Synthesis of di- and trivalent β″-aluminas by ion exchange

Many of the mono-, di-, and trivalent cations in the periodic chart diffuse rapidly in the β″-alumina structure. β″-Aluminas containing multivalent cations can be synthesized by ion exchange reactions starting with the sodium form of the compound. These facile reactions make it possible to prepare a wide variety of β″-alumina compositions, many of which are metastable and inaccessible by normal synthetic means. This paper describes the methods used to synthesize multivalent β″-aluminas and the preparation of a number of specific transition metal and lanthanide forms of these compounds.     

Synthesis and characterization of β-fused porphyrin-BODIPY dyads

Novel dyads in which a porphyrin ring is directly fused through two β-pyrrolic carbons to a BODIPY^® moiety have been prepared using a stepwise approach starting from the copper(II) complex of pyrrolo[2,3-c]-5,10,15,20-tetraphenylporphyrin. Formylation and reaction with 3,5-dimethylpyrrole afforded 8; subsequent BF₂ complexation gave the TPP-BODIPY^® dyad in reasonable yields. Demetalation in TFA/H₂SO₄ led to the corresponding free base 12, opening the way to the subsequent preparation of the Zn complex 13. Both 12 and 13 exhibited complex optical spectra with an intensely red-shifted Q-band. Luminescence spectra displayed a very intense band around 700 nm making these species suitable as near-IR dyes and sensors in biological media. Optical analyses of 12, using the INDO/SCI technique, were performed to obtain information to establish the origin of the novel optical properties. These studies showed that the optical properties of 12 cannot be attributed to deformation of the molecular skeleton, but derive from the increased extension of the conjugation between the TPP and BODIPY^® π-systems.     

Synthesis and characterization of novel β-amino acid derivatives

In the work discussed in this paper, novel β-amino acid derivatives were prepared by Michael addition between 3-substituted-2-propenic acid and hydrazine hydrate. The optimum reaction conditions were determined by analyzing the effects of the ratio of the starting materials, temperature, and reaction time. The conclusions were: reaction temperature 80 °C, reaction time 8 h, n (3-substituted-2-propenic acid)/n (hydrazine hydrate) = 1:15. Products were characterized by measurement of melting point, elemental analysis, and IR and ¹H NMR spectroscopy.     

Synthesis of modified β-cyclodextrin polymers and characterization of their fuchsin adsorption

Three water insoluble β-cyclodextrin polymers HP-β-CDP, CM-β-CDP and AE-β-CDP were synthesized by cross-linking epoxychloropropane with corresponding β-CD derivatives and utilized to adsorb water-soluble dye fuchsin from aqueous solution. FT-IR spectra confirmed the existence of hydroxypropyl, carboxyl group and amidogen in polymers. The influences of several parameters (contact time, pH and temperature) and the degree of substitution (DS) of CM-β-CDP in range of 1.5–4.5 on the adsorption capacity (Q _e) were evaluated. The results showed that all maximum Q _e of polymers appeared at pH 5.2–5.3. CM-β-CDP with carboxyl group was the most effective extractant, and the Q _e of CM-β-CDP with DS 1.5–2.5 kept nearly constant but decreased sharply over 2.5. However, AE-β-CDP with amidogen had displayed a quite low Q _e to fuchsin, even lower than that of unmodified β-CD polymer. The preliminary studies on the morphology of both CM-β-CDP and AE-β-CDP by AFM disclosed the differences in topography of their surfaces.     

Synthesis,characterization and coordination chemistry of substituted β-amino dicarbonyls

An efficient and facile method for the synthesis of novel structurally diverse β-amino dicarbonyl compounds is described by exploring the aza-Michael addition reaction in an aqueous medium as a key step. Thereby, 2-(aryl-disubstituted-amino-1-yl-methyl)-malonic acid diethyl esters were achieved in a good to excellent yields. These products were easily isolated with enough purity just by using simple recrystallization. The crystals of the compounds (17) and (24) have been obtained and studied by X-ray crystallographic analyses.     

Synthesis and characterization of β-diketiminate germanium(II) compounds

Reactions of LGeCl (L = CH[C(Me)N(Ar)](2); Ar = 2,6-iPr(2)C(6)H(3)) with KOtBu or LiR (R = 2-thienyl, N(H)Ar, PPh(2)) yielded the germanium(II) compounds LGeR [R = OtBu (1), 2-thienyl (2), N(H)Ar (3), PPh(2) (4)]. The reduction of (2-thienyl)(2)PCl with lithium afforded the diphosphane [(2-thienyl)(2)P](2) (5). The treatment of (2-thienyl)(2)PCl with LiAlH(4) or KHBtBu(3) led to the formation of (2-thienyl)(2)PH (6). The NHC-assisted reaction of LGeCl and 6 resulted in the isolation of LGeP(2-thienyl)(2) (7). This is the first example where NHC is used for eliminating HCl from compounds with P-H and Ge-Cl bonds. All solid products were characterized by elemental analysis, NMR and IR spectroscopy, and single-crystal X-ray structure determination.     

