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Ten new macrocyclic Schiff base Rh(III) compounds were synthesized by treating the corresponding macrocycles with rhodium
chloride in 1:1 ratio. The resulting compounds were characterized by elemental, IR, 1H NMR, 13C NMR, mass, electronic spectral analysis, and their structures have been proposed. These compounds were utilized as catalysts
in the...
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Investigation of acetylcholinesterase (AChE) inhibition potency of some new Schiff base derivatives of tacrine (9-amino-1,2,3,4-tetrahydroacridine) was reported in this paper. Novel Schiff base derivatives of tacrine (3a–g) have been synthesized, and they have been characterized by several methods (FT-IR, 1H-NMR, 13C-NMR, etc.). Then, inhibition ef...
Citations
... The infrared spectral studies of oxo-metal complexes not only knowing the coordinating groups/atoms of the ligands but also in the nature of metal-oxygen bond and its force constant .The reports of the authors [32,33] about the existence of mononuclear complexes of ZrO 2+ and the five coordinate zirconium species was questioned [34]. The characteristics absorptions are given in the table 3. ...
... The H 1 -NMR spectra of EBAB, PBAB, and PhBAB complexes of ZrO 2+ , recorded at room temperature in d6-DMSO exhibit same number of resonance signals, but a few have shifted either to low field or high field side, as presented in the table 5. The low field side of amine and amide nitrogen protons resonance signals indicate that the coordination takes place through these atoms [5,14,32,33,[35][36][37][38]. There is no pronounced effect on the aliphatic and aromatic proton resonance signals. ...
... EBCPH2 and PBCPH2 another set of closely related ligands have coordinating groups as the carboxyl and amide. The COOH proton signal at 9.2 ppm disappears in the 1 H-NMR spectra of complexes, confirming the deprotonation [5,29,32,33,[35][36][37][38]. The amide proton resonance signal shifts to low field side. ...
The reactions have been carried between the metal ion salt ZrOCl2 and the ligands N,N’-ethylene-bis-(2-amino benzamide) [EBAB], N,N’-propylene-bis-(2-aminobenzamide) [PBAB], N,N’-(o-Phenylene)-bis-(2-aminobenzamid) [PhBAB], N,N’-ethylene-bis-(3-carboxypropanamide) [EBCP], N,N-propylene-bis-(3-carboxypropanamide) [PBCP], and 1-(2’-hydroxyphenyl)-3-phenyl-1,3-propanedione [HPPPD] to form the complexes. The complexes have been characterized by the physiochemical and spectral studies like elemental analysis, conductance, thermal, IR, UV, and NMR spectra. From the spectral data it is found Zr-O-Zr interaction and hexa coordination of ZrO(IV). Thermal studies confirm such interaction between two [LZrO] species through the oxygen atom is very weak.
... The Infrared spectra of Schiff base ligand was compared to metal complexes in order to elucidate the binding modes of ligand to metal ion in all the metal complexes [15][16][17][18][19][20][21]. IR spectra of Schiff base ligand gives a high intensity characteristic band at around 1636 cm -1 assigned to azomethine (-HC=N) stretching frequency (Table 1). ...
In the present study some new isoaxazole based Shciff base binary metal complexes were synthesized from Schiff base ligand The spectral studies revealed that Co(II) and Cu(II) complexes have octahedral geometry; Zn(II) complex has Tetrahedral structure where as Pd(II) complex shown square planar geometry. The Schiff base ligand and its corresponding metal complexes were further screened for their DNA binding activity and antimicrobial evaluation studies and in vitro cytotoxic activity. Graphical Abstract Synthesis of Schiff base Ligand
... There are some valuable peaks in the spectra of the complexes such as m(C@N), m(MAN) and m(MACl). The m(C@N) stretching vibration is shown in the free ligand TPTTP at 1628 cm À1 [35]. This peak was shifted to lower wavenumber region by 25 cm À1 in both the complexes, signifying that the sharing of azomethine nitrogen in coordination to the metal ions. ...
... It is known that the presence of bonded metal ions of biologically active compounds may lead to strengthen its activities P [14] P . A wide range of Schiff base macro cycles has evolved from the early studiesP [15][16][17][18][19][20] P , over the last few years working extensive research in many laboratories all over the world, and macrocyclic chemistry is well-established and highly recognized branch of science and thus it provided Schiff bases foundation stone for the building of modern chemistry macrocyclicP [21] P . The role of the metal ion in these metal-ion tern plated cyclizations is to control the supra molecular assembly of pre-cyclization fragments, most likely through the formation of metal complexes derived from the precursors. ...
... The ligand shows its characteristic =C=N-band at ca. 1653cm -1 , which are also shifted to higher frequencies in the spectra of the complexes (1667~1658 cm -1 ). The metal chelates show some new bands in the region 559~548 cm -1 and 428~420 cm -1 which are due to the formation of M-O and M-N bonds respectively [19][20][21]. Hence, it is concluded that the coordination to the metal ion occurs through the enolisable acidic group of 2-benzoyl benzoic acid and the azomethine nitrogen atoms of the Schiff base. The free ligand (H 2 L) exhibits an absorption bonds at (1700)cm -1 due to the stretching vibration of υ(C=O) of carboxylic group [23] . ...
