Synthesis and characterizations of meso-disubstituted asymmetric porphycenes

A post-synthetic method has been developed to synthesize novel asymmetric porphycenes bearing two different substituents on the meso-positions. Nitration of 9-acetoxy-2,7,12,17-tetra-n-propylporphycene with AgNO₃ in CH₃COOH/CH₂Cl₂ occurs regioselectively at the 19-position of the macrocycle to give 9-acetoxy-19-nitro-2,7,12,17-tetra-n-propylporphycene (3a) which was readily converted to 9-acetoxy-19-amino-2,7,12,17-tetra-n-propylporphycene (4a) by the reduction with SnCl₂ in pyridine.     

Synthesis, molecular conformation, vibrational and electronic transition, isometric chemical shift, polarizability and hyperpolarizability analysis of 3-(4-methoxy-phenyl)-2-(4-nitro-phenyl)-acrylonitrile: a combined experimental and theoretical analysis

This work presents the synthesis and characterization of a novel compound, 3-(4-Methoxy-phenyl)-2-(4-nitro-phenyl)-acrylonitrile (abbreviated as 3-(4MP)-2-(4-NP)-AN, C₁₆H₁₂N₂O₃). The spectroscopic properties of the compound were examined by FT-IR, UV–vis and NMR (¹H and ¹³C) techniques. FT-IR spectrum in solid state was observed in the region 4000–400 cm⁻¹. The UV–vis absorption spectrum of the compound which dissolved in chloroform was recorded in the range of 200–800 nm. The ¹H and ¹³C NMR spectra were recorded in CDCl₃ solution. To determine lowest-energy molecular conformation of the title molecule, the selected torsion angle is varied every 10° and molecular energy profile is calculated from 0° to 360°. The structural and spectroscopic data of the molecule in the ground state were calculated using density functional theory (DFT) employing B3LYP/6-31G(d,p) basis set. The dipole moment, linear polarizability and first hyperpolarizability values were also computed using the same basis set. A study on the electronic properties, such as HOMO and LUMO energies, were performed by time-dependent DFT (TD-DFT) approach. The HOMO and LUMO analysis were used to elucidate information regarding charge transfer within the molecule. The vibrational wavenumbers were calculated and scaled values were compared with experimental FT-IR spectrum. The complete assignments were performed on the basis of the experimental results and total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. Isotropic chemical shifts were calculated using the gauge-invariant atomic orbital (GIAO) method. Comparison of the calculated frequencies, NMR chemical shifts, absorption wavelengths with the experimental values revealed that DFT and TD-DFT method produce good results. The linear polarizabilities and first hyperpolarizabilities of the studied molecule indicate that the title compound can be used as a good nonlinear optical material. The thermodynamic properties of the studied compound at different temperatures were calculated, revealing the correlations between standard heat capacity, standard entropy, standard enthalpy changes and temperatures.     

Synthesis, characterization and antimicrobial activity of palladium(II) complexes with some alkyl derivates of thiosalicylic acids: Crystal structure of the bis(S-benzyl-thiosalicylate)-palladium(II) complex, [Pd(S-bz-thiosal)2]

S-Alkyl (R = benzyl, methyl, ethyl, propyl and butyl) derivatives of thiosalicylic acid and the corresponding palladium(II) complexes were prepared and their structures were proposed on the basis of infrared, ¹H and ¹³C NMR spectroscopy. The cis geometrical configurations of the isolated complexes were proposed on the basis of an X-ray structural study of the bis(S-benzyl-thiosalicylate)-palladium(II), [Pd(S-bz-thiosal)₂] complex.Antimicrobial activity of the tested compounds was evaluated by determining the minimum inhibitory concentration (MIC) and minimum microbicidal concentration (MMC) in relation to 26 species of microorganisms. The tested ligands, with a few exceptions, show low antimicrobial activity. The palladium(II) complexes, [Pd(S-R-thiosal)₂], have statistically significant higher activity than the corresponding ligands. The complexes [Pd(S-et-thiosal)₂] and [Pd(S-pro-thiosal)₂] displayed the strongest activity amongst the all tested compounds. The palladium(II) complexes show selective and moderate antibacterial activity and significant antifungal activity. The most sensitive were Aspergillus fumigatus and Aspergillus flavus.     

