13028-89-2Relevant academic research and scientific papers
Hemoglobin: A New Biocatalyst for the Synthesis of 2-substituted Benzoxazoles via Oxidative Cyclization
Li, Fengxi,Li, Zhengqiang,Tang, Xuyong,Cao, Xinyu,Wang, Chunyu,Li, Jialin,Wang, Lei
, p. 1192 - 1195 (2019)
Efficient and mild synthesis of a series of 2-substituted benzoxazoles via oxidative cyclization catalyzed by hemoglobins reported here for the first time. Satisfactory yields (84 %–97 %) and mild reaction conditions make this method highly viable for practical applications.
Effect of substituents on the UV spectra of supermolecular system: Silver nanoparticles with bi-aryl Schiff bases containing hydroxyl
Cao, Chao-Tun,Cheng, Shimao,Zhang, Jingyuan,Cao, Chenzhong
, (2018/11/25)
Effect of substituents on the ultraviolet (UV) spectra of supermolecular system involving silver nanoparticles (AgNPs) and Schiff bases was investigated. AgNPs and 49 samples of model compounds (MC), bi-aryl Schiff bases containing hydroxyl (XBAY, involving 4-OHArCH?NArY, 2-OHArCH?NArY, XArCH?NAr-4′-OH, and XArCH?NAr-2′-OH), were synthesized. The size of AgNPs was characterized by transmission electron microscopy (TEM), and the UV absorption spectra of AgNPs, XBAYs, and MC-AgNPs mixed solutions were measured, respectively. The results show that (1) the size of AgNPs is larger in MC-AgNPs solutions than that in AgNPs solution due to the distribution of MC molecules on the surface of AgNPs; (2) the UV absorption wavelength of XBAYs changes in the action of AgNPs and their wavelength shift exists limitation between XBAY and MC-AgNPs solutions; and (3) the wavelength shift limit of MC-AgNPs (λWSL) is influenced by the substituents X and Y and the position of hydroxyl OH. The wavenumber ΔνWSL of λWSL can be quantified by employing the excited-state substituent constant σexCC and Hammett constant σ of substituents X and Y. Comparing with the 4-OH, the 4′-OH makes the ΔνWSL a red shift, whereas the 2′-OH, comparing with the 2-OH, makes the ΔνWSL a blue shift.
Abnormal effect of hydroxyl on the longest wavelength maximum in ultraviolet absorption spectra for bis-aryl Schiff bases
Cao, Chao-Tun,Zhou, Wei,Cao, Chenzhong
, (2017/09/19)
Two sets of bis-aryl Schiff bases that contain 4(or 4′)-OH and 2(or 2′)-OH were synthesized. The first set consists of 4-HOArCH=NArY and XArCH=NArOH-4′, and the second set consists of 2-HOArCH=NArY and XArCH=NArOH-2′. Their ultraviolet absorption spectra were measured and investigated. A very interesting phenomenon was observed by analyzing their wave number νmax (cm?1) of longest wavelength maximum λmax (nm) of ultraviolet. Compared with the change regularity of the νmax of XArCH=NArY (where the X and Y excluded OH), the 4′-position hydroxyl (4′-OH) and 2′-position hydroxyl (2′-OH) have abnormal performance. The details are the following: the 4′-OH contributes an additional red shift to the νmax of XArCH=NArOH-4′ (λmax increase), whereas the 2′-OH contributes an additional blue shift to the νmax of XArCH=NArOH-2′ (λmax decrease). In addition, there are ortho steric effects of all 2-OH and 2′-OH on the νmax for 2-HOArCH=NArY and XArCH=NArOH-2′, and the ortho steric effect contributes a red shift to their νmax. These experimental facts can provide an important theoretical reference for us using aryl Schiff base compounds as optical materials and performing the molecular design.
OMS-2/H2O2/Dimethyl Carbonate: An Environmentally-Friendly Heterogeneous Catalytic System for the Oxidative Synthesis of Benzoxazoles at Room Temperature
Meng, Xu,Wang, Yuanguang,Chen, Baohua,Chen, Gexin,Jing, Zhenqiang,Zhao, Peiqing
supporting information, p. 2018 - 2024 (2017/12/26)
A manganese octahedral molecular sieve (OMS-2) was found to be an efficient and recyclable heterogeneous catalyst for the oxidative synthesis of benzoxazoles in the gram-scale from phenolic imines at room temperature. H2O2 and biobased reagent dimethyl carbonate (DMC) were successfully employed as the environmentally friendly oxidant and solvent, respectively, in an OMS-2-catalysted redox reaction for the first time. Benzoxazoles could also be obtained from N-substituted 2-aminophenols via Cu(OH)x/OMS-2-catalyzed sequential oxidative transformation at elevated temperatures.
Synthetic, spectral, structural and antimicrobial studies of some Schiff bases 3-d metal complexes
Mishra,Mishra,Pandey, Mrituanjay D.
experimental part, p. 1757 - 1764 (2012/01/31)
The complexes of tailor made ligands with life essential metal ions may be an emerging area to answer the problems of multi-drug resistance (MDR). The coordination complexes of VO(II), Co(II), Ni(II) and Cu(II) with the Schiff bases derived from 3-bromobenzaldehyde/3-chlorobenzaldehyde with 2-aminophenol have been synthesized and characterized by elemental analysis, molar conductance, electronic spectra, FT-IR, ESR, FAB mass, thermal and magnetic susceptibility measurements, FAB mass and thermal data show degradation of complexes. Both the ligands behave as bidentate coordinating through O and N donor. The complexes exhibit coordination number 4, 5 or 6. X-ray powder diffraction data shows that four (2, 3, 6 and 7) complexes are crystallized in tetragonal system. The in vitro biological screening effects of the investigated compounds were tested against the bacteria Escherichia coli, Staphylococcus aureus and Streptococcus fecalis and the fungi Aspergillus niger, Trichoderma polysporum and Candida albicans by serial dilution method. A comparative study of the MIC values of the Schiff base and their Co(II) (6) and Cu(II) (8) complexes, indicates that the metal complexes exhibit higher or lower antimicrobial activity than the free ligand (L2).
