite (Gr@TiO2 NCs) catalyst. To validate the merits of the Gr@TiO2 NCs as a catalyst, we have also designed TiO2 nanoparticle (NPs) under similar conditions. Successful comprehension realization of Gr@TiO2 NCs and TiO2 NPs were concluded from the XRD, SEM, HR‐TEM, EDS elemental mapping, FT‐IR, Raman, UV–Vis and TGA analysis. Gr@TiO2 NCs has the propitious catalyst performance (~98%) over the TiO2 NPs (~77%), which could be scrutinized in terms of graphene support toward the TiO2 NPs and enable the large contact area between graphene and TiO2 NPs. Incorporated graphene maintaining TiO2 as a catalytically active and attracting electron to site isolation, as well as protecting TiO2 from oxidative degradation during the reaction. Moreover, the role of graphene is suggested to prolonged reaction duration, yield and unaltered throughout the reaction because of the π‐π interaction between graphene and TiO2 NPs. Additionally, the catalyst is recycled by filtration and reprocessed six times without having a significant loss in its catalytic activity. 相似文献
994.
Rizwan Ahmad Niyaz Ahmad Mohd Amir Fatema Aljishi Marwah Hussain Alamer Heba Radhi Al-Shaban Zainab Alawi Alsadah Bayan Mohammed Alsultan Noor Ali Aldawood Shahanas Chathoth Sarah Ameen Almofty 《Biomedical chromatography : BMC》2020,34(3):e4772
Black pepper (Piper nigrum; BP), known as the ‘king of spices’, imported from various countries is widely available in Saudi Arabian markets, as its demand as a food as well as a medicine for minor ailments is increasing in the country. However, there is a lack of appropriate information regarding these samples in terms of quality variation and standardization. We thus aimed to evaluate the quality and standardize the BP sample with respect to its physicochemical characters, active principle variation [i.e. piperine (PPN)], toxicity, and biological activity. The main focus is to validate whether any difference exists in the quality and quantity of active principle in these samples. For this purpose, physicochemical (chemical tests and ash values) and instrumental analyses [accelerated solvent extraction (ASE), ultra-high-pressure liquid chromatography (UHPLC)-diode array detector, infrared (IR), nuclear magnetic resonance (NMR), and inductively coupled plasma-MS (ICP-MS)] and biological evaluation {in vitro antioxidant activity [2,2-diphenyl-1-picrylhydrazyl and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)] and cytotoxicity assay} were performed. An extract yield (g) with %recovery of 2.26 ± 4.24 (11.3) was obtained for the Vietnamese sample, using a fast and rapid method of extraction (ASE). These values were 1.22 ± 2.64 (6.1) and 0.75 ± 1.69 (3.75) for the Pakistani and Indian samples. Physicochemical tests revealed the presence of flavonoids and phenolic compounds in all samples; however, in the Vietnamese sample a low amount of total, acid-insoluble, and high water-soluble ash value was noted. IR and NMR was applied to further standardize the samples. Results of ICP-MS analysis showed a high amount of macronutrients and micronutrients in the samples tested while UHPLC analysis revealed a high amount of PPN (ng/mL) in the Pakistani sample (1,362,614.09); these values were 1,051,848.04 and 768,512.81 for the Vietnamese and Indian samples, respectively. In vitro antioxidant and cytotoxicity activities revealed higher potential for the Vietnamese sample. The samples were properly standardized and effectively differentiated in terms of quality and biological activities using a fast and reliable method, however it certainly does not mean that a particular geographical region is more better or productive in terms of herbal products. 相似文献
995.
Dr. Jinquan Wang Justin Chua Zhi En Dr. Siti Nurhanna Riduan Dr. Yugen Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(12):2581-2585
Nitrogen-linked hexaazatrinaphthylene polymer ( N2-HATN ) as organic cathode material with low HOMO–LOMO gap was synthesized and was observed to possess reversible high capacity and unexpected long-term cycling stability. The pre-treated N2-HATN and pRGO combination demonstrated good structure compatibility and the resultant cathode exhibited a constant increment of capacity during the redox cycles. The initial capacity at 0.05 A g−1 was 406 mA h−1 g−1, and increased to 630 mA h−1 g−1 after 70 cycles. At 0.5 A g−1 discharging rate, the capacity increased from an initial value of 186 mA h−1 g−1 to 588 mA h−1 g−1 after 1600 cycles. The pseudocapacitance-type behavior is postulated to be attributed to the structure compatibility between the active material and pRGO. 相似文献
996.
