Regioselectively Halogenated Expanded Porphyrinoids as Building Blocks for Constructing Porphyrin–Porphyrinoid Heterodyads with Tunable Energy Transfer

Abstract

Expanded porphyrins have been attracting increasing attention owing to their unique optical and electrochemical properties as well as switchable aromaticity. Toward material applications, regioselective functionalization of the expanded porphyrins at their periphery is indeed challenging due to the presence of multiple reactive sites. Herein, a set of regioselective halogenated isomers (L5-Br-A/B/C) of neo-confused isosmaragdyrin (L5) are synthesized by a combination of the halogenation reaction of L5 and sequential macrocycle-to-macrocycle transformation reactions of its halogenated isomers. On this basis, the regioselectively functionalized isosmaragdyrins are utilized as building blocks for constructing multichromophoric porphyrinoids, specifically, heterodyads L5-ZnP-A/B/C, in which a common zinc porphyrin is linked at three different pyrrolic positions of isosmaragdyrins, respectively, by Sonogashira coupling reactions. The highly efficient energy cascade from porphyrin to isosmaragdyrin is elucidated using steady-state/time-resolved spectroscopies and theoretical calculations. Notably, the energy transfer processes from the porphyrin to the isosmaragdyrin moieties as well as the excitation energy transfer rates in L5-ZnP-A/B/C are highly dependent on the linking sites by through-bond and Förster-type resonance energy transfer mechanisms. The site-selective functionalization and subsequent construction of a set of heterodyads of the expanded porphyrinoid would provide opportunities for developing new materials for optoelectronic applications.

A Novel Charge Transfer Channel to Simultaneously Enhance Photocatalytic Water Splitting Activity and Stability of CdS

“…Recently, porphyrins, existing widely in natural organisms, have attracted much attention owning to the following reasons: 1) porphyrin ligand can be easily modified through carboxyl or phosphate groups; 2) low‐cost molecular catalyst in improving the photo‐electrochemical cell performance; 3) unique optical and electrochemical properties by modifying the peripheral substituents and metal center; 4) high hole mobility and matched energy band …”

Twisted-Planar-Twisted expanded porphyrinoid dimer as a rudimentary reaction-based methanol indicator

“…1d ). Although a number of expanded porphyrins with twisted conformations (e.g., “figure-of-eight” structures) are known, they usually do not exhibit biased reactivity and are not readily dimerized in high yield 27 , 28 . However, we felt that if the confusion- and expansion-based approaches to porphyrin analog generation were combined, it might prove possible to obtain such dimers.…”

Porpholactone Chemistry: Shining New Light on an Old Cofactor

“…In addition, the intriguing merits of porpholactone derivatives enable construction of high efficiency sensitizers for energy materials such as porphyrin‐based dye‐sensitized solar cells (DSSCs). In fact, recently significant progress have been achieved on porphyrin‐based DSSCs and an impressive power conversion efficiency (∼13 %) using push–pull porphyrin SM315 as sensitizer has been achieved [84–91] . Given the robust light‐harvesting capability, porpholactone and its derivatives are undoubtedly attractive constructing units for the design and preparation of highly efficient DSSCs.…”