Two new isolated Zn-ε-Keggin clusters modified by conjugated organic ligands with decent electrocatalytic and third-order NLO properties

Abstract

Two new bifunctional isolated hybrid compounds, [ε-PMo^V₈Mo^VI₄O₃₇(OH)₃Zn₄][iql]₄·6H₂O (1) and [ε-PMo^V₈Mo^VI₄O₃₈(OH)₂Zn₄][bipy]₃[(CH₃COO)(bipy)₂Zn]·2H₂O (2) (where iql = isoquinoline and bipy = 2,2′-bipyridine), based on Zn-ε-Keggin were successfully synthesized by self-assembly under hydrothermal conditions. It is interesting to note that acetate in 2 acted as a linker connecting the ε-Keggin anion with the one Zn atom (Zn5) and enabled the ε-Keggin anion to coordinate with more bipy ligands, culminating with a larger isolated system, which is the first reported isolated cluster of Zn₅PMo₁₂. Meanwhile, compounds 1–2 show great electrochemical behaviors and excellent electrocatalytic activity for the degradation of NaNO₂. In addition, compound 2 displays better third-order NLO performance than 1 due to the presence of more conjugated rings, with a TPA cross section (σ) of 1819 GM, which suggests that compound 2 has the potential to function as a bifunctional material with tremendous prospects.