Synthesis and spectroscopic and structural characterization of two novel photoactivatable Ca2+ compounds

Two novel photoactivatable Ca(2+) compounds were synthesized to achieve a fast concentration jump of calcium ions in solution; this is of paramount importance for investigating the physiological cellular response. The light-sensitive ligands 4-(2-nitrophenyl)-3,6-dioxaoctane dioic acid (H2L1) and 4-(4,5-dimethoxy-2-nitrophenyl)-3,6-dioxaoctane dioic acid (H2L2) were generated by multistep syntheses, and the corresponding calcium complexes, Ca1 and Ca2, were isolated and characterized. The solution equilibria of H2L1 and H2L2 with Ca2+ were investigated; for both ligands, the formation of a 1:2 Ca2+/ligand species is detected and the complete characterization is presented. The crystal structures of Ca1 and Ca2 were determined. In Ca1 the solid state assembly is attained by a polymeric association of [(CaL1(H2O))2(mu-OH2)] dimeric units. Each calcium ion coordinates four oxygen atoms of one ligand (two ethereal, one carboxylic, and one bridging carboxylic oxygen atom), one water molecule, one bridging water molecule, and a carboxylate group of the other ligand within the dimer. The octacoordination of the metal is completed by an interaction with the adjacent dimeric unit. The crystal structure of the complex Ca2 does not show a polymeric nature, but it is a centrosymmetric dimer. The coordination number of the metal ion is still 8:4 oxygen atoms of the ligand; 3 water molecules; 1 bridging carboxylate group. A preliminary study of the photochemical features of the complexes Ca1 and Ca2 is reported: photoexcitation by a nanosecond pulsed UV laser induces the cleavage of the ligand. This drastically reduces the affinity of the ligand toward Ca2+, which is then released in solution.     

Synthesis and spectroscopic and structural studies of cross-conjugated dienones derived from cyclic ketones and aromatic aldehydes

Cross-conjugated dienones were synthesized by the reactions of cyclic ketones with two equivalents of aromatic aldehydes under basic conditions. An NMR spectroscopic study and X-ray diffraction analysis demonstrated that all reaction products are formed as E,E isomers. Spontaneous photochemical trans-cis isomerization of cross-conjugated dienones under the scattered light in solution was observed for the first time. The degree of isomerization depends mainly on the nature of the central fragment of the dienone molecule. The previously unknown product of photochemical [2+2]-cycloaddition of 2,5-bis[(E)-(3-pyridyl)methylidene]cyclopentanone was synthesized and characterized by spectroscopic methods and X-ray diffraction. Under the conditions used, only one isomer of the cyclobutane adduct was obtained. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1141–1150, July, 2006.     

Synthesis,spectroscopic and structural perspective of new ferrocenyl amides

Two new ferrocene derivatives with amide linkages were synthesized by the condensation of 4-ferrocenylaniline with n-alkyl acid chloride derivatives as pristine orange solids in good yields. FTIR and ¹H/¹³C NMR studies have confirmed the basic structure of the molecules with the involvement of intermolecular H-bonding, which together with the ferrocene-like packing ensures the stability of the crystal structure. Crystal structures for both compounds were solved by Rietveld refinements of high resolution X-ray powder diffraction data. The XRD results show that both compounds crystallize in the monoclinic space group P2₁/c. The primary feature of the crystal structure is a double layer of ferrocenyl groups stretched out in the b-c -plane perpendicular to the a-axis, with packing of the ferrocenyl groups occurring in a manner similar to that of pure ferrocene. Despite the close structural similarity, both compounds differ in the optimized geometry of respective Ferrocene conformers. The Cp rings are eclipsed for one Ferrocene conformer and close to staggered for the other, owing to the low energy barrier for the rotation of a cyclopentadienyl ring relative to the rest of the molecule.     

Two fluoro compounds of main group elements: Synthesis,characterization, theoretical and spectroscopic study

Two new compounds of fluorine: (C₂H₅)₄N[I₂F] and (C₂H₅)₄N[Br₂F], have been easily synthesized in a nearly quantitative by a direct reaction of (C₂H₅)₄NF, I₂ and Br₂. The products were isolated and characterized by elemental analysis and spectroscopic methods such as: Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible spectroscopy (UV-Vis). These compounds have been studied computationally with the Scalar ZORA relativistic level of theory using the ADF program package. The molecular parameters, and vibrational spectra were calculated. The excitation energies were found by timedependent perturbation density functional theory (TD-DFT). Molecule optimization, frequencies and excitation energies were calculated with standard Slatertype-orbital (STO) basis sets with triple-zeta quality double plus polarization functions (TZ2P) for all atoms. The FTIR, UV-Vis spectra and assignment of principal transitions and total density of state (TDOS) were extracted using the GaussSum 2.2 program. The comparison between experimental and calculated values showes that the experimental results correlate well with the predicted data.     

