The multiaddition chemistry of azafullerene C N has been scarcely explored, and the isolation of pure bisadducts is in its infancy. Encouraged by the recent regioselective synthesis of the inherently chiral equatorial bisadduct of C N, we focused on the isolation of the first trans-4 bisadduct in a simple two-step approach. The first regioselective synthesis of the trans-4 bisadduct of C N by using cyclo-[2]-dodecylmalonate as a tether is now reported.
View Article and Find Full Text PDFBisazafullerene (C N) has been functionalized under aerobic conditions with cyclo-[2]-octylmalonate through a Mannich-type reaction, furnishing the corresponding monoadduct. A regioselective tether-directed Bingel cyclopropanation reaction was then carried out on the azafullerene core to yield a single bisadduct. Spectroscopic analysis of the formed bisadduct showed it to have a C symmetrical structure, making it inherently chiral.
View Article and Find Full Text PDFDouble-walled nanoporous networks based on the Schiff base reaction of nonplanar tripodic building blocks and subsequent dipole-directed self-assembly were fabricated on highly oriented pyrolytic graphite (HOPG) at the gas-solid interface. This is the first example of nonplanar molecules exploited as precursors for a surface reaction.
View Article and Find Full Text PDFThe synthesis of T-symmetrical [6:0]-hexakis adducts of C60 bearing enantiopure cyclo-monomalonate addends equipped with 1,2-glycol groups masked as isopropylidene acetals is presented. The deprotection of the acetals afforded functional fullerene building blocks bearing six 1,2-glycol moieties in an octahedral geometry as connection sites with appropriate linear organic spacers targeting 3D chiral extended networks with cubic building units. Evaluation of the experimental results revealed the advantageous synthetic accessibility to hexakis adduct (-)-9 which carries six homochiral C12 cyclo-monomalonate addends.
View Article and Find Full Text PDFInherently chiral multi-adducts of [60]fullerene represent unique chiral molecular tectons featuring fascinating optoelectronic properties. Herein we discuss the most recent progress in the synthesis of enantiomerically pure bis- and trisadducts of C60 with the inherently chiral trans-3 and all-trans-3 addition patterns utilizing cyclo-[n]-malonate tethers derived from (-)-dimethyl-2,3-O-isopropylidene-L-tartrate. Some future perspectives regarding the investigation of these chiral building blocks in modern areas of research are discussed.
View Article and Find Full Text PDFWe have synthesized and isolated two C2-symmetric enantiomerically pure trisadducts of C60 with an inherently chiral trans-3,trans-3,trans-3 addition pattern with the aid of an enantiopure cyclo-tris-malonate tether. An unexpected stereoisomerism was observed which was attributed to the spatial arrangement of spacers in the tether.
View Article and Find Full Text PDFA pentakis-adduct of C60 with an incomplete octahedral addition pattern was synthesised via a one-pot procedure using a tether equipped with five malonate moieties. The five-fold Bingel cyclopropanation of C60 was completely regioselective and afforded a chiral, C2-symmetric pentakis-adduct which was easily separated by column chromatography on SiO2.
View Article and Find Full Text PDFIn this Article, we describe the synthesis of two optically pure diols bearing a 1,2-diol moiety masked as an isopropylidene acetal group and long alkyl chains comprised of 12 and 14 carbon atoms, respectively. The synthetic methodology that was developed offers a general way for the synthesis of optically pure diols with long alkyl chains. Diols (-)-4 and (-)-9 were subjected to a condensation reaction with malonyl dichloride to afford two cyclo-[2]-malonate tethers that were separated by column chromatography in optically pure form.
View Article and Find Full Text PDFThe initial use of a novel elongated tricarboxylic acid H(3)hmpib in metal-organic framework (MOF) chemistry resulted in a [Zn(4)O(hmpib)(2)] MOF (UCY-1) with pyrite topology. The compound displays a remarkably high internal surface area despite its double-interpenetrated structure as well as high CO(2) uptake and selective adsorption for it over CH(4).
