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51.
M Porel CH Chuang C Burda V Ramamurthy 《Journal of the American Chemical Society》2012,134(36):14718-14721
Supramolecular photoinduced electron transfer dynamics between coumarin 153 (C153) and 4,4'-dimethyl viologen dichloride (MV(2+)) across the molecular barrier of a host molecule, octa acid (OA), has been investigated with femtosecond time resolution. The ultrafast electron transfer from C153 to MV(2+) followed excitation with 150 fs laser pulses at a wavelength of 390 nm despite the fact that C153 was incarcerated within an OA(2) capsule. As a result, the photoexcited coumarin did not show any of the typical relaxation dynamics that is usually observed in free solution. Instead, the excited electron was transferred across the molecular wall of the capsuleplex within 20 ps. Likewise, the lifetime of the charge transfer state was short (724 ps), and electron back-transfer reestablished the ground state of the system within 1 ns, showing strong electronic coupling among the excited electron donor, host, and acceptor. When the donor was encapsulated into the host molecule, the electron transfer process showed significantly accelerated dynamics and essentially no solvent relaxation compared with that in free solution. The study was also extended to N-methylpyridinium iodide as the acceptor with similar results. 相似文献
52.
SR Samanta R Kulasekharan R Choudhury P Jagadesan N Jayaraj V Ramamurthy 《Langmuir : the ACS journal of surfaces and colloids》2012,28(32):11920-11928
In this report, we present methods of functionalization of AuNP's with deep-cavity cavitands that can include organic molecules. Two types of deep-cavity cavitand-functionalized AuNP's have been synthesized and characterized, one soluble in organic solvents and the other in water. Functionalized AuNP soluble in organic solvents forms a 1:1 host-guest complex where the guest is exposed to the exterior solvents. The one soluble in water forms a 2:1 host-guest complex where the guest is protected from solvent water. Phosphorescence from thiones and benzil included within heterocapsules attached to AuNP was quenched by gold atoms present closer to the guests included within deep-cavity cavitands. During this investigation, we have synthesized four new deep-cavity cavitands. Of these, two thiol-functionalized hosts allowed us to make stable AuNP's. However, AuNP's protected with two amine-functionalized cavitands tended to aggregate within a day. 相似文献
53.
Porel M Jockusch S Parthasarathy A Rao VJ Turro NJ Ramamurthy V 《Chemical communications (Cambridge, England)》2012,48(21):2710-2712
The efficient photoinduced electron transfer from a stilbene derivative incarcerated within a negatively charged organic nanocapsule to positively charged acceptors (methyl viologen and a pyridinium salt) adsorbed outside and the back electron transfer were controlled by supramolecular effects. 相似文献
54.
The nucleon exchange process between two nuclei in close proximity and its application to an explanation of fragment mass
and charge distributions in fission and in heavy ion deep inelastic collisions are reviewed. An analysis of the measured correlations
between the energy loss from relative motion and the fragment mass and charge variances in the heavy ion deep inelastic collisions
is presented. The recent data on fragment mass and charge variances as a function of the fragment kinetic energy in thermal
neutron induced fission of235U, lends added support to the hypothesis that the nucleon transport process plays a similar role both in fission and in heavy
ion deep inelastic collisions. 相似文献
55.
Smriti KoodanjeriAjit R Pradhan Lakshmi S KaanumalleV Ramamurthy 《Tetrahedron letters》2003,44(15):3207-3210
1-Naphthyl phenyl acylates upon irradiation in solution yield eight products via β-cleavage process. However, excitation of these molecules as included in γ-cyclodextrin results in a single product (>95%). This medium dependent product selectivity is attributed to conformational and translational restrictions enforced on the reactant as well as intermediates by the cyclodextrin cavity. 相似文献
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Fragment angular distributions in heavy ion-induced fission reactions have been analysed in terms of a two component model—fission
following compound nucleus formation and fast fission events. It is seen that, contrary to the general assumption, fast fission
competes with compound nucleus fission even when the composite system is formed with a spin less than the rotating liquid
drop model limit for vanishing fission barrier. 相似文献