Similarities and differences between Mn(ii) and Zn(ii) coordination polymers supported by porphyrin-based ligands: synthesis, structures and nonlinear optical properties

Bo Wei Xu, Ru Jie Niu, Quan Liu, Jun Yi Yang, Wen Hua Zhang, David J. Young

Research output: Contribution to journalArticle

Abstract

Four coordination polymers (CPs) Mn-TMPP (1), Zn-TMPP (2), Mn-THPP (3), and Zn-THPP (4) have been synthesized and characterized (H2TMPP =meso-tetrakis (6-methylpyridin-3-yl) porphyrin; H2THPP =meso-tetrakis (6-(hydroxymethyl) pyridin-3-yl) porphyrin). The one-dimensional (1D) chain compound1is formedviaa head-to-tail connection of the Mn-TMPP unit, wherein the central Mn2+features a square pyramidal geometry coordinated by four N atoms from the porphyrin skeleton and one additional N atom from an adjacent Mn-TMPP unit. Compound2features an octahedral Zn2+center associated with four N atoms from the porphyrin skeleton to define the equatorial plane and two additional N donors at the axial positions to give a two-dimensional (2D) CP. The 1D chain of1and the 2D layer of2possess distinctive molecular structures but nearly identical molecular arrangements in their unit cells viewed along all three crystallographic axes. By contrast, Mn- and Zn-based CPs3and4supported by the THPP ligand share both identical molecular connectivities and crystal packing. In3/4, each Mn/Zn center is chelated by four N donors of the porphyrin interior to define the equatorial plane of an octahedron, whose axial sites are occupied by two alcoholic OH groups from a pair oftrans-located pyridinemethanol moieties. The third-order nonlinear optical properties of1-4investigated using theZ-scan technique at 532 nm revealed reverse saturable absorption and self-focusing effects for all four CPs, with hyperpolarizability values (γ) in the range 1.42 × 10−28esu to 7.64 × 10−28esu. These highγvalues are comparable to the best porphyrin-based molecular assemblies, demonstrating potential for these materials in optical limiting applications.

Original languageEnglish
Pages (from-to)12622-12631
Number of pages10
JournalDalton Transactions
Volume49
Issue number36
DOIs
Publication statusPublished - 28 Sep 2020

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