View Article and Find Full Text PDFThe Bingel functionalisation of C(60) with a structurally novel tether equipped with three reactive malonate groups afforded a C(2v)-symmetrical e(edge),e(face),trans-1 trisadduct in a complete regioselective manner and in an excellent yield of 65%. The [60]fullerene trisadduct showed pronounced ability to crystallise and gave X-ray quality single crystals for analysis.
View Article and Find Full Text PDFThe Bingel reaction between C(60) and an enantiopure bismalonate tether equipped with two acetonide moieties led to the synthesis and successful column chromatographic isolation of the enantiomerically pure (f,s)C and (f,s)A bisadducts with the inherently chiral trans-3 addition pattern. Acidic deprotection of the acetonide groups gave access to novel chiral fullerene compounds which combine the inherent chirality of the fullerene core with the functional glycol groups located on the tether.
View Article and Find Full Text PDFA series of experimentally reported as well as computationally designed monoadducts and bisadducts of [60]fullerene analogues have been used in order to analyze the binding interactions between fullerene based inhibitors and HIV-1 PR employing docking studies. MD simulations of ligand-free and the inhibitor bound HIV-1 PR systems complemented the above studies and provided proper input structure of HIV-1 PR in docking simulations. The obtained results revealed a different orientation of the beta-hairpin flaps at these two systems.
View Article and Find Full Text PDFOver the past decade, surface-modified, water soluble fullerenes have been shown by many different investigators to exhibit strong antioxidant activity against reactive oxygen species (ROS) in vitro and to protect cells and tissues from oxidative injury and cell death in vivo. Nevertheless, progress in developing fullerenes as bona fide drug candidates has been hampered by three development issues: 1) lack of methods for scalable synthesis; 2) inability to produce highly purified, single-species regioisomers compatible with pharmaceutical applications; and 3) inadequate understanding of structure-function relationships with respect to various surface modifications (e.g.
View Article and Find Full Text PDFA variety of derivatized fullerenes have been studied by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. Of particular emphasis has been the evaluation of a recently introduced solvent-free sample/target preparation method. Solvent-free MALDI is particularly valuable in overcoming adverse solvent-related effects, such as insolubility and/or degradation of the sample.
View Article and Find Full Text PDFThe first icosacationic bis(fullerene) whose water solubility is provided by twenty peripheral ammonium groups has a rigid, almost cylindrical shape and was synthesized by connecting two fullerene cores with a chiral cyclo-bis(malonate), followed by the regioselective addition of ten amino-terminated malonates into the octahedral positions of the fullerene moieties and subsequent cleavage of the Boc-protecting groups.
View Article and Find Full Text PDFThe synthesis and flash column chromatographic separation of enantiomerically pure tris-adducts of C60 with an e,e,e-addition pattern is achieved via cyclopropanation with chiral D3-symmetrical cyclo-tris(malonate) tethers.
View Article and Find Full Text PDFD(3h)-symmetrical tripodal tris(malonate) tethers have been used for the synthesis of [60]fullerene tris-adducts with an e,e,e addition pattern bearing topologically distinct polar and equatorial addend zones that can selectively be deprotected.
View Article and Find Full Text PDF[reaction: see text] The reaction between the C(59)N(+) carbocation and the electron-rich aromatic compounds toluene and anisole has been mechanistically studied. The measured intermolecular kinetic isotope effects are consistent with an electrophilic aromatic substitution mechanism in which the arenium cation is formed by electrophilic attack of C(59)N(+) on the aromatic ring in the first step of the reaction, followed by hydrogen abstraction in a rate-determining second step.
View Article and Find Full Text PDFThe [4 + 2] cycloaddition of trans,trans-2,4-hexadiene with C(60) proceeds via a concerted mechanism with retention of stereochemistry in the cycloadduct 1a. However, when cis,trans-2,4-hexadiene reacts with C(60), isomerization of the cis,trans to the thermodynamically more stable trans,trans isomer occurs. Subsequently, the cis,trans diene isomerized to the trans,trans isomer and cycloadds to C(60), to form adduct 1a.
View Article and Find Full Text PDF[reaction: see text] Alkenyl-linked C(60) derivatives undergo self-photooxygenation regioselectively, by the preferential abstraction of allylic hydrogens on the fullerene side of the double bond.
View Article and Find Full Text PDF