Peng Cheng's scientific contributionswhile working at CUNY Graduate Center (New York City, United States) and other institutions
- Abstract: A novel covalently linked C60–porphyrin dyad has been prepared by cyclopropanation of C60 with a strapped porphyrin malonate; its fluorescence spectrum shows strong quenching of the porphyrin singlet excited state by the attached C60.
- Abstract: The pronounced ability of fullerene C60 to act as an electron and energy acceptor has led to the synthesis of a large number of compounds in which C60 is covalently linked to photoactivatable groups which can serve as potential donors. Such compounds are of interest as model systems for photosynthetic reaction centers and also have potential applications in photodynamic therapy because of the highly efficient photosensitization of singlet molecular oxygen formation by C60 and C60... Show More
- Abstract: As part of a continuing investigation of the topological control of intramolecular electron transfer (ET) in donor-acceptor systems, a symmetrical parachute-shaped octaethylporphyrin-fullerene dyad has been synthesized. A symmetrical strap, attached to ortho positions of phenyl groups at opposing meso positions of the porphyrin, was linked to -fullerene in the final step of the synthesis. The dyad structures were confirmed by (1)H, (13)C, and (3)He NMR, and MALDI-TOF mass spectra. The... Show More
- Abstract: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Publications citing this author (310)
[Show abstract] [Hide abstract] ABSTRACT: This chapter reviews the different synthetic methodologies for the covalent functionalization of fullerene along with the most examples in advanced materials-oriented applications. Fullerenes are polyhedral carbon cages in which sp2-carbons are directly bonded to three neighbors in an arrangement of five- and six-membered rings. C60 has been the most extensively studied since its discovery because of its Ih-symmetrical structure, and bulk production. The structure includes two different types of bonds, namely those at the junction of two hexagons, and those at the junction of a pentagon, and a hexagon. The measured bond lengths clearly show that the formal double bonds correspond to the 6-6 junctions, and thus there are no double bonds in the pentagons. The mean diameter of the sphere is ∼7.1 Å. The van der Waals radius of the carbon atoms, the external diameter, is ∼10.4 Å, whereas the inner diameter is ∼3.5 Å. The crystal structure of C60 revealed low-electron delocalization over the spherical surface, and the bond alternation clearly shows a preference for the resonance structure with the 30 double bonds localized at 6-6 junctions. The low delocalization is explained by considering the partial rehybridization of the sp2-C-atoms leading to a higher contribution from the s-orbitals. As a consequence, the double bonds are located exocyclic to the pentagons, providing radialene nature to the five membered rings, and 1,3,5-cyclohexatriene nature to the six-membered rings.
- Analogous systems have been prepared with phthalocyanines181182183, tetrathiafulvalene [184,185], vinyl spacers bearing tetrathiafulvalene (TTF) moieties [186,187], along with azides bearing TTF , ;7r-extended-TTF units [189,190], and ferrocene [161,185,191192193194. Strapped and parachute-Uke fullerene-porphyrin architectures have been prepared via Bingel reaction with flexible linkers that allow the porphyrin to get very close to the fuUerene195196197198199. Novel CgQ-based [4+2] adducts were recently synthesized through 1,4-dihalide elimination, giving fused TTF-Cgo dyads, Cgo-TTF-Cgo triads200201202203 , and ;r-extened- TTF-Cgo dyads , leading to efficient electron and energy transfer through the covalent bonds (Fig. 8).
[Show abstract] [Hide abstract] ABSTRACT: IntroductionFullerenes in Electron TransferFullerenes in Solar CellsSummaryAcknowledgmentsReferences
- The simplest possible combination of an electron-accepting fullerene is with an electron donor linked by a charge-mediating bridge. As electron donors, a wide range of building blocks—porphyrins3536373839404142434445, phthalocyanines [46,47], amines , polycondensed aromatics , transition complexes505152, carotenoids , ferrocenes [54,55], tetrathiafulvalenes (TTFs) , and others —have been employed. Scheme 21-1 summarizes the photophysical processes taking place in a prototype electron donor–acceptor conjugate, that is, ZnP–C 60 (1), and the corresponding energetics in benzonitrile .