A semiconducting organic radical cationic host-guest complex.
The self-assembly and solid-state semiconducting properties of single crystals of a trisradical tricationic complex composed of the diradical dicationic cyclobis(paraquat-p-phenylene) (CBPQT(2(•+))) ring and methyl viologen radical cation (MV(•+)) are reported. An organic field effect transistor incorporating single crystals of the CBPQT(2(•+))⊂MV(•+) complex was constructed using lithographic techniques on a silicon substrate and shown to exhibit p-type semiconductivity with a mobility of 0.05 cm(2) V(-1) s(-1). The morphology of the crystals on the silicon substrate was characterized using scanning electron microscopy which revealed that the complexes self-assemble into "molecular wires" observable by the naked-eye as millimeter long crystalline needles. The nature of the recognition processes driving this self-assembly, radical-radical interactions between bipyridinium radical cations (BIPY(•+)), was further investigated by resonance Raman spectroscopy in conjunction with theoretical investigations of the vibrational modes, and was supported by X-ray structural analyses of the complex and its free components in both their radical cationic and dicationic redox states. These spectroscopic investigations demonstrate that the bond order of the BIPY(•+) radical cationic units of host and guest components is not changed upon complexation, an observation which relates to its conductivity in the solid-state. We envision the modularity inherent in this kind of host-guest complexation could be harnessed to construct a library of custom-made electronic organic materials tailored to fit the specific needs of a given electronic application.
Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States.
Albert C
AC
Fahrenbach
Srinivasan
S
Sampath
Dattatray J
DJ
Late
Jonathan C
JC
Barnes
Samuel L
SL
Kleinman
Nicholas
N
Valley
Karel J
KJ
Hartlieb
Zhichang
Z
Liu
Vinayak P
VP
Dravid
George C
GC
Schatz
Richard P
RP
Van Duyne
J Fraser
JF
Stoddart
D002412:Cations; D004553:Electric Conductivity; D005609:Free Radicals; D008422:Materials Testing; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D009930:Organic Chemicals / Q000737:chemistry*; D010316:Particle Size; D012666:Semiconductors
D002412:Cations; D005609:Free Radicals; D009930:Organic Chemicals