Chaudhary, Arvind ; Rath, Sankar Prasad (2011) Efficient Complexation of Pyrrole-Bridged Dizinc(II) Bisporphyrin with Fluorescent Probe Pyrene: Synthesis, Structure, and Photoinduced Singlet-Singlet Energy Transfer Chemistry - A European Journal, 17 (41). pp. 11478-11487. ISSN 0947-6539
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Official URL: http://doi.org/10.1002/chem.201101324
Related URL: http://dx.doi.org/10.1002/chem.201101324
Abstract
A diethylpyrrole-bridged dizinc(II) bisporphyrin (Zn2DEP) is reported that encapsulates fluorescent probe pyrene molecules through strong π–π interactions, which can relay information about the chemical environment in the interior of the host–guest supramolecular assembly. X-ray structures of both Zn2DEP and the encapsulated pyrene complex are reported, which provides a rare opportunity to investigate the structural changes upon guest binding. A comparative structural analysis demonstrated the exceptional ability of this bisporphyrin platform to open its binding pocket for pyrene encapsulation by a vertical displacement of more than 2.45 Å, although both Zn2DEP and the pyrene complex have nearly parallel porphyrin ring orientations. The 1H NMR spectrum of the encapsulated pyrene complex in solution shows the upfield shifts of the pyrene protons due to a strong ring current effect, which demonstrates the retention of the solid-state structure in solution. To further assess the extent to which pyrene guests remain encapsulated in solution, a known fluorescence quencher, dimethylaniline, was added to the host–guest assembly, which shows no exciplex formation for days in nonpolar solvents. Thus, the assembly also retained the structural integrity in solution for a long time. The association constant (Kasso) for such a complexation process in solution was observed to be 1.78×105 M−2 for 1:2 binding. Steady-state fluorescence and lifetime studies indicate significant photoinduced singlet–singlet energy transformation from the excited state of pyrene to zinc bisporphyrin.
Item Type: | Article |
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Source: | Copyright of this article belongs to John Wiley and Sons, Inc. |
ID Code: | 120913 |
Deposited On: | 07 Jul 2021 06:20 |
Last Modified: | 07 Jul 2021 06:20 |
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