Synthesis of 2,2'-Quinocyanines with Long N-Alkyl Substituents

2,2'-Quinocyanines with long alkyl substituents on one or both nitrogen atoms have been synthesized. ¹H NMR spectroscopy has been used to study the processes occurring during the alkylation of the starting quinoline bases.     

Nuclear magnetic resonance of donor atoms as a tool for determination of the structure of platinum metal complexes in solutions

Data on the NMR spectroscopy of C, N, O, Si, P, and Sn donor atoms of platinum metal complexes in solutions are surveyed. The chemical shift of a donor atom mainly depends on the ligand in the trans-position (due to the trans-effect). The chemical shift of a donor atom on a particular coordinate of the complex (coordinate shift, CSh) is an attribute of this coordinate and can be used to identify such a coordinate in platinum metal complexes and to determine the structures of complexes. Based on the known data, CSh diagrams were composed for ¹H, ¹³C, ¹⁴N, ¹⁷O, ¹⁹F, ³¹P, and ¹¹⁹Sn. Examples of using the CShs for determining the structures of platinum metal complexes in solutions are presented.     

The structure of a triosmium carbonyl cluster-phenylarsine oxide derivative

The reaction between the dihydride of decacarbonyltriosmium [H₂Os₃(CO)₁₀] and phenyl arsine oxide (PAO) in benzene yields only one product [Os₃(O)₉(μ-H){μ-PhAs(O)OAsPh}] (1), which is characterized by high resolution mass spectrometry (HRMS), Fast Atomic Bombardment Mass Spectrometry (FAB)⁺, IR, ¹H and ¹³C NMR, and single crystal X-ray diffraction. The solid state X-ray diffraction study of compound (1) shows that the molecule is polycyclic and has an osmium triangle with a bridging hydride bonded to a PhAs(O)-O-AsPh ligand.     

Synthesis of bridged isoflavone derivatives

Summary 7-Chloroalkoxyisoflavones (10–26) have been prepared by chemoselective-in the case of 5,7-dihydroxyisoflavones also regioselective-alkylation of hydroxyisoflavones (3–9) with -bromo--chloroalkanes. Compounds10–26 were allowed to react either with 2,4-dihydroxy-3-n-propylacetophenone (1) or with 2-ethoxycarbonyl-7-hydroxy-8-n-propylchromone (2) to afford bridged isoflavone derivatives27–51 with methylene spacers of various length. Carboxylic acid ethyl esters43–51 have been saponified to obtain the carboxylic acids52–60.

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Darstellung überbrückter Isoflavonderivate

Zusammenfassung Die chemoselektive und bei den 5,7-Dihydroxyisoflavonen auch regioselektive Alkylierung von Hydroxyisoflavonen3 bis9 mit -Brom--chloralkanen ergibt 7-Chloralkoxyisoflavone10 bis26. Die Umsetzung des 2,4-Dihydroxy-3-n-propylacetophenons und 2-Ethoxycarbonyl-7-hydroxy-8-n-propylchromons mit den Verbindungen10 bis26 liefert die überbrückten Isoflavone27 bis51 mit einem Methylen-Spacer verschiedener Länge. Die Verseifung der Ester43 bis51 führt zu den Carbonsäuren52 bis60.

     

The stereochemistry of a nine-membered ring analogue of nefopam,a nonnarcotic analgesic drug

The solid-state structure of a (±)-homonefopam hydrogenfumarate salt having an-O(CH₂)₃N-fragment was determined by single-crystal X-ray diffraction analysis. Homonefopam hydrogenfumarate gave crystals belonging to the monoclinicP2₁/c space group, and at ambient temperaturea=10.220(1),b=18.187(2),c=10.687(2)A,=94.43(1),V=1980.5(5)å³ Z=4,R(F)=0.039,R _w =0.039,R _W (F)=0.025. The¹H NMR spectrum of homonefopam hydrochloride in CD₂Cl₂ solution showed two species (7:1 ratio) at the prototropic shift-nitrogen inversion slow exchange limit. The solution-state major species has the same conformation andtrans-to-phenyl axial N-methyl disposition found in the crystal as evidenced by three antiperiplanar vicinal³ J (HH) coupling constants in the oxytrimethyleneamino fragment and vicinal coupling constants involving theN-H proton. TheR-ratio method was used to estimate 64(2) O-C(3)-C(4)-C(5) and 75(3) C(3)-C(4)-C(5)-N(6) dihedral angles for the major species in CD₂Cl₂ solution in accord with its proposed structure. The finding of C(3)-C(4) bond time-averaged magnitude³ J (HH) values and severe broadening of signals from other minor species protons suggests conformational heterogeneity for the solution-state minor species.     

