Synthesis and characterization of water-soluble zinc(II) Schiff-base complexes derived from amino acids and 3-formyl-4-hydroxybenzyl-triphenylphosphonium chloride

Tridentate Schiff-base ligands derived from condensation of 3-formyl-4-hydroxybenzyl-triphenylphosphonium chloride with glycine, L-alanine, L-valine, L-leucine and L-phenylalanine in the presence of Zn(OAc)₂ · 2H₂O form five new water-soluble Zn(II) complexes, which were characterized by elemental analyses, IR, electronic absorption and ¹H, ¹³C NMR spectroscopies. In the IR spectra of the complexes, the difference between the asymmetric and the symmetric carboxylate stretching frequencies is larger than ～210 cm^?1, which implies that the carboxylate groups are monodentate. UV-Vis electronic absorption studies show that Zn(II) functions as a trap for the Schiff-base intermediate. Schiff-base complexes formation were confirmed by the appearance of new signals in the ¹H NMR for the azomethine hydrogen at ～8 ppm and condensed L-amino acids at 3.4–3.8 ppm (C(3)–H). These complexes are formed through coordination of the ONO from the carboxyl, imino and phenoxy groups of the ligands to Zn(II).     

Synthesis and characterization of polyamidoamine dendrimers surface-functionalized with bromotricarbonylpyridyliminerhenium(I) units

A novel type of rhenium-containing dendrimers has been prepared and characterized. A series of Schiff base-terminated PAMAM dendrimers were prepared by condensing the terminal amine groups of PAMAM dendrimers with pyridine-2-carboxaldehyde. Complete condensation of the terminal amines was confirmed by ¹H NMR spectroscopy. Bromotricarbonylrhenium(I) moieties were introduced onto the surface of these modified PAMAM derivatives by refluxing with bromopentacarbonylrhenium(I). These complexes had been characterized by a variety of analytical and spectroscopic techniques and their IR, NMR, and mass spectra discussed. The crystal structure of the model compound [(CH₃CONHCH₂CH₂NCHPy)ReBr(CO)₃] confirms a facial configuration of the three carbonyl ligands. UV-Vis absorption spectroscopy suggests that the {Re(CO)₃} moieties are quite far apart even in the second generation PAMAM dendrimers and do not interact with one another. In fact, the intensity of the metal-to-ligand (dπ-pπ^∗) charge-transfer is a linear function of the number of {Re(CO)₃} chromophores.     

Synthesis and Crystal Structure of (Z)-Ethyl 5-(phenylamino)-3-(phenylimino)-3H-1,2-dithiole-4-carboxylate

The compound (Z)-ethyl 5-(phenylamino)-3-(phenylimino)-3H-1,2-dithiole-4-carboxylate 3 has been synthesized by the reaction of ethylacetoacetate 1 and phenylisothiocyanate 2. Its structure has been established by ¹H NMR, ¹³C NMR, infrared, mass spectra, and x-ray crystallography.      

Synthesis,characterization and fluorescence spectra of mononuclear Zn(II), Cd(II) and Hg(II) complexes with 1,10-phenanthroline-5,6-dione ligand

The mononuclear complexes of Zn(II), Cd(II) and Hg(II), [Zn(phen-dione)Cl₂], [Cd(phen-dione)Cl₂] and [Hg(phen-dione)Cl₂], where phen-dione?=?1,10-phenanthroline-5,6-dione, have been synthesized and characterized by elemental analysis and IR, ¹H?NMR and electronic absorption spectroscopies. The ν(C=O) of coordinated phen-dione ligands in these complexes shows that the phen-dione is not coordinated to metal ion from its C=O sites. Electronic spectra of the complexes show two absorption bands for intraligand transitions. These absorption bands show dependence on the dielectric constant of solvents. These complexes exhibit an intense fluorescence band around 545?nm in DMSO when the excitation wavelengths are 200?nm at room temperature.     

