Macroscopic and nanoscopic current−voltage measurements reveal
asymmetries in the DC electrical
conductivity through Langmuir−Blodgett multilayers and even
monolayers of γ-(n-hexadecyl)quinolinum
tricyanoquinodimethanide, C16H33Q-3CNQ (5).
These asymmetries are due to a transition of the ground-state
zwitterion to
an excited-state conformer which is probably neutral. Unimolecular
electrical rectification by monolayers of 5 is
unequivocally confirmed.
Circularly polarized luminescence, or CPL, is a luminescence phenomenon that provides the differential emission intensity of right and left circularly polarized light, thereby providing information on the excited state properties of the chiral molecular systems. In recent years, there has been a growing interest toward the development of organic chromophores capable of circularly polarized emission due to their potential applications in sensors, asymmetric synthesis as well as display and optical storage devices. The major drawback with organic molecules is the low dissymmetric factors exhibited by these systems. One of the recent strategies adopted for the improvement in luminescence dissymmetry of organic systems is through the controlled self-assembly of chromophores. In this Perspective, we highlight the recent experimental and theoretical developments in the field of chiral organic chromophoric systems and their self-assembly, that has produced promising results toward the enhancement of glum values in CPL.
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