Evidences of a hydrolysis process in the synthesis of N-vinylcaprolactam-based microgels

The hydrolysis process suffered by vinylcaprolactam (VCL) monomer during polymerization and the way of avoiding it is a matter of considerable interest when the final material is used in biomedical applications. In this work, in order to study the hydrolysis process in the synthesis of VCL-based microgels, VCL was polymerized by emulsion polymerization in batch and semi-batch reactors by using N,N′-methylenebisacrylamide (BA) as cross-linker and potassium persulfate (KPS) as initiator. Moreover, the partial conversion evolutions of VCL and BA were analyzed by ¹H NMR. The colloidal characterization was carried out by measuring the final average diameters as a function of temperature. The results showed that there were two competitive reactions (hydrolysis and propagation) in the polymerizations carried out in the absence of a buffer. However, VCL did not suffer hydrolysis by adding a buffer in the recipes. A new reliable method for the determination of the partial conversions was developed using the quantitative NMR method. The final cross-linked colloidal particles (microgel particles) obtained in the buffered reaction presented the conventional swelling de-swelling behavior corresponding to temperature sensitive microgels.     

Pentamethylated derivatives of [60]fullerene: X-ray structure of the C60Me5H and ESR spectroscopy evidence for the stable radical C60Me5

Single-crystal X-ray study of 6,9,12,15,18-pentamethyl-1,6,9,12,15,18-hexahydro(C₆₀-I_h)[5,6]fullerene (C₆₀Me₅H) has been reported. In crystal packing, the stacking self-organization of molecules is realized. It is concluded that the formation of such polar columns is a general rule for crystals of C₆₀R₅H independent of the nature of the R group. An ESR spectrum of the stable fullerenyl radical of the cyclopentadienyl-type, C₆₀Me₅, was observed in a sample of the pentamethylated[60]fullerene. Rotation of methyl groups around C-C bonds is restricted on the ESR scale time and therefore protons within each methyl group are non-equivalent.     

Synthesis and structure of (trichlorogermyl)methyl adamantane-1-carboxylate

The reaction of adamantane-1-carboxylic acid chloride with trichlorogermylmethanol afforded (trichlorogermyl)methyl adamantane-1-carboxylate, whose molecular structure was established by ¹H NMR spectroscopy and X-ray diffraction analysis. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1576–1579, July, 2005.     

Thermochromism in nickel(II) complexes: thermal, solid state H NMR and single crystal X-ray analysis of bis-(N,N-dimethyl-1,2-ethanediamine) nickel(II) perchlorate

The complex bis-(N,N-dimethyl-1,2-ethanediamine) nickel(II) perchlorate undergoes a first-order thermochromic phase transition at ca. 476 K, changing its color from orange to red. The room temperature X-ray crystal structure determination showed that the nickel ion possesses a square-planar geometry with two five membered chelate rings, in the δλ conformation, forming the NiN₄ chromophore. The broad-line ¹H NMR indicates the onset of a dynamic disorder of diamine chelate rings at the phase transition temperature region, while T₁ measurement of ¹H affords the activation energy of the puckering metal chelate rings to be 26 kJ mol⁻¹. The electronic spectrum revealed that a weakening of ligand field around the nickel is associated with the phase transition.     