Syntheses,Electronic Structure,and Second-Order Optical Nonlinearity of Two New Bidentate Monoazo Schiff-Base Compounds

Two new bidentate salicylaldiminato Schiff-base ligands have been synthesized by condensation of various precursor ligands and n-propylamine. The results of elemental analysis are in conformity with the suggested formula. The main bands in IR spectra, signals in ¹H NMR and electronic absorption spectra are assigned and discussed in terms of molecular structure. Semiempirical calculations of the structures and second-order nonlinear optical polarizabilities () of molecules were performed. The value for one of these Schiff-base compounds is 134 times that of urea.     

Photochromic and thermochromic spiranes. 19. 2-thioxo-3-phenyl-5,5-diivietiiylspiro (1,3-oxazolidine-4,2′-[2h]chromenes)

We have synthesized and characterized by IR, UY,¹H, and¹³C NMR spectroscopy new spiropyrans based on 2-thioxo-3 phenyl-5,5-dimethyl-1,3-oxazolidine. We have studied their photochromic properties in 2 propanol at -80°C. In the electronic spectra of photo-induced farms, we have detected two long-wavelength absorption bands in the 370–438 and 480–677 nm region.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, p. 1253–1259, September, 1995.     

Synthesis,characterization and fluorescence spectra of mixed ligand Zn(II), Cd(II) and Hg(II) complexes with 1,10-phenanthroline-5,6-dione ligand

The novel mixed ligand complexes [M(bpy)(phen-dione)](PF₆)₂ (M?=?Zn(II), Cd(II) and Hg(II), bpy?=?2,2^′-bipyridine and phen-dione?=?1,10-phenanthroline-5,6-dione) have been synthesized and characterized by elemental analysis, IR, ¹H NMR and electronic absorption spectroscopies. The ν(C=O) of coordinated phen-dione in these complexes are very similar to the free phen-dione ligand showing that phen-dione is not coordinated to metal ion from its C=O sites. Absorption spectra of the complexes show two absorption bands for intraligand transitions. These absorption bands show dependence to the dielectric constant of solvent. These complexes exhibit an intensive fluorescence band around 535?nm in DMF when the excitation wavelength is 260?nm at room temperature. The fluorescence intensity of these complexes is larger than that of the free ligand.     

Theoretical Study and Experimental Analysis on 2-(1-Ethyl-4-hydroxy-2-oxo-1,2-dihydroquinolin-3-yl)-2-oxoacetic Acid (<Emphasis Type="Bold">3</Emphasis>) Using the DFT Approach

Riley oxidation of 3-acetyl-4-hydroxyquinolin-2(1H)-one (1) with selenium dioxide furnished the unexpected product 2-(1-ethyl-4-hydroxy-2-oxo-1,2-dihydroquinolin-3-yl)-2-oxoacetic acid (3). The expected product 2-(1-ethyl-4-hydroxy-2-oxo-1,2-dihydroquinolin-3-yl)-2-oxoacetaldehyde (2) was excluded based on the spectral data. The elemental analysis and spectral data (IR, and ¹H NMR) was used to deduce the structure of compound 3. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations of the electronic structure at the B3LYP/6-311G (d,p) level of theory have been employed for compound 3 to investigated its geometry, linear polarizability 〈Δα〉, first-order hyperpolarizability 〈β〉, natural bonding orbital (NBO), molecular electrostatic potential contours (MEP and ESP), electrophilicity, and UV–Vis spectra in both ethanol and dioxane solvents. The geometrical and energetic parameters have been extensively investigated to reveal the reason behind the selective formation of compound 3, rather than the expected product 2. FT-IR spectra in the solid phase were recorded for compound 3. The thermo-chemical parameters, harmonic vibration frequencies, and the equilibrium geometries have been calculated at the DFT/B3LYP/6-311G (d,p) level. Time-dependent density functional theory (TD-DFT) was used to calculate the excited states of compound 3. Changes in the solvent cause changes in the band intensities and in the positions of the band maxima (λ_max). The excited state was identified and contributes to the electronic configurations, and it was characterized in terms of the relevant MOs. The theoretical spectra were computed using the Coulomb-attenuating method (CAM-B3LYP), using the basis set 6-311G (d,p) in the gas phase, and the polarizable continuum model (PCM) in dioxane and ethanol. The results indicate good agreement with the observed spectra.     

