On Dec. 9, 2013, Journal of the American Chemical Society published a paper entitled “Macrocycle contraction and expansion of a dihydro-sapphyrin isomer” (http://pubs.acs.org/doi/abs/10.1021/ja4112644). This work was cooperatively published by Prof. Yongshu Xie’s group at School of Chemistry and Molecular Engineering, East China University of Science & Technology and Prof. Hiroyuki Furuta’s group at Kyushu University. The reviewers ranked the novelty of this work in top 5%. And it was recommended to JACS spotlights by the editor.

    Macrocyclic frameworks widely occur in nature. Porphyrin, which contains 4 pyrrole units, is one of the most prominent representative due to its rich optoelectronic properties. In recent years, porphyrins and porphyrin analogues with unique structures and versatile properties have attracted considerable attention. In this work, two reactive N-confused pyrroles were attached to the terminals of a linear pentapyrrane, and subsequent oxidative cyclization afforded a novel dihydro-sapphyrin isomer (1), which underwent interesting ring-contracted rearrangement to a pyrrolyl norrole (2), and succeeding ring expansion afforded a terpyrrole-containing isosmaragdyrin analogue (4). 1, 2, and 4 contain internal ring pathways with the minimum of 17, 15, and 16 atoms, respectively. 1, 2, and 4 are almost nonfluorescent. Whereas, the complex of 2 with Zn2+ (3) shows a distinct NIR emission peak at 736 nm. Thus, 2 may be developed as a novel prototype of Zn2+ probe with NIR emission, which may find applications in biochemical systems. All these macrocyclic compounds were clearly characterized by single crystal X-ray diffraction analyses.

    The experiments were performed by doctoral students Pingchun wei and Kai Zhang, and a master student Tao Hong under the direction of Prof. Yongshu Xie. This work was financially supported by NSFC/China (21072060, 91227201), National Basic Research 973 Program (2013CB733700), and SRFDP (20100074110015).