1749-05-9Relevant articles and documents
Synthesis of new cyclotriphosphazene derivatives bearing Schiff bases and their thermal and absorbance properties
Besli, Serap,Do?an, Semih,Mutlu Balci, Ceylan,Tümay, Süreyya O?uz,Ye?i?Lot, Serkan
, p. 31 - 47 (2020)
In this study, a series of cyclotriphosphazene derivatives containing a Schiff base (3a–3d) were synthesized by the reactions of hexachlorocyclotriphosphazene (1) with bis-aryl Schiff bases (2a–2d) having different terminal groups (H, F, Cl, and Br). The products (3a–3d) were characterized by elemental and mass analyses, FT-IR, and 1 H, 13 C, and 31 P NMR spectroscopies. Furthermore, the structure of compound 3a was also determined by X-ray crystallography. The thermal behaviors and the spectral properties of the new cyclotriphosphazene compounds (3a–3d) were investigated and the results were compared in the series.
Additional effect of para-hydroxyl on the reduction potentials of the N-benzylidenebenzenamines
Cao, Chao-Tun,Zhou, Wei,Cao, Chenzhong
, (2019/12/27)
The reduction potential ERed of disubstituted N-benzylidenebenzenamines XArCH NArY (abbreviated as XBAY) is a measure of the electron acceptance ability of the Lowest-energy Unoccupied Molecular Orbital (LUMO) in molecule, which is closely related to the electronic effects of substituents X and Y in molecule. Previous studies on the ERed of XBAY reported by Luo, Wang, and Yuan all did not involve these molecules containing hydroxyl. In this work, 28 samples of disubstituted N-benzylidenebenzenamines containing para-hydroxyl, (abbreviated as 4-OHBAY or XBAOH-4′) were synthesized, and their ERed values were measured. Then, 127 compounds were taken as a complicated ERed data set, which involved 28 compounds (4-OHBAY and XBAOH-4′) of this work and 99 compounds XBAY reported by Luo. Based on these data ERed set, through a quantitative regression analysis method and comparison of the factors affecting the ERed, the following results are obtained: (a) Because the phenolic hydroxyl OH can dissociate H+ to form phenolic oxygen anion, the change regularity of ERed of compounds 4-OHBAY and XBAOH-4′ is somewhat different from that of ERed of XBAY compounds without hydroxyl OH. That is, hydroxyl OH has an additional effect on the ERed, which decreases the ERed value. (b) The additional effects of 4-OH on the ERed is different from that of 4′-OH. The effect of hydroxyl OH attached to the aldehyde aromatic ring on the ERed is more than that of OH attached to the amine aromatic ring.
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.
Versatile synthesis of 4-spiro-β-lactam-3-carbonitriles via the intramolecular nucleophilic cyclization of N-(p-hydroxyphenyl)cyanoacetamides
Abdellaoui, Hassane,Xu, Jiaxi
, p. 4323 - 4330 (2014/06/10)
A series of 4-spiro-cyclohexadienonyl-β-lactam-3-carbonitriles, 2,7-dioxo-1-azaspiro[3.5]nona-5,8-diene-3-carbonitriles, was synthesized in satisfactory to excellent yields via the intramolecular nucleophilic cyclization of N-(p-hydroxyphenyl)cyanoacetamides with iodobenzene diacetate (IBD) as oxidant and potassium hydroxide as base. Acetic 4-spiro-cyclohexadienonyl- β-lactam-3-carbimidic anhydrides were obtained when organic base triethylamine was applied instead of potassium hydroxide. The mechanisms of the intramolecular nucleophilic cyclization and formation of acetic β-lactam-3-carbimidic anhydrides were proposed. The cyclization is a sequence of nucleophilic ipso addition and oxidative dearomatization. The formation of acetic carbimidic anhydrides is an acid-catalyzed acetate addition to the nitriles.
An efficient catalyst for the synthesis of schiff bases
Fareed, Ghulam,Versiani, Muhammad Ali,Afza, Nighat,Fareed, Nazia,Kalhoro, Mahboob Ali,Yasmeen, Shazia,Anwar, Muhammad Aijaz
, p. 426 - 430 (2013/07/27)
An efficient high yielding synthesis of Schiff bases (1-17) is derived from condensation of 2-fluorenamine and 4-amino phenol with a variety of aldehydes catalyzed by dodecatungstosilicic acid / P2O5 under solvent free conditions at room temperature. The catayst is found to be more efficient in terms of ease of reaction workup and high yields. This methodology contributes to an energy efficient, facile and environamental friendly synthesis for the preparation of Schiff bases. The structures of afforded Schiff bases were characterized by spectroscopic data and elemental analysis.