Synthesis,Spectroscopic and Magnetic Studies on Metal Complexes of 5-Methyl-3-(2-Hydroxyphenyl)Pyrazole

A tridentate ONN donor ligand, 5-methyl-3-(2-hydroxyphenyl)pyrazole; H₂L, was synthesized by reaction of 2-(3-ketobutanoyl)phenol with hydrazine hydrate. The ligand was characterized by IR, ¹H NMR and mass spectra. ¹H NMR spectra indicated the presence of the phenolic OH group and the imine NH group of the heterocyclic moiety. Different types of mononuclear metal complexes of the following formulae [(HL)₂M][sdot]xH₂O (M=VO, Co, Ni, Cu, Zn and Cd), [(HL)₂M(H₂O)₂] (M=Mn and UO₂) and [(HL)LFe(H₂O)₂] were obtained. The Fe(III) complex, [(HL)LFe(H₂O)₂] undergoes solvatochromism. Elemental analyses, IR, electronic and ESR spectra as well as thermal, conductivity and magnetic susceptibility measurements were used to elucidate the structures of the newly prepared metal complexes. A square-pyramidal geometry is suggested for the VO(IV) complex, square-planar for the Cu(II), Co(II) and Ni(II) complexes, octahedral for the Fe(III) and Mn(II) complexes and tetrahedral for the Zn(II) and Cd(II) complexes, while the UO₂(VI) complex is eight-coordinate. Transmetallation of the UO₂(VI) ion in its mononuclear complex by Fe(III), Ni(II) or Cu(II) ions occurred and mononuclear Fe(III), Ni(II) and Cu(II) complexes were obtained. IR spectra of the products did not have the characteristic UO₂ absorption band and the electronic spectra showed absorption bands similar to those obtained for the corresponding mononuclear complexes. Also, transmetallation of the Ni(II) ion in its mononuclear complex by Fe(III) has occurred. The antifungal activity of the ligand and the mononuclear complexes were investigated.     

Spectroscopic characterization,X-ray structure and DFT studies on 4-[3-(2,5-dimethylphenyl)-3-methylcyclobutyl]-N-methylthiazol-2-amine

The titled molecule 4-[3-(2,5-dimethylphenyl)-3-methylcyclobutyl]-N-methylthiazol-2-amine (C₁₇H₂₂N₂S) is synthesized and characterized by ¹H NMR, ¹³C NMR, IR, and X-ray single crystal determination. The compound crystallizes in the monoclinic space group P2_1/c with a = 6.3972(4) Å, b = 9.4988(6) Å, c = 26.016(2) Å and β = 93.496(7)°. In addition to the molecular geometry from the X-ray determination, vibrational frequencies and gauge, including the atomic orbital (GIAO), ¹H and ¹³C NMR chemical shift values of the titled compound in the ground state are calculated using the density functional (B3LYP) method with 6-31G(d), 6-31++G(d,p) and 6-311+G(2d,p) basis sets. The calculated results show that the optimized geometries can well reproduce the crystal structure. Moreover, the theoretical vibrational frequencies and chemical shift values show good agreement with the experimental values. The predicted nonlinear optical properties of the titled compound are greater than those of urea. DFT calculations of the molecular electrostatic potentials and frontier molecular orbitals of the titled compound are carried out at the B3LYP/6-31G(d) level of theory.     

Influence of ligand donor-acceptor properties on the structure,optical, and electrochemical characteristics of Ir(III) complexes with cyclometallated 2-phenylbenzotiazole

The cis-C,C-structure of a series of cyclometallated Ir(III) complexes with 2-phenylbenzotiazole was determined by the methods of X-ray diffraction (XRD) analysis, ¹H, ¹³C, ³¹P NMR, and IR spectroscopy. Long-wave absorption bands, phosphorescence, and processes of electrochemical oxidation and reduction of the complexes were assigned to the transfer of electrons presumably located on d _π and π* orbitals of cyclometallated 2-phenylbenzotiazole. The decrease in donor and acceptor properties of the ligands leads to the blue shift of absorption spectra and phosphorescence and to the anodic shift of oxidation and reduction potentials of the complexes.     

