title: Polarization of charge-transfer bands and rectification in hexadecylquinolinium 7,7,8-tricyanoquinodimethanide and its tetrafluoro analog.
abstract: A Langmuir-Blodgett (LB) multilayer film of the unimolecular rectifier hexadecyl-gamma-quinolinium-7,7,8-tricyanoquinodimethanide (C(16)H(33)gammaQ-3CNQ) has two distinct polarized charge-transfer bands, one at lower film pressures (28 mN m(-1)) with a peak at 530 nm, due to an intramolecular charge transfer or intervalence transfer (IVT); past the collapse point (32 to 35 mN m(-1)), this band disappears, and a new intermolecular charge-transfer band appears with peak at 570 nm. An LB multilayer film of the tetrafluoro analogue, hexadecyl-gamma-quinolinium-2,3,5,6-tetrafluoro-7,7,8-tricyanoquinodimethanide (C(16)H(33)gammaQ-3CNQF(4)) shows, for all film pressures, only one IVT band with a peak at 504 nm; when sandwiched between gold electrodes, (C(16)H(33)gammaQ-3CNQF(4) is also an LB monolayer electrical rectifier.
authors.affiliation: Laboratory for Molecular Electronics, Chemistry Department, University of Alabama, Tuscaloosa, Alabama 35487-0336, USA.
authors.forename: Andrei
authors.initials: A
authors.lastname: Honciuc
authors.forename: Akihiro
authors.initials: A
authors.lastname: Otsuka
authors.forename: Yu-Hsiang
authors.initials: YH
authors.lastname: Wang
authors.forename: Samuel K
authors.initials: SK
authors.lastname: McElwee
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Woski
authors.forename: Gunzi
authors.initials: G
authors.lastname: Saito
authors.forename: Robert M
authors.initials: RM
authors.lastname: Metzger
mesh_terms: D004566:Electrodes; D006046:Gold / Q000737:chemistry; D008567:Membranes, Artificial; D015394:Molecular Structure; D009570:Nitriles / Q000737:chemistry*; D011804:Quinolines / Q000737:chemistry*
chemical_list: D008567:Membranes, Artificial; D009570:Nitriles; D011804:Quinolines; C522515:hexadecyl-quinolinium-2,3,5,6-tetrafluoro-7,7,8-tricyanoquinodimethanide; C522514:hexadecylquinolinium 7,7,8-tricyanoquinodimethanide; D006046:Gold