... The electronic spectrum exhibits two absorption bands at 412 nm (24271 cm P -1 P )P P and 559 nm (17889 cm P -1 P ) .These bands may be assigned to the transitions: P 6 P AR 1 (F) R→P 1 P AR 2 (G) R and P 6 P AR 1 (F) R→P 4 P ER (G) R transitions respectively . Position of these bands indicates a tetrahedral geometry around the Mn(II) ion P [21] P . iv) mercury(II) complex is diamagnetic moments for dP 10 P ion and the electronic spectra there complex do not show any d-d band P [25] P . ...
A new tetradentate schiff-base derived from 2-benzoyl benzoic acid with O-phenylene diamine have namely[2,2'-(1E,1'Z)-
(1,2-phenylenebis(azan-1–yl-1-ylidene)bis(phenylmethan -1-yl-1-ylidene)dibenzoic acid].Tetradental Schiff base type (NNOO) have been
synthesized and characterized using IR, UV, P
1
PH & P
13
PC-NMR spectroscopy, elemental analysis.
The ligand used in the preparation of five transition metal complexes with CoP(II)P, NiP(II)P, MnP(II)P, HgP(II)P&CuP(II)P and characterized via elemental analysis, FT-IR, UV, magnetic susceptibility and molar conductivity from the above data the geometrical formula was the square planar has suggested for Cu , Ni and Hg complexes and the tetrahedral geometry has suggested for Co and Mn complexes and in vitro tests for antibacterial activity showed that most of the prepared compounds display a good activity to (Staphylococcus aureus), (Escherichia coli) , (Bacillus )and (Pseudomonas).
... Orthophthalaldehyde (OPA) serves as a good starting material for the synthesis of macrocycles [10] . Literature study discloses that a little bit of work was done to synthesize Schiff bases from OPA by either template or non-template methods101112131415161718. In previous work, we have reported the non-template synthesis of NA , OA, donor macrocycles, benzimidazo/indolo [1,2-c] quinazolines19202122232425 and their metal complexes1415162627282930. Still, the many of the existing OPA based macrocyclic metal compounds were synthesized by the direct treatment of OPA, diamine and metal salts [11,12] . ...
... Since, macrocyclic Rhodium (I) complexes are not synthesized by the initial preparation of macrocycle followed by its treatment with [Rh(COD)Cl] 2 . In recent years, research towards the catalytic applications of macrocyclic metal complexes is rapidly increasing [26,27]. It bids attractive chances for industry, which attempts to develop more environmentally benign manufacturing methods. ...
... d corresponding to carbon atoms adjacent to oxygens. This range was shifted to up field region to 61.8–72.1 d in the Rh(I) complexes, representing the coordination of the oxygen atoms of OACH 2 group to Rh(I) ion in addition to the two nitrogen atoms of CH@N group [14,26,27]. Significant changes in peak positions were not observed with respect to aryl carbons and carbons adjacent to ring nitrogen atom [28]. ...
... Cu(II) complexes are known to play a significant role either in naturally occurring biological systems or as pharmacological agents [18,19]. In connection with previous investigations [1,2,20], on the coordinating properties of tetraaza macrocycles, and in order to isolate new transition metal complexes with potential antimicrobial properties, we have studied the synthesis, spectroscopic and biochemical aspects of tetraaza macrocyclic complexes of copper(II) derived from o-phthalaldehyde with various diamines. ...
A novel family of tetraaza macrocyclic Cu(II) complexes [CuLX2] (where L = N4 donor macrocyclic ligands) and (X = Cl−, NO3
−) have been synthesized and characterized by elemental analysis, magnetic moments, IR, EPR, mass, electronic spectra and thermal studies. The magnetic moments and electronic spectral studies suggest square planar geometry for [Cu(DBACDT)]Cl2 and [Cu(DBACDT)](NO3)2 complexes and distorted octahedral geometry to the rest of the ten complexes. The biological activity of all these complexes against gram-positive and gram-negative bacteria was compared with the activity of existing commercial antibacterial compounds like Linezolid and Cefaclor. Six complexes out of twelve were found to be most potent against both gram-positive as well as gram-negative bacteria due to the presence of thio group in the coordinated ligands.
... The physical and analytical data for the newly synthesized compounds is in good agreement with the proposed molecular formulae (Table 1).know the binding mode of metal and ligand (Table 2). In the IR spectra of the macrocyclic ligands, a medium intensity m C=N band was observed in the range of 1618–1602 cm À1[30]. This band is shifted towards lower side about 1605–1570 cm À1 in macrocyclic metal complexes. ...
A series of tetraaza (N(4) donor) macrocyclic ligands (L(1)-L(4)) were derived from the condensation of o-phthalaldehyde (OPA) with some substituted aromatic amines/azide, and subsequently used to synthesize the metal complexes of Ru(II), Pd(II) and Pt(II). The structures of macrocyclic ligands and their metal complexes were characterized by elemental analyses, IR, (1)H &(13)C NMR, mass and electronic spectroscopy, thermal, magnetic and conductance measurements. Both the ligands and their complexes were screened for their antibacterial activities against Gram positive and Gram negative bacteria by MIC method. Besides, these macrocyclic complexes were investigated as catalysts in the oxidation of pharmaceutical drug didanosine. The oxidized products were further treated with sulphanilic acid to develop the colored products to determine by spectrophotometrically. The current oxidation method is an environmentally friendly, simple to set-up, requires short reaction time, produces high yields and does not require co-oxidant.