Synthesis and spectral characterization of some complexes of platinum(II) containing η-methyleugenol

Several complexes of the formula trans-[Pt(Meug)(Am)Cl₂], Meug: methyleugenol (4-allyl-1,2-dimethoxybenzene), a η²-coordinated olefin, and Am: ammine, methylamine, diethylamine, o-toluidine, m-toluidine, p-toluidine, o-anisidine, m-anisidine and p-anisidine have been prepared. UV, IR, Raman, ¹H NMR, ¹³C NMR and 2D NMR spectra of the complexes were recorded and analyzed.     

Synthesis of optically active hydridocarbonyl triosmium clusters with terpene derivatives as ligands. Molecular structure and absolute configuration of a cluster with a bridging dihydroimidazole ligand

Reactions of the triosmium clusters Os₃(CO)₁₁(NCMe) (1) and Os₃(CO)₁₀(NCMe)₂ (2) with terpene derivatives,viz., (1S,3S,4R,6R)-3-(N,N-dimethylamino)-4-amino-3,7,7-trimethylbicyclo [4.1.0]heptane (3). (3bR,4aR)-(3,4,4-trimethyl-3b,4,4a,5-tetrahydrocyclopropa [3,4]cyclopenta[1,2-c]pyrazol-1-yl)acetic acid (4a), and (3bR,4aR)-3-(3,4,4-trimethyl-3b, 4,4a,5-tetrahydrocyclopropa[3,4]cyclopenta[1,2-c]pyrazol-1-yl)propionic acid (4b), were studied. A complex with the terminally coordinated ligand is formed in the first step of the reaction of diamine3 with cluster1. Heating of the resulting complex is accompanied by activation of one of the methyl groups of the ligand to form diastereomers with the bridging tricyclic dihydroimidazole ligand. One of these diastereomers was studied by X-ray diffraction analysis and its absolute configuration was established. Pyrazolycarboxylic acids react with cluster2 as simple organic acids and are coordinated as a bridge at the Os—Os bond through the carboxyl group. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1447–1454, August, 2000.     

Synthesis and characterization of some novel cadmium(II) complexes with 3-hydroxypicolinic acid (3-OHpicH): Crystal and molecular structures of [CdI(3-OHpic)(3-OHpicH)(H2O)]2, [Cd(3-OHpic)2(H2O)2] and [Cd(3-OHpic)2]n

Cadmium(II) complexes of 3-hydroxypicolinic acid, namely [CdI(3-OHpic)(3-OHpicH)(H₂O)]₂ (1), [Cd(3-OHpic)₂(H₂O)₂] (2) and [Cd(3-OHpic)₂]_n (3) were prepared and characterized by spectroscopic methods (IR, NMR) and their molecular and crystal structures were determined by X-ray crystal structure analysis. Complexes 1 and 2 were prepared in similar reaction conditions using different cadmium(II) salts: cadmium(II) iodide and cadmium(II) acetate dihydrate, respectively, while 3 was prepared by recrystallization of 2 from N,N-dimethylformamide solution. Various coordination modes of 3-OHpicH in 1–3 were established in the solid state: bidentate N,O-chelated mode in 1 and 2, monodentate mode through the carboxylate O atom from zwitterionic ligand in 1 and bidentate N,O-chelated and bridging mode in 3. In the DMF solution of all prepared complexes, only monodentate mode of 3-OHpicH binding to cadmium(II) through the carboxylate O atom was established by ¹H, ¹³C, ¹⁵N and ¹¹³Cd NMR spectroscopy.     

Branched polyphenylenes and phenylene dendrimers: NMR and optical studies

Two branched polyphenylenes with 1,3,5-triphenylbenzene as branching centers were synthesized together with a family of phenylene cyclotrimers as model compounds. On the basis of the NMR analysis, specifically ¹H NMR, ¹³C NMR and 2D heteronuclear correlation experiments (HSQC and HMBC) of model compounds, the huge number of overlapping signals in the polymer spectra are attributed to aromatic protons and carbon atoms of the branched phenylene structure. The comparison with absorption spectra of linear model compounds clearly shows that the polymer optical properties depend on the length of the segments between the branching cores. This result strongly supports the proposed NMR assignment proving that the combination of the two techniques is a powerful tool for unveiling complex branched structures.     