Regioselective bromination of (Tetraphenyltetrabenzoporphyrinato)palladium(II). Synthesis of a new octabromo derivative of the tetraphenyltetrabenzoporphyrin series

Bromination of (meso-tetraphenyltetrabenzoporphyrinato)palladium(II) with bromine in the presence of tetramethylammonium bromide occurs exclusively at the benzene rings fused to the porphyrin system while the phenyl rings in the meso positions are not involved. The corresponding octabromo-substituted complex was obtained using a large excess of bromine on prolonged reaction time. The complex was isolated and characterized by ¹H NMR spectra, electronic absorption spectra in the UV and visible regions, and MALDI-TOF mass spectra. It was assigned the structure of symmetric (22,23,72,73,122,123,172,173-octabromo-5,10,15,20-tetraphenyltetrabenzoporphyrinato)palladium(II).     

Heteroannulated Quinazoline and Quinazolinone Derivatives from (Z)-2-[1-Benzamido-2-(3,4,5-trimethoxyphenyl)]vinyl-3,1-benzoxazin-4(3H)-one

The title compound 1 was prepared and allowed to react with a series of nitrogen nucleophiles to afford the quinazoline and quinazolinone derivatives 2–12 and tetrazole derivative 13. The IR, ¹H NMR, ¹³C NMR, and mass spectra of all the synthesized compounds were discussed.     

Structure and spectral property of 8-(2-(5-(4-methylphenyl)-2-thienyl)vinyl)-10,10-dimethyl-10H-pyrido[1,2-a]indolium perchlorate

The title compound 8-(2-(5-(4-methylphenyl)-2-thienyl)vinyl)l-10,10-dimethyl-10H-pyrido[1,2-a]indolium perchlorate (3) has been synthesized by cycloaddition and condensation reactions, and characterized by elemental analysis, IR, ¹H NMR, and single-crystal X-ray diffraction. The crystal structure analysis exhibits that the molecule of 3 possesses good coplanarity, and the three rings (10H-pyrido[1,2-a]indolium, thienyl and phenyl) and vinyl moiety can make up a large conjugated system. Its UV-Vis and fluorescence spectra were measured, and found that it displays larger maximum absorptions and emission wavelengths in comparison with 8-(4-methylphenyl)vinyl analogue.     

Co(II) and Co(III) macrocyclic boron-bearing dioximates

Syntheses are reported for CoD₃(BF)₂ and [CoD₃(BF)₂]BF₄,where H ₂ D is dimethylglyoxime, -benzyldioxime, or cyclohexanedione dioxime. The IR spectra at 400–4000 cm ^–1 have been measured, as have the electronic absorption spectra and the¹H,¹³C,and ¹¹BNMR spectra; a comparison is made with the spectra of the analogous iron(II) complexes.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 26, No. 3, pp. 375–377, May–June, 1990.     

1H NMR,IR and UV/VIS Spectroscopic Studies of Some Schiff Bases Derived from 2‐Aminobenzothiazole and 2‐Amino‐3‐Hydroxypyridine

By condensing 2‐aminobenzothiazole with 2‐hydroxy‐1‐naphthaldehyde, 2‐hydroxybenzaldehyde, 4‐methoxybenzaldehyde, 4‐hydroxybenzal‐dehyde, benzaldehyde and 4‐dimethylaminobenzaldehyde, and five Schiff bases Ia‐Ie are prepared. Also, two Schiff bases IIa and IIb are prepared by condensation of 2‐amino‐3‐hydroxypyridine with 2‐hydroxy‐1‐naphthaldehyde and 2‐hydroxybenzaldehyde. The ¹H NMR, IR and UV/Vis spectra of these seven Schiff bases are investigated. The signals of the ¹H NMR spectra as well as the important bands in the IR spectra are considered and discussed in relation to molecular structure. The UV/Vis absorption bands in ethanol are assigned to the corresponding electronic transitions and the electronic absorption spectra of Schiff bases Ib and IIb are studied in organic solvents of different polarities. The UV/Vis absorption spectra of 2‐amino‐3‐hydroxypyridine Schiff bases IIa and IIb are investigated in buffer solutions of different pH values containing 5% (v/v) methanol, and the results are utilized for the determination of pK_a and ΔG^* of the ionization of the phenolic OH‐groups. The fluorescence spectra of IIa and IIb are studied in organic solvents of different polarities. The obtained spectral results are confirmed by some molecular calculations using the atom super position and electron delocalization molecular orbital theory for the Schiff base IIb.     

