Silica Hybrid Containing (R)-2,2′-Binaphtho-20-crown-6 Moieties via the Sol-Gel Process

IntroductionThesol gelprocessconstitutesoneofthemostimpor tantrouteforthepreparationofinorganicamorphoussolids.1,2 Themildreactionconditionsofthesol gelap proachallowadeliberatetailoringofhybridorganic inor ganicmaterialsbyhydrolysisandpolycondensationofmolecularprecursorsfunctionalizedbyhydrolysabletri ethoxysilanegroups .3Suchsilicahybridmaterialsconsist ingofcovalentlylinkedorganicandinorganiccomponentsarewelldefinedatthemolecularlevel.Theyhavereceivedconsiderableattentionindifferentresearc…     

POLYBINAPHTHYLS INCORPORATING (R)-2,2’-BINAPHTHO-20-CROWN-6 AND NAPHTHYL MOITIES

Chiral polymer was synthesized by the polymerization of （R）-6,6＇-bistributylstannyl-2,2＇-binaphtho-20-crown-6 （M-1） with 1,4-dibromo-2,3-bisbutoxy-naphthyl （M-2） by Pd（PPhs）4 catalyzed Stille coupling reaction. Both monomer and polymer were analyzed by NMR, MS, FT-IR, UV, polarimetry, DSC-TGA, CD, fluorescent spectroscopy and GPC. The major difference between monomer and polymer is that a long wavelength Cotton Effect was observed for the polymer due to its more extended conjugation in the repeating unit and a highly rigid backbone in the polymer chain. Polymer has strong blue fluorescence due to the efficient energy migration from the extended n-electronic structure of the repeating unit of the polymer to the chiral binaphthyl core and is expected to have potential application in the materials of fluorescent sensors and chiral chromatographic packing for resolution ofracemic amino acid.     

Asymmetric Hydrogenation Synthesis of （S）-（＋）-2-（6＇-methoxyl-2-naphthyl） propionic Acid by Cinchona Modified Pd（0）-α-FeOOH Catalyst

Asymmetric hydrogenation of (6-methoxyl-2-naphthyl)-2-acrylic acid catalyzed by cinchona modified Pd(0)-α-FeOOH was reported and ee‘s of (S)-( )-2-(6‘-methoxyl-2-naphthyl)propionic acid ((S)-( )-naproxen) up to 98% was achieved firstly.     

Synthesis and Characterization of 5, 5＇,6,6＇ -（2, 2＇-Bipyridine）tetraacid

5,5‘,6,6‘-(2,2‘-Bipyridine)tetraacid, a new aza-aromatic tetraacid, was synthesizedstarting from diquinoline, and its structure was confirmed by means of mass spectrum and infrared spectrum.     

Asymmetric Synthesis of （S）-Dimethyl -4, 4＇-dimethoxy-5, 6, 5＇, 6＇-dimethenedioxybiphenyl-2, 2＇-dicarboxylate

(S)-Dimethyl-4, 4‘-dimethoxy-5, 6, 5‘, 6‘-dimethenedioxy-biphenyl-2, 2‘-dicarbonylate was synthesized in reasonable yield through a series of reactions, including chiral oxazolinemediated asymmetric Ullmann coupling, from methyl 2-bromo-5-methoxy-3, 4-methenedioxybenzoate.     

Perpentylated （2, 3, 6-Tri-O-pentyl）-β-cyclodextrin Used as Capillary Gas Chromatographic Stationary Phase Prepared by Sol-gel Technology

Capillary column preparation using perpentylated (2,3,6-tri-O-pentyl)-β-cyclodextrin as stationary phase by sol-gel technology with simplicity and rapidity is described. Multiple preparation steps in conventional column technology were avoided. The prepared columns exhibit satisfactory chromatographic performances and pronounced selectivity for a wide range of test solutes, and have been successfully used for the separation of nitrotoluene, dimethoxybenzene,alcohols, alkanes, dimethylphenol and cresol isomers.     

