A Versatile and Conformationally Adaptable Fluorene-Based Receptor for Efficient Binding of Silver Cation
摘要:
We have designed and synthesized a versatile fluorene-based receptor (1) in a one-pot reaction from readily available precursors, which adapts a deltaphane- or pi-prismand-like conformer via a simple C-C bond rotation. Such a conformational adaptability of 1 allows it to bind a single silver cation with remarkable efficiency (K approximately 15 000 M-1) as monitored by 1H NMR or UV-vis spectroscopy and further confirmed by competition experiments with tris[2.2.2]paracyclophane (or pi-prismand 2) as well as a model compound 3 containing only one fluoranyl ring.
A Versatile and Conformationally Adaptable Fluorene-Based Receptor for Efficient Binding of Silver Cation
摘要:
We have designed and synthesized a versatile fluorene-based receptor (1) in a one-pot reaction from readily available precursors, which adapts a deltaphane- or pi-prismand-like conformer via a simple C-C bond rotation. Such a conformational adaptability of 1 allows it to bind a single silver cation with remarkable efficiency (K approximately 15 000 M-1) as monitored by 1H NMR or UV-vis spectroscopy and further confirmed by competition experiments with tris[2.2.2]paracyclophane (or pi-prismand 2) as well as a model compound 3 containing only one fluoranyl ring.
Convergent Synthesis of Alternating Fluorene-<i>p</i>-xylene Oligomers and Delineation of the (Silver) Cation-Induced Folding
作者:Vincent J. Chebny、Rajendra Rathore
DOI:10.1021/ja0687522
日期:2007.7.1
Convergent synthetic routes for the preparation of hitherto unknown fluorene-p-xylene oligomers (containing up to 10 fluorene moieties) from readily available starting materials are described. The conformationally adaptable monomeric receptor (which is made of a pair of fluorene and one p-xylene ring, i.e., Z1 undergoes a simple C-C bond rotation in the presence of silver cations to produce a pi-prismand-like receptor which binds a single silver cation with remarkable efficiency (i.e., K approximate to 15 000 M-1). The data on H-1 NMR spectroscopic titrations with Ag+ together with the density functional theory and AM1 calculations allows us to establish that various oligomers of Z1(i. e... Z2-Z9) also undergo ready folding into the structures that contain multiple pi-prismand-like receptor sites in the presence of silver cations. The multiple cavities in Z3-Z9 accommodate a single silver cation per cavity with efficiency similar to that of Z1.