Two Polyoxometalate-Based Hybrid Compounds Modified by Iron Schiff Base Complexes: Syntheses, Crystal structures, Cyclic Voltametric Studies and Nonlinear Optical Properties.

Abstract

Two new polyoxometalate (POM)-based hybrid compounds modified by a Schiff base, [Fe(DAPSC)(H2 O)2 ]2 [HPMo2 V Mo10 VI O40 ] ⋅ 5H2 O (1) and [Fe(DAPSC)(H2 O)]2 [HPV3 IV Mo4 V Mo7 VI O42 ] ⋅ 6H2 O (2), (DAPSC=2,6-diacetylpyridine bis-(semicarbazone)), have been successfully constructed from typical Keggin POMs, iron ions, and DAPSC ligands under hydrothermal condition. Structural analysis demonstrates that the Fe-Schiff base ligand units are free from polyacid anions in compound 1. While in compound 2, the Fe-Schiff base ligand units are bridged with polyacid anions via Fe-O bonds to emerge a stable double-supported skeleton. Noticeably, owing to the introduction of vanadium in H5 PMo10 V2 O40 ⋅ 32.5H2 O, a divanadium-capped configuration is shaped in compound 2. Besides, the third-order nonlinear optical (NLO) properties of two compounds were explored. It should be noted that both compounds 1 and 2 have two-photon absorption properties, which indicates that the two compounds are potential nonlinear optical materials.