Synthesis and characterization of magnetic nanoparticles

Magnetic nanoparticles with average diameter in the range of 6.4-8.3 nni have been synthesized by a chemical co-precipitation of Fe(Ⅱ)and Fe(Ⅲ)salts in 1.5 M NH4OH solution.The size of the magnetic particles is dependent on both temperature and the ionic strength of the iron ion solutions.The magnetic particles formed at higher temperature or lower ionic strength were slightly larger than those formed at lower temperature or higher ionic strength respectively.In spite of the different reaction conditions,all the resultant nanoparticles are nearly spherical and have a similar crystalline structure.At 300 K,such prepared nanoparticles are superparam-agnetic.The saturation magnetizations for 7.8 and 6.4 nm particles are 71 and 63 emu/g respectively,which are only ~ 20-30% less than the saturation magnetization(90 emu/g)of bulk Fe3O4 Our results indicated that a control of the reaction conditions could be used to tailor the size of magnetic nanoparticles in free precipitation.     

Mixed ligand complexes of β-diketonates: synthesis,characterization, and FAB mass spectral analysis

Complexes of the type MLL′ · nB (where M = Ni(II) and Cu(II); LH and L′H = 2,4-pentanedione (acacH), 1-phenyl-1,3-butanedione (bacH), and 1,3-diphenyl-1,3-propanedione (dbmH); n = 0 to 2 and B = water or pyridine) have been synthesized and characterized. IR spectra are consistent with uninegative bidentate ligands. Magnetic moments and electronic spectral studies reveal high-spin octahedral geometry for nickel(II) complexes and distorted octahedral stereochemistry for copper(II) complexes. Frozen chloroform solution ESR spectra of the copper(II) complexes display significant Jahn–Teller distortion and dimeric behavior of the complexes in solution. FAB mass spectra of the copper(II) complexes also exhibit peaks corresponding to dimers. Molecular, pseudo-molecular, dimeric pseudo-molecular, and fragment ion peaks in unit resolution mass spectra have been identified with the help of their isotope distribution pattern expected due to natural abundances of the ⁶³Cu and ⁶⁵Cu isotopes. All the FAB mass spectral peaks from the fragment ions containing copper have been interpreted on the basis of isotope distribution pattern.     

Synthesis and characterization of inclusion complex of the vasodilator drug minoxidil with β-cyclodextrin

The inclusion complex of β-cyclodextrin and minoxidil (2,4-diamino-6-piperidinopyrimidine 3-oxide) was synthesized using two methods—kneading and freeze-drying—and characterized by UV-Vis spectroscopy, infrared spectroscopy, powder X-ray diffractometry, differential scanning calorimetry, thermal gravimetric analysis, and nuclear magnetic resonance spectroscopy. These techniques have demonstrated the existence of inclusion compound formation between the host and guest with a molar ratio of 1:1. The studies of solubility and the data obtained by nuclear magnetic resonance spectroscopy showed a weak interaction between the guest and the cyclodextrin molecules in solution.     

Liquid-liquid partition and aqueous phase hydration of beryllium β-diketonates

Partition coefficients of four beryllium β-diketonates of two homologous series in aqueous NaClO₄ solution/n-hexane systems have been measured as functions of temperature (5–45°C) and of sodium perchlorate concentration (0–3 M). The ligands examined were: acetylacetone, propionylacetone, 3-methylacetylacetone, and 3-ethylacetylacetone. ΔG°, ΔH°, ΔS°, and ΔC°_p2 values for the partition processes have been evaluated as well as salting-out coefficients of the chelates and the corresponding ΔH° and ΔS° values.The results have been interpreted in terms of water structure changes (hydrophobic hydration) and of specific hydration in the outer coordination sphere of the coordinatively saturated chelates (hydration of the bonded ligands). The effect of changing both number and position of the CH₂ groups in the ligand molecules on ΔG°_p can be described using the surface area approach to the hydrophobic interaction. Irregularities in the remaining thermodynamic quantities indicate, however, a possibility of changes in the outer-sphere hydration of the chelates, probably due to the inductive effect of the ligand substituents.A contribution from the outer-sphere hydration must not be neglected when analysing thermodynamics of extraction of metal complexes.     

Synthesis and characterization of poly(ethylene glycol) based β-cyclodextrin polymers

A series of novel water soluble β-cyclodextrin (βCD) polymers has been synthesized from functionalized poly(ethylene glycol) (PEG). The chemical composition of the polymers has been characterized by ¹H NMR and the βCD content is found to be between 48 and 33% (w/w). The molecular weight has been determined by Size Exclusion Chromatography (SEC) and depends on the ratio between βCD and PEG, varying from 2.1 × 10⁴ to 8.6 × 10⁴ g mol^?1. The physico chemical properties have been characterized by differential scanning calorimetry (DSC), viscometry and isothermal titration calorimetry (ITC). ITC shows that the polymers have association constants comparable to βCD with different guest molecules, indicating a good accessibility of the CDs.     