高岭石结构缺陷的 1H MAS NMR和Raman研究

The structure default of kaolinites was characterized with ¹H MAS NMR and Raman spectra. Although the HI indexes of Suzhou and Maoming kaolinite are similar, their ¹H MAS NMR and Raman spectra are very different. ¹H MAS NMR showed that the hydroxyl proton chemical shifts of Suzhou kaolinite are in the higher field and with larger different between the inner surface hydroxyls protons and inner hydroxyls proton chemical shifts than Maoming kaolinite. Raman spectra showed that the surface hydroxyls stretching vibration bands of Suzhou kaolinite are in the high frequency region, and the half height widths of the bands are 7.0～14 cm^-1. The area ratio S_z/(S_z+S_A), where S_Z and S_A are the areas of bands 3685 cm^-1 and 3695 cm^-1 respectively, is 0.23. But the surface hydroxyls stretching vibration bands of Maoming kaolinite are in the low frequency region, and the half height widths of the bands are 8.9～15.1 cm^-1. The area ratio S_z/(S_z+S_A) is 0.77. Those data proved that Suzhou kaolinite has lower structure default than Maoming kaolinite and ¹H MAS NMR and Raman spectra are effective method for study of kaolinite structure default.     

Structural investigations on diorgano- and triorganotin(IV) derivatives of [meso-tetra(4-sulfonatophenyl)porphine] metal chlorides

Several new complexes of organotin(IV) moieties with MCl_n[meso-tetra(4-sulfonatophenyl)porphine], (R₂Sn)₂MCl_n[meso-tetra(4-sulfonatophenyl)-porphinate]s and (R₃Sn)₄MCl_n [meso-tetra(4-sulfonatophenyl)porphinate]s, [M = Fe(III), Mn(III): n = 1, R = Me, n-Bu; Ph; M = Sn(IV): n = 2, R = Me, n-Bu] have been synthesized and their solid state configuration investigated by infrared (IR) and Mössbauer spectroscopy, and by ¹H and ¹³C NMR in D₂O.The electron density on the metal ion coordinated inside the porphyrin ring is not influenced by the organotin(IV) moieties bonded to the oxygen atoms of the side chain sulfonatophenyl groups, as it has been inferred on the basis of Mössbauer spectroscopy and, in particular, from the invariance of the isomer shift of the Fe(III) and Sn(IV) atoms coordinated into the porphyrin square plane of the newly synthesized complexes, with respect to the same atoms in the free ligand.As far as the coordination polyhedra around the peripheral tin atoms are concerned, infrared spectra and experimental Mössbauer data would suggest octahedral and trigonal bipyramidal environments around tin, in polymeric configurations obtained, respectively, in the diorganotin derivatives through chelating or bridging sulfonate groups coordinating in the square plane, and in triorganotin(IV) complexes through bridging sulfonate oxygen atoms in axial positions.The structures of the (Me₃Sn)₄Sn(IV)Cl₂[meso-tetra(4-sulfonatophenyl)porphinate] and of the two model systems, Me₃Sn(PS)(HPS) and Me₂Sn(PS)₂ [HPS = phenylsulfonic acid], have been studied by a two layer ONIOM method, using the hybrid DFT B3LYP functional for the higher layer, including the significant tin environment. This approach allowed us to support the structural hypotheses inferred by the IR and Mössbauer spectroscopy analysis and to obtain detailed geometrical information of the tin environment in the compounds investigated.¹H and ¹³C NMR data suggested retention of the geometry around the tin(IV) atom in D₂O solution.     

Synthesis and isomerism of hydrazones of 2-(5-thioxo-4,5-dihydro-1,3,4-thiadiazol-2-ylthio)acetohydrazide

New hydrazones of 2-(5-thioxo-4,5-dihydro-1,3,4-thiadiazol-2-ylthio)acetohydrazide have been obtained and the percentages of anti/syn - conformers were determined. Based on the analyses of ¹H NMR spectra, it was concluded that for hydrazones obtained from the 2- hydroxybenzaldehydes and 2’-hydroxycetophenones the ratio between the anti-and syn-conformers depends on the strength of intramolecular hydrogen bond (IMHB) between the nitrogen atom of the imino group and the proton of the 2-hydroxy group. It was shown that increase in IMHB strength results in stabilization of the anti-conformer in solution.