Synthesis and characterization of bis-cyclopropanated 1,3,5-tricarbonyl compounds. A combined synthetic, spectroscopic and theoretical study

Bis-cyclopropanated 1,3,5-tricarbonyl compounds were prepared by a sequence of Claisen condensations and cyclopropanations. The optimization of the conditions proved to be very important to suppress retro-Claisen reactions. The conformation of these molecules was studied by experimental and computational methods. The syn/syn;syn/syn conformation is present for all derivatives. It is exclusively present in the case of the derivative containing a phenyl group located at the terminal carbon atom. In most cases, equilibria with other conformers are found.     

芳基取代咪唑衍生物的合成及其紫外、荧光性质研究

设计合成了两种新颖的三芳基咪唑类化合物5和6,研究了其反应机理,优化了环合加成反应的工艺条件,化合物经FT-IR、HMR和MS进行结构表征。研究了两个化合物在不同溶剂中的紫外与荧光光谱,发现官能苄基的引入,会使吸收峰和发射峰均有不同程度的蓝移,这些光谱性质为今后研究其双光子吸收、双光子荧光和非线性光学性质奠定了实验基础。     

Synthesis, structural, spectroscopic and electrochemical studies of carborane substituted naphthyl selenides

New unsymmetrical selenides bearing an o-carborane and a naphthalene ring as the substituents were prepared by the cleavage of the corresponding diselenides. The compounds were characterized by means of spectroscopic and analytical methods. (77)Se NMR signals of the selenium atoms attached to the carbon atoms of the carborane cages are shifted downfield in comparison to those bonded only to the aromatic rings, indicating an electron withdrawing effect of the o-carboranyl substituent. Compounds 1-(2-R-1,2-dicarba-closo-carboranyl)naphthyl selenides (R = Me, 1; Ph, 2) were characterized by means of single crystal X-ray diffraction. The influence of the electronic nature of the substituents attached to the selenium atoms on the structural parameters and packing properties of naphthyl selenides are discussed. Theoretical calculations and cyclic voltammetry (CV) studies were carried out to compare the bonding nature of carboranyl and analogous aryl selenium compounds. Cyclic voltammetry studies of naphthyl carboranyl mono and diselenides have shown that the carboranyl fragment polarizes the Se lone pair making it less prone to generate a Se-Se bond.     

Synthesis, spectroscopic, and X-ray structural characterization of pharmacologically active substituted pyrazolyl-acetanilides

Five new pyrazole acetanilides were synthesized by N-alkylation of pyrazole and its derivatives with 4′-propionyl-2-iodoacetanilide. Compounds 1–5 were characterized by ¹H NMR, ¹³C NMR, IR, UV–Vis, MS, and elemental analysis. X-ray structures of representative compounds 1, 3, and 5 established their conformations and solid-state hydrogen bonding preferences. Acute toxicity, local anesthetic, and antiarrhythmic activities were assessed for compounds 1–5 using established protocols. Lower potencies and lower acute toxicities were recorded relative to lidocaine. Enhanced anesthetic activity of compound 3 was attributed to the presence of the propionyl group in the molecule. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Synthesis, spectroscopic, and structural aspects of two trinuclear cyano-bridged heterometallic complexes

Two new cyano-bridged trinuclear heterometallic complexes [Sr₂(Phen)₄(CF₃CO₂)(H₂O)₃Fe(CN)₆]·2H₂O (1) [Ca₂(Phen)₄(CF₃CO₂)(H₂O)Co(CN)₆]·2H₂O (2) (where Phen=1,10-phenanthroline) have been synthesized and their crystal structures have been determined. The structure of complex (1) features a central [Fe(CN)₆]³⁻ unit that links a monocation, [Sr(Phen)₂(OH₂)(OOCCF₃)]⁺ and a dication, [Sr(Phen)₂(OH₂)₂]²⁺ via two trans cyanide bridges. The complex (2) features a central [Co(CN)₆]³⁻ unit that links two monocations of [Ca(Phen)₂(OH₂)(OOCCF₃)]⁺ (the positions of the trifluoro acetate and water molecules are disordered over two positions) via two trans cyanide bridges. Each metal atom is seven coordinated and achieves pentagonal bipyramidal geometry. Two cocrystallized water molecules are present in both the complexes. The presence of an extensive network of hydrogen bonding imparts the overall stability to both the systems.     

