Using the concepts of self-assembly developed for the construction of topologically complex molecules such as [2]-catenanes and rotaxanes, the syntheses of several prophyrin-catenanes are described. The successful insertion of the porphyrin subunit into [2]-catenanes has resulted from the adaptation of previously devised template-directed syntheses based primarily on pi-pi interactions and C-H...O and C-H...pi and hydrogen bonding. Several hydroquinol containing ether chains were successfully synthesized and subsequently strapped across a porphyrin ring; the X-ray crystal structures of two such molecules which vary in the length of the ether chain are reported. These strapped porphyrins were found to complex paraquat with a parallel orientation of the hydroquinol, paraquat, and porphyrin rings. The complexation of paraquat (K-a 1955 and 1640 M(-1), Delta G degrees = -4.5 and -4.4 kcal mol(-1) for 9 and 11, respectively) by these strapped porphyrins led to their subsequent inclusion, using template-directed self-assembly, into structures which represent the first examples of porphyrin-containing [2]-catenanes. The catenanes were subsequently characterized by FAB-MS and thoroughly examined using dynamic H-1 NMR. In the case of the hydroquinol-containing catenanes, a dynamic process was observed in solution in which the bipyridinium subunits of the tetracation were exchanged between ''inside'' and ''outside'' environments (rotation around the hydroquinol ring axis). The diethylene glycol containing catenanes 14 and 15 were observed to maintain an orientation of the tetracation in which the bipyridinium subunits are parallel to the porphyrin ring. The length of the ether strap in these catenanes influenced the rotation rates of the tetracation macrocycles (50 and 80 times per second for 14 and 15 and 2500 and 1500 times per second for 16 and 17, respectively) at ambient temperature. However, in air the catenanes, the overall orientation of the tetracation,with bipyridinium and porphyrin rings coparallel, is retained in solution. As an extension of the original concepts, an analogous strapped porphyrin containing a naphthoquinol moiety was synthesized and found to complex paraquat with K-a = 21 000 M(-1) and Delta G degrees = -5.9 kcal mol(-1). The general applicability of the template-directed synthetic procedure developed for porphyrin catenane synthesis was illustrated by the successful isolation of the naphthalene containing porphyrin [2]-catenane 23 in 45% yield. Tetracation exchange processes similar to those for the hydroquinol catenanes were observed, along with an additional process which was found to be the decomplexation/complexation of the naphthalene ring in what is termed an ''out, turn around, and in again'' process similar to that occurring in nonporphyrinic naphthalene [2]-catenanes.
Using the concepts of self-assembly developed for the construction of topologically complex molecules such as [2]-catenanes and rotaxanes, the syntheses of several prophyrin-catenanes are described. The successful insertion of the porphyrin subunit into [2]-catenanes has resulted from the adaptation of previously devised template-directed syntheses based primarily on pi-pi interactions and C-H...O and C-H...pi and hydrogen bonding. Several hydroquinol containing ether chains were successfully synthesized and subsequently strapped across a porphyrin ring; the X-ray crystal structures of two such molecules which vary in the length of the ether chain are reported. These strapped porphyrins were found to complex paraquat with a parallel orientation of the hydroquinol, paraquat, and porphyrin rings. The complexation of paraquat (K-a 1955 and 1640 M(-1), Delta G degrees = -4.5 and -4.4 kcal mol(-1) for 9 and 11, respectively) by these strapped porphyrins led to their subsequent inclusion, using template-directed self-assembly, into structures which represent the first examples of porphyrin-containing [2]-catenanes. The catenanes were subsequently characterized by FAB-MS and thoroughly examined using dynamic H-1 NMR. In the case of the hydroquinol-containing catenanes, a dynamic process was observed in solution in which the bipyridinium subunits of the tetracation were exchanged between ''inside'' and ''outside'' environments (rotation around the hydroquinol ring axis). The diethylene glycol containing catenanes 14 and 15 were observed to maintain an orientation of the tetracation in which the bipyridinium subunits are parallel to the porphyrin ring. The length of the ether strap in these catenanes influenced the rotation rates of the tetracation macrocycles (50 and 80 times per second for 14 and 15 and 2500 and 1500 times per second for 16 and 17, respectively) at ambient temperature. However, in air the catenanes, the overall orientation of the tetracation,with bipyridinium and porphyrin rings coparallel, is retained in solution. As an extension of the original concepts, an analogous strapped porphyrin containing a naphthoquinol moiety was synthesized and found to complex paraquat with K-a = 21 000 M(-1) and Delta G degrees = -5.9 kcal mol(-1). The general applicability of the template-directed synthetic procedure developed for porphyrin catenane synthesis was illustrated by the successful isolation of the naphthalene containing porphyrin [2]-catenane 23 in 45% yield. Tetracation exchange processes similar to those for the hydroquinol catenanes were observed, along with an additional process which was found to be the decomplexation/complexation of the naphthalene ring in what is termed an ''out, turn around, and in again'' process similar to that occurring in nonporphyrinic naphthalene [2]-catenanes.
Towards molecular scale mechano–electronic devices: porphyrin catenanes
作者:Maxwell J. Gunter、Martin R. Johnston
DOI:10.1039/c39920001163
日期:——
Using self-assembly strategies, catenanes consisting of zinc and free base porphyrins with hydroquinol-containing polyether straps of different lengths interlinked with a tetracationic bipyridinium cyclophane have been synthesised.
Synthesis of New Strapped Porphyrins via a Bisdipyrromethane Condensation
作者:Jeremy Sanders、Diana Gonçalves
DOI:10.1055/s-2007-967967
日期:——
Two new cationic strapped meso-porphyrins were synthesized via a new route, which consists of the condensation of a bisdipyrromethane with an aldehyde under acidic conditions. One of the strapped porphyrins binds to G-quadruplex DNA.
我们通过一种新方法合成了两种新的阳离子带介卟啉,该方法包括在酸性条件下将双二吡咯甲烷与醛缩合。其中一种带状卟啉能与 G 型四联 DNA 结合。
Thermodynamic Synthesis of Rotaxanes by Imine Exchange
作者:Stuart J. Rowan、J. Fraser Stoddart
DOI:10.1021/ol991047w
日期:1999.12.1
[GRAPHICS]By utilizing the dynamic nature of imine bonds, it is possible to construct [2]rotaxanes from a ring and a preformed dumbbell under thermodynamic control, These dynamic [a]rotaxanes, which exhibit reversible supramolecular-like behavior in the presence of appropriate catalysts, can be "fixed" by reduction of their imine bonds.