Modulating Charge Separation and Charge Recombination Dynamics in Porphyrin−Fullerene Linked Dyads and Triads: Marcus-Normal versus Inverted Region
作者:Hiroshi Imahori、Koichi Tamaki、Dirk M. Guldi、Chuping Luo、Mamoru Fujitsuka、Osamu Ito、Yoshiteru Sakata、Shunichi Fukuzumi
DOI:10.1021/ja003346i
日期:2001.3.1
zincporphyrin-freebase porphyrin-C60 triad (ZnP-H2P-C60). Most importantly, the lowest lying charge-separated state of all the investigated systems, namely, that of ferrocenium ion (Fc+) and the C60 radical anion (C60.-) pair in the Fc-ZnP-C60 triad, has been generated with the highest quantum yields (close to unity) and reveals a lifetime as long as 16 micros. Determination of CS and CR rate constants, together with
Controlling the structure of transparent Langmuir–Blodgett films for nonlinear optical applications
作者:Geoffrey J. Ashwell、Paul D. Jackson、Gary Jefferies、Ian R. Gentle、Colin H. L. Kennard
DOI:10.1039/jm9960600137
日期:——
Langmuir-Blodgett (LB) multilayers of (E)-N-alkyl-4-[2-(4-docosyloxyphenyl)ethenyl]pyridinium bromide, CBH2n+1-Py(+)-CH=CH-C6H4-O-C22H45Br- (dye I), are centrosymmetric (Y-type) for n less than or equal to 6 and non-centrosymmetric (Z-type) for 8 less than or equal to n less than or equal to 20. The areas obtained from grazing incidence synchrotron X-ray diffraction indicate that the molecules adopt a 'stretched' rather than a 'U-shaped' configuration and, unlike conventional amphiphilic materials, the long chain homologues do not invert during deposition. The second-harmonic intensity from films of the higher homologues (n greater than or equal to 10) increases quadratically with the number of LB layers (I-2 omega(N) = I-2 omega(1)N-2) whereas for the lower homologues (n less than or equal to 6) the intensity is negligible for even numbers of layers. The nonlinear optical properties of the sulfur (dye II), selenium (dye III) and quinolinium (dye TV) analogues are also reported and, in each case, quadratic enhancement of the second-harmonic intensity has been observed for suitable combinations of alkyl chain lengths. The second-order susceptibility, chi((2))(zzz), of a 100 layer LB film of (E)-N-dodecyl-4-[2-(4-docosyloxyphenyl)ethenyl] quinolinium bromide (dye IV) is 20 pm V-1.
Controlling the formation of heliconical smectic phases by molecular design of achiral bent-core molecules
Fluids with spontaneous helical structures formed by achiral low molecular mass molecules is a newly emerging field with great application potential. Here, we explore the chemical mechanisms of the helix formation by systematically modifying the structure of a bent 4-cyanoresorcinol unit functionalized with two different phenyl benzoate based aromatic rods and terminated with two alkyl chains of variable
Enantioselective Fluorescent Recognition of a Soluble “Supported” Chiral Acid: Toward a New Method for Chiral Catalyst Screening
作者:Zi-Bo Li、Jing Lin、Ying-Chuan Qin、Lin Pu
DOI:10.1021/ol0510163
日期:2005.8.1
The long-chain aliphatic-group-substituted mandelic acid 3c, which is soluble only in THF and insoluble in water and many polar/nonpolar organic solvents, has been synthesized. This unique solubility allows 3c to be easily isolated from reaction mixtures and makes it potentially useful for catalyst screening. The fluorescent sensors (R)- and (S)-1 can be used to determine the ees of various samples