Khursheed Ansari Mohd Nazeef Shabir Ali Malik A. Waseem Wajaht A. Shah Saif Ansari Ibadur R. Siddiqui Jagdamba Singh 《Journal of heterocyclic chemistry》2021,58(2):622-629
A mild and efficient visible light–mediated one-pot multicomponent tandem approach to construct 4-oxo-tetrahydroindoles in ethanol–water medium at room temperature has been described. The characteristics of reported methodology are the utilization of visible light, an ideal source of energy to generate C C and C N bonds from commercially available substrates namely dimedone, phenacyl bromides, and amines. The presented protocol is highly compatible for developing 4-oxo-tetrahydroindole derivatives with improved selectivity and high yields. Moreover, metal-free synthesis, environmental friendly solvent, easy workup process, high atom economy, cost-effectiveness, short reaction time, and broad substratescope are the major advantages of reported protocol. 相似文献
997.
Shafiqul Islam A. K. M. Krishnan Hemavathi Ahmad Mohd Noor Nadaraja Pubalan Uddin A. B. M. Helal 《Russian Journal of Electrochemistry》2021,57(6):671-679
Russian Journal of Electrochemistry - A novel quartz crystal microbalance (QCM) sensor based on molecular imprint polymer (MIP) has been developed for the detection of andrographolide in the... 相似文献
998.
Dr. Zhenghai Yang Dr. Bing-Jian Sun Dr. Chao He Dr. Siti Fatimah Prof. Dr. Agnes H. H. Chang Prof. Dr. Ralf I. Kaiser 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(10):e202103999
The hitherto elusive monobridged Ge(μ-H)GeH (X1A′) molecule was prepared in the gas phase by bimolecular reaction of atomic germanium with germane (GeH4). Electronic structure calculations revealed that this reaction commenced on the triplet surface with the formation of a van der Waals complex, followed by insertion of germanium into a germanium-hydrogen bond over a submerged barrier to form the triplet digermanylidene intermediate (HGeGeH3); the latter underwent intersystem crossing from the triplet to the singlet surface. On the singlet surface, HGeGeH3 predominantly isomerized through two successive hydrogen shifts prior to unimolecular decomposition to Ge(μ-H)GeH isomer, which is in equilibrium with the vinylidene-type (H2GeGe) and dibridged (Ge(μ-H2)Ge) isomers. This reaction leads to the formation of cyclic dinuclear germanium molecules, which do not exist on the isovalent C2H2 surface, thus deepening our understanding of the role of nonadiabatic reaction dynamics in preparing nonclassical, hydrogen-bridged isomers carrying main group XIV elements. 相似文献
999.
Aftab Alam Najeeb Ur Rehman Mohd Nazam Ansari Amber Hanif Palla 《Molecules (Basel, Switzerland)》2021,26(9)
The present study examined the chemical composition and antimicrobial and gastrointestinal activity of the essential oils of Elettaria cardamomum (L.) Maton harvested in India (EC-I) and Guatemala (EC-G). Monoterpenes were present in higher concentration in EC-I (83.24%) than in EC-G (73.03%), whereas sesquiterpenes were present in a higher concentration in EC-G (18.35%) than in EC-I (9.27%). Minimum inhibitory concentrations (MICs) of 0.5 and 0.25 mg/mL were demonstrated against Pseudomonas aeruginosa in EC-G and EC-I, respectively, whereas MICs of 1 and 0.5 mg/mL were demonstrated against Escherichia coli in EC-G and EC-I, respectively. The treatment with control had the highest kill-time potential, whereas the treatment with oils had shorter kill-time. EC-I was observed to be more potent in the castor oil-induced diarrhea model than EC-G. At 100 and 200 mg/kg, P.O., EC-I exhibited 40% and 80% protection, respectively, and EC-G exhibited 20% and 60% protection, respectively, in mice, whereas loperamide (10 mg/kg, i.p., positive control) exhibited 100% protection. In the in vitro experiments, EC-I inhibited both carbachol (CCh, 1 µM) and high K+ (80 mM)-induced contractions at significantly lower concentrations than EC-G. Thus, EC-I significantly inhibited P. aeruginosa and E. coli and exhibited more potent antidiarrheal and antispasmodic effects than EC-G. 相似文献
1000.
Zaharani Lia Khaligh Nader Ghaffari Mihankhah Taraneh Johan Mohd Rafie 《Molecular diversity》2021,25(1):323-332
Molecular Diversity - This paper presents the efficient synthesis of 2-amino-4H-benzo[b]pyrans using mesoporous poly-melamine-formaldehyde as a polymeric heterogeneous catalyst. According to the... 相似文献