The [1,1′‐biisoquinoline]‐4,4′‐diol ( 4a ), which was obtained as hydrochloride 4a ?2 HCl in two steps starting from the methoxymethyl (MOM)‐protected 1‐chloroisoquinoline 8 (Scheme 3), opens access to further O‐functionalized biisoquinoline derivatives. Compound 4a ?2 HCl was esterified with 4‐(hexadecyloxy)benzoyl chloride ( 5b ) to give the corresponding diester 3b (Scheme 4), which could not be obtained by Ni‐mediated homocoupling of 6b (Scheme 2). The ether derivative 2b was accessible in good yield by reaction of 4a ?2 HCl with the respective alkyl bromide 9 under the conditions of Williamson etherification (Scheme 4). Slightly modified conditions were applied to the esterification of 4a ?2 HCl with galloyl chlorides 10a – h as well as etherification of 4a ?2 HCl with 6‐bromohexyl tris(alkyloxy)benzoates 11b , d – h and [(6‐bromohexyl)oxy]‐substituted pentakis(alkyloxy)triphenylenes 14a – c (Scheme 5). Despite the bulky substituents, the respective target 1,1′‐biisoquinolines 12, 13 , and 15 were isolated in 14–86% yield (Table). 相似文献
New uses for ALD : By applying standard metal oxide atomic layer deposition (ALD) to two types of porphyrins, site‐specific chemical infiltration of substrate molecules is achieved: Diethylzinc can diffuse into the interior of porphyrin supramolecular structures and induce metalation of the porphyrin molecules from the vapor phase. A=Ph, p‐HO3SC6H4.
The fabrication of nanoporous templates from poly(styrene)-b-poly(methyl methacrylate) diblock copolymer thin films (PS-b-PMMA, volume ratio 70:30) on silicon requires precise control of interfacial energies to achieve a perpendicular orientation of the PMMA cylindrical microdomains relative to the substrate. To provide a simple, rapid, yet tunable approach for surface neutralization, we investigated the self-assembled ordering of PS-b-PMMA diblock copolymer thin films on silicon substrates modified with a partial monolayer of octadecyldimethyl chlorosilane (ODMS), i.e., a layer of ODMS with a grafting density less than the maximum possible monolayer surface coverage. We demonstrate herein the fabrication of nanoporous PS templates from annealed PS-b-PMMA diblock copolymer thin films on these partial ODMS SAMs. 相似文献
The present study describes a novel approach based on electrochemical impedance measurements to follow the adsorption of giant liposomes on protein-coated solid surfaces with a time resolution in the order of seconds. The technical key features are circular gold-film electrodes as small as a few hundred micrometers in diameter and measurements of the electrode capacitance using AC signals in the kilohertz regime. Using Monte Carlo simulations, we were able to support the experiments and extract the rate constant of liposome adsorption. Besides monitoring the adsorption of liposomes on protein-coated surfaces, we also applied this technique to study shape fluctuations of the adsorbed vesicles and compared the corresponding power spectra with those recorded for hard particles and living animal cells. 相似文献
We report the deposition of DNA-conjugated gold nanospheres into arrays of surface nanopores obtained from hexagonally ordered thin polystyrene-b-poly(methyl methacrylate) (PS-b-PMMA) diblock copolymer films on silicon. The deposition occurs spontaneously from aqueous solution and is driven by either electrostatic interactions or specific DNA hybridization events between the DNA nanospheres and the surface nanopores. To mitigate this spontaneous deposition, we have chemically modified the nanopores with either positively charged aminosilanes or oligonucleotide probe sequences. The deposition of DNA nanospheres into the surface nanopores was characterized by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). We have observed preferential immobilization of individual DNA nanospheres within the nanopores, based on the size matching between the two entities. The inclusion density and selectivity of DNA nanosphere deposition into the surface nanopores was found to depend predominantly on the methods through which the nanoporous surfaces were prepared and chemically functionalized. 相似文献