Synthesis, spectroscopic, and structural properties of spirocyclopropanated bicyclobutylidenes and their radical cations

The spirocyclopropanated bicyclobutylidenes 3-7 have been prepared by McMurry coupling of the corresponding spirocyclopropanated cyclobutanone (3 and 5), Staudinger-Pfenniger reaction (4), oxidative coupling of a Wittig ylide (4) or Wittig olefination of perspirocyclopropanated cyclobutanone (6 and 7). The structure of the parent 2a and the perspirocyclopropanated bicyclobutylidene 5 was determined by X-ray crystallography which disclosed considerable steric congestion around the double bond. As a result 5 did undergo addition of dichlorocarbene, epoxidation with meta-chloroperbenzoic acid, and cyclopropanation with CH2I2/ZnEt2, but did not add the more bulky dibromocarbene. The reaction of 5 with tetracyanoethene proceeded smoothly, but led to a formal [3+2] cycloadduct across the proximal single bond of one of the inner cyclopropane rings. The consecutive spirocyclopropanation of bicyclobutylidene led to a bathochromic shift in the UV spectra of 12 and 17nm, respectively, for each pair of beta- and alpha-spirocyclopropane groups. In the He(I)-photoelectron spectra of these bicyclobutylidenes, the effect of spirocyclopropanation upon their pi-ionization energies (pi-IE,) was found to be almost additive, leading to a lowering of 0.05 eV per any additional beta-spirocyclopropane, and 0.28-0.22 eV per additional alpha-spirocyclopropane group; this indicates an increasing nucleophilicity of the double bonds in the order 1 < 4 < 3 < 5. Following the radical cations of the three symmetrical bicyclobutylidenes without (2a, b) and with six (5) spiroannelated cyclopropane rings, the radical cations of two symmetrical bicyclobutylidenes with two (4) and four (3) such rings were studied by ESR spectroscopy. Whereas 2b.+, 3.+, and 5.+ could be generated by electrolytic oxidation of the corresponding hydrocarbons in solution, the spectra of 2a.+ and 4.+, with unsubstituted 2,2',4,4'-positions, were observed upon radiolysis of their neutral precursors in a Freon matrix. On going from 2a.+ to 4.+, the coupling constant [aH] of the eight beta protons in the 2,2',4,4'-positions of bicyclobutylidene increases from 2.62 to 3.08 mT, and that of the four gamma protons in the 3,3'-positions changes from 0.27 to 0.049 to 0.401 mT on passing from 2a.+ via 2b.+ to 3.+. Computations by means of the density functional theory (DFT) at the B3LYP/6-311+G*//B3LYP/6-31G* level reproduce well the experimental hyperfine data.     

Sorption of vapors of aromatic compounds by cross-linked polymer particles containing luminophores: A spectroscopic study

Monodispersed core-shell particles 290–315 nm in diameter were prepared by seed emulsion copolymerization of styrene with divinylbenzene in the presence of luminophore-containing comonomers. The capability of the particles obtained to sorb toluene vapor was shown by solid-state ¹H and ¹³C NMR spectroscopy.     

Synthesis and thermal and spectroscopic properties of macrocyclic vinyl aromatic polymers

Well‐defined and narrow molecular weight distribution macrocyclic poly(2‐vinylnaphthalene) (P2VN) and poly(2‐vinyl‐9,9‐dimethylfluorene) (PDMVF) containing a single 1,4‐benzylidene or 9,10‐anthracenylidene unit have been synthesized via the potassium naphthalide initiated polymerization of the monomers followed by the end‐to‐end coupling of the resulting P2VN dianions under high‐dilution conditions with 1,4‐bis(bromomethyl)benzene or 9,10‐bis(chloromethyl)anthracene. Molecular characterization has been carried out by size exclusion chromatography, nuclear magnetic resonance, differential scanning calorimetry, ultraviolet–visible spectroscopy, and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. The thermal properties show distinct differences between the cyclic and matching linear polymers, with the macrocycles showing much higher glass‐transition and decomposition temperatures. The absorption bands are both hyperchromic and hypochromic with respect to the model aromatic compounds, and this is consistent with intensity borrowing. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5488–5503, 2004     

