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Giant meso – meso ‐Linked Porphyrin Arrays of Micrometer Molecular Length and Their Fabrication
Author(s) -
Aratani Naoki,
Takagi Akihiko,
Yanagawa Yoshiki,
Matsumoto Takuya,
Kawai Tomoji,
Yoon Zin Seok,
Kim Dongho,
Osuka Atsuhiro
Publication year - 2005
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200401306
Subject(s) - porphyrin , chemistry , scanning tunneling microscope , spectroscopy , crystallography , molecular wire , raman spectroscopy , analytical chemistry (journal) , molecule , materials science , photochemistry , nanotechnology , organic chemistry , physics , quantum mechanics , optics
On the basis of the Ag I ‐promoted coupling reaction of zinc( II )–5,15‐bis(3,5‐dioctyloxyphenyl)porphyrin Z1 , chain elongation has been attempted by using a stepwise doubling approach, which provides Z2 , Z4 , Z8 , Z16 , Z32 , Z64 , Z128 , Z256 , Z384 , and Z512 . The porphyrin arrays up to Z128 are sufficiently soluble in CHCl 3 and THF despite their very long molecular lengths and rodlike structures, while the arrays over Z128 show a significant drop in solubility and stability. The discrete porphyrin arrays thus isolated were characterized by means of 1 H NMR spectroscopy, matrix‐assisted laser desorption ionization time‐of‐flight (MALDI‐TOF) mass spectrometry, UV/Vis spectroscopy, gel‐permeation chromatography (GPC), cyclic voltammetry (CV), single‐crystal X‐ray crystallography, scanning tunneling microscopy (STM), and atomic force microscopy (AFM). Contrary to expected linear conformations of the arrays Z n (where n is the number of porphyrins), the single molecular images of Z128 , Z256 , and Z512 revealed largely bent structures; this finding indicates the substantial conformational flexibility of Z n . We also exploited an effective synthetic route by means of which Z n can be fabricated with a thiol‐protected aryl group to provide Z n S 2 through Z n Br 2 , by bromination with N ‐bromosuccinimide and subsequent Pd‐catalyzed Suzuki–Miyaura arylation. Finally, the reaction of Z256 provided Z512 , Z768 , and Z1024 . Collectively, this work provides an important milestone in the preparation of sub‐microscale discrete organic molecules and the fabrication of molecular‐based materials, hence significantly contributing to device applications.