TY - JOUR
T1 - Mechanical-Bond-Protected, Air-Stable Radicals
AU - Sun, Junling
AU - Liu, Zhichang
AU - Liu, Wei Guang
AU - Wu, Yilei
AU - Wang, Yuping
AU - Barnes, Jonathan C.
AU - Hermann, Keith R.
AU - Goddard, William A.
AU - Wasielewski, Michael R.
AU - Stoddart, J. Fraser
N1 - Funding Information:
This research is part of the Joint Center of Excellence in Integrated Nano-Systems (JCIN) at King Abdulaziz City for Science and Technology (KACST) and Northwestern University (NU). The authors thank both KACST and NU for their continued support of this research. The computational studies at Caltech were supported by NSF EFRI-1332411 (ODISSEI). This work was also supported by National Science Foundation grant no. CHE-1565925 (M.R.W.)
PY - 2017/9/13
Y1 - 2017/9/13
N2 - Radical templation centered around a heterotrisradical tricationic inclusion complex DB•+⊂DAPQT2(•+), assembled from an equimolar mixture of a disubstituted 4,4′-bipyridinium radical cation (DB•+) and an asymmetric cyclophane bisradical dication (DAPQT2(•+)), affords a symmetric [2]catenane (SC·7PF6) and an asymmetric [2]catenane (AC·7PF6) on reaction of the 1:1 complex with diazapyrene and bipyridine, respectively. Both these highly charged [2]catenanes have been isolated as air-stable monoradicals and characterized by EPR spectroscopy. X-ray crystallography suggests that the unpaired electrons are delocalized in each case across two inner 4,4′-bipyridinium (BIPY2+) units forming a mixed-valence (BIPY2)•3+ state inside both [2]catenanes, an observation which is in good agreement with spin-density calculations using density functional theory. Electrochemical studies indicate that by replacing the BIPY2+ units in homo[2]catenane HC•7+ - composed of two mechanically interlocked cyclobis(paraquat-p-phenylene) rings - with "zero", one, and two more highly conjugated diazapyrenium dication (DAP2+) units, respectively, a consecutive series of five, six, and seven redox states can be accessed in the resulting SC·7PF6 (0, 4+, 6+, 7+, and 8+), HC·7PF6 (0, 2+, 4+, 6+, 7+, and 8+), and AC·7PF6 (0, 1+, 2+, 4+, 6+, 7+, and 8+), respectively. These unique [2]catenanes present a promising prototype for the fabrication of high-density data memories.
AB - Radical templation centered around a heterotrisradical tricationic inclusion complex DB•+⊂DAPQT2(•+), assembled from an equimolar mixture of a disubstituted 4,4′-bipyridinium radical cation (DB•+) and an asymmetric cyclophane bisradical dication (DAPQT2(•+)), affords a symmetric [2]catenane (SC·7PF6) and an asymmetric [2]catenane (AC·7PF6) on reaction of the 1:1 complex with diazapyrene and bipyridine, respectively. Both these highly charged [2]catenanes have been isolated as air-stable monoradicals and characterized by EPR spectroscopy. X-ray crystallography suggests that the unpaired electrons are delocalized in each case across two inner 4,4′-bipyridinium (BIPY2+) units forming a mixed-valence (BIPY2)•3+ state inside both [2]catenanes, an observation which is in good agreement with spin-density calculations using density functional theory. Electrochemical studies indicate that by replacing the BIPY2+ units in homo[2]catenane HC•7+ - composed of two mechanically interlocked cyclobis(paraquat-p-phenylene) rings - with "zero", one, and two more highly conjugated diazapyrenium dication (DAP2+) units, respectively, a consecutive series of five, six, and seven redox states can be accessed in the resulting SC·7PF6 (0, 4+, 6+, 7+, and 8+), HC·7PF6 (0, 2+, 4+, 6+, 7+, and 8+), and AC·7PF6 (0, 1+, 2+, 4+, 6+, 7+, and 8+), respectively. These unique [2]catenanes present a promising prototype for the fabrication of high-density data memories.
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U2 - 10.1021/jacs.7b06857
DO - 10.1021/jacs.7b06857
M3 - Article
C2 - 28806074
AN - SCOPUS:85029540289
VL - 139
SP - 12704
EP - 12709
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 36
ER -