Synthesis and characterization of N-phenylated aromatic polyureas from dianilino compounds and aromatic diisocyanates

N-phenylated aromatic polyureas were synthesized by the polyaddition of dianilino compounds to aromatic diisocyanates in sym-tetrachloroethane at around 100°C. Factors that influence the reaction, such as monomer concentration, reaction solvent, catalyst, temperature, and time, were studied to optimize the conditions for the preparation of high molecular weight polymers. Compared with the analogous unsubstituted aromatic polyureas, the N-phenylated polyureas were almost amorphous and soluble in a variety of solvents and had low glass transition temperatures. Some of the polymers could be cast into transparent flexible films from chloroform solutions.     

Synthesis and structural study on MnO2 nanosheet material by X-ray absorption spectroscopic technique

MnO2 nanosheet with acetylene black composite material has been synthesized from layered K0.45MnO2 powder. The electrochemical lithiation reaction of nanosheet composite material proceeds in a different manner from that of the parent material, layered K0.45MnO2 powder. To elucidate the origin of the changes in discharge profile, the electronic and local structures for the nanosheet composites and its parent and protonated material have been investigated by Mn K-edge and O K-edge X-ray absorption spectroscopy (XAS). The results showed that local and electronic structure around Mn ions does not vary during nanosheet formation, while significant changes in electronic structure around oxide ions were observed. Accordingly, it is suggested that the difference observed in discharge profile is due to the electronic structural change induced by nanosheet formation.     

Synthesis,structural characterization,and reactions of cyclic organohydroborate half-zirconocene compounds

Cyclic organohydroborate complexes of zirconium monocyclopentadienyl CpZr[(mu-H)(2)BC(5)H(10)](3), 1, and CpZr[(mu-H)(2)BC(8)H(14)](3), 2, were prepared from the reaction of CpZrCl(3) with 3 mol of K[H(2)BC(5)H(10)] and K[H(2)BC(8)H(10)], respectively, in diethyl ether. Compounds 1 and 2 react with the hydride ion abstracting agent B(C(6)F(5))(3) to form the same salt [CpZr(OEt)(OEt(2))(mu-OEt)](2)[HB(C(6)F(5))(3)](2), 5. The complexes CpZr(Cl)[(mu-H)(2)BC(8)H(14)](2), 3, and CpZr(Cl)[(mu-H)(2)BC(8)H(14)](2) [where Cp = C(5)(CH(3))(5)], 4, were prepared from the reaction of CpZrCl(3) and CpZrCl(3) with K[H(2)BC(8)H(10)] in 1:2 molar ratios, respectively. An alpha-hydrogen of a BC(8)H(14) unit forms an agostic interaction with Zr in compound 3 but not in 4. All of the compounds were characterized by single-crystal X-ray diffraction analysis.     

Synthesis,structural and spectroscopic properties of two new ethylenediamine-templated gallophosphate-oxalate layered materials

Two new layered gallophosphate-oxalate materials have been prepared hydrothermally using ethylenediamine and oxalic acid as structure-directing agents. The compounds (C2N2H10)2[Ga2(C2O4)2(HPO4)3].H2O 1 and (C2N2H10)3- [Ga4(C2O4)4(HPO4)4(H2PO4)2] 2 are closely related, consisting of anionic double chains built of alternating paris of GaO6 and HPO4 polyhedra. These double chains are linked via bridging HPO4 or H2PO4 tetrahedra to form corrugated layers containing eight-membered rings. The oxalate group acts as a bidentate ligand to each of the GaO6 octahedron. The corrugated layers are held together by strong to weak hydrogen-bonding interactions between oxalate groups, water and diprotonated ethylenediamine molecules, and the framework components. The compounds were characterized by single-crystal X-ray diffraction, thermogravimetric analysis, and infrared and Raman spectroscopy. Crystal data for 1: monoclinic, space group P21/C (No. 14), a = 6.355(1) A, b = 39.362(8) A, c = 9.249(2) A, beta = 106.7(1) degrees, Z = 2. Crystal data for 2: triclinic, space group P1 (No. 2), a = 8.730(1) A, b = 11.575(1) A, c = 11.696(1) A, alpha = 115.12(1) degree, beta = 90.07(1) degree, gamma = 111.23(1) degree, Z = 2.     