Tetrazole derivatives. 25. Investigation of the synthesis of 1-(5-tetrazolyl)-3,5-diphenylleucoverdazyl. Structure and some properties of the accompanying product — 1,3,7,9-tetraphenyl-5-oxo-5H-1,2,4-triazolo[3′,4′:5,1]imidazo[4,3-c] -1,2,4-triazole

In the reaction of 1,3-diphenyl-5-(5-tetrazolyl)formazan with formaldehyde, in addition to a leucoverdazyl, one can obtain 1,3-diphenyl-1,2,4-triazole and 1,3,7,9-tetraphenyl-5-oxo-5H-1,2,4-triazolo[3,45,1]imidazo[4,3-c]-1,2,4-triazole. The structure of the latter was established from data from the mass spectrum and the ¹H and ¹³C NMR, UV, and IR spectra, as well as from the products of alcoholysis of this compound, which leads to 1,3-diphenyl-1,2,4-triazole and 1,3-diphenyl-5-carbethoxy-1,2,4-triazole. According to the data from the PMR spectra, the leucoverdazyl displays prototropic tautomerism due to the NH proton of the tetrazine ring.See [1] for Communication 24.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 694–700, May, 1981.The author thank V. I. Svergun ans M. B. Smirnov for recording the ¹³C NMR spectra and their assistance in their interpretation.     

Synthesis, characterization and in vitro DNA binding studies of tin(IV) complexes of tert-butyl 1-(2-hydroxy-1-phenylethylamino)-3-methyl-1-oxobutan-2-yl carbamate

Tin(IV) complexes 1(a and b) and 2(a and b) of valine derived peptide derivatives were synthesized and characterized on the basis of elemental analysis, IR, ¹H, ¹³C, ¹¹⁹Sn NMR, ESI-MS spectra and molar conductance measurements. The C-Sn-C angle was estimated from ^I3C and ¹H NMR data ¹J(¹¹⁹Sn, ^I3C) = 623 Hz; solution ²J(¹¹⁹Sn, ¹H) = 93.04 Hz to be 149.9°. In vitro binding studies of complexes 1 and 2 under physiological conditions at room temperature with CT-DNA were carried out employing UV-visible, fluorescence, circular dichroism and viscometric studies. The binding affinity of the complexes was quantified by calculating the K_b values and it follows the order 2a > 1a > 2b > 1b. To further examine the specific mode of binding, the interaction of complexes 2(a and b) were carried out with 5′GMP and 5′TMP by using absorption and NMR (¹H, ³¹P) spectroscopy. The supercoiled pBR322 plasmid DNA cleavage activity of the complexes was ascertained by gel electrophoresis assay. The complexes cleave supercoiled pBR322 plasmid DNA efficiently into its nicked form at micromolar concentrations.     

UV/Vis,IR and 1H NMR spectroscopic studies of bisazo-dianil compounds based on 5-(2-carboxyphenyl azo)-salicylaldehyde and primary diamines

The electronic absorption and emission spectra of the titled biazo-dianils are studied in organic solvents of different polarity as well as in aqueous buffer solutions of varying pH. The important bands in the IR spectra as well as the main signals of the 1H NMR spectra are assigned. The observed UV/Vis absorption bands are assigned to the corresponding electronic transitions. The fluorescence quantum yield and pK(a)(-) values in the ground and excited states are determined.     

Extraction of rhodium(III) with petroleum sulfoxides from hydrochloric acid solutions

Extraction of rhodium(III) from hydrochloric acid solutions with petroleum sulfoxides was studied. The optimal conditions of its recovery were found. The composition and structure of the compound being extracted was determined by electronic absorption, ¹H NMR, and IR spectroscopies and elemental analysis.