SYNTHESIS OF POLYBINAPHTHYLS INCORPORATING CHIRAL （R）-1,1′-BI-2,2′-NAPHTHOL ENTITIES WITH p-DIVINYLBENZENE BY Pd-CATALYZED HECK REACTION

Polymer (Ⅰ) and polymer (Ⅱ) were obtained by the polymerization of (R)-6,6′-dibromo-2,2′-binaphtho-20-crown-6 (M-l) and (R)-6,6′-dibromo-2,2′-di(methoxyethoxymethyloxy)-1,1′-binaphthyl (M-2) with p-divinylbenzene under Pdcatalyzed Heck reaction. The UV, fluorescence and CD spectra of polymer (Ⅰ) and (Ⅱ) are similar due to the same linkers present in their polymer chain. Polymers (Ⅰ) and (Ⅱ) can emit strong blue fluorescence and are expected to have potential applications in polarized blue-light emitting sensors. The chiral conjugated polymers (Ⅰ) and (Ⅱ) exhibit a strong Cotton effect in their circular dichroism (CD) spectra, indicating a high rigidity of polymer backbone.     

A Convenient Method for Synthesis of Novel Cyclic Ethers （IR, 2R,3R, 5S, 7S, 9R, 12R）-3-（t-Butyldimethylsilyl）oxy-7-methoxymethyl- oxy-2, 10-dimethyl-12-oxatricyclo [7.2.1.0^5,12] dodecane

Novel cyclic esters (1R, 2R, 3R, 5S, 7S, 9R, 12R)-3-(t-butyldimethylsilyl)oxy-7-methoxymethyloxy-2, 10-dimethyl-12-oxatricyclo [7.2.1.0^5,12] dodecane were prepared when their precursor 1 was treated with SOC12/pyridine. A plausible mechanism was hypothesized.     

Hybrid Nonlinear Optical Materials Containing Imidazole Chromophore through the Sol‐Gel Process

A new sol‐gel hybrid film based on heterocyclic chromophore, namely 2‐[4′‐(N‐ethyl‐N‐hydroxyethyl)amino phenyl azo]‐4,5‐dicyanoimidazole (IZ), has been synthesized and characterized. The hybrid system possesses a high chromophore loading density up to 65 wt.‐% without observing a phase separation. The initial decomposition temperatures of the chromophore and hybrid material were determined to be 260 and 272 °C, respectively. Poled films show a fairly high and stable nonlinear optical (NLO) response, even at an elevated temperature.

     

Polyimide–Silica Gel Hybrids Containing Metal Salts: Preparation via the Sol–Gel Reaction

A facile preparation of polyimide–silica gel hybrids by the simultaneous in-situ formation of polyimides during the hydrolysis–condensation of tetramethoxysilane (TMOS) is reported here. The hydrolysis and condensation of TMOS was carried out in a solution of DMAc containing 5% LiCl, CaCl₂ or ZnCl₂ and the seven-membered cyclic polyimide intermediate. The seven-membered cyclic intermediates, precursors of polyimides, were derived from the low-temperature polycondensation of dianhydrides [benzophenonetetracarboxylic dianhydride (BTDA), pyromellitic dianhydride (PMDA), and 4,4-bis(hexafluoroisopropylidene)phthalic dianhydride (6FDA)] and di-isocyanates [isophorone di-isocyanate (IPDI), toluene di-isocyanate (TDI), hexamethylene di-isocyanate (HDI) and 4,4′-diphenylmethane di-isocyanate (MDI)]. These intermediates could readily be converted to the corresponding polyimides. Films were cast from the resulting mixtures and the solvent was gradually evaporated at 130 °C to result in the formation of clear, transparent, pale yellow or amber-colored hybrid films in which the salts were dispersed at the molecular level. Pyrolysis of polyimide–silica gel hybrids at 600 °C gave mesoporous silica. Silica gel obtained from hybrids HPI-8 (containing no salt) and HPI-11 (containing ZnCl₂) had a pore radius (BJH method) of 2.9 nm, while that from hybrid HPI-9 (containing LiCl) had a pore radius of 11.4 nm. The surface areas (BET method) obtained were 203 m² g⁻¹, 19 m² g⁻¹ and 285 m² g⁻¹, while the pore volumes were 0.373 cm³ g⁻¹, 0.158 cm³ g⁻¹ and 0.387 cm³ g⁻¹, respectively, for samples obtained from hybrids HPI-8, HPI-9 and HPI-11. © 1997 by John Wiley & Sons, Ltd.     