Cylindramide (1) was built up from three components: a hydroxyornithine derivative 7, a tetrazolylsulfone 8, and a substituted pentalene subunit 9. Derivative 7 was prepared in a six-step reaction sequence involving the Wittig reaction and a Sharpless asymmetric dihydroxylation starting from N-Boc-3-aminopropanal (12). Tetrazolylsulfone 8 was accessible in four steps from dioxinone 22. The synthesis of the pentalene fragment 9 started from cycloocta-1,5-diene 26, that was converted into enantiopure bicyclo[3.3.0]octanedione 29. The latter was functionalized to give derivative 9. The total synthesis was accomplished by inducing C-C bond formation by Sonogashira coupling of derivatives 9 and 7 followed by olefination with tetrazolylsulfone 8 under Julia-Kocienski conditions, macrocyclization, and subsequent Lacey-Dieckmann condensation to form the tetramic acid unit. As indicated by extensive 1H and 13C NMR spectroscopic investigations (DQF-COSY, ROESY spectra), the stereochemistry of synthetic cylindramide (1) corresponds with that of the naturally occurring product. ROE data were used for molecular modeling of the lowest-energy structures for cylindramide. 相似文献
A series of unsubstituted and 1,4-disubstituted gallic catecholates 1, 6 and 7 as possible candidates for wedge-shaped mesogens were prepared starting from the respective benzene derivatives 2a-c and gallic esters 5a-h. The mesomorphic properties were investigated by DSC. However, only the 4,5-dinitro derivatives 1d,f-h with C8H17 and C10H21 to C12H25 alkyl side chains displayed mesophases, as evaluated by fluidity and optical anisotropy. 相似文献
New triphenylene-based silanes 2-(ω-(chlorodimethylsilyl)-n-alkyl)-3,6,7,10,11-penta-m-alkoxytriphenylene 4 (Tm-Cn) with n = 8 or 9 and m = 7, 8, 9, 10, or 11 were synthesized, and their self-assembly behavior in the liquid state and at glass and silicon oxide surfaces was investigated. The mesomorphic properties of triphenylene silanes 4 (Tm-Cn) and their precursors 3 (Tm-Cn) were determined by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and X-ray diffraction. From the small-angle X-ray scattering (SAXS) regime, a preferential discotic lamellar mesophase can be deduced, and wide-angle X-ray scattering (WAXS) highlights the liquid-like characteristics of the alkyl side chains. To transfer these bulk structural properties to thin films, self-assembled monolayers (SAMs) were obtained by adsorption from solution and characterized by water contact angle measurements, null ellipsometry, and atomic force microscopy (AFM). Employing the concentration as an additional degree of freedom, binary SAMs of 2-(ω-(chlorodimethylsilyl)-undecyl)-3,6,7,10,11-penta-decyloxytriphenylene 4 (T10-C11) were coassembled with chlorodecyldimethylsilane or chlorodimethyloctadecylsilane, and their capability as model systems for organic templating was evaluated. The structure of the resulting binary mixed SAMs was analyzed by water contact angle measurements, null ellipsometry, and X-ray reflectivity (XRR) in combination with theoretical modeling by a multidimensional Parratt algorithm and AFM. The composition dependence of film thickness and roughness can be explained by a microscopic model including the steric hindrance of the respective molecular constituents. 相似文献
Taking the regio‐ and chemoselectivities of our iron complex precursors with pyridine core in aerobic oxidations into account, we envisioned a more effective influence on catalytic properties by the introduction of different substituents in 4‐position of the pyridine moiety. The synthesis of these novel 4‐substituted (pyridine‐2,6‐diyl)dipropanoic acids 4 is described. Analogously to the unsubstituted derivative, ligands 4 reacted with Fe(ClO4)3 to form trinuclear Fe3(μ3‐O) complexes 3 , which were tested in the aerobic Gif‐type oxidation of α‐pinene to myrtenol, verbenone, myrtenal, and pinene oxide. The electronic nature of the substituents was found to slightly effect the ratio of allylic oxidation/epoxidation, whereas its influence on the oxidation preference of secondary to primary C? H bonds is negligible as compared to the unsubstituted complex. 相似文献