... In previous studies, we have described the synthesis, catalytic and biological applications of Schiff bases and their metal complexes derived from o-phthalaldehyde (OPA) with various amines. [19][20][21][22][23][24][25][26][27] In this respect, we have also developed some useful macrocyclic Schiff bases and their metal complexes. Results from these studies have also shown that complexation of metals with Schiff base ligands serves to improve their antimicrobial activity. ...
... ppm in the complex NMR spectra indicates that the ligand coordinates through both the nitrogen atom of CHϭN and the oxygen of COO Ϫ ion. [19][20][21][22][23][24][25][26][27] Electronic Spectra The Co(II) complex exhibited well resolved bands at 1040-1090, 518-540 nm and a strong high energy band at 426-494 nm and are assigned to transitions, 4 T 2g ← 4 T 1g (F) (n 1 ), 4 A 2g ← 4 T 1g (F) (n 2 ) and 4 T 1g (P)← 4 T 1g (F) (n 3 ) for a high spin octahedral geometry. 19) The magnetic susceptibility measurements for the solid Co(II) complex is also indicative of four unpaired electrons per Co(II) ion suggesting consistency with their octahedral environment. ...
New tetradentate N(2)O(2) donor Schiff bases and their mononuclear Co(II), Ni(II), Cu(II), and Pd(II) complexes were synthesized and characterized extensively by IR, (1)H-, (13)C-NMR, mass, ESR, conductivity measurements, elemental and thermal analysis. Specifically the magnetic and electronic spectral measurements demonstrate the octahedral structures of cobalt(II), nickel(II) complexes and square planar geometries of copper(II), palladium(II) complexes. All the ligands and complexes were screened for their in vitro antibacterial activity against two gram-positive bacteria (Bacillus subtilis, Staphylococcus aureus) and two gram-negative bacteria (Escherichia coli, Klebsiella pneumonia). In this study, Pd(II) complexes exhibited potent antibacterial activity against B. subtilis, S. aureus whereas other metal complexes also exerted good activity towards all tested strains even than standard drugs streptomycin and ampicillin.
... Similarly, the binuclear Ni(II) and Pd(II) complexes have been prepared and characterized by Al-Kubaisi [13]. Recently, the authors group developed various coordination compounds including Schiff-base macrocycles derived from o-phthalaldehyde and different amines [14][15][16][17][18][19][20][21][22][23][24]. Further, we also disclosed the excellent catalytic and antibacterial activity of the macrocyclic Schiff-bases and their metal complexes in our recent reports [14][15][16][17][18][19][20][21][22][23][24]. ...
... Recently, the authors group developed various coordination compounds including Schiff-base macrocycles derived from o-phthalaldehyde and different amines [14][15][16][17][18][19][20][21][22][23][24]. Further, we also disclosed the excellent catalytic and antibacterial activity of the macrocyclic Schiff-bases and their metal complexes in our recent reports [14][15][16][17][18][19][20][21][22][23][24]. However, to our knowledge the combination of o-phthalaldehyde and aminoacids has never been used to synthesize Schiff-base ligands. ...
... This band was shifted towards lower side about 90-110 cm −1 compared to the ligand spectrum indicating the coordination of amino nitrogen to the metal ion [5]. A medium intensity band due to C N appeared at 1620-1630 cm −1 was also found to be shifted towards lower side about 13-23 cm −1 compared to ligand spectrum and supports the coordination of imino nitrogen (C N) of ligand to the metal ion [14,15,17,18]. In addition to this, the appearance of new band in the range of 1565-1570 cm −1 assignable to (C-O) suggests the coordination of carbonyl group of glycyl-glycine moiety in the enol form through deprotonation. ...
A binucleating new Schiff-base ligand with a phenylene spacer, afforded by the condensation of glycyl-glycine and o-phthalaldehyde has been served as an octadentate N₄O₄ ligand in designing some binuclear complexes of cobalt(II), nickel(II), copper(II), and palladium(II). The binding manner of the ligand to the metal and the composition and geometry of the metal complexes were examined by elemental analysis, conductivity measurements, magnetic moments, IR, ¹H, ¹³C NMR, ESR and electronic spectroscopies, and TGA measurements. There are two different coordination/chelation environments present around two metal centers of each binuclear complex. The composition of the complexes in the coordination sphere was found to be [M₂(L)(H(2)O)₄] (where M=Co(II) and Ni(II)) and [M₂(L)] (where M=Cu(II) and Pd(II)). In the case of Cu(II) complexes, ESR spectra provided further information to confirm the binuclear structure and the presence of magnetic interactions. All the above metal complexes have shown moderate to good antibacterial activity against Gram-positive and Gram-negative bacteria.