Synthesis and structural,spectroscopic, and electrochemical characterization of new ruthenium dimethyl sulfoxide nitrosyls

The reactivity of ruthenium(II)- and ruthenium(III)-chloride-dimethyl sulfoxide precursors and of the antimetastatic drug [ImH][trans-RuCl(4)(dmso-S)(Im)] (NAMI-A, Im = imidazole, dmso = dimethyl sulfoxide) toward NO was investigated. Treatment of [(dmso)(2)H][trans-RuCl(4)(dmso-S)(2)] and mer-RuCl(3)(dmso)(3) with gaseous NO yielded [(dmso)(2)H][trans-RuCl(4)(dmso-O)(NO)] (1) and mer,cis-RuCl(3)(dmso-O)(2)(NO) (2), respectively. Thus, coordination of the strong pi-acceptor NO induces a S to O linkage isomerization of the dmso trans to it to avoid competition for pi-electrons. In light-protected nitromethane solutions, complex 2 equilibrates slowly with the two isomers mer-RuCl(3)(dmso-S)(dmso-O)(NO) (3), with NO trans to Cl, and mer-RuCl(3)(dmso-S)(dmso-O)(NO) (4), with NO trans to dmso-O; the equilibrium mixture consists of ca. 64% 2, 3% 3, and 33% 4. Treatment of the Ru(II) precursor trans-RuCl(2)(dmso-S)(4) with gaseous NO in CH(2)Cl(2) solution yielded the nitrosyl-nitro derivative trans,cis,cis-RuCl(2)(dmso-O)(2)(NO)(NO(2)) (5). Finally, [(Im)(2)H][trans-RuCl(4)(Im)(NO)] (6) was prepared by treatment of [ImH][trans-RuCl(4)(dmso-O)(NO)] (1Im) with an excess of imidazole in refluxing acetone. The spectroscopic features are consistent with the [Ru(NO)](6) formulation for all complexes, that is, a diamagnetic Ru(II) nucleus bound to NO(+). Compounds 1, 2, 5, and 6 were characterized also by X-ray crystallography; they all show a linear nitrosyl group, with short Ru-NO bond distances consistent with a strong d(pi) --> pi NO back-bonding. An unusual inertness of O-bonded dmso was observed in compound 1. Complexes 1, 2, 3, 5, and 6 are all redox active in DMF solutions showing irreversible reductions whose peak potentials depend on the other ligands attached to the Ru metal center. The site of reduction is the NO(+) moiety. The reduced complexes are not stable and release a Cl(-) or NO(2)(-) ligand followed by the NO(*) radical. The chemical reactions following electron transfer are all fast (rate constant >100 s(-1) at 293 K). The Ru product species are not redox active within the DMF window.     

Synthetic, spectroscopic and structural studies of two novel phosphanyl(organyl)borane compounds

The titanium (II) complex, Cp₂Ti(HBcat)₂, catalyzes the hydroboration of diphenylvinylphosphine by catecholborane and pinacolborane to afford exclusive anti-Markovnikov phosphanyl(organyl)boranes cleanly, rapidly and in good yields. Spectroscopic and X-ray studies of the phosphanyl(organyl)borane products show no evidence of boron-phosphorus interaction, indicating that the compounds preclude formation of Lewis pairs.     

Synthesis, reactivity and structural studies of selenide bridged carboranyl compounds

Reaction of the lithium salt Li[1-R-1,2-closo-C(2)B(10)H(10)] with selenium under mild conditions, followed by hydrolysis gave the diselenide compound (1-Se-2-R-1,2-closo-C(2)B(10)H(10))(2) in contrast to the well-reported mercapto compounds 1-SH-2-R-1,2-closo-C(2)B(10)H(10) obtained using a similar synthetic procedure. Details for the preparation and X-ray structural characterisation of the new compounds (2-Me-1,2-closo-C(2)B(10)H(10))(2)Se, (1-Se-2-R-1,2-closo-C(2)B(10)H(10))(2) (R = Me, Ph, ) are specified. To further explore the mechanism of the dimerization reaction, the complex [Au(1-Se-2-Me-1,2-closo-C(2)B(10)H(10))(PPh(3))] was synthesized, confirming the existence of the intermediate Li[1-Se-2-R-1,2-closo-C(2)B(10)H(10)] at the early stages of the reaction before selenium oxidation. Theoretical calculations and cyclic voltammetry (CV) studies were carried out to compare the bonding nature of the sulfur and the selenium analog compounds. It was determined that diselenides have a higher tendency to reduce with respect to the disulfides and all chalcogen atoms were found to be positively charged.