Isolation of short-lived isotopes of lanthanum and indium by β-diketonates sublimation

Trace amounts of lanthanum hexafluoroacetylacetonate and indium acetylacetonate were isolated by combination of methods, which includes synthesis of volatile elements -diketonates by nucleophilic ligands exchange and fractional sublimation. This method is useful for produce isotope generators.     

Improved Synthesis of Icaritin and Total Synthesis of β-Anhydroicaritin

Natural products icaritin and β-anhydroicaritin with P-glycoprotein(P-gp) inhibitory activities were ciently synthesized in nine steps from commercially available phloroglucinol. A modified Algar-Flynn-Oyamada cyclization and relay Claisen-Cope rearrangement were employed in this concise route. Oiir synthesis offers opportunities to synthesize various icariin analogues for biological and pharmacological investigations.     

Size-dependent luminescence of boron difluoride β-diketonates

Size-dependent luminescence properties of boron difluoride β-diketonates were detected. Most compounds investigated are characterized by noticeable hypsochromic shifts of luminescence band maxima on going from bulk crystals to microcrystals. However, a decrease in the crystal size of (dibenzoylmethanato)boron difluoride with unique supramolecular structure was accompanied by a bathochromic shift of the luminescence band maximum. Size-dependent luminescence properties of complexes examined were analyzed in the framework of excitonic mechanism. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1168–1170, June, 2008.     

Synthesis and characterization of β-diketonato- and phenoxoderivatives of mono(dizirconium-ennea-isopropoxy)copper(II)

Summary -Diketonato- and phenoxo-derivatives of mono(dizirconium-ennea-isopropoxy) copper(II), [Cu{Zr₂(OPr-i)₉}-(RCOCHCOR)] and [Cu{Zr₂(OPr-i)₉}(-OAr)], have been prepared by the interaction of K(RCOCHCOR) or KOAr (1 mol) [R = R = Me (1a); R = R = CF₃ (1b); R = Me, R = CF₃ (1c); OAr = 2,6-Me₂C₆H₃O (2a), 3,5-Me₂C₆H₃O (2b), p-ClC₆H₄O (2c)] with [Cu{Zr₂-(OPr-i) ₉}(-Cl)] (1 mol) in PhH. Alcohol interchanges of the derivative [Cu{Zr₂(OPr-i)₉}(-Cl)] have also been studied. These new compounds have been characterized by elemental analyses, i.r., electronic and e.s.r. spectra, and magnetic susceptibility measurements. The studies indicate a distorted octahedral geometry around Cu^II.     

Phenyl bismuth β-diketonate complexes: Synthesis and structural characterization

The first examples of arylbismuth diketonate complexes are reported. Phenylbismuth(III) bis(hexafluoroacetylacetonate), BiPh(hfac)₂ (1) and its adducts [BiPh(hfac)₂(L)] (Hhfac = 1,1,1,5,5,5-hexafluoro-2,4-pentanedione; L = H₂O (1a), Me₂CO (1b), THF (1c), DMA (N,N-dimethylacetamide) (1d), DMSO (1e), PhCN (1f), as well as a mixed hexafluoroacetylacetonate-trifluoroacetate complex, [BiPh(hfac)(O₂CCF₃)]₂ (2), have been synthesized and characterized. Compound 1 is isolated from the reaction of BiPh₃ with 2 equiv. of Hhfac in dry hexanes. Compound 2 can be synthesized using two different routes: one utilizes the reaction between stoichiometric amounts of 1 and CF₃CO₂H, while the second method involves the interaction of the previously described BiPh₂(O₂CCF₃) (3) with Hhfac. Crystallographic analysis of the [BiPh(hfac)₂(L)] adducts reveals a pentagonal pyramidal geometry around the metal center; similarly, the dinuclear [BiPh(hfac)(O₂CCF₃)]₂ complex is composed of two distorted pentagonal pyramids connected into dimers by the bridging carboxylate groups. The effect of replacing the Lewis base in the coordination sphere of Bi(III) on the coordination polyhedron and crystal packing is discussed. The ¹H and ¹⁹F NMR spectra of the title complexes at room temperature indicate single environments for the hfac group and suggest that they are fluxional in solutions on the NMR time scale. Compounds 1 and 2 are promising starting materials in the chemistry of bismuth(III) and as building blocks for the construction of heterometallic species.     

Electronic and geometric structure of the protonated forms of nickel β-diketonates

The effect of protonation on the electronic and spatial structure of nickel malonodialdehynate Ni(Mal)₂ and acetylacetonate Ni(Acac)₂ were studied by quantum chemical density functional theory (DFT) method. The metal ring geometry, the energies and the composition of molecular orbitals (MO), the effective charges on atoms, and the total overlap populations were determined, and the possible proton location sites were identified. The variation of the MO energy depending on the electron density distribution on the protonated and non-protonated ligands was considered. Proton addition to one of the oxygen atoms was shown to be most likely.