Spectral investigation of the activities of amino substituted bases
Ashraf, Muhammad Aqeel,Wajid, Abdul,Mahmood, Karamat,Maah, Mohd. Jamil,Yusoff, Ismail
experimental part, p. 363 - 372 (2012/04/04)
Three new series of biologically active amino substituted Schiff bases with general formula, R1N=CHR2. Here R1 = 2-amino-benzthiazole, 4-amino-salicylic acid and 4-aminophenol. R 2=4-chloro-benzaldehyde, 2-chloro-benzaldehyde, salicylaldehyde, vanillin and benzaldehyde were synthesized by the reaction of three different amino substituted compounds and substituted aldehydes in ethanol. Such compounds were characterized by different physico-chemical techniques like, melting point, elemental analysis, multinuclear nmr (1H, 13C). The free ligands and their metal complexes have been screened for their in vitro biological activities against bacteria, fungi and yeast. The metal complexes show more potent activities compared with Schiff base ligands.
Synthesis, spectral investigation (1H, 13C) of new (N, O and S based) schiff bases and evaluation of their antimicrobial activities
Khosa, Muhammad Kaleem,Chatha, Shahzad Ali Shahid,Nisar, Madhia,Zia, Khalid Mahmood,Khalil-Ur-Rehman,Jamal, Muhammad Asghar,Yousaf, Muhammad
experimental part, p. 421 - 425 (2012/04/17)
Three new series of biologically active amino substituted Schiff bases (1-12) with general formula, R1N=CHR2 (R1 = 2-amino-benzthiazole, 4-amino-salicylic acid and 4-aminophenol; R2 = benzaldehyde, 2-chloro-benzaldehyde, 4-chloro-benzaldehyde, salicylaldehyde and vanillin) were synthesized by the reaction of three different amino substituted compounds and substituted aldehydes in ethanol. The synthesized compounds were characterized by different physico-chemical techniques like, melting point, elemental analysis, multinuclear nmr (1H, 13C). The compounds were subjected for bioassay screening and showed promising antibacterial and antifungal activities using Amoxicillin and Ciprofloxacin as standard drugs.
Microwave-assisted, solvent-free and parallel synthesis of some novel substituted imidazoles of biological interest
Sharma, Gyanendra Kumar,Pathak, Devender
experimental part, p. 375 - 380 (2011/02/25)
Solvent free microwave assisted synthesis of some novel substituted imidazoles of biological interest is reported. First, primary aromatic or heteryl amine was condensed with aryl or heteryl aldehydes to afford corresponding Schiff's base. The Schiff's base further on treatment with ammonium acetate (NH4OAC) and isatin using silica gel as the solid support, yielded the corresponding aryl imidazoles. In this paper a comparative study between the developed microwave method and conventional method is described. The synthesized compounds were analyzed by physical and analytical data. The synthesized compounds were evaluated for their antibacterial, anthelmintic, short-term anticancer and antitubercular activity. All the synthesized substituted imidazoles have shown good antibacterial activity against gram negative bacterial strains Klebsiella pneumoniae and Escherichia coli and moderate to good anthelmintic activity. The synthesized imidazole derivative possessed signifi-cant cytotoxic activity against Ehrlich's ascites carcinoma (EAC) cell lines. None of the compounds exhibited prominent antitubercular activity.
Synthesis and mesomorphic properties of Schiff base esters possessing terminal chloro substituent
Ha, Sie Tiong,Ong, Lay Khoon,Lee, Siew Ling,Lin, Hong Cheu,Win, Yip Foo,Ong, Siew Teng
scheme or table, p. 637 - 640 (2011/10/18)
A homologous series of Schiff base esters, 4-chlorobenzylidene-4′-n-alkanoyloxyanilines, containing even number of carbons at the end groups of the molecules (Cn-1H2n-1COO-, n = 4, 6, 8, 10, 12, 14, 16) were synthesized. The mesomorp
