Host–Guest Complexation of Bisporphyrin Cleft and Electron-Deficient Aromatic Guests

Abstract

The host–guest complexation of a bisporphyrin cleft with various electron-deficient guest molecules was studied in solution and in the solid-state. X-ray crystal structures of a bisporphyrin cleft with naphthalene dianhydride and 2,4,7-trinitrofluorenone reveal that these guest molecules were located within the bisporphyrin cleft and formed ideal π–π stacking interactions in a host–guest ratio of 1:1. Isothermal titration calorimetry determined the binding constants and thermodynamic parameters for the 1:1 host–guest complexations in 1,2-dichloroethane and toluene. Two types of enthalpy–entropy compensation effects were found: (1) The tightly stacked host–guest structures restrict guest movement within the cleft, which results in significant desolvation with large intrinsic entropies. (2) The loosely bound guests maintain their molecular freedom within the bisporphyrin cleft, which leads to less desolvation with small intrinsic entropies. Chiral guest encapsulation directed the clockwise and anticlockwise twisted conformations of the bisporphyrin units, which induced bisignate CDs.

Two carbazole disulfonamide-diamide macrocycles with semi-flexible meta-xylyl linkages for anion recognition

“…Consistent with our original idea, all of the NH groups in the macrocycle oriented towards its internal cavity, which was beneficial to anion complexation. In line with previous reports, 29,30 the pyridine nitrogen atom established two intramolecular hydrogen bonds with its nearby amide NHs (NÁ Á ÁN distances of 2.677 and 2.704 Å and N-HÁ Á ÁN bond angles of 104.71 and 109.31, respectively). Moreover, two extra intramolecular hydrogen bonds were also observed involving the carbazole NH and its adjacent sulfonyl oxygen atoms (NÁ Á ÁO distances of 2.926 and 2.974 Å and N-HÁ Á ÁO bond angles of 118.71 and 115.51, respectively).…”

Porphyrin-based supramolecular polymers

“…[51][52][53][54][55][56][57][58][59][60][61] The flat and expanded p aromatic structure of porphyrins allows for strong p-p interaction between the porphyrin units. [67][68][69][70][71][72][73][74][75] The p-p interactions often play a crucial role in the formation of porphyrin-based supramolecular polymers. However, p-p interaction mainly serves as a supplement unlike hydrogen bonding or coordination bonding because it is not an effective directional force to form linear structures.…”

“…[73][74][75] Host-guest complex formation is also useful for the formation of supramolecular polymers. [67][68][69][70][71][72][77][78][79][80][81][82][83][84][85][86][87][88][89][90][91] Several multiporphyrin systems having cavities for specific guest binding through p-p or axial coordination interactions have been designed to obtain porphyrin-based supramolecular polymers. 61,[67][68][69][70][71][72] Hydrophobic porphyrin derivatives can be used as guest species for several macrocyclic host molecules.…”

“…[67][68][69][70][71][72][77][78][79][80][81][82][83][84][85][86][87][88][89][90][91] Several multiporphyrin systems having cavities for specific guest binding through p-p or axial coordination interactions have been designed to obtain porphyrin-based supramolecular polymers. 61,[67][68][69][70][71][72] Hydrophobic porphyrin derivatives can be used as guest species for several macrocyclic host molecules. 77,[79][80][81][82][83][84][85][86][87] Adding multiple guestbinding sites to porphyrin derivatives and associating them with molecules having multiple guest sites is another strategy for producing supramolecular polymers.…”

“…Several porphyrin-based host compounds for specific guest bindings have been reported. 61,[67][68][69][70][71][72] Porphyrin derivatives are often used as guest species for host-guest complex formation. [79][80][81][82][83][84][85][86][87][114][115][116]…”