(R)‐(6,6′‐Dihydroxybiphenyl‐2,2′‐diyl)bis(diphenylphosphine oxide) methanol solvate

The title compound, C₃₆H₂₈O₄P₂·CH₄O, was synthesized directly from the methoxy analogue. The crystal structure shows that one OH group interacts with an O atom of a phosphine oxide group in an adjacent mol­ecule, while the other OH group complexes with the methanol solvent molecule via intermolecular hydrogen bonds. An O atom of one phosphine oxide group interacts with the hydroxy H atom of methanol via a hydrogen bond. There are intra‐ and intermolecular π–π interactions between the phenyl rings. All these interactions result in the formation of supramolecular chiral parallelogram channels via self‐assembly.     

(3R*,3′R*)‐1,1′‐Dimethyl‐3,3′‐biindoline‐2,2′‐dithione

The (3R*,3′R*) configuration of the title compound, C₁₈H₁₆N₂S₂, (I), has been unambiguously elucidated by X‐­ray analysis. Mol­ecules of (I) have C₂ symmetry to a good approximation and a strongly folded shape. The interplanar angle between the two halves of a mol­ecule is 67.11 (6)°.     

HPLC of fluoroquinolone antibacterials using chiral stationary phase based on enantiomeric (3,3′‐diphenyl‐1,1′‐binaphthyl)‐20‐crown‐6

A residual silanol group‐protecting chiral stationary phase (CSP) based on optically active (3,3′‐diphenyl‐1,1′‐binaphthyl)‐20‐crown‐6 was successfully applied to the resolution of fluoroquinolone compounds including gemifloxacin mesylate. The chiral recognition ability of the residual silanol group‐protecting CSP was generally greater than that of the residual silanol group‐containing CSP. From these results, it was concluded that the simple protection of the residual silanol groups of the latter CSP with lipophilic n‐octyl groups can improve its chiral recognition ability for the resolution of racemic fluoroquinolone compounds. The chromatographic resolution behaviors were investigated as a function of the content and type of organic and acidic modifiers and the ammonium acetate concentration in aqueous mobile phase and the column temperature. Especially, the addition of ammonium acetate to the mobile phase was found to be a quite effective means of reducing the enantiomer retentions without sacrificing the chiral recognition efficiency of the CSP.     

Cobalt(II) and cobalt(III) complexes with 4′‐(4‐cyanophenyl)‐2,2′:6′,2′′‐terpyridine

4′‐Cyanophenyl‐2,2′:6′,2′′‐terpyridine (cptpy) was employed as an N,N′,N′′‐tridentate ligand to synthesize the compounds bis[4′‐(4‐cyanophenyl)‐2,2′:6′,2′′‐terpyridine]cobalt(II) bis(tetrafluoridoborate) nitromethane solvate, [Co^II(C₂₂H₁₄N₄)₂](BF₄)₂·CH₃NO₂, (I), and bis[4′‐(4‐cyanophenyl)‐2,2′:6′,2′′‐terpyridine]cobalt(III) tris(tetrafluoridoborate) nitromethane sesquisolvate, [Co^III(C₂₂H₁₄N₄)₂](BF₄)₃·1.5CH₃NO₂, (II). In both complexes, the cobalt ions occupy a distorted octahedral geometry with two cptpy ligands in a meridional configuration. A greater distortion from octahedral geometry is observed in (I), which indicates a different steric consequence of the constrained ligand bite on the Co^II and Co^III ions. The crystal structure of (I) features an interlocked sheet motif, which differs from the one‐dimensional chain packing style present in (II). The lower dimensionality in (II) can be explained by the disturbance caused by the larger number of anions and solvent molecules involved in the crystal structure of (II). All atoms in (I) are on general positions, and the F atoms of one BF₄⁻ anion are disordered. In (II), one B atom is on an inversion center, necessitating disorder of the four attached F atoms, another B atom is on a twofold axis with ordered F atoms, and the C and N atoms of one nitromethane solvent molecule are on a twofold axis, causing disorder of the methyl H atoms. This relatively uncommon study of analogous Co^II and Co^III complexes provides a better understanding of the effects of different oxidation states on coordination geometry and crystal packing.     

