RESUMO
This paper reports the first magnetic circularly polarized luminescence (MCPL) characteristics of racemic helicenes, including four unsubstituted [n]helicenes (n=3,4,5,7) and two [4]helicene derivatives bearing methoxy substituents, in tetrahydrofuran (THF) and dimethyl sulfoxide (DMSO) solutions. The value of |gMCPL | was calculated to be of the order of 10-3 â T-1 within 350-430â nm under the north-up (N-up) and south-up (S-up) Faraday geometries in an external magnetic field of 1.6â T. The [n]-dependent MCPL signs were altered by the N-up and S-up geometries.
RESUMO
Diamagnetic achiral pyrene and phenanthrene derivatives substituted with electron-donating hydroxyl/methoxy groups and electron-withdrawing carboxylic acid groups exhibited clear magnetic circularly polarised luminescence (MCPL) spectra at 360-460 nm in dilute solvents upon the application of N-up and S-up Faraday geometries under an external magnetic field of 1.6 T. Their MCPL signs were also susceptible upon application of the same Faraday geometry.
RESUMO
Optically active linear polyurethane and a cyclic dimer were synthesized from 2,7-diisocyanatofluorene and 2,2'-dihydroxy-1,1'-binaphthyl. The circular dichroism (CD) spectral intensity of the polymer was amplified at a higher concentration through aggregate formation, while circularly polarized light (CPL) emission was not enhanced. The cyclic dimer's CPL emission was largely amplified (glum 1.1 × 10-2) due to intermolecular excimer formation through aggregation, while the CD intensity was not affected.
Assuntos
Corantes Fluorescentes/química , Poliuretanos/química , Dicroísmo Circular , Teoria da Densidade Funcional , Dimerização , Naftóis/química , EstereoisomerismoRESUMO
Although 12 diamagnetic fused aromatics with or without substituents exhibit mirror-symmetric magnetic circularly polarised luminescence (MCPL) through N-up and S-up Faraday geometries under a magnetic field intensity of 1.6 T, their signs (single and multiple) and magnitudes depend strongly on either the aromatic structures or the peripheral positions of the substituents.