TY - JOUR
T1 - Ex2box
T2 - Interdependent modes of binding in a two-nanometer-long synthetic receptor
AU - Juríček, Michal
AU - Barnes, Jonathan C.
AU - Dale, Edward J.
AU - Liu, Wei Guang
AU - Strutt, Nathan L.
AU - Bruns, Carson J.
AU - Vermeulen, Nicolaas A.
AU - Ghooray, Kala C.
AU - Sarjeant, Amy A.
AU - Stern, Charlotte L.
AU - Botros, Youssry Y.
AU - Goddard, William A.
AU - Stoddart, J. Fraser
PY - 2013/8/28
Y1 - 2013/8/28
N2 - Incorporation of two biphenylene-bridged 4,4′-bipyridinium extended viologen units into a para-phenylene-based cyclophane results in a synthetic receptor that is ∼2 nm long and adopts a box-like geometry. This cyclophane, Ex2Box4+, possesses the ability to form binary and ternary complexes with a myriad of guest molecules ranging from long π-electron-rich polycyclic aromatic hydrocarbons, such as tetracene, tetraphene, and chrysene, to π-electron-poor 2,6-dinitrotoluene, 1,2,4-trichlorobenzene, and both the 9,10- and 1,4-anthraquinone molecules. Moreover, Ex2Box4+ is capable of forming one-to-one complexes with polyether macrocycles that consist of two π-electron-rich dioxynaphthalene units, namely, 1,5-dinaphtho[38]crown-10. This type of broad molecular recognition is possible because the electronic constitution of Ex 2Box4+ is such that the pyridinium rings located at the "ends" of the cyclophane are electron-poor and prefer to enter into donor-acceptor interactions with π-electron-rich guests, while the "middle" of the cyclophane, consisting of the biphenylene spacer, is more electron-rich and can interact with π-electron-poor guests. In some cases, these different modes of binding can act in concert to generate one-to-one complexes which possess high stability constants in organic media. The binding affinity of Ex2Box4+ was investigated in the solid state by way of single-crystal X-ray diffraction and in solution by using UV-vis and NMR spectroscopy for 12 inclusion complexes consisting of the tetracationic cyclophane and the corresponding guests of different sizes, shapes, and electronic compositions. Additionally, density functional theory was carried out to elucidate the relative energetic differences between the different modes of binding of Ex2Box4+ with anthracene, 9,10-anthraquinone, and 1,4-anthraquinone in order to understand the degree with which each mode of binding contributes to the overall encapsulation of each guest.
AB - Incorporation of two biphenylene-bridged 4,4′-bipyridinium extended viologen units into a para-phenylene-based cyclophane results in a synthetic receptor that is ∼2 nm long and adopts a box-like geometry. This cyclophane, Ex2Box4+, possesses the ability to form binary and ternary complexes with a myriad of guest molecules ranging from long π-electron-rich polycyclic aromatic hydrocarbons, such as tetracene, tetraphene, and chrysene, to π-electron-poor 2,6-dinitrotoluene, 1,2,4-trichlorobenzene, and both the 9,10- and 1,4-anthraquinone molecules. Moreover, Ex2Box4+ is capable of forming one-to-one complexes with polyether macrocycles that consist of two π-electron-rich dioxynaphthalene units, namely, 1,5-dinaphtho[38]crown-10. This type of broad molecular recognition is possible because the electronic constitution of Ex 2Box4+ is such that the pyridinium rings located at the "ends" of the cyclophane are electron-poor and prefer to enter into donor-acceptor interactions with π-electron-rich guests, while the "middle" of the cyclophane, consisting of the biphenylene spacer, is more electron-rich and can interact with π-electron-poor guests. In some cases, these different modes of binding can act in concert to generate one-to-one complexes which possess high stability constants in organic media. The binding affinity of Ex2Box4+ was investigated in the solid state by way of single-crystal X-ray diffraction and in solution by using UV-vis and NMR spectroscopy for 12 inclusion complexes consisting of the tetracationic cyclophane and the corresponding guests of different sizes, shapes, and electronic compositions. Additionally, density functional theory was carried out to elucidate the relative energetic differences between the different modes of binding of Ex2Box4+ with anthracene, 9,10-anthraquinone, and 1,4-anthraquinone in order to understand the degree with which each mode of binding contributes to the overall encapsulation of each guest.
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U2 - 10.1021/ja4052763
DO - 10.1021/ja4052763
M3 - Article
C2 - 23865381
AN - SCOPUS:84883307735
VL - 135
SP - 12736
EP - 12746
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 34
ER -