Bis[S‐6‐(2,2:6′,2′′‐terpyridin‐4′‐yloxy)hexyl thioacetate]manganese(II) bis(hexafluorophosphate)

The structure of a manganese(II) complex of terpyridine functionalized with acetylsulfanyl‐terminated hexyloxy chains, [Mn(C₂₃H₂₅N₃O₂S)₂](PF₆)₂, is described. This type of complex is of interest in the study of single‐molecule transport properties in open‐shell systems. The manganese coordination environment is distorted octahedral but, importantly, with no larger deviations from the idealized geometry than those observed for other metal–terpyridine complexes. The Mn—N bond lengths range from 2.192 (2) to 2.272 (3) Å. The title compound crystallizes with the cation and anions all on general positions, with the hexafluorophosphate anions exhibiting orientational disorder. When compared with other bis‐terpyridine complexes, this structure demonstrates that manganese(II) is no more prone to undergo low‐symmetry distortions than systems with ligand field stabilization energy contributions.     

Metallophilic interactions in iodido(2,2′:6′,2′′‐terpyridine)platinum(II) diiodidoaurate(I)

In the title compound, [PtI(C₁₅H₁₁N₃)][AuI₂], the [PtI(terpy)]⁺ cations (terpy is 2,2′:6′,2′′‐terpyridine) stack in pairs about inversion centers through Pt...Pt interactions of 3.5279 (5) Å. The [AuI₂]⁻ anions also exhibit pairwise stacking, with Au...I distances of 3.7713 (5) Å. The [PtI(terpy)]⁺ cations and [AuI₂]⁻ anions aggregate forming infinite arrays of stacked ...({[PtI(terpy)]⁺...[PtI(terpy)]⁺}...{[AuI₂]⁻...[AuI₂]⁻})... units.     

4′‐Iodo‐2,2′:6′,2′′‐terpyridine

In the nearly planar title compound, C₁₅H₁₀IN₃, the three pyridine rings exhibit transoid conformations about the interannular C—C bonds. Very weak C—H...N and C—H...I interactions link the molecules into ribbons. Significant π–π stacking between molecules from different ribbons completes a three‐dimensional framework of intermolecular interactions. Four different packing motifs are observed among the known structures of simple 4′‐substituted terpyridines.     

Synthesis,Coordination, and Spectroscopic Properties of 2,2′‐Bipyridyldimesitylpalladium(II) and 6‐Mesityl‐2,2′‐bipyridyldimesitylpalladium(II)

The synthetic route to the dimesitylpalladium(II) complex [(bpy)PdMes₂] ( 1 ) (Mes = mesityl = 2,4,6‐trimethyl phenyl) does not only give the desired compound but also the 6‐mesityl‐2,2′bipyridyldimesitylpalladium [(6‐Mes‐bpy)PdMes₂] ( 2 ) complex and the free ligand 6,6′‐dimesityl‐2,2′‐bipyridine in reasonable yields. Single crystals of 2 were examined by X‐Ray diffraction. The compound reveals a sterically crowded molecular structure. An intramolecular π‐stacking interaction was found between the mesityl substituent on the bipyridine ligand and the adjacent mesityl ligand. The electrochemical behaviour of 1 and 2 together with a related compound was examined at various temperatures showing two reversible reduction reactions and reversible one‐electron oxidation steps at low temperatures. The latter are assigned to